/*******************************************************************************
 * Copyright (c) 2000, 2018 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.graphics;

import org.eclipse.swt.*;
import org.eclipse.swt.internal.*;
import org.eclipse.swt.internal.cairo.*;
import org.eclipse.swt.internal.gtk.*;
import org.eclipse.swt.widgets.*;

/**
 * Class <code>GC</code> is where all of the drawing capabilities that are
 * supported by SWT are located. Instances are used to draw on either an
 * <code>Image</code>, a <code>Control</code>, or directly on a <code>Display</code>.
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>LEFT_TO_RIGHT, RIGHT_TO_LEFT</dd>
 * </dl>
 *
 * <p>
 * The SWT drawing coordinate system is the two-dimensional space with the origin
 * (0,0) at the top left corner of the drawing area and with (x,y) values increasing
 * to the right and downward respectively.
 * </p>
 *
 * <p>
 * The result of drawing on an image that was created with an indexed
 * palette using a color that is not in the palette is platform specific.
 * Some platforms will match to the nearest color while other will draw
 * the color itself. This happens because the allocated image might use
 * a direct palette on platforms that do not support indexed palette.
 * </p>
 *
 * <p>
 * Application code must explicitly invoke the <code>GC.dispose()</code>
 * method to release the operating system resources managed by each instance
 * when those instances are no longer required. This is <em>particularly</em>
 * important on Windows95 and Windows98 where the operating system has a limited
 * number of device contexts available.
 * </p>
 *
 * <p>
 * Note: Only one of LEFT_TO_RIGHT and RIGHT_TO_LEFT may be specified.
 * </p>
 *
 * @see org.eclipse.swt.events.PaintEvent
 * @see <a href="http://www.eclipse.org/swt/snippets/#gc">GC snippets</a>
 * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Examples: GraphicsExample, PaintExample</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 */
public final class GC extends Resource {
	/**
	 * the handle to the OS device context
	 * (Warning: This field is platform dependent)
	 * <p>
	 * <b>IMPORTANT:</b> This field is <em>not</em> part of the SWT
	 * public API. It is marked public only so that it can be shared
	 * within the packages provided by SWT. It is not available on all
	 * platforms and should never be accessed from application code.
	 * </p>
	 *
	 * @noreference This field is not intended to be referenced by clients.
	 */
	public long /*int*/ handle;

	Drawable drawable;
	GCData data;

	/**
	 * The current Cairo matrix, which positions widgets in the shell.
	 * Client transformations come on top of this matrix.
	 */
	private double[] cairoTransformationMatrix;

	/**
	 * Tracks the last transformation with which {@link #setTransform(Transform)} was called,
	 * so that we can answer clients of {@link #getTransform(Transform)}.
	 */
	private double[] currentTransform;

	/**
	 * Original clipping set on this GC
	 */
	private Rectangle clipping;

	final static int FOREGROUND = 1 << 0;
	final static int BACKGROUND = 1 << 1;
	final static int FONT = 1 << 2;
	final static int LINE_STYLE = 1 << 3;
	final static int LINE_CAP = 1 << 4;
	final static int LINE_JOIN = 1 << 5;
	final static int LINE_WIDTH = 1 << 6;
	final static int LINE_MITERLIMIT = 1 << 7;
	final static int BACKGROUND_BG = 1 << 8;
	final static int DRAW_OFFSET = 1 << 9;
	final static int DRAW = FOREGROUND | LINE_WIDTH | LINE_STYLE  | LINE_CAP  | LINE_JOIN | LINE_MITERLIMIT | DRAW_OFFSET;
	final static int FILL = BACKGROUND;

	static final float[] LINE_DOT = new float[]{1, 1};
	static final float[] LINE_DASH = new float[]{3, 1};
	static final float[] LINE_DASHDOT = new float[]{3, 1, 1, 1};
	static final float[] LINE_DASHDOTDOT = new float[]{3, 1, 1, 1, 1, 1};
	static final float[] LINE_DOT_ZERO = new float[]{3, 3};
	static final float[] LINE_DASH_ZERO = new float[]{18, 6};
	static final float[] LINE_DASHDOT_ZERO = new float[]{9, 6, 3, 6};
	static final float[] LINE_DASHDOTDOT_ZERO = new float[]{9, 3, 3, 3, 3, 3};

GC() {
}

/**
 * Constructs a new instance of this class which has been
 * configured to draw on the specified drawable. Sets the
 * foreground color, background color and font in the GC
 * to match those in the drawable.
 * <p>
 * You must dispose the graphics context when it is no longer required.
 * </p>
 * @param drawable the drawable to draw on
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the drawable is null</li>
 *    <li>ERROR_NULL_ARGUMENT - if there is no current device</li>
 *    <li>ERROR_INVALID_ARGUMENT
 *          - if the drawable is an image that is not a bitmap or an icon
 *          - if the drawable is an image or printer that is already selected
 *            into another graphics context</li>
 * </ul>
 * @exception SWTError <ul>
 *    <li>ERROR_NO_HANDLES if a handle could not be obtained for GC creation</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS if not called from the thread that created the drawable</li>
 * </ul>
 * @see #dispose()
 */
public GC(Drawable drawable) {
	this(drawable, 0);
}

/**
 * Constructs a new instance of this class which has been
 * configured to draw on the specified drawable. Sets the
 * foreground color, background color and font in the GC
 * to match those in the drawable.
 * <p>
 * You must dispose the graphics context when it is no longer required.
 * </p>
 *
 * @param drawable the drawable to draw on
 * @param style the style of GC to construct
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the drawable is null</li>
 *    <li>ERROR_NULL_ARGUMENT - if there is no current device</li>
 *    <li>ERROR_INVALID_ARGUMENT
 *          - if the drawable is an image that is not a bitmap or an icon
 *          - if the drawable is an image or printer that is already selected
 *            into another graphics context</li>
 * </ul>
 * @exception SWTError <ul>
 *    <li>ERROR_NO_HANDLES if a handle could not be obtained for GC creation</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS if not called from the thread that created the drawable</li>
 * </ul>
 *
 * @see #dispose()
 *
 * @since 2.1.2
 */
public GC(Drawable drawable, int style) {
	if (drawable == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	GCData data = new GCData();
	data.style = checkStyle(style);
	long /*int*/ gdkGC = drawable.internal_new_GC(data);
	Device device = data.device;
	if (device == null) device = Device.getDevice();
	if (device == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	this.device = data.device = device;
	init(drawable, data, gdkGC);
	init();
}

static void addCairoString(long /*int*/ cairo, String string, float x, float y, Font font) {
	byte[] buffer = Converter.wcsToMbcs(string, true);
	long /*int*/ layout = OS.pango_cairo_create_layout(cairo);
	if (layout == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	OS.pango_layout_set_text(layout, buffer, -1);
	OS.pango_layout_set_font_description(layout, font.handle);
	double[] currentX = new double[1], currentY = new double[1];
	Cairo.cairo_get_current_point(cairo, currentX, currentY);
	if (currentX[0] != x || currentY[0] != y) {
		Cairo.cairo_move_to(cairo, x, y);
	}
	OS.pango_cairo_layout_path(cairo, layout);
	OS.g_object_unref(layout);
}

static int checkStyle (int style) {
	if ((style & SWT.LEFT_TO_RIGHT) != 0) style &= ~SWT.RIGHT_TO_LEFT;
	return style & (SWT.LEFT_TO_RIGHT | SWT.RIGHT_TO_LEFT);
}

/**
 * Convenience method that applies a region to the Control using cairo_clip.
 *
 * @param cairo the cairo context to apply the region to
 */
void cairoClipRegion (long /*int*/ cairo) {
	if (cairo == 0) return;
	GdkRectangle rect = new GdkRectangle ();
	GDK.gdk_cairo_get_clip_rectangle (cairo, rect);
	long /*int*/ regionHandle = data.regionSet;
	long /*int*/ actualRegion = GDK.gdk_region_rectangle(rect);
	GDK.gdk_region_subtract(actualRegion, regionHandle);
	GDK.gdk_cairo_region(cairo, actualRegion);
	Cairo.cairo_clip(cairo);
	Cairo.cairo_paint(cairo);
}

/**
 * Invokes platform specific functionality to wrap a graphics context.
 * <p>
 * <b>IMPORTANT:</b> This method is <em>not</em> part of the public
 * API for <code>GC</code>. It is marked public only so that it
 * can be shared within the packages provided by SWT. It is not
 * available on all platforms, and should never be called from
 * application code.
 * </p>
 *
 * @param handle the handle to the OS device context
 * @param data the data for the receiver.
 *
 * @return a new <code>GC</code>
 *
 * @noreference This method is not intended to be referenced by clients.
 */
public static GC gtk_new(long /*int*/ handle, GCData data) {
	GC gc = new GC();
	gc.device = data.device;
	gc.init(null, data, handle);
	return gc;
}

/**
 * Invokes platform specific functionality to allocate a new graphics context.
 * <p>
 * <b>IMPORTANT:</b> This method is <em>not</em> part of the public
 * API for <code>GC</code>. It is marked public only so that it
 * can be shared within the packages provided by SWT. It is not
 * available on all platforms, and should never be called from
 * application code.
 * </p>
 *
 * @param drawable the Drawable for the receiver.
 * @param data the data for the receiver.
 *
 * @return a new <code>GC</code>
 *
 * @noreference This method is not intended to be referenced by clients.
 */
public static GC gtk_new(Drawable drawable, GCData data) {
	GC gc = new GC();
	long /*int*/ gdkGC = drawable.internal_new_GC(data);
	gc.device = data.device;
	gc.init(drawable, data, gdkGC);
	return gc;
}

void checkGC (int mask) {
	int state = data.state;
	if ((state & mask) == mask) return;
	state = (state ^ mask) & mask;
	data.state |= mask;
	long /*int*/ cairo = data.cairo;
	if ((state & (BACKGROUND | FOREGROUND)) != 0) {
		GdkColor color = null;
		GdkRGBA colorRGBA = null;
		Pattern pattern;
		if ((state & FOREGROUND) != 0) {
			if (GTK.GTK3) {
				colorRGBA = data.foregroundRGBA;
			} else {
				color = data.foreground;
			}
			pattern = data.foregroundPattern;
			data.state &= ~BACKGROUND;
		} else {
			if (GTK.GTK3) {
				colorRGBA = data.backgroundRGBA;
			} else {
				color = data.background;
			}
			pattern = data.backgroundPattern;
			data.state &= ~FOREGROUND;
		}
		if  (pattern != null) {
			if ((data.style & SWT.MIRRORED) != 0 && pattern.surface != 0) {
				long /*int*/ newPattern = Cairo.cairo_pattern_create_for_surface(pattern.surface);
				if (newPattern == 0) SWT.error(SWT.ERROR_NO_HANDLES);
				Cairo.cairo_pattern_set_extend(newPattern, Cairo.CAIRO_EXTEND_REPEAT);
				double[] matrix = {-1, 0, 0, 1, 0, 0};
				Cairo.cairo_pattern_set_matrix(newPattern, matrix);
				Cairo.cairo_set_source(cairo, newPattern);
				Cairo.cairo_pattern_destroy(newPattern);
			} else {
				Cairo.cairo_set_source(cairo, pattern.handle);
			}
		} else {
			if (GTK.GTK3) {
				Cairo.cairo_set_source_rgba(cairo, colorRGBA.red, colorRGBA.green, colorRGBA.blue, data.alpha / (float)0xFF);
			} else {
				Cairo.cairo_set_source_rgba(cairo, (color.red & 0xFFFF) / (float)0xFFFF, (color.green & 0xFFFF) / (float)0xFFFF, (color.blue & 0xFFFF) / (float)0xFFFF, data.alpha / (float)0xFF);
			}
		}
	}
	if ((state & FONT) != 0) {
		if (data.layout != 0) {
			Font font = data.font;
			OS.pango_layout_set_font_description(data.layout, font.handle);
		}
	}
	if ((state & LINE_CAP) != 0) {
		int cap_style = 0;
		switch (data.lineCap) {
			case SWT.CAP_ROUND: cap_style = Cairo.CAIRO_LINE_CAP_ROUND; break;
			case SWT.CAP_FLAT: cap_style = Cairo.CAIRO_LINE_CAP_BUTT; break;
			case SWT.CAP_SQUARE: cap_style = Cairo.CAIRO_LINE_CAP_SQUARE; break;
		}
		Cairo.cairo_set_line_cap(cairo, cap_style);
	}
	if ((state & LINE_JOIN) != 0) {
		int join_style = 0;
		switch (data.lineJoin) {
			case SWT.JOIN_MITER: join_style = Cairo.CAIRO_LINE_JOIN_MITER; break;
			case SWT.JOIN_ROUND:  join_style = Cairo.CAIRO_LINE_JOIN_ROUND; break;
			case SWT.JOIN_BEVEL: join_style = Cairo.CAIRO_LINE_JOIN_BEVEL; break;
		}
		Cairo.cairo_set_line_join(cairo, join_style);
	}
	if ((state & LINE_WIDTH) != 0) {
		Cairo.cairo_set_line_width(cairo, data.lineWidth == 0 ? DPIUtil.autoScaleUp(drawable, 1) : data.lineWidth);
		switch (data.lineStyle) {
			case SWT.LINE_DOT:
			case SWT.LINE_DASH:
			case SWT.LINE_DASHDOT:
			case SWT.LINE_DASHDOTDOT:
				state |= LINE_STYLE;
		}
	}
	if ((state & LINE_STYLE) != 0) {
		float dashesOffset = 0;
		float[] dashes = null;
		float width = data.lineWidth;
		switch (data.lineStyle) {
			case SWT.LINE_SOLID: break;
			case SWT.LINE_DASH: dashes = width != 0 ? LINE_DASH : LINE_DASH_ZERO; break;
			case SWT.LINE_DOT: dashes = width != 0 ? LINE_DOT : LINE_DOT_ZERO; break;
			case SWT.LINE_DASHDOT: dashes = width != 0 ? LINE_DASHDOT : LINE_DASHDOT_ZERO; break;
			case SWT.LINE_DASHDOTDOT: dashes = width != 0 ? LINE_DASHDOTDOT : LINE_DASHDOTDOT_ZERO; break;
			case SWT.LINE_CUSTOM: dashes = data.lineDashes; break;
		}
		if (dashes != null) {
			dashesOffset = data.lineDashesOffset;
			double[] cairoDashes = new double[dashes.length];
			for (int i = 0; i < cairoDashes.length; i++) {
				cairoDashes[i] = width == 0 || data.lineStyle == SWT.LINE_CUSTOM ? dashes[i] : dashes[i] * width;
			}
			Cairo.cairo_set_dash(cairo, cairoDashes, cairoDashes.length, dashesOffset);
		} else {
			Cairo.cairo_set_dash(cairo, null, 0, 0);
		}
	}
	if ((state & LINE_MITERLIMIT) != 0) {
		Cairo.cairo_set_miter_limit(cairo, data.lineMiterLimit);
	}
	if ((state & DRAW_OFFSET) != 0) {
		data.cairoXoffset = data.cairoYoffset = 0;
		double[] matrix = new double[6];
		Cairo.cairo_get_matrix(cairo, matrix);
		double[] dx = new double[]{1};
		double[] dy = new double[]{1};
		Cairo.cairo_user_to_device_distance(cairo, dx, dy);
		double scaling = dx[0];
		if (scaling < 0) scaling = -scaling;
		double strokeWidth = data.lineWidth * scaling;
		if (strokeWidth == 0 || ((int)strokeWidth % 2) == 1) {
			data.cairoXoffset = 0.5 / scaling;
		}
		scaling = dy[0];
		if (scaling < 0) scaling = -scaling;
		strokeWidth = data.lineWidth * scaling;
		if (strokeWidth == 0 || ((int)strokeWidth % 2) == 1) {
			data.cairoYoffset = 0.5 / scaling;
		}
	}
}

long /*int*/ convertRgn(long /*int*/ rgn, double[] matrix) {
	long /*int*/ newRgn = GDK.gdk_region_new();
	if (isIdentity(matrix)) {
		GDK.gdk_region_union(newRgn, rgn);
		return newRgn;
	}
	int[] nRects = new int[1];
	long /*int*/[] rects = new long /*int*/[1];
	Region.gdk_region_get_rectangles(rgn, rects, nRects);
	GdkRectangle rect = new GdkRectangle();
	int[] pointArray = new int[8];
	double[] x = new double[1], y = new double[1];
	for (int i=0; i<nRects[0]; i++) {
		OS.memmove(rect, rects[0] + (i * GdkRectangle.sizeof), GdkRectangle.sizeof);
		x[0] = rect.x;
		y[0] = rect.y;
		Cairo.cairo_matrix_transform_point(matrix, x, y);
		pointArray[0] = (int)x[0];
		pointArray[1] = (int)y[0];
		x[0] = rect.x + rect.width;
		y[0] = rect.y;
		Cairo.cairo_matrix_transform_point(matrix, x, y);
		pointArray[2] = (int)Math.round(x[0]);
		pointArray[3] = (int)y[0];
		x[0] = rect.x + rect.width;
		y[0] = rect.y + rect.height;
		Cairo.cairo_matrix_transform_point(matrix, x, y);
		pointArray[4] = (int)Math.round(x[0]);
		pointArray[5] = (int)Math.round(y[0]);
		x[0] = rect.x;
		y[0] = rect.y + rect.height;
		Cairo.cairo_matrix_transform_point(matrix, x, y);
		pointArray[6] = (int)x[0];
		pointArray[7] = (int)Math.round(y[0]);
		long /*int*/ polyRgn = Region.gdk_region_polygon(pointArray, pointArray.length / 2, GDK.GDK_EVEN_ODD_RULE);
		GDK.gdk_region_union(newRgn, polyRgn);
		GDK.gdk_region_destroy(polyRgn);
	}
	if (rects[0] != 0) OS.g_free(rects[0]);
	return newRgn;
}

/**
 * Copies a rectangular area of the receiver at the specified
 * position into the image, which must be of type <code>SWT.BITMAP</code>.
 *
 * @param image the image to copy into
 * @param x the x coordinate in the receiver of the area to be copied
 * @param y the y coordinate in the receiver of the area to be copied
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the image is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the image is not a bitmap or has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void copyArea(Image image, int x, int y) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (image == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (image.type != SWT.BITMAP || image.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	Point loc = DPIUtil.autoScaleUp(drawable, new Point(x, y));
	copyAreaInPixels(image, loc.x, loc.y);
}
void copyAreaInPixels(Image image, int x, int y) {
	long /*int*/ cairo = Cairo.cairo_create(image.surface);
	if (cairo == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	Cairo.cairo_translate(cairo, -x, -y);
	Cairo.cairo_push_group(cairo);
	if (data.image != null) {
		Cairo.cairo_set_source_surface(cairo, data.image.surface, 0, 0);
	} else if (data.drawable != 0) {
		GDK.gdk_cairo_set_source_window(cairo, data.drawable, 0, 0);
	} else {
		Cairo.cairo_destroy(cairo);
		return;
	}
	Cairo.cairo_set_operator(cairo, Cairo.CAIRO_OPERATOR_SOURCE);
	Cairo.cairo_paint(cairo);
	Cairo.cairo_pop_group_to_source(cairo);
	Cairo.cairo_paint(cairo);
	Cairo.cairo_destroy(cairo);
}

/**
 * Copies a rectangular area of the receiver at the source
 * position onto the receiver at the destination position.
 *
 * @param srcX the x coordinate in the receiver of the area to be copied
 * @param srcY the y coordinate in the receiver of the area to be copied
 * @param width the width of the area to copy
 * @param height the height of the area to copy
 * @param destX the x coordinate in the receiver of the area to copy to
 * @param destY the y coordinate in the receiver of the area to copy to
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void copyArea(int srcX, int srcY, int width, int height, int destX, int destY) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	Rectangle src = DPIUtil.autoScaleUp(drawable, new Rectangle(srcX, srcY, width, height));
	Point dest = DPIUtil.autoScaleUp(drawable, new Point(destX, destY));
	copyAreaInPixels(src.x, src.y, src.width, src.height, dest.x, dest.y);
}

void copyAreaInPixels(int srcX, int srcY, int width, int height, int destX, int destY) {
	copyAreaInPixels(srcX, srcY, width, height, destX, destY, true);
}
/**
 * Copies a rectangular area of the receiver at the source
 * position onto the receiver at the destination position.
 *
 * @param srcX the x coordinate in the receiver of the area to be copied
 * @param srcY the y coordinate in the receiver of the area to be copied
 * @param width the width of the area to copy
 * @param height the height of the area to copy
 * @param destX the x coordinate in the receiver of the area to copy to
 * @param destY the y coordinate in the receiver of the area to copy to
 * @param paint if <code>true</code> paint events will be generated for old and obscured areas
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.1
 */
public void copyArea(int srcX, int srcY, int width, int height, int destX, int destY, boolean paint) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	Rectangle srcLoc = DPIUtil.autoScaleUp(drawable, new Rectangle(srcX, srcY, width, height));
	Point destLoc = DPIUtil.autoScaleUp(drawable, new Point(destX, destY));
	copyAreaInPixels(srcLoc.x, srcLoc.y, srcLoc.width, srcLoc.height, destLoc.x, destLoc.y, paint);
}
void copyAreaInPixels(int srcX, int srcY, int width, int height, int destX, int destY, boolean paint) {
	if (width <= 0 || height <= 0) return;
	int deltaX = destX - srcX, deltaY = destY - srcY;
	if (deltaX == 0 && deltaY == 0) return;
	long /*int*/ drawable = data.drawable;
	if (data.image != null) {
		Cairo.cairo_set_source_surface(handle, data.image.surface, deltaX, deltaY);
		Cairo.cairo_rectangle(handle, destX, destY, width, height);
		Cairo.cairo_set_operator(handle, Cairo.CAIRO_OPERATOR_SOURCE);
		Cairo.cairo_fill(handle);
	} else if (drawable != 0) {
		Cairo.cairo_save(handle);
		Cairo.cairo_rectangle(handle, destX, destY, width, height);
		Cairo.cairo_clip(handle);
		Cairo.cairo_translate(handle, deltaX, deltaY);
		Cairo.cairo_set_operator(handle, Cairo.CAIRO_OPERATOR_SOURCE);
		Cairo.cairo_push_group(handle);
		GDK.gdk_cairo_set_source_window(handle, drawable, 0, 0);
		Cairo.cairo_paint(handle);
		Cairo.cairo_pop_group_to_source(handle);
		Cairo.cairo_rectangle(handle, destX - deltaX, destY - deltaY, width, height);
		Cairo.cairo_clip(handle);
		Cairo.cairo_paint(handle);
		Cairo.cairo_restore(handle);
		if (paint) {
			long /*int*/ visibleRegion;
			if (GTK.GTK3) {
				visibleRegion = GDK.gdk_window_get_visible_region (drawable);
			} else {
				visibleRegion = GDK.gdk_drawable_get_visible_region (drawable);
			}
			GdkRectangle srcRect = new GdkRectangle ();
			srcRect.x = srcX;
			srcRect.y = srcY;
			srcRect.width = width;
			srcRect.height = height;
			long /*int*/ copyRegion = GDK.gdk_region_rectangle (srcRect);
			GDK.gdk_region_intersect(copyRegion, visibleRegion);
			long /*int*/ invalidateRegion = GDK.gdk_region_rectangle (srcRect);
			GDK.gdk_region_subtract (invalidateRegion, visibleRegion);
			GDK.gdk_region_offset (invalidateRegion, deltaX, deltaY);
			GDK.gdk_window_invalidate_region(drawable, invalidateRegion, false);
			GDK.gdk_region_destroy (visibleRegion);
			GDK.gdk_region_destroy (copyRegion);
			GDK.gdk_region_destroy (invalidateRegion);
		}
	}
	if (data.image == null & paint) {
		boolean disjoint = (destX + width < srcX) || (srcX + width < destX) || (destY + height < srcY) || (srcY + height < destY);
		GdkRectangle rect = new GdkRectangle ();
		if (disjoint) {
			rect.x = srcX;
			rect.y = srcY;
			rect.width = Math.max (0, width);
			rect.height = Math.max (0, height);
			GDK.gdk_window_invalidate_rect (drawable, rect, false);
//			OS.gdk_window_clear_area_e(drawable, srcX, srcY, width, height);
		} else {
			if (deltaX != 0) {
				int newX = destX - deltaX;
				if (deltaX < 0) newX = destX + width;
				rect.x = newX;
				rect.y = srcY;
				rect.width = Math.abs(deltaX);
				rect.height = Math.max (0, height);
				GDK.gdk_window_invalidate_rect (drawable, rect, false);
//				OS.gdk_window_clear_area_e(drawable, newX, srcY, Math.abs(deltaX), height);
			}
			if (deltaY != 0) {
				int newY = destY - deltaY;
				if (deltaY < 0) newY = destY + height;
				rect.x = srcX;
				rect.y = newY;
				rect.width = Math.max (0, width);
				rect.height = Math.abs(deltaY);
				GDK.gdk_window_invalidate_rect (drawable, rect, false);
//				OS.gdk_window_clear_area_e(drawable, srcX, newY, width, Math.abs(deltaY));
			}
		}
	}
}

void createLayout() {
	long /*int*/ context = GDK.gdk_pango_context_get();
	if (context == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	data.context = context;
	long /*int*/ layout = OS.pango_layout_new(context);
	if (layout == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	data.layout = layout;
	OS.pango_context_set_language(context, GTK.gtk_get_default_language());
	OS.pango_context_set_base_dir(context, (data.style & SWT.MIRRORED) != 0 ? OS.PANGO_DIRECTION_RTL : OS.PANGO_DIRECTION_LTR);
	OS.pango_layout_set_auto_dir(layout, false);
}

void disposeLayout() {
	data.string = null;
	if (data.context != 0) OS.g_object_unref(data.context);
	if (data.layout != 0) OS.g_object_unref(data.layout);
	data.layout = data.context = 0;
}

@Override
void destroy() {
	if (data.disposeCairo) {
		long /*int*/ cairo = data.cairo;
		Cairo.cairo_destroy(cairo);
	}
	data.cairo = 0;

	/* Free resources */
	long /*int*/ clipRgn = data.clipRgn;
	if (clipRgn != 0) GDK.gdk_region_destroy(clipRgn);
	Image image = data.image;
	if (image != null) {
		image.memGC = null;
		if (image.transparentPixel != -1) image.createMask();
	}

	disposeLayout();

	/* Dispose the GC */
	if (drawable != null) {
		drawable.internal_dispose_GC(handle, data);
	}
	data.drawable = data.clipRgn = 0;
	drawable = null;
	handle = 0;
	data.image = null;
	data.string = null;
	data = null;
}

/**
 * Draws the outline of a circular or elliptical arc
 * within the specified rectangular area.
 * <p>
 * The resulting arc begins at <code>startAngle</code> and extends
 * for <code>arcAngle</code> degrees, using the current color.
 * Angles are interpreted such that 0 degrees is at the 3 o'clock
 * position. A positive value indicates a counter-clockwise rotation
 * while a negative value indicates a clockwise rotation.
 * </p><p>
 * The center of the arc is the center of the rectangle whose origin
 * is (<code>x</code>, <code>y</code>) and whose size is specified by the
 * <code>width</code> and <code>height</code> arguments.
 * </p><p>
 * The resulting arc covers an area <code>width + 1</code> pixels wide
 * by <code>height + 1</code> pixels tall.
 * </p>
 *
 * @param x the x coordinate of the upper-left corner of the arc to be drawn
 * @param y the y coordinate of the upper-left corner of the arc to be drawn
 * @param width the width of the arc to be drawn
 * @param height the height of the arc to be drawn
 * @param startAngle the beginning angle
 * @param arcAngle the angular extent of the arc, relative to the start angle
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void drawArc(int x, int y, int width, int height, int startAngle, int arcAngle) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	Rectangle loc = DPIUtil.autoScaleUp(drawable, new Rectangle(x, y, width, height));
	drawArcInPixels(loc.x, loc.y, loc.width, loc.height, startAngle, arcAngle);
}
void drawArcInPixels(int x, int y, int width, int height, int startAngle, int arcAngle) {
	checkGC(DRAW);
	if (width < 0) {
		x = x + width;
		width = -width;
	}
	if (height < 0) {
		y = y + height;
		height = -height;
	}
	if (width == 0 || height == 0 || arcAngle == 0) return;
	long /*int*/ cairo = data.cairo;
	double xOffset = data.cairoXoffset, yOffset = data.cairoYoffset;
	if (width == height) {
        if (arcAngle >= 0) {
            Cairo.cairo_arc_negative(cairo, x + xOffset + width / 2f, y + yOffset + height / 2f, width / 2f, -startAngle * (float)Math.PI / 180, -(startAngle + arcAngle) * (float)Math.PI / 180);
        } else {
            Cairo.cairo_arc(cairo, x + xOffset + width / 2f, y + yOffset + height / 2f, width / 2f, -startAngle * (float)Math.PI / 180, -(startAngle + arcAngle) * (float)Math.PI / 180);
        }
	} else {
		Cairo.cairo_save(cairo);
		Cairo.cairo_translate(cairo, x + xOffset + width / 2f, y + yOffset + height / 2f);
		Cairo.cairo_scale(cairo, width / 2f, height / 2f);
        if (arcAngle >= 0) {
            Cairo.cairo_arc_negative(cairo, 0, 0, 1, -startAngle * (float)Math.PI / 180, -(startAngle + arcAngle) * (float)Math.PI / 180);
        } else {
            Cairo.cairo_arc(cairo, 0, 0, 1, -startAngle * (float)Math.PI / 180, -(startAngle + arcAngle) * (float)Math.PI / 180);
        }
		Cairo.cairo_restore(cairo);
	}
	Cairo.cairo_stroke(cairo);
}

/**
 * Draws a rectangle, based on the specified arguments, which has
 * the appearance of the platform's <em>focus rectangle</em> if the
 * platform supports such a notion, and otherwise draws a simple
 * rectangle in the receiver's foreground color.
 *
 * @param x the x coordinate of the rectangle
 * @param y the y coordinate of the rectangle
 * @param width the width of the rectangle
 * @param height the height of the rectangle
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #drawRectangle(int, int, int, int)
 */
public void drawFocus(int x, int y, int width, int height) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	Rectangle loc = DPIUtil.autoScaleUp(drawable, new Rectangle(x, y, width, height));
	drawFocusInPixels(loc.x, loc.y, loc.width, loc.height);
}
void drawFocusInPixels(int x, int y, int width, int height) {
	long /*int*/ cairo = data.cairo;
	checkGC(FOREGROUND);
	if (GTK.GTK3) {
		long /*int*/  context = GTK.gtk_widget_get_style_context(data.device.shellHandle);
		GTK.gtk_render_focus(context, cairo, x, y, width, height);
	} else {
		int[] lineWidth = new int[1];
		GTK.gtk_widget_style_get(data.device.shellHandle, OS.focus_line_width, lineWidth, 0);
		Cairo.cairo_save(cairo);
		Cairo.cairo_set_line_width(cairo, lineWidth[0]);
		double[] dashes = new double[]{1, 1};
		double dash_offset = -lineWidth[0] / 2f;
		while (dash_offset < 0) dash_offset += 2;
		Cairo.cairo_set_dash(cairo, dashes, dashes.length, dash_offset);
		Cairo.cairo_rectangle(cairo, x + lineWidth[0] / 2f, y + lineWidth[0] / 2f, width, height);
		Cairo.cairo_stroke(cairo);
		Cairo.cairo_restore(cairo);
	}
}

/**
 * Draws the given image in the receiver at the specified
 * coordinates.
 *
 * @param image the image to draw
 * @param x the x coordinate of where to draw
 * @param y the y coordinate of where to draw
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the image is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the image has been disposed</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the given coordinates are outside the bounds of the image</li>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 * @exception SWTError <ul>
 *    <li>ERROR_NO_HANDLES - if no handles are available to perform the operation</li>
 * </ul>
 */
public void drawImage(Image image, int x, int y) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (image == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (image.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	Point loc = DPIUtil.autoScaleUp(drawable, new Point(x, y));
	drawImageInPixels(image, loc.x, loc.y);
}
void drawImageInPixels(Image image, int x, int y) {
	drawImage(image, 0, 0, -1, -1, x, y, -1, -1, true);
}

/**
 * Copies a rectangular area from the source image into a (potentially
 * different sized) rectangular area in the receiver. If the source
 * and destination areas are of differing sizes, then the source
 * area will be stretched or shrunk to fit the destination area
 * as it is copied. The copy fails if any part of the source rectangle
 * lies outside the bounds of the source image, or if any of the width
 * or height arguments are negative.
 *
 * @param image the source image
 * @param srcX the x coordinate in the source image to copy from
 * @param srcY the y coordinate in the source image to copy from
 * @param srcWidth the width in points to copy from the source
 * @param srcHeight the height in points to copy from the source
 * @param destX the x coordinate in the destination to copy to
 * @param destY the y coordinate in the destination to copy to
 * @param destWidth the width in points of the destination rectangle
 * @param destHeight the height in points of the destination rectangle
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the image is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the image has been disposed</li>
 *    <li>ERROR_INVALID_ARGUMENT - if any of the width or height arguments are negative.
 *    <li>ERROR_INVALID_ARGUMENT - if the source rectangle is not contained within the bounds of the source image</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 * @exception SWTError <ul>
 *    <li>ERROR_NO_HANDLES - if no handles are available to perform the operation</li>
 * </ul>
 */
public void drawImage(Image image, int srcX, int srcY, int srcWidth, int srcHeight, int destX, int destY, int destWidth, int destHeight) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (srcWidth == 0 || srcHeight == 0 || destWidth == 0 || destHeight == 0) return;
	if (srcX < 0 || srcY < 0 || srcWidth < 0 || srcHeight < 0 || destWidth < 0 || destHeight < 0) {
		SWT.error (SWT.ERROR_INVALID_ARGUMENT);
	}
	if (image == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (image.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	Rectangle srcRect = DPIUtil.autoScaleUp(drawable, new Rectangle(srcX, srcY, srcWidth, srcHeight));
	Rectangle destRect = DPIUtil.autoScaleUp(drawable, new Rectangle(destX, destY, destWidth, destHeight));
	drawImage(image, srcRect.x, srcRect.y, srcRect.width, srcRect.height, destRect.x, destRect.y, destRect.width, destRect.height, false);
}
void drawImage(Image srcImage, int srcX, int srcY, int srcWidth, int srcHeight, int destX, int destY, int destWidth, int destHeight, boolean simple) {
	/* Refresh Image as per zoom level, if required. */
	srcImage.refreshImageForZoom ();

	int	imgWidth = srcImage.width;
	int	imgHeight = srcImage.height;
 	if (simple) {
 		srcWidth = destWidth = imgWidth;
 		srcHeight = destHeight = imgHeight;
 	} else {
 		simple = srcX == 0 && srcY == 0 &&
 			srcWidth == destWidth && destWidth == imgWidth &&
 			srcHeight == destHeight && destHeight == imgHeight;
		if (srcX + srcWidth > imgWidth + 1 || srcY + srcHeight > imgHeight + 1) { //rounding error correction for hidpi
			SWT.error(SWT.ERROR_INVALID_ARGUMENT);
		}
 	}
	long /*int*/ cairo = data.cairo;
	if (data.alpha != 0) {
		srcImage.createSurface();
		Cairo.cairo_save(cairo);
		if ((data.style & SWT.MIRRORED) != 0) {
			Cairo.cairo_scale(cairo, -1f,  1);
			Cairo.cairo_translate(cairo, - 2 * destX - destWidth, 0);
		}
		Cairo.cairo_rectangle(cairo, destX , destY, destWidth, destHeight);
		Cairo.cairo_clip(cairo);
		if (srcWidth != destWidth || srcHeight != destHeight) {
			float scaleX = destWidth / (float)srcWidth;
			float scaleY = destHeight / (float)srcHeight;
			Cairo.cairo_translate(cairo, destX - (int)(srcX * scaleX), destY - (int)(srcY * scaleY));
			Cairo.cairo_scale(cairo, scaleX, scaleY);
		} else {
			Cairo.cairo_translate(cairo, destX - srcX, destY - srcY);
		}
		int filter = Cairo.CAIRO_FILTER_GOOD;
		switch (data.interpolation) {
			case SWT.DEFAULT: filter = Cairo.CAIRO_FILTER_GOOD; break;
			case SWT.NONE: filter = Cairo.CAIRO_FILTER_NEAREST; break;
			case SWT.LOW: filter = Cairo.CAIRO_FILTER_FAST; break;
			case SWT.HIGH: filter = Cairo.CAIRO_FILTER_BEST; break;
		}
		long /*int*/ pattern = Cairo.cairo_pattern_create_for_surface(srcImage.surface);
		if (pattern == 0) SWT.error(SWT.ERROR_NO_HANDLES);
		if (srcWidth != destWidth || srcHeight != destHeight) {
			Cairo.cairo_pattern_set_extend(pattern, Cairo.CAIRO_EXTEND_PAD);
		}
		Cairo.cairo_pattern_set_filter(pattern, filter);
		Cairo.cairo_set_source(cairo, pattern);
		if (data.alpha != 0xFF) {
			Cairo.cairo_paint_with_alpha(cairo, data.alpha / (float)0xFF);
		} else {
			Cairo.cairo_paint(cairo);
		}
		Cairo.cairo_restore(cairo);
		Cairo.cairo_pattern_destroy(pattern);
	}
}

/**
 * Draws a line, using the foreground color, between the points
 * (<code>x1</code>, <code>y1</code>) and (<code>x2</code>, <code>y2</code>).
 *
 * @param x1 the first point's x coordinate
 * @param y1 the first point's y coordinate
 * @param x2 the second point's x coordinate
 * @param y2 the second point's y coordinate
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void drawLine(int x1, int y1, int x2, int y2) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	Point loc1 = DPIUtil.autoScaleUp(drawable, new Point(x1, y1));
	Point loc2 = DPIUtil.autoScaleUp(drawable, new Point(x2, y2));
	drawLineInPixels(loc1.x, loc1.y, loc2.x, loc2.y);
}
void drawLineInPixels(int x1, int y1, int x2, int y2) {
	checkGC(DRAW);
	long /*int*/ cairo = data.cairo;
	double xOffset = data.cairoXoffset, yOffset = data.cairoYoffset;
	if (Cairo.cairo_version() >= Cairo.CAIRO_VERSION_ENCODE(1, 12, 0)) {
		Cairo.cairo_set_antialias(cairo, Cairo.CAIRO_ANTIALIAS_BEST);
	}
	Cairo.cairo_move_to(cairo, x1 + xOffset, y1 + yOffset);
	Cairo.cairo_line_to(cairo, x2 + xOffset, y2 + yOffset);
	Cairo.cairo_stroke(cairo);
}

/**
 * Draws the outline of an oval, using the foreground color,
 * within the specified rectangular area.
 * <p>
 * The result is a circle or ellipse that fits within the
 * rectangle specified by the <code>x</code>, <code>y</code>,
 * <code>width</code>, and <code>height</code> arguments.
 * </p><p>
 * The oval covers an area that is <code>width + 1</code>
 * pixels wide and <code>height + 1</code> pixels tall.
 * </p>
 *
 * @param x the x coordinate of the upper left corner of the oval to be drawn
 * @param y the y coordinate of the upper left corner of the oval to be drawn
 * @param width the width of the oval to be drawn
 * @param height the height of the oval to be drawn
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void drawOval(int x, int y, int width, int height) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	Rectangle rect = DPIUtil.autoScaleUp(drawable, new Rectangle(x, y, width, height));
	drawOvalInPixels(rect.x, rect.y, rect.width, rect.height);
}
void drawOvalInPixels(int x, int y, int width, int height) {
	checkGC(DRAW);
	if (width < 0) {
		x = x + width;
		width = -width;
	}
	if (height < 0) {
		y = y + height;
		height = -height;
	}
	long /*int*/ cairo = data.cairo;
	double xOffset = data.cairoXoffset, yOffset = data.cairoYoffset;
	if (width == height) {
		Cairo.cairo_arc_negative(cairo, x + xOffset + width / 2f, y + yOffset + height / 2f, width / 2f, 0, -2 * (float)Math.PI);
	} else {
		Cairo.cairo_save(cairo);
		Cairo.cairo_translate(cairo, x + xOffset + width / 2f, y + yOffset + height / 2f);
		Cairo.cairo_scale(cairo, width / 2f, height / 2f);
		Cairo.cairo_arc_negative(cairo, 0, 0, 1, 0, -2 * (float)Math.PI);
		Cairo.cairo_restore(cairo);
	}
	Cairo.cairo_stroke(cairo);
}

/**
 * Draws the path described by the parameter.
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 *
 * @param path the path to draw
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parameter is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the parameter has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 *
 * @see Path
 *
 * @since 3.1
 */
public void drawPath(Path path) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (path == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (path.handle == 0) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	initCairo();
	checkGC(DRAW);
	long /*int*/ cairo = data.cairo;
	Cairo.cairo_save(cairo);
	double xOffset = data.cairoXoffset, yOffset = data.cairoYoffset;
	Cairo.cairo_translate(cairo, xOffset, yOffset);
	long /*int*/ copy = Cairo.cairo_copy_path(path.handle);
	if (copy == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	Cairo.cairo_append_path(cairo, copy);
	Cairo.cairo_path_destroy(copy);
	Cairo.cairo_stroke(cairo);
	Cairo.cairo_restore(cairo);
}

/**
 * Draws a pixel, using the foreground color, at the specified
 * point (<code>x</code>, <code>y</code>).
 * <p>
 * Note that the receiver's line attributes do not affect this
 * operation.
 * </p>
 *
 * @param x the point's x coordinate
 * @param y the point's y coordinate
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.0
 */
public void drawPoint (int x, int y) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	Point loc = DPIUtil.autoScaleUp(drawable, new Point(x, y));
	drawPointInPixels(loc.x, loc.y);
}
void drawPointInPixels (int x, int y) {
	checkGC(DRAW);
	long /*int*/ cairo = data.cairo;
	Cairo.cairo_rectangle(cairo, x, y, 1, 1);
	Cairo.cairo_fill(cairo);
}

/**
 * Draws the closed polygon which is defined by the specified array
 * of integer coordinates, using the receiver's foreground color. The array
 * contains alternating x and y values which are considered to represent
 * points which are the vertices of the polygon. Lines are drawn between
 * each consecutive pair, and between the first pair and last pair in the
 * array.
 *
 * @param pointArray an array of alternating x and y values which are the vertices of the polygon
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT if pointArray is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void drawPolygon(int[] pointArray) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (pointArray == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	int [] scaledPointArray = DPIUtil.autoScaleUp(drawable, pointArray);
	drawPolygonInPixels(scaledPointArray);
}
void drawPolygonInPixels(int[] pointArray) {
	checkGC(DRAW);
	long /*int*/ cairo = data.cairo;
	drawPolyline(cairo, pointArray, true);
	Cairo.cairo_stroke(cairo);
}

/**
 * Draws the polyline which is defined by the specified array
 * of integer coordinates, using the receiver's foreground color. The array
 * contains alternating x and y values which are considered to represent
 * points which are the corners of the polyline. Lines are drawn between
 * each consecutive pair, but not between the first pair and last pair in
 * the array.
 *
 * @param pointArray an array of alternating x and y values which are the corners of the polyline
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the point array is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void drawPolyline(int[] pointArray) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (pointArray == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	int [] scaledPointArray = DPIUtil.autoScaleUp(drawable, pointArray);
	drawPolylineInPixels(scaledPointArray);
}
void drawPolylineInPixels(int[] pointArray) {
	checkGC(DRAW);
	long /*int*/ cairo = data.cairo;
	drawPolyline(cairo, pointArray, false);
	Cairo.cairo_stroke(cairo);
}

void drawPolyline(long /*int*/ cairo, int[] pointArray, boolean close) {
	int count = pointArray.length / 2;
	if (count == 0) return;
	double xOffset = data.cairoXoffset, yOffset = data.cairoYoffset;
	Cairo.cairo_move_to(cairo, pointArray[0] + xOffset, pointArray[1] + yOffset);
	for (int i = 1, j=2; i < count; i++, j += 2) {
		Cairo.cairo_line_to(cairo, pointArray[j] + xOffset, pointArray[j + 1] + yOffset);
	}
	if (close) Cairo.cairo_close_path(cairo);
}

/**
 * Draws the outline of the rectangle specified by the arguments,
 * using the receiver's foreground color. The left and right edges
 * of the rectangle are at <code>x</code> and <code>x + width</code>.
 * The top and bottom edges are at <code>y</code> and <code>y + height</code>.
 *
 * @param x the x coordinate of the rectangle to be drawn
 * @param y the y coordinate of the rectangle to be drawn
 * @param width the width of the rectangle to be drawn
 * @param height the height of the rectangle to be drawn
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void drawRectangle(int x, int y, int width, int height) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	drawRectangle(new Rectangle(x, y, width, height));
}
void drawRectangleInPixels(int x, int y, int width, int height) {
	checkGC(DRAW);
	if (width < 0) {
		x = x + width;
		width = -width;
	}
	if (height < 0) {
		y = y + height;
		height = -height;
	}
	long /*int*/ cairo = data.cairo;
	double xOffset = data.cairoXoffset, yOffset = data.cairoYoffset;
	Cairo.cairo_rectangle(cairo, x + xOffset, y + yOffset, width, height);
	Cairo.cairo_stroke(cairo);
}

/**
 * Draws the outline of the specified rectangle, using the receiver's
 * foreground color. The left and right edges of the rectangle are at
 * <code>rect.x</code> and <code>rect.x + rect.width</code>. The top
 * and bottom edges are at <code>rect.y</code> and
 * <code>rect.y + rect.height</code>.
 *
 * @param rect the rectangle to draw
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the rectangle is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void drawRectangle(Rectangle rect) {
	if (rect == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	drawRectangleInPixels(DPIUtil.autoScaleUp(drawable, rect));
}
void drawRectangleInPixels(Rectangle rect) {
	drawRectangleInPixels (rect.x, rect.y, rect.width, rect.height);
}
/**
 * Draws the outline of the round-cornered rectangle specified by
 * the arguments, using the receiver's foreground color. The left and
 * right edges of the rectangle are at <code>x</code> and <code>x + width</code>.
 * The top and bottom edges are at <code>y</code> and <code>y + height</code>.
 * The <em>roundness</em> of the corners is specified by the
 * <code>arcWidth</code> and <code>arcHeight</code> arguments, which
 * are respectively the width and height of the ellipse used to draw
 * the corners.
 *
 * @param x the x coordinate of the rectangle to be drawn
 * @param y the y coordinate of the rectangle to be drawn
 * @param width the width of the rectangle to be drawn
 * @param height the height of the rectangle to be drawn
 * @param arcWidth the width of the arc
 * @param arcHeight the height of the arc
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void drawRoundRectangle(int x, int y, int width, int height, int arcWidth, int arcHeight) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	Rectangle rect = DPIUtil.autoScaleUp(drawable, new Rectangle(x, y, width, height));
	Point arcSize = DPIUtil.autoScaleUp(drawable, new Point(arcWidth, arcHeight));
	drawRoundRectangleInPixels(rect.x, rect.y, rect.width, rect.height, arcSize.x, arcSize.y);
}
void drawRoundRectangleInPixels(int x, int y, int width, int height, int arcWidth, int arcHeight) {
	checkGC(DRAW);
	int nx = x;
	int ny = y;
	int nw = width;
	int nh = height;
	int naw = arcWidth;
	int nah = arcHeight;
	if (nw < 0) {
		nw = 0 - nw;
		nx = nx - nw;
	}
	if (nh < 0) {
		nh = 0 - nh;
		ny = ny -nh;
	}
	if (naw < 0) naw = 0 - naw;
	if (nah < 0) nah = 0 - nah;
	long /*int*/ cairo = data.cairo;
	double xOffset = data.cairoXoffset, yOffset = data.cairoYoffset;
	if (naw == 0 || nah == 0) {
		Cairo.cairo_rectangle(cairo, x + xOffset, y + yOffset, width, height);
	} else {
		float naw2 = naw / 2f;
		float nah2 = nah / 2f;
		float fw = nw / naw2;
		float fh = nh / nah2;
		Cairo.cairo_save(cairo);
		Cairo.cairo_translate(cairo, nx + xOffset, ny + yOffset);
		Cairo.cairo_scale(cairo, naw2, nah2);
		Cairo.cairo_move_to(cairo, fw - 1, 0);
	    Cairo.cairo_arc(cairo, fw - 1, 1, 1, Math.PI + Math.PI/2.0, Math.PI*2.0);
	    Cairo.cairo_arc(cairo, fw - 1, fh - 1, 1, 0, Math.PI/2.0);
	    Cairo.cairo_arc(cairo, 1, fh - 1, 1, Math.PI/2, Math.PI);
	    Cairo.cairo_arc(cairo, 1, 1, 1, Math.PI, 270.0*Math.PI/180.0);
		Cairo.cairo_close_path(cairo);
		Cairo.cairo_restore(cairo);
	}
	Cairo.cairo_stroke(cairo);
}

/**
 * Draws the given string, using the receiver's current font and
 * foreground color. No tab expansion or carriage return processing
 * will be performed. The background of the rectangular area where
 * the string is being drawn will be filled with the receiver's
 * background color.
 *
 * @param string the string to be drawn
 * @param x the x coordinate of the top left corner of the rectangular area where the string is to be drawn
 * @param y the y coordinate of the top left corner of the rectangular area where the string is to be drawn
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void drawString (String string, int x, int y) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (string == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	drawString (string, x, y, false);
}

void drawStringInPixels (String string, int x, int y) {
	drawStringInPixels(string, x, y, false);
}
/**
 * Draws the given string, using the receiver's current font and
 * foreground color. No tab expansion or carriage return processing
 * will be performed. If <code>isTransparent</code> is <code>true</code>,
 * then the background of the rectangular area where the string is being
 * drawn will not be modified, otherwise it will be filled with the
 * receiver's background color.
 *
 * @param string the string to be drawn
 * @param x the x coordinate of the top left corner of the rectangular area where the string is to be drawn
 * @param y the y coordinate of the top left corner of the rectangular area where the string is to be drawn
 * @param isTransparent if <code>true</code> the background will be transparent, otherwise it will be opaque
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void drawString(String string, int x, int y, boolean isTransparent) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (string == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	Point loc = DPIUtil.autoScaleUp(drawable, new Point(x, y));
	drawStringInPixels(string, loc.x, loc.y, isTransparent);
}

void drawStringInPixels(String string, int x, int y, boolean isTransparent) {
	drawTextInPixels(string, x, y, isTransparent ? SWT.DRAW_TRANSPARENT : 0);
}

/**
 * Draws the given string, using the receiver's current font and
 * foreground color. Tab expansion and carriage return processing
 * are performed. The background of the rectangular area where
 * the text is being drawn will be filled with the receiver's
 * background color.
 *
 * @param string the string to be drawn
 * @param x the x coordinate of the top left corner of the rectangular area where the text is to be drawn
 * @param y the y coordinate of the top left corner of the rectangular area where the text is to be drawn
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void drawText(String string, int x, int y) {
	drawText(string, x, y, SWT.DRAW_DELIMITER | SWT.DRAW_TAB);
}
void drawTextInPixels(String string, int x, int y) {
	drawTextInPixels(string, x, y, SWT.DRAW_DELIMITER | SWT.DRAW_TAB);
}

/**
 * Draws the given string, using the receiver's current font and
 * foreground color. Tab expansion and carriage return processing
 * are performed. If <code>isTransparent</code> is <code>true</code>,
 * then the background of the rectangular area where the text is being
 * drawn will not be modified, otherwise it will be filled with the
 * receiver's background color.
 *
 * @param string the string to be drawn
 * @param x the x coordinate of the top left corner of the rectangular area where the text is to be drawn
 * @param y the y coordinate of the top left corner of the rectangular area where the text is to be drawn
 * @param isTransparent if <code>true</code> the background will be transparent, otherwise it will be opaque
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void drawText(String string, int x, int y, boolean isTransparent) {
	Point loc = DPIUtil.autoScaleUp(drawable, new Point (x, y));
	drawTextInPixels(string, loc.x, loc.y, isTransparent);
}
void drawTextInPixels(String string, int x, int y, boolean isTransparent) {
	int flags = SWT.DRAW_DELIMITER | SWT.DRAW_TAB;
	if (isTransparent) flags |= SWT.DRAW_TRANSPARENT;
	drawTextInPixels(string, x, y, flags);
}

/**
 * Draws the given string, using the receiver's current font and
 * foreground color. Tab expansion, line delimiter and mnemonic
 * processing are performed according to the specified flags. If
 * <code>flags</code> includes <code>DRAW_TRANSPARENT</code>,
 * then the background of the rectangular area where the text is being
 * drawn will not be modified, otherwise it will be filled with the
 * receiver's background color.
 * <p>
 * The parameter <code>flags</code> may be a combination of:
 * <dl>
 * <dt><b>DRAW_DELIMITER</b></dt>
 * <dd>draw multiple lines</dd>
 * <dt><b>DRAW_TAB</b></dt>
 * <dd>expand tabs</dd>
 * <dt><b>DRAW_MNEMONIC</b></dt>
 * <dd>underline the mnemonic character</dd>
 * <dt><b>DRAW_TRANSPARENT</b></dt>
 * <dd>transparent background</dd>
 * </dl>
 * </p>
 *
 * @param string the string to be drawn
 * @param x the x coordinate of the top left corner of the rectangular area where the text is to be drawn
 * @param y the y coordinate of the top left corner of the rectangular area where the text is to be drawn
 * @param flags the flags specifying how to process the text
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void drawText (String string, int x, int y, int flags) {
	Point loc = DPIUtil.autoScaleUp(drawable, new Point (x, y));
	drawTextInPixels(string, loc.x, loc.y, flags);
}
void drawTextInPixels (String string, int x, int y, int flags) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (string == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (string.length() == 0) return;
	long /*int*/ cairo = data.cairo;
	setString(string, flags);
	checkGC(FONT);
	if ((flags & SWT.DRAW_TRANSPARENT) == 0) {
		checkGC(BACKGROUND);
		if (data.stringWidth == -1) {
			computeStringSize();
		}
		Cairo.cairo_rectangle(cairo, x, y, data.stringWidth, data.stringHeight);
		Cairo.cairo_fill(cairo);
	}
	checkGC(FOREGROUND);
	if ((data.style & SWT.MIRRORED) != 0) {
		Cairo.cairo_save(cairo);
		if (data.stringWidth == -1) {
			computeStringSize();
		}
		Cairo.cairo_scale(cairo, -1f,  1);
		Cairo.cairo_translate(cairo, -2 * x - data.stringWidth, 0);
	}
	Cairo.cairo_move_to(cairo, x, y);
	OS.pango_cairo_show_layout(cairo, data.layout);
	if ((data.style & SWT.MIRRORED) != 0) {
		Cairo.cairo_restore(cairo);
	}
	Cairo.cairo_new_path(cairo);
}

/**
 * Compares the argument to the receiver, and returns true
 * if they represent the <em>same</em> object using a class
 * specific comparison.
 *
 * @param object the object to compare with this object
 * @return <code>true</code> if the object is the same as this object and <code>false</code> otherwise
 *
 * @see #hashCode
 */
@Override
public boolean equals(Object object) {
	if (object == this) return true;
	if (!(object instanceof GC)) return false;
	return handle == ((GC)object).handle;
}

/**
 * Fills the interior of a circular or elliptical arc within
 * the specified rectangular area, with the receiver's background
 * color.
 * <p>
 * The resulting arc begins at <code>startAngle</code> and extends
 * for <code>arcAngle</code> degrees, using the current color.
 * Angles are interpreted such that 0 degrees is at the 3 o'clock
 * position. A positive value indicates a counter-clockwise rotation
 * while a negative value indicates a clockwise rotation.
 * </p><p>
 * The center of the arc is the center of the rectangle whose origin
 * is (<code>x</code>, <code>y</code>) and whose size is specified by the
 * <code>width</code> and <code>height</code> arguments.
 * </p><p>
 * The resulting arc covers an area <code>width + 1</code> pixels wide
 * by <code>height + 1</code> pixels tall.
 * </p>
 *
 * @param x the x coordinate of the upper-left corner of the arc to be filled
 * @param y the y coordinate of the upper-left corner of the arc to be filled
 * @param width the width of the arc to be filled
 * @param height the height of the arc to be filled
 * @param startAngle the beginning angle
 * @param arcAngle the angular extent of the arc, relative to the start angle
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #drawArc
 */
public void fillArc(int x, int y, int width, int height, int startAngle, int arcAngle) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	Rectangle rect = DPIUtil.autoScaleUp(drawable, new Rectangle(x, y, width, height));
	fillArcInPixels(rect.x, rect.y, rect.width, rect.height, startAngle, arcAngle);
}
void fillArcInPixels(int x, int y, int width, int height, int startAngle, int arcAngle) {
	checkGC(FILL);
	if (width < 0) {
		x = x + width;
		width = -width;
	}
	if (height < 0) {
		y = y + height;
		height = -height;
	}
	if (width == 0 || height == 0 || arcAngle == 0) return;
	long /*int*/ cairo = data.cairo;
	if (width == height) {
        if (arcAngle >= 0) {
        	Cairo.cairo_arc_negative(cairo, x + width / 2f, y + height / 2f, width / 2f, -startAngle * (float)Math.PI / 180,  -(startAngle + arcAngle) * (float)Math.PI / 180);
        } else {
        	Cairo.cairo_arc(cairo, x + width / 2f, y + height / 2f, width / 2f, -startAngle * (float)Math.PI / 180,  -(startAngle + arcAngle) * (float)Math.PI / 180);
        }
		Cairo.cairo_line_to(cairo, x + width / 2f, y + height / 2f);
	} else {
		Cairo.cairo_save(cairo);
		Cairo.cairo_translate(cairo, x + width / 2f, y + height / 2f);
		Cairo.cairo_scale(cairo, width / 2f, height / 2f);
		if (arcAngle >= 0) {
			Cairo.cairo_arc_negative(cairo, 0, 0, 1, -startAngle * (float)Math.PI / 180,  -(startAngle + arcAngle) * (float)Math.PI / 180);
		} else {
			Cairo.cairo_arc(cairo, 0, 0, 1, -startAngle * (float)Math.PI / 180,  -(startAngle + arcAngle) * (float)Math.PI / 180);
		}
		Cairo.cairo_line_to(cairo, 0, 0);
		Cairo.cairo_restore(cairo);
	}
	Cairo.cairo_fill(cairo);
}

/**
 * Fills the interior of the specified rectangle with a gradient
 * sweeping from left to right or top to bottom progressing
 * from the receiver's foreground color to its background color.
 *
 * @param x the x coordinate of the rectangle to be filled
 * @param y the y coordinate of the rectangle to be filled
 * @param width the width of the rectangle to be filled, may be negative
 *        (inverts direction of gradient if horizontal)
 * @param height the height of the rectangle to be filled, may be negative
 *        (inverts direction of gradient if vertical)
 * @param vertical if true sweeps from top to bottom, else
 *        sweeps from left to right
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #drawRectangle(int, int, int, int)
 */
public void fillGradientRectangle(int x, int y, int width, int height, boolean vertical) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	Rectangle rect = DPIUtil.autoScaleUp(drawable, new Rectangle(x, y, width, height));
	fillGradientRectangleInPixels(rect.x, rect.y, rect.width, rect.height, vertical);
}

void fillGradientRectangleInPixels(int x, int y, int width, int height, boolean vertical) {
	if ((width == 0) || (height == 0)) return;

	/* Rewrite this to use GdkPixbuf */

	RGB backgroundRGB, foregroundRGB;
	backgroundRGB = getBackground().getRGB();
	foregroundRGB = getForeground().getRGB();

	RGB fromRGB, toRGB;
	fromRGB = foregroundRGB;
	toRGB   = backgroundRGB;
	boolean swapColors = false;
	if (width < 0) {
		x += width; width = -width;
		if (! vertical) swapColors = true;
	}
	if (height < 0) {
		y += height; height = -height;
		if (vertical) swapColors = true;
	}
	if (swapColors) {
		fromRGB = backgroundRGB;
		toRGB   = foregroundRGB;
	}
	long /*int*/ cairo = data.cairo;
	long /*int*/ pattern;

	if (DPIUtil.useCairoAutoScale() ) {
		/*
		 * Here the co-ordinates passed are in points for GTK3.
		 * That means the user is expecting surface to be at
		 * device scale equal to current scale factor. So need
		 * to set the device scale to current scale factor
		 */
		long /*int*/ surface = Cairo.cairo_get_target(cairo);
		if ((GTK.GTK3)&&(surface != 0)) {
			float scaleFactor = DPIUtil.getDeviceZoom() / 100f;
			Cairo.cairo_surface_set_device_scale(surface, scaleFactor, scaleFactor);
		}
	}

	if (fromRGB.equals(toRGB)) {
		fillRectangleInPixels(x, y, width, height);
		return;
	}

	if (vertical) {
		pattern = Cairo.cairo_pattern_create_linear (0.0, 0.0, 0.0, 1.0);
	} else {
		pattern = Cairo.cairo_pattern_create_linear (0.0, 0.0, 1.0, 0.0);
	}
	Cairo.cairo_pattern_add_color_stop_rgba (pattern, 0, fromRGB.red / 255f, fromRGB.green / 255f, fromRGB.blue / 255f, data.alpha / 255f);
	Cairo.cairo_pattern_add_color_stop_rgba (pattern, 1, toRGB.red / 255f, toRGB.green / 255f, toRGB.blue / 255f, data.alpha / 255f);
	Cairo.cairo_save(cairo);
	Cairo.cairo_translate(cairo, x, y);
	Cairo.cairo_scale(cairo, width, height);
	Cairo.cairo_rectangle(cairo, 0, 0, 1, 1);
	Cairo.cairo_set_source(cairo, pattern);
	Cairo.cairo_fill(cairo);
	Cairo.cairo_restore(cairo);
	Cairo.cairo_pattern_destroy(pattern);
}

/**
 * Fills the interior of an oval, within the specified
 * rectangular area, with the receiver's background
 * color.
 *
 * @param x the x coordinate of the upper left corner of the oval to be filled
 * @param y the y coordinate of the upper left corner of the oval to be filled
 * @param width the width of the oval to be filled
 * @param height the height of the oval to be filled
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #drawOval
 */
public void fillOval(int x, int y, int width, int height) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	Rectangle rect = DPIUtil.autoScaleUp(drawable, new Rectangle(x, y, width, height));
	fillOvalInPixels(rect.x, rect.y, rect.width, rect.height);
}
void fillOvalInPixels(int x, int y, int width, int height) {
	checkGC(FILL);
	if (width < 0) {
		x = x + width;
		width = -width;
	}
	if (height < 0) {
		y = y + height;
		height = -height;
	}
	long /*int*/ cairo = data.cairo;
	if (width == height) {
		Cairo.cairo_arc_negative(cairo, x + width / 2f, y + height / 2f, width / 2f, 0, 2 * (float)Math.PI);
	} else {
		Cairo.cairo_save(cairo);
		Cairo.cairo_translate(cairo, x + width / 2f, y + height / 2f);
		Cairo.cairo_scale(cairo, width / 2f, height / 2f);
		Cairo.cairo_arc_negative(cairo, 0, 0, 1, 0, 2 * (float)Math.PI);
		Cairo.cairo_restore(cairo);
	}
	Cairo.cairo_fill(cairo);
}

/**
 * Fills the path described by the parameter.
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 *
 * @param path the path to fill
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parameter is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the parameter has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 *
 * @see Path
 *
 * @since 3.1
 */
public void fillPath (Path path) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (path == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (path.handle == 0) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	initCairo();
	checkGC(FILL);
	long /*int*/ cairo = data.cairo;
	long /*int*/ copy = Cairo.cairo_copy_path(path.handle);
	if (copy == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	Cairo.cairo_append_path(cairo, copy);
	Cairo.cairo_path_destroy(copy);
	Cairo.cairo_fill(cairo);
}

/**
 * Fills the interior of the closed polygon which is defined by the
 * specified array of integer coordinates, using the receiver's
 * background color. The array contains alternating x and y values
 * which are considered to represent points which are the vertices of
 * the polygon. Lines are drawn between each consecutive pair, and
 * between the first pair and last pair in the array.
 *
 * @param pointArray an array of alternating x and y values which are the vertices of the polygon
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT if pointArray is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #drawPolygon
 */
public void fillPolygon(int[] pointArray) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (pointArray == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	int [] scaledPointArray = DPIUtil.autoScaleUp(drawable, pointArray);
	fillPolygonInPixels(scaledPointArray);
}
void fillPolygonInPixels(int[] pointArray) {
	checkGC(FILL);
	long /*int*/ cairo = data.cairo;
	drawPolyline(cairo, pointArray, true);
	Cairo.cairo_fill(cairo);
}

/**
 * Fills the interior of the rectangle specified by the arguments,
 * using the receiver's background color.
 *
 * @param x the x coordinate of the rectangle to be filled
 * @param y the y coordinate of the rectangle to be filled
 * @param width the width of the rectangle to be filled
 * @param height the height of the rectangle to be filled
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #drawRectangle(int, int, int, int)
 */
public void fillRectangle(int x, int y, int width, int height) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	fillRectangle(new Rectangle(x, y, width, height));
}
void fillRectangleInPixels(int x, int y, int width, int height) {
	checkGC(FILL);
	if (width < 0) {
		x = x + width;
		width = -width;
	}
	if (height < 0) {
		y = y + height;
		height = -height;
	}
	long /*int*/ cairo = data.cairo;
	if (data.regionSet != 0) {
		cairoClipRegion(cairo);
	} else {
		Cairo.cairo_rectangle(cairo, x, y, width, height);
	}
	Cairo.cairo_fill(cairo);
}

/**
 * Fills the interior of the specified rectangle, using the receiver's
 * background color.
 *
 * @param rect the rectangle to be filled
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the rectangle is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #drawRectangle(int, int, int, int)
 */
public void fillRectangle(Rectangle rect) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (rect == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	fillRectangleInPixels(DPIUtil.autoScaleUp(drawable, rect));
}
void fillRectangleInPixels(Rectangle rect) {
	fillRectangleInPixels(rect.x, rect.y, rect.width, rect.height);
}

/**
 * Fills the interior of the round-cornered rectangle specified by
 * the arguments, using the receiver's background color.
 *
 * @param x the x coordinate of the rectangle to be filled
 * @param y the y coordinate of the rectangle to be filled
 * @param width the width of the rectangle to be filled
 * @param height the height of the rectangle to be filled
 * @param arcWidth the width of the arc
 * @param arcHeight the height of the arc
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #drawRoundRectangle
 */
public void fillRoundRectangle(int x, int y, int width, int height, int arcWidth, int arcHeight) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	Rectangle rect = DPIUtil.autoScaleUp(drawable, new Rectangle(x, y, width, height));
	Point arcSize = DPIUtil.autoScaleUp(drawable, new Point(arcWidth, arcHeight));
	fillRoundRectangleInPixels(rect.x, rect.y, rect.width, rect.height, arcSize.x, arcSize.y);
}
void fillRoundRectangleInPixels(int x, int y, int width, int height, int arcWidth, int arcHeight) {
	checkGC(FILL);
	int nx = x;
	int ny = y;
	int nw = width;
	int nh = height;
	int naw = arcWidth;
	int nah = arcHeight;
	if (nw < 0) {
		nw = 0 - nw;
		nx = nx - nw;
	}
	if (nh < 0) {
		nh = 0 - nh;
		ny = ny -nh;
	}
	if (naw < 0) naw = 0 - naw;
	if (nah < 0) nah = 0 - nah;
	long /*int*/ cairo = data.cairo;
	if (naw == 0 || nah == 0) {
		Cairo.cairo_rectangle(cairo, x, y, width, height);
	} else {
		float naw2 = naw / 2f;
		float nah2 = nah / 2f;
		float fw = nw / naw2;
		float fh = nh / nah2;
		Cairo.cairo_save(cairo);
		Cairo.cairo_translate(cairo, nx, ny);
		Cairo.cairo_scale(cairo, naw2, nah2);
		Cairo.cairo_move_to(cairo, fw - 1, 0);
	    Cairo.cairo_arc(cairo, fw - 1, 1, 1, Math.PI + Math.PI/2.0, Math.PI*2.0);
	    Cairo.cairo_arc(cairo, fw - 1, fh - 1, 1, 0, Math.PI/2.0);
	    Cairo.cairo_arc(cairo, 1, fh - 1, 1, Math.PI/2, Math.PI);
	    Cairo.cairo_arc(cairo, 1, 1, 1, Math.PI, 270.0*Math.PI/180.0);
		Cairo.cairo_close_path(cairo);
		Cairo.cairo_restore(cairo);
	}
	Cairo.cairo_fill(cairo);
}

int fixMnemonic (char [] buffer) {
	int i=0, j=0;
	int mnemonic=-1;
	while (i < buffer.length) {
		if ((buffer [j++] = buffer [i++]) == '&') {
			if (i == buffer.length) {continue;}
			if (buffer [i] == '&') {i++; continue;}
			if (mnemonic == -1) mnemonic = j;
			j--;
		}
	}
	while (j < buffer.length) buffer [j++] = 0;
	return mnemonic;
}

/**
 * Returns the <em>advance width</em> of the specified character in
 * the font which is currently selected into the receiver.
 * <p>
 * The advance width is defined as the horizontal distance the cursor
 * should move after printing the character in the selected font.
 * </p>
 *
 * @param ch the character to measure
 * @return the distance in the x direction to move past the character before painting the next
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int getAdvanceWidth(char ch) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	//BOGUS
	return stringExtentInPixels(new String(new char[]{ch})).x;
}

/**
 * Returns <code>true</code> if receiver is using the operating system's
 * advanced graphics subsystem.  Otherwise, <code>false</code> is returned
 * to indicate that normal graphics are in use.
 * <p>
 * Advanced graphics may not be installed for the operating system.  In this
 * case, <code>false</code> is always returned.  Some operating system have
 * only one graphics subsystem.  If this subsystem supports advanced graphics,
 * then <code>true</code> is always returned.  If any graphics operation such
 * as alpha, antialias, patterns, interpolation, paths, clipping or transformation
 * has caused the receiver to switch from regular to advanced graphics mode,
 * <code>true</code> is returned.  If the receiver has been explicitly switched
 * to advanced mode and this mode is supported, <code>true</code> is returned.
 * </p>
 *
 * @return the advanced value
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #setAdvanced
 *
 * @since 3.1
 */
public boolean getAdvanced() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return data.cairo != 0;
}

/**
 * Returns the receiver's alpha value. The alpha value
 * is between 0 (transparent) and 255 (opaque).
 *
 * @return the alpha value
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.1
 */
public int getAlpha() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return data.alpha;
}

/**
 * Returns the receiver's anti-aliasing setting value, which will be
 * one of <code>SWT.DEFAULT</code>, <code>SWT.OFF</code> or
 * <code>SWT.ON</code>. Note that this controls anti-aliasing for all
 * <em>non-text drawing</em> operations.
 *
 * @return the anti-aliasing setting
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #getTextAntialias
 *
 * @since 3.1
 */
public int getAntialias() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
    if (data.cairo == 0) return SWT.DEFAULT;
    int antialias = Cairo.cairo_get_antialias(data.cairo);
	switch (antialias) {
		case Cairo.CAIRO_ANTIALIAS_DEFAULT: return SWT.DEFAULT;
		case Cairo.CAIRO_ANTIALIAS_NONE: return SWT.OFF;
		case Cairo.CAIRO_ANTIALIAS_GRAY:
		case Cairo.CAIRO_ANTIALIAS_SUBPIXEL: return SWT.ON;
	}
	return SWT.DEFAULT;
}

/**
 * Returns the background color.
 *
 * @return the receiver's background color
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public Color getBackground() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (GTK.GTK3) {
		return Color.gtk_new(data.device, data.backgroundRGBA);
	} else {
		return Color.gtk_new(data.device, data.background);
	}
}

/**
 * Returns the background pattern. The default value is
 * <code>null</code>.
 *
 * @return the receiver's background pattern
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see Pattern
 *
 * @since 3.1
 */
public Pattern getBackgroundPattern() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return data.backgroundPattern;
}

/**
 * Returns the width of the specified character in the font
 * selected into the receiver.
 * <p>
 * The width is defined as the space taken up by the actual
 * character, not including the leading and tailing whitespace
 * or overhang.
 * </p>
 *
 * @param ch the character to measure
 * @return the width of the character
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int getCharWidth(char ch) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	//BOGUS
	return stringExtentInPixels(new String(new char[]{ch})).x;
}

/**
 * Returns the bounding rectangle of the receiver's clipping
 * region. If no clipping region is set, the return value
 * will be a rectangle which covers the entire bounds of the
 * object the receiver is drawing on.
 *
 * @return the bounding rectangle of the clipping region
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public Rectangle getClipping() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return DPIUtil.autoScaleDown(drawable, getClippingInPixels());
}
Rectangle getClippingInPixels() {
	/* Calculate visible bounds in device space */
	int x = 0, y = 0, width = 0, height = 0;
	int[] w = new int[1], h = new int[1];
	getSize(w, h);
	width = w[0];
	height = h[0];
	/* Intersect visible bounds with clipping in device space and then convert then to user space */
	long /*int*/ cairo = data.cairo;
	long /*int*/ clipRgn = data.clipRgn;
	long /*int*/ damageRgn = data.damageRgn;
	if (clipRgn != 0 || damageRgn != 0 || cairo != 0) {
		long /*int*/ rgn = GDK.gdk_region_new();
		GdkRectangle rect = new GdkRectangle();
		rect.width = width;
		rect.height = height;
		GDK.gdk_region_union_with_rect(rgn, rect);
		if (damageRgn != 0) {
			GDK.gdk_region_intersect (rgn, damageRgn);
		}
		/* Intersect visible bounds with clipping */
		if (clipRgn != 0) {
			/* Convert clipping to device space if needed */
			if (data.clippingTransform != null && GTK.GTK_VERSION < OS.VERSION (3, 14, 0)) {
				clipRgn = convertRgn(clipRgn, data.clippingTransform);
				GDK.gdk_region_intersect(rgn, clipRgn);
				GDK.gdk_region_destroy(clipRgn);
			} else {
				GDK.gdk_region_intersect(rgn, clipRgn);
			}
		}
		/* Convert to user space */
		if (cairo != 0 && GTK.GTK_VERSION < OS.VERSION (3, 14, 0)) {
			double[] matrix = new double[6];
			Cairo.cairo_get_matrix(cairo, matrix);
			Cairo.cairo_matrix_invert(matrix);
			clipRgn = convertRgn(rgn, matrix);
			GDK.gdk_region_destroy(rgn);
			rgn = clipRgn;
		}
		GDK.gdk_region_get_clipbox(rgn, rect);
		GDK.gdk_region_destroy(rgn);
		x = rect.x;
		y = rect.y;
		width = rect.width;
		height = rect.height;
	}
	return new Rectangle(x, y, width, height);
}

/**
 * Sets the region managed by the argument to the current
 * clipping region of the receiver.
 *
 * @param region the region to fill with the clipping region
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the region is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the region is disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void getClipping(Region region) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (region == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (region.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	long /*int*/ clipping = region.handle;
	GDK.gdk_region_subtract(clipping, clipping);
	long /*int*/ cairo = data.cairo;
	long /*int*/ clipRgn = data.clipRgn;
	if (clipRgn == 0) {
		GdkRectangle rect = new GdkRectangle();
		int[] width = new int[1], height = new int[1];
		getSize(width, height);
		rect.width = width[0];
		rect.height = height[0];
		GDK.gdk_region_union_with_rect(clipping, rect);
	} else {
		/* Convert clipping to device space if needed */
		if (data.clippingTransform != null && GTK.GTK_VERSION < OS.VERSION (3, 14, 0)) {
			long /*int*/ rgn = convertRgn(clipRgn, data.clippingTransform);
			GDK.gdk_region_union(clipping, rgn);
			GDK.gdk_region_destroy(rgn);
		} else {
			GDK.gdk_region_union(clipping, clipRgn);
		}
	}
	if (data.damageRgn != 0) {
		GDK.gdk_region_intersect(clipping, data.damageRgn);
	}
	/* Convert to user space */
	if (cairo != 0 && GTK.GTK_VERSION < OS.VERSION (3, 14, 0)) {
		double[] matrix = new double[6];
		Cairo.cairo_get_matrix(cairo, matrix);
		Cairo.cairo_matrix_invert(matrix);
		long /*int*/ rgn = convertRgn(clipping, matrix);
		GDK.gdk_region_subtract(clipping, clipping);
		GDK.gdk_region_union(clipping, rgn);
		GDK.gdk_region_destroy(rgn);
	}
}

/**
 * Returns the receiver's fill rule, which will be one of
 * <code>SWT.FILL_EVEN_ODD</code> or <code>SWT.FILL_WINDING</code>.
 *
 * @return the receiver's fill rule
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.1
 */
public int getFillRule() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	long /*int*/ cairo = data.cairo;
	if (cairo == 0) return SWT.FILL_EVEN_ODD;
	return Cairo.cairo_get_fill_rule(cairo) == Cairo.CAIRO_FILL_RULE_WINDING ? SWT.FILL_WINDING : SWT.FILL_EVEN_ODD;
}

/**
 * Returns the font currently being used by the receiver
 * to draw and measure text.
 *
 * @return the receiver's font
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public Font getFont() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return data.font;
}

/**
 * Returns a FontMetrics which contains information
 * about the font currently being used by the receiver
 * to draw and measure text.
 *
 * @return font metrics for the receiver's font
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public FontMetrics getFontMetrics() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (data.context == 0) createLayout();
	checkGC(FONT);
	Font font = data.font;
	long /*int*/ context = data.context;
	long /*int*/ lang = OS.pango_context_get_language(context);
	long /*int*/ metrics = OS.pango_context_get_metrics(context, font.handle, lang);
	FontMetrics fm = new FontMetrics();
	int ascent = OS.pango_font_metrics_get_ascent(metrics);
	int descent = OS.pango_font_metrics_get_descent(metrics);
	int ascentInPoints = DPIUtil.autoScaleDown(drawable, OS.PANGO_PIXELS(ascent));
	fm.ascentInPoints = ascentInPoints;
	int heightInPoints = DPIUtil.autoScaleDown(drawable, OS.PANGO_PIXELS(ascent + descent));
	fm.descentInPoints = heightInPoints - ascentInPoints;
	fm.averageCharWidthInPoints = DPIUtil.autoScaleDown(drawable, OS.PANGO_PIXELS(OS.pango_font_metrics_get_approximate_char_width(metrics)));
	OS.pango_font_metrics_unref(metrics);
	return fm;
}

/**
 * Returns the receiver's foreground color.
 *
 * @return the color used for drawing foreground things
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public Color getForeground() {
	if (handle == 0) SWT.error(SWT.ERROR_WIDGET_DISPOSED);
	if (GTK.GTK3) {
		return Color.gtk_new(data.device, data.foregroundRGBA);
	} else {
		return Color.gtk_new(data.device, data.foreground);
	}
}

/**
 * Returns the foreground pattern. The default value is
 * <code>null</code>.
 *
 * @return the receiver's foreground pattern
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see Pattern
 *
 * @since 3.1
 */
public Pattern getForegroundPattern() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return data.foregroundPattern;
}

/**
 * Returns the GCData.
 * <p>
 * <b>IMPORTANT:</b> This method is <em>not</em> part of the public
 * API for <code>GC</code>. It is marked public only so that it
 * can be shared within the packages provided by SWT. It is not
 * available on all platforms, and should never be called from
 * application code.
 * </p>
 *
 * @return the receiver's GCData
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see GCData
 *
 * @noreference This method is not intended to be referenced by clients.
 *
 * @since 3.2
 */
public GCData getGCData() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return data;
}

/**
 * Returns the receiver's interpolation setting, which will be one of
 * <code>SWT.DEFAULT</code>, <code>SWT.NONE</code>,
 * <code>SWT.LOW</code> or <code>SWT.HIGH</code>.
 *
 * @return the receiver's interpolation setting
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.1
 */
public int getInterpolation() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return data.interpolation;
}

/**
 * Returns the receiver's line attributes.
 *
 * @return the line attributes used for drawing lines
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.3
 */
public LineAttributes getLineAttributes() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	LineAttributes attributes = getLineAttributesInPixels();
	attributes.width = DPIUtil.autoScaleDown(drawable, attributes.width);
	return attributes;
}
LineAttributes getLineAttributesInPixels() {
	float[] dashes = null;
	if (data.lineDashes != null) {
		dashes = new float[data.lineDashes.length];
		System.arraycopy(data.lineDashes, 0, dashes, 0, dashes.length);
	}
	return new LineAttributes(data.lineWidth, data.lineCap, data.lineJoin, data.lineStyle, dashes, data.lineDashesOffset, data.lineMiterLimit);
}

/**
 * Returns the receiver's line cap style, which will be one
 * of the constants <code>SWT.CAP_FLAT</code>, <code>SWT.CAP_ROUND</code>,
 * or <code>SWT.CAP_SQUARE</code>.
 *
 * @return the cap style used for drawing lines
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.1
 */
public int getLineCap() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return data.lineCap;
}

/**
 * Returns the receiver's line dash style. The default value is
 * <code>null</code>.
 *
 * @return the line dash style used for drawing lines
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.1
 */
public int[] getLineDash() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (data.lineDashes == null) return null;
	int[] lineDashes = new int[data.lineDashes.length];
	for (int i = 0; i < lineDashes.length; i++) {
		lineDashes[i] = (int)data.lineDashes[i];
	}
	return lineDashes;
}

/**
 * Returns the receiver's line join style, which will be one
 * of the constants <code>SWT.JOIN_MITER</code>, <code>SWT.JOIN_ROUND</code>,
 * or <code>SWT.JOIN_BEVEL</code>.
 *
 * @return the join style used for drawing lines
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.1
 */
public int getLineJoin() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return data.lineJoin;
}

/**
 * Returns the receiver's line style, which will be one
 * of the constants <code>SWT.LINE_SOLID</code>, <code>SWT.LINE_DASH</code>,
 * <code>SWT.LINE_DOT</code>, <code>SWT.LINE_DASHDOT</code> or
 * <code>SWT.LINE_DASHDOTDOT</code>.
 *
 * @return the style used for drawing lines
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int getLineStyle() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return data.lineStyle;
}

/**
 * Returns the width that will be used when drawing lines
 * for all of the figure drawing operations (that is,
 * <code>drawLine</code>, <code>drawRectangle</code>,
 * <code>drawPolyline</code>, and so forth.
 *
 * @return the receiver's line width
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public int getLineWidth() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return (int)DPIUtil.autoScaleDown(drawable, data.lineWidth);
}
int getLineWidthInPixels() {
	return (int)data.lineWidth;
}

/**
 * Returns the receiver's style information.
 * <p>
 * Note that the value which is returned by this method <em>may
 * not match</em> the value which was provided to the constructor
 * when the receiver was created. This can occur when the underlying
 * operating system does not support a particular combination of
 * requested styles.
 * </p>
 *
 * @return the style bits
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 2.1.2
 */
public int getStyle () {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return data.style;
}

void getSize(int[] width, int[] height) {
	if (data.width != -1 && data.height != -1) {
		width[0] = data.width;
		height[0] = data.height;
		return;
	}
	if (data.drawable != 0) {
		width[0] = GDK.gdk_window_get_width(data.drawable);
		height[0] = GDK.gdk_window_get_height(data.drawable);
		return;
	}
	long /*int*/ surface = Cairo.cairo_get_target(handle);
	switch (Cairo.cairo_surface_get_type(surface)) {
		case Cairo.CAIRO_SURFACE_TYPE_IMAGE:
			width[0] = Cairo.cairo_image_surface_get_width(surface);
			height[0] = Cairo.cairo_image_surface_get_height(surface);
			break;
		case Cairo.CAIRO_SURFACE_TYPE_XLIB:
			width[0] = Cairo.cairo_xlib_surface_get_width(surface);
			height[0] = Cairo.cairo_xlib_surface_get_height(surface);
			break;
	}
}

/**
 * Returns the receiver's text drawing anti-aliasing setting value,
 * which will be one of <code>SWT.DEFAULT</code>, <code>SWT.OFF</code> or
 * <code>SWT.ON</code>. Note that this controls anti-aliasing
 * <em>only</em> for text drawing operations.
 *
 * @return the anti-aliasing setting
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #getAntialias
 *
 * @since 3.1
 */
public int getTextAntialias() {
    if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
    if (data.cairo == 0) return SWT.DEFAULT;
    int antialias = Cairo.CAIRO_ANTIALIAS_DEFAULT;
	if (data.context != 0) {
		long /*int*/ options = OS.pango_cairo_context_get_font_options(data.context);
		if (options != 0) antialias = Cairo.cairo_font_options_get_antialias(options);
	}
	switch (antialias) {
		case Cairo.CAIRO_ANTIALIAS_DEFAULT: return SWT.DEFAULT;
		case Cairo.CAIRO_ANTIALIAS_NONE: return SWT.OFF;
		case Cairo.CAIRO_ANTIALIAS_GRAY:
		case Cairo.CAIRO_ANTIALIAS_SUBPIXEL: return SWT.ON;
	}
	return SWT.DEFAULT;
}

/**
 * Sets the parameter to the transform that is currently being
 * used by the receiver.
 *
 * @param transform the destination to copy the transform into
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parameter is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the parameter has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see Transform
 *
 * @since 3.1
 */
public void getTransform(Transform transform) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (transform == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (transform.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	long /*int*/ cairo = data.cairo;
	if (cairo != 0) {
		/*
		 * The client wants to know the relative transformation they set for their widgets.
		 * They do not want to know about the global coordinates of their widget, which is contained in Cairo.cairo_get_matrix().
		 * So we return whatever the client specified with setTransform.
		 */
		if (GTK.GTK_VERSION >= OS.VERSION (3, 14, 0)) {
			if (currentTransform != null) {
				transform.handle = currentTransform.clone();
			} else {
				transform.handle = new double[] { 1.0, 0.0, 0.0, 1.0, 0.0, 0.0 };
			}
		} else {
			Cairo.cairo_get_matrix(cairo, transform.handle);
			double[] identity = identity();
			Cairo.cairo_matrix_invert(identity);
			Cairo.cairo_matrix_multiply(transform.handle, transform.handle, identity);
		}
	} else {
		transform.setElements(1, 0, 0, 1, 0, 0);
	}
}

/**
 * Returns <code>true</code> if this GC is drawing in the mode
 * where the resulting color in the destination is the
 * <em>exclusive or</em> of the color values in the source
 * and the destination, and <code>false</code> if it is
 * drawing in the mode where the destination color is being
 * replaced with the source color value.
 *
 * @return <code>true</code> true if the receiver is in XOR mode, and false otherwise
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public boolean getXORMode() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return data.xorMode;
}

/**
 * Returns an integer hash code for the receiver. Any two
 * objects that return <code>true</code> when passed to
 * <code>equals</code> must return the same value for this
 * method.
 *
 * @return the receiver's hash
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #equals
 */
@Override
public int hashCode() {
	return (int)/*64*/handle;
}

double[] identity() {
	double[] identity = new double[6];
	if ((data.style & SWT.MIRRORED) != 0) {
		int[] w = new int[1], h = new int[1];
		getSize(w, h);
		Cairo.cairo_matrix_init(identity, -1, 0, 0, 1, w[0], 0);
	} else {
		Cairo.cairo_matrix_init_identity(identity);
	}
	if (data.identity != null) {
		Cairo.cairo_matrix_multiply(identity, data.identity, identity);
	}
	return identity;
}

void init(Drawable drawable, GCData data, long /*int*/ gdkGC) {
	if (GTK.GTK3) {
		if (data.foregroundRGBA != null) data.state &= ~FOREGROUND;
		if (data.backgroundRGBA != null) data.state &= ~(BACKGROUND | BACKGROUND_BG);
	} else {
		if (data.foreground != null) data.state &= ~FOREGROUND;
		if (data.background != null) data.state &= ~(BACKGROUND | BACKGROUND_BG);
	}
	if (data.font != null) data.state &= ~FONT;
	Image image = data.image;
	if (image != null) {
		image.memGC = this;
		/*
		 * The transparent pixel mask might change when drawing on
		 * the image.  Destroy it so that it is regenerated when
		 * necessary.
		 */
		if (image.transparentPixel != -1) image.destroyMask();
	}
	this.drawable = drawable;
	this.data = data;
	handle = gdkGC;
	long /*int*/ cairo = data.cairo = handle;
	Cairo.cairo_set_fill_rule(cairo, Cairo.CAIRO_FILL_RULE_EVEN_ODD);
	data.state &= ~(BACKGROUND | FOREGROUND | FONT | LINE_WIDTH | LINE_CAP | LINE_JOIN | LINE_STYLE | DRAW_OFFSET);
	setClipping(data.clipRgn);
	initCairo();
	if ((data.style & SWT.MIRRORED) != 0) {
		// Don't overwrite the Cairo transformation matrix in GTK 3.14 and above; it contains a translation relative to the parent widget.
		if (GTK.GTK_VERSION >= OS.VERSION (3, 14, 0)) {
			int[] w = new int[1], h = new int[1];
			getSize(w, h);
			Cairo.cairo_translate(cairo, w[0], 0);
			Cairo.cairo_scale(cairo, -1.0, 1.0);
		} else {
			Cairo.cairo_set_matrix(data.cairo, identity());
		}
	}
	if (cairoTransformationMatrix == null) cairoTransformationMatrix = new double[6];
	Cairo.cairo_get_matrix(data.cairo, cairoTransformationMatrix);
	clipping = getClipping();
}

void initCairo() {
	long /*int*/ cairo = data.cairo;
	if (cairo != 0) return;
	data.cairo = cairo = GDK.gdk_cairo_create(data.drawable);
	if (cairo == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	data.disposeCairo = true;
	Cairo.cairo_set_fill_rule(cairo, Cairo.CAIRO_FILL_RULE_EVEN_ODD);
	data.state &= ~(BACKGROUND | FOREGROUND | FONT | LINE_WIDTH | LINE_CAP | LINE_JOIN | LINE_STYLE | DRAW_OFFSET);
	setCairoClip(data.damageRgn, data.clipRgn);
}

void computeStringSize() {
	int[] width = new int[1], height = new int[1];
	OS.pango_layout_get_pixel_size(data.layout, width, height);
	data.stringHeight = height[0];
	data.stringWidth = width[0];
}

/**
 * Returns <code>true</code> if the receiver has a clipping
 * region set into it, and <code>false</code> otherwise.
 * If this method returns false, the receiver will draw on all
 * available space in the destination. If it returns true,
 * it will draw only in the area that is covered by the region
 * that can be accessed with <code>getClipping(region)</code>.
 *
 * @return <code>true</code> if the GC has a clipping region, and <code>false</code> otherwise
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public boolean isClipped() {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return data.clipRgn != 0;
}

/**
 * Returns <code>true</code> if the GC has been disposed,
 * and <code>false</code> otherwise.
 * <p>
 * This method gets the dispose state for the GC.
 * When a GC has been disposed, it is an error to
 * invoke any other method (except {@link #dispose()}) using the GC.
 *
 * @return <code>true</code> when the GC is disposed and <code>false</code> otherwise
 */
@Override
public boolean isDisposed() {
	return handle == 0;
}

boolean isIdentity(double[] matrix) {
	if (matrix == null) return true;
	return matrix[0] == 1 && matrix[1] == 0 && matrix[2] == 0 && matrix[3] == 1 && matrix[4] == 0 && matrix[5] == 0;
}

/**
 * Sets the receiver to always use the operating system's advanced graphics
 * subsystem for all graphics operations if the argument is <code>true</code>.
 * If the argument is <code>false</code>, the advanced graphics subsystem is
 * no longer used, advanced graphics state is cleared and the normal graphics
 * subsystem is used from now on.
 * <p>
 * Normally, the advanced graphics subsystem is invoked automatically when
 * any one of the alpha, antialias, patterns, interpolation, paths, clipping
 * or transformation operations in the receiver is requested.  When the receiver
 * is switched into advanced mode, the advanced graphics subsystem performs both
 * advanced and normal graphics operations.  Because the two subsystems are
 * different, their output may differ.  Switching to advanced graphics before
 * any graphics operations are performed ensures that the output is consistent.
 * </p><p>
 * Advanced graphics may not be installed for the operating system.  In this
 * case, this operation does nothing.  Some operating system have only one
 * graphics subsystem, so switching from normal to advanced graphics does
 * nothing.  However, switching from advanced to normal graphics will always
 * clear the advanced graphics state, even for operating systems that have
 * only one graphics subsystem.
 * </p>
 *
 * @param advanced the new advanced graphics state
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see #setAlpha
 * @see #setAntialias
 * @see #setBackgroundPattern
 * @see #setClipping(Path)
 * @see #setForegroundPattern
 * @see #setLineAttributes
 * @see #setInterpolation
 * @see #setTextAntialias
 * @see #setTransform
 * @see #getAdvanced
 *
 * @since 3.1
 */
public void setAdvanced(boolean advanced) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (!advanced) {
		setAlpha(0xFF);
		setAntialias(SWT.DEFAULT);
		setBackgroundPattern(null);
		resetClipping();
		setForegroundPattern(null);
		setInterpolation(SWT.DEFAULT);
		setTextAntialias(SWT.DEFAULT);
		setTransform(null);
	}
}

/**
 * Sets the receiver's alpha value which must be
 * between 0 (transparent) and 255 (opaque).
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 * @param alpha the alpha value
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 *
 * @see #getAdvanced
 * @see #setAdvanced
 *
 * @since 3.1
 */
public void setAlpha(int alpha) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (data.cairo == 0 && (alpha & 0xff) == 0xff) return;
	initCairo();
	data.alpha = alpha & 0xff;
	data.state &= ~(BACKGROUND | FOREGROUND | BACKGROUND_BG);
}

/**
 * Sets the receiver's anti-aliasing value to the parameter,
 * which must be one of <code>SWT.DEFAULT</code>, <code>SWT.OFF</code>
 * or <code>SWT.ON</code>. Note that this controls anti-aliasing for all
 * <em>non-text drawing</em> operations.
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 *
 * @param antialias the anti-aliasing setting
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the parameter is not one of <code>SWT.DEFAULT</code>,
 *                                 <code>SWT.OFF</code> or <code>SWT.ON</code></li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 *
 * @see #getAdvanced
 * @see #setAdvanced
 * @see #setTextAntialias
 *
 * @since 3.1
 */
public void setAntialias(int antialias) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (data.cairo == 0 && antialias == SWT.DEFAULT) return;
	int mode = 0;
	switch (antialias) {
		case SWT.DEFAULT: mode = Cairo.CAIRO_ANTIALIAS_DEFAULT; break;
		case SWT.OFF: mode = Cairo.CAIRO_ANTIALIAS_NONE; break;
		case SWT.ON: mode = Cairo.CAIRO_ANTIALIAS_GRAY;
            break;
		default:
			SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	}
    initCairo();
    long /*int*/ cairo = data.cairo;
    Cairo.cairo_set_antialias(cairo, mode);
}

/**
 * Sets the background color. The background color is used
 * for fill operations and as the background color when text
 * is drawn.
 *
 * @param color the new background color for the receiver
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the color is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the color has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setBackground(Color color) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (color == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (color.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	if (GTK.GTK3) {
		data.backgroundRGBA = color.handleRGBA;
	} else {
		data.background = color.handle;
	}
	data.backgroundPattern = null;
	data.state &= ~(BACKGROUND | BACKGROUND_BG);
}

/**
 * Sets the background pattern. The default value is <code>null</code>.
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 *
 * @param pattern the new background pattern
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the parameter has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 *
 * @see Pattern
 * @see #getAdvanced
 * @see #setAdvanced
 *
 * @since 3.1
 */
public void setBackgroundPattern(Pattern pattern) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (pattern != null && pattern.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	if (data.cairo == 0 && pattern == null) return;
	initCairo();
	if (data.backgroundPattern == pattern) return;
	data.backgroundPattern = pattern;
	data.state &= ~BACKGROUND;
}

static void setCairoFont(long /*int*/ cairo, Font font) {
	if (font == null || font.isDisposed()) return;
	setCairoFont(cairo, font.handle);
}

static void setCairoFont(long /*int*/ cairo, long /*int*/ font) {
	long /*int*/ family = OS.pango_font_description_get_family(font);
	int length = C.strlen(family);
	byte[] buffer = new byte[length + 1];
	C.memmove(buffer, family, length);
	//TODO - convert font height from pango to cairo
	double height = OS.PANGO_PIXELS(OS.pango_font_description_get_size(font)) * 96 / 72;
	int pangoStyle = OS.pango_font_description_get_style(font);
	int pangoWeight = OS.pango_font_description_get_weight(font);
	int slant = Cairo.CAIRO_FONT_SLANT_NORMAL;
	if (pangoStyle == OS.PANGO_STYLE_ITALIC) slant = Cairo.CAIRO_FONT_SLANT_ITALIC;
	if (pangoStyle == OS.PANGO_STYLE_OBLIQUE) slant = Cairo.CAIRO_FONT_SLANT_OBLIQUE;
	int weight = Cairo.CAIRO_FONT_WEIGHT_NORMAL;
	if (pangoWeight == OS.PANGO_WEIGHT_BOLD) weight = Cairo.CAIRO_FONT_WEIGHT_BOLD;
	Cairo.cairo_select_font_face(cairo, buffer, slant, weight);
	Cairo.cairo_set_font_size(cairo, height);
}

static void setCairoRegion(long /*int*/ cairo, long /*int*/ rgn) {
	GDK.gdk_cairo_region(cairo, rgn);
}

static void setCairoPatternColor(long /*int*/ pattern, int offset, Color c, int alpha) {
	if (GTK.GTK3) {
		GdkRGBA rgba = c.handleRGBA;
		Cairo.cairo_pattern_add_color_stop_rgba(pattern, offset, rgba.red, rgba.green, rgba.blue, alpha / 255f);
	} else {
		GdkColor color = c.handle;
		double aa = (alpha & 0xFF) / (double)0xFF;
		double red = ((color.red & 0xFFFF) / (double)0xFFFF);
		double green = ((color.green & 0xFFFF) / (double)0xFFFF);
		double blue = ((color.blue & 0xFFFF) / (double)0xFFFF);
		Cairo.cairo_pattern_add_color_stop_rgba(pattern, offset, red, green, blue, aa);
	}
}

void setCairoClip(long /*int*/ damageRgn, long /*int*/ clipRgn) {
	long /*int*/ cairo = data.cairo;
	if (data.drawable != 0 && !GTK.GTK3) {
		GDK.gdk_cairo_reset_clip(cairo, data.drawable);
	} else {
		Cairo.cairo_reset_clip(cairo);
	}
	if (damageRgn != 0) {
		double[] matrix = new double[6];
		Cairo.cairo_get_matrix(cairo, matrix);
		double[] identity = new double[6];
		Cairo.cairo_matrix_init_identity(identity);
		Cairo.cairo_set_matrix(cairo, identity);
		setCairoRegion(cairo, damageRgn);
		Cairo.cairo_clip(cairo);
		Cairo.cairo_set_matrix(cairo, matrix);
	}
	if (clipRgn != 0) {
		long /*int*/ clipRgnCopy = GDK.gdk_region_new();
		GDK.gdk_region_union(clipRgnCopy, clipRgn);

		/*
		 * Bug 531667: widgets paint over other widgets
		 *
		 * The Cairo handle is shared by all widgets, but GC.setClipping allows global clipping changes.
		 * So we intersect whatever the client sets with the initial GC clipping.
		 */
		if (GTK.GTK_VERSION >= OS.VERSION(3, 14, 0)) {
			limitClipping(clipRgnCopy);
		}

		setCairoRegion(cairo, clipRgnCopy);
		Cairo.cairo_clip(cairo);
		GDK.gdk_region_destroy(clipRgnCopy);
	}
}

/**
 * Intersects given clipping with original clipping of this context, so
 * that resulting clip does not allow to paint outside of the GC bounds.
 */
private void limitClipping(long /*int*/ gcClipping) {
	Region clippingRegion = new Region();
	if (currentTransform != null) {
		// we want to apply GC clipping stored in init() as is, so we invert user transformations that may distort it
		double[] invertedCurrentTransform = currentTransform.clone();
		Cairo.cairo_matrix_invert(invertedCurrentTransform);
		int[] clippingWithoutUserTransform = transformRectangle(invertedCurrentTransform, clipping);
		clippingRegion.add(clippingWithoutUserTransform);
		GDK.gdk_region_intersect(gcClipping, clippingRegion.handle);
	} else {
		clippingRegion.add(clipping);
	}
	GDK.gdk_region_intersect(gcClipping, clippingRegion.handle);
	clippingRegion.dispose();
}

/**
 * Transforms rectangle with given matrix
 *
 * @return transformed rectangle corner coordinates, with x,y order of points.
 */
private static int[] transformRectangle(double[] affineTransformation, Rectangle rectangle) {
	Point[] endPoints = {
			new Point(rectangle.x                  , rectangle.y                   ),
			new Point(rectangle.x + rectangle.width, rectangle.y                   ),
			new Point(rectangle.x + rectangle.width, rectangle.y + rectangle.height),
			new Point(rectangle.x                  , rectangle.y + rectangle.height),
	};
	return transformPoints(affineTransformation, endPoints);
}

/**
 * Transforms x,y coordinate pairs with given matrix
 *
 * @return transformed x,y coordinates.
 */
private static int[] transformPoints(double[] transformation, Point[] points) {
	int[] transformedPoints = new int[points.length * 2];
	double[] px = new double[1], py = new double[1];
	for (int i = 0; i < points.length; ++i) {
		px[0] = points[i].x;
		py[0] = points[i].y;
		Cairo.cairo_matrix_transform_point(transformation, px, py);
		transformedPoints[(i * 2) + 0] = (int) Math.round(px[0]);
		transformedPoints[(i * 2) + 1] = (int) Math.round(py[0]);
	}
	return transformedPoints;
}

void setClipping(long /*int*/ clipRgn) {
	long /*int*/ cairo = data.cairo;
	if (clipRgn == 0) {
		if (data.clipRgn != 0) {
			GDK.gdk_region_destroy(data.clipRgn);
			data.clipRgn = 0;
		}
		data.clippingTransform = null;
		setCairoClip(data.damageRgn, 0);
	} else {
		if (data.clipRgn == 0) data.clipRgn = GDK.gdk_region_new();
		GDK.gdk_region_subtract(data.clipRgn, data.clipRgn);
		GDK.gdk_region_union(data.clipRgn, clipRgn);
		if (GTK.GTK_VERSION < OS.VERSION (3, 14, 0)) {
			if (data.clippingTransform == null) data.clippingTransform = new double[6];
			Cairo.cairo_get_matrix(cairo, data.clippingTransform);
		}
		setCairoClip(data.damageRgn, clipRgn);
	}
}

/**
 * Sets the area of the receiver which can be changed
 * by drawing operations to the rectangular area specified
 * by the arguments.
 *
 * @param x the x coordinate of the clipping rectangle
 * @param y the y coordinate of the clipping rectangle
 * @param width the width of the clipping rectangle
 * @param height the height of the clipping rectangle
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setClipping(int x, int y, int width, int height) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	setClippingInPixels(DPIUtil.autoScaleUp(drawable, x), DPIUtil.autoScaleUp(drawable, y), DPIUtil.autoScaleUp(drawable, width), DPIUtil.autoScaleUp(drawable, height));
}
void setClippingInPixels(int x, int y, int width, int height) {
	if (width < 0) {
		x = x + width;
		width = -width;
	}
	if (height < 0) {
		y = y + height;
		height = -height;
	}
	GdkRectangle rect = new GdkRectangle();
	rect.x = x;
	rect.y = y;
	rect.width = width;
	rect.height = height;
	long /*int*/ clipRgn = GDK.gdk_region_new();
	GDK.gdk_region_union_with_rect(clipRgn, rect);
	setClipping(clipRgn);
	GDK.gdk_region_destroy(clipRgn);
}

/**
 * Sets the area of the receiver which can be changed
 * by drawing operations to the path specified
 * by the argument.
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 *
 * @param path the clipping path.
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the path has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 *
 * @see Path
 * @see #getAdvanced
 * @see #setAdvanced
 *
 * @since 3.1
 */
public void setClipping(Path path) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (path != null && path.isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	resetClipping();
	if (path != null) {
		initCairo();
		long /*int*/ cairo = data.cairo;
		long /*int*/ copy = Cairo.cairo_copy_path(path.handle);
		if (copy == 0) SWT.error(SWT.ERROR_NO_HANDLES);
		Cairo.cairo_append_path(cairo, copy);
		Cairo.cairo_path_destroy(copy);
		Cairo.cairo_clip(cairo);
	}
}

/**
 * Sets the area of the receiver which can be changed
 * by drawing operations to the rectangular area specified
 * by the argument.  Specifying <code>null</code> for the
 * rectangle reverts the receiver's clipping area to its
 * original value.
 *
 * @param rect the clipping rectangle or <code>null</code>
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setClipping(Rectangle rect) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	setClippingInPixels(DPIUtil.autoScaleUp(drawable, rect));
}
void setClippingInPixels(Rectangle rect) {
	if (GTK.GTK_VERSION >= OS.VERSION(3, 9, 0) && (drawable instanceof Tree || drawable instanceof Table)) {
		return; //FIXME: This is an atrocious hack for bug 446075
	}
	if (rect == null) {
		resetClipping();
	} else {
		setClippingInPixels(rect.x, rect.y, rect.width, rect.height);
	}
}

private void resetClipping() {
	if (GTK.GTK_VERSION >= OS.VERSION(3, 14, 0)) {
		/*
		 * Bug 531667: widgets paint over other widgets
		 *
		 * The Cairo handle is shared by all widgets, and GC.setClipping(0) allows painting outside the current GC area.
		 * So if we reset any custom clipping we still want to restrict GC operations with the initial GC clipping.
		 */
		setClipping(clipping);
	} else {
		setClipping(0);
	}
}

/**
 * Sets the area of the receiver which can be changed
 * by drawing operations to the region specified
 * by the argument.  Specifying <code>null</code> for the
 * region reverts the receiver's clipping area to its
 * original value.
 *
 * @param region the clipping region or <code>null</code>
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the region has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setClipping(Region region) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (region != null && region.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	if (region != null) {
		setClipping(region.handle);
	} else {
		resetClipping();
	}
}

/**
 * Sets the font which will be used by the receiver
 * to draw and measure text to the argument. If the
 * argument is null, then a default font appropriate
 * for the platform will be used instead.
 *
 * @param font the new font for the receiver, or null to indicate a default font
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the font has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setFont(Font font) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (font != null && font.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	data.font = font != null ? font : data.device.systemFont;
	data.state &= ~FONT;
	data.stringWidth = data.stringHeight = -1;
}

/**
 * Sets the receiver's fill rule to the parameter, which must be one of
 * <code>SWT.FILL_EVEN_ODD</code> or <code>SWT.FILL_WINDING</code>.
 *
 * @param rule the new fill rule
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the rule is not one of <code>SWT.FILL_EVEN_ODD</code>
 *                                 or <code>SWT.FILL_WINDING</code></li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.1
 */
public void setFillRule(int rule) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	int cairo_mode = Cairo.CAIRO_FILL_RULE_EVEN_ODD;
	switch (rule) {
		case SWT.FILL_WINDING:
			cairo_mode = Cairo.CAIRO_FILL_RULE_WINDING; break;
		case SWT.FILL_EVEN_ODD:
			cairo_mode = Cairo.CAIRO_FILL_RULE_EVEN_ODD; break;
		default:
			SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	}
	initCairo();
	Cairo.cairo_set_fill_rule(data.cairo, cairo_mode);
}

/**
 * Sets the foreground color. The foreground color is used
 * for drawing operations including when text is drawn.
 *
 * @param color the new foreground color for the receiver
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the color is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the color has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setForeground(Color color) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (color == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (color.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	if (GTK.GTK3) {
		data.foregroundRGBA = color.handleRGBA;
	} else {
		data.foreground = color.handle;
	}
	data.foregroundPattern = null;
	data.state &= ~FOREGROUND;
}

/**
 * Sets the foreground pattern. The default value is <code>null</code>.
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 * @param pattern the new foreground pattern
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the parameter has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 *
 * @see Pattern
 * @see #getAdvanced
 * @see #setAdvanced
 *
 * @since 3.1
 */
public void setForegroundPattern(Pattern pattern) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (pattern != null && pattern.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	if (data.cairo == 0 && pattern == null) return;
	initCairo();
	if (data.foregroundPattern == pattern) return;
	data.foregroundPattern = pattern;
	data.state &= ~FOREGROUND;
}

/**
 * Sets the receiver's interpolation setting to the parameter, which
 * must be one of <code>SWT.DEFAULT</code>, <code>SWT.NONE</code>,
 * <code>SWT.LOW</code> or <code>SWT.HIGH</code>.
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 *
 * @param interpolation the new interpolation setting
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the rule is not one of <code>SWT.DEFAULT</code>,
 *                                 <code>SWT.NONE</code>, <code>SWT.LOW</code> or <code>SWT.HIGH</code>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 *
 * @see #getAdvanced
 * @see #setAdvanced
 *
 * @since 3.1
 */
public void setInterpolation(int interpolation) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (data.cairo == 0 && interpolation == SWT.DEFAULT) return;
	switch (interpolation) {
		case SWT.DEFAULT:
		case SWT.NONE:
		case SWT.LOW:
		case SWT.HIGH:
			break;
		default:
			SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	}
	initCairo();
	data.interpolation = interpolation;
}

/**
 * Sets the receiver's line attributes.
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 * @param attributes the line attributes
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the attributes is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if any of the line attributes is not valid</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 *
 * @see LineAttributes
 * @see #getAdvanced
 * @see #setAdvanced
 *
 * @since 3.3
 */
public void setLineAttributes(LineAttributes attributes) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (attributes == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	attributes.width = DPIUtil.autoScaleUp(drawable, attributes.width);
	setLineAttributesInPixels(attributes);
}
void setLineAttributesInPixels(LineAttributes attributes) {
	int mask = 0;
	float lineWidth = attributes.width;
	if (lineWidth != data.lineWidth) {
		mask |= LINE_WIDTH | DRAW_OFFSET;
	}
	int lineStyle = attributes.style;
	if (lineStyle != data.lineStyle) {
		mask |= LINE_STYLE;
		switch (lineStyle) {
			case SWT.LINE_SOLID:
			case SWT.LINE_DASH:
			case SWT.LINE_DOT:
			case SWT.LINE_DASHDOT:
			case SWT.LINE_DASHDOTDOT:
				break;
			case SWT.LINE_CUSTOM:
				if (attributes.dash == null) lineStyle = SWT.LINE_SOLID;
				break;
			default:
				SWT.error(SWT.ERROR_INVALID_ARGUMENT);
		}
	}
	int join = attributes.join;
	if (join != data.lineJoin) {
		mask |= LINE_JOIN;
		switch (join) {
			case SWT.JOIN_MITER:
			case SWT.JOIN_ROUND:
			case SWT.JOIN_BEVEL:
				break;
			default:
				SWT.error(SWT.ERROR_INVALID_ARGUMENT);
		}
	}
	int cap = attributes.cap;
	if (cap != data.lineCap) {
		mask |= LINE_CAP;
		switch (cap) {
			case SWT.CAP_FLAT:
			case SWT.CAP_ROUND:
			case SWT.CAP_SQUARE:
				break;
			default:
				SWT.error(SWT.ERROR_INVALID_ARGUMENT);
		}
	}
	float[] dashes = attributes.dash;
	float[] lineDashes = data.lineDashes;
	if (dashes != null && dashes.length > 0) {
		boolean changed = lineDashes == null || lineDashes.length != dashes.length;
		for (int i = 0; i < dashes.length; i++) {
			float dash = dashes[i];
			if (dash <= 0) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
			if (!changed && lineDashes[i] != dash) changed = true;
		}
		if (changed) {
			float[] newDashes = new float[dashes.length];
			System.arraycopy(dashes, 0, newDashes, 0, dashes.length);
			dashes = newDashes;
			mask |= LINE_STYLE;
		} else {
			dashes = lineDashes;
		}
	} else {
		if (lineDashes != null && lineDashes.length > 0) {
			mask |= LINE_STYLE;
		} else {
			dashes = lineDashes;
		}
	}
	float dashOffset = attributes.dashOffset;
	if (dashOffset != data.lineDashesOffset) {
		mask |= LINE_STYLE;
	}
	float miterLimit = attributes.miterLimit;
	if (miterLimit != data.lineMiterLimit) {
		mask |= LINE_MITERLIMIT;
	}
	initCairo();
	if (mask == 0) return;
	data.lineWidth = lineWidth;
	data.lineStyle = lineStyle;
	data.lineCap = cap;
	data.lineJoin = join;
	data.lineDashes = dashes;
	data.lineDashesOffset = dashOffset;
	data.lineMiterLimit = miterLimit;
	data.state &= ~mask;
}

/**
 * Sets the receiver's line cap style to the argument, which must be one
 * of the constants <code>SWT.CAP_FLAT</code>, <code>SWT.CAP_ROUND</code>,
 * or <code>SWT.CAP_SQUARE</code>.
 *
 * @param cap the cap style to be used for drawing lines
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the style is not valid</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.1
 */
public void setLineCap(int cap) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (data.lineCap == cap) return;
	switch (cap) {
		case SWT.CAP_ROUND:
		case SWT.CAP_FLAT:
		case SWT.CAP_SQUARE:
			break;
		default:
			SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	}
	data.lineCap = cap;
	data.state &= ~LINE_CAP;
}

/**
 * Sets the receiver's line dash style to the argument. The default
 * value is <code>null</code>. If the argument is not <code>null</code>,
 * the receiver's line style is set to <code>SWT.LINE_CUSTOM</code>, otherwise
 * it is set to <code>SWT.LINE_SOLID</code>.
 *
 * @param dashes the dash style to be used for drawing lines
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if any of the values in the array is less than or equal 0</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.1
 */
public void setLineDash(int[] dashes) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	float[] lineDashes = data.lineDashes;
	if (dashes != null && dashes.length > 0) {
		boolean changed = data.lineStyle != SWT.LINE_CUSTOM || lineDashes == null || lineDashes.length != dashes.length;
		for (int i = 0; i < dashes.length; i++) {
			int dash = dashes[i];
			if (dash <= 0) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
			if (!changed && lineDashes[i] != dash) changed = true;
		}
		if (!changed) return;
		data.lineDashes = new float[dashes.length];
		for (int i = 0; i < dashes.length; i++) {
			data.lineDashes[i] = dashes[i];
		}
		data.lineStyle = SWT.LINE_CUSTOM;
	} else {
		if (data.lineStyle == SWT.LINE_SOLID && (lineDashes == null || lineDashes.length == 0)) return;
		data.lineDashes = null;
		data.lineStyle = SWT.LINE_SOLID;
	}
	data.state &= ~LINE_STYLE;
}

/**
 * Sets the receiver's line join style to the argument, which must be one
 * of the constants <code>SWT.JOIN_MITER</code>, <code>SWT.JOIN_ROUND</code>,
 * or <code>SWT.JOIN_BEVEL</code>.
 *
 * @param join the join style to be used for drawing lines
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the style is not valid</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.1
 */
public void setLineJoin(int join) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (data.lineJoin == join) return;
	switch (join) {
		case SWT.JOIN_MITER:
		case SWT.JOIN_ROUND:
		case SWT.JOIN_BEVEL:
			break;
		default:
			SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	}
	data.lineJoin = join;
	data.state &= ~LINE_JOIN;
}

/**
 * Sets the receiver's line style to the argument, which must be one
 * of the constants <code>SWT.LINE_SOLID</code>, <code>SWT.LINE_DASH</code>,
 * <code>SWT.LINE_DOT</code>, <code>SWT.LINE_DASHDOT</code> or
 * <code>SWT.LINE_DASHDOTDOT</code>.
 *
 * @param lineStyle the style to be used for drawing lines
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the style is not valid</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setLineStyle(int lineStyle) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (data.lineStyle == lineStyle) return;
	switch (lineStyle) {
		case SWT.LINE_SOLID:
		case SWT.LINE_DASH:
		case SWT.LINE_DOT:
		case SWT.LINE_DASHDOT:
		case SWT.LINE_DASHDOTDOT:
			break;
		case SWT.LINE_CUSTOM:
			if (data.lineDashes == null) lineStyle = SWT.LINE_SOLID;
			break;
		default:
			SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	}
	data.lineStyle = lineStyle;
	data.state &= ~LINE_STYLE;
}

/**
 * Sets the width that will be used when drawing lines
 * for all of the figure drawing operations (that is,
 * <code>drawLine</code>, <code>drawRectangle</code>,
 * <code>drawPolyline</code>, and so forth.
 * <p>
 * Note that line width of zero is used as a hint to
 * indicate that the fastest possible line drawing
 * algorithms should be used. This means that the
 * output may be different from line width one and
 * specially at high DPI it's not recommended to mix
 * line width zero with other line widths.
 * </p>
 *
 * @param lineWidth the width of a line
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setLineWidth(int lineWidth) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	setLineWidthInPixels(DPIUtil.autoScaleUp(drawable, lineWidth));
}
void setLineWidthInPixels(int lineWidth) {
	if (data.lineWidth == lineWidth) return;
	data.lineWidth = lineWidth;
	data.state &= ~(LINE_WIDTH | DRAW_OFFSET);
}

void setString(String string, int flags) {
	if (data.layout == 0) createLayout();
	if (string == data.string && (flags & ~SWT.DRAW_TRANSPARENT) == (data.drawFlags  & ~SWT.DRAW_TRANSPARENT)) {
		return;
	}
	byte[] buffer;
	int mnemonic, length = string.length ();
	long /*int*/ layout = data.layout;
	char[] text = new char[length];
	string.getChars(0, length, text, 0);
	if ((flags & SWT.DRAW_MNEMONIC) != 0 && (mnemonic = fixMnemonic(text)) != -1) {
		char[] text1 = new char[mnemonic - 1];
		System.arraycopy(text, 0, text1, 0, text1.length);
		byte[] buffer1 = Converter.wcsToMbcs(text1, false);
		char[] text2 = new char[text.length - mnemonic];
		System.arraycopy(text, mnemonic - 1, text2, 0, text2.length);
		byte[] buffer2 = Converter.wcsToMbcs(text2, false);
		buffer = new byte[buffer1.length + buffer2.length];
		System.arraycopy(buffer1, 0, buffer, 0, buffer1.length);
		System.arraycopy(buffer2, 0, buffer, buffer1.length, buffer2.length);
		long /*int*/ attr_list = OS.pango_attr_list_new();
		long /*int*/ attr = OS.pango_attr_underline_new(OS.PANGO_UNDERLINE_LOW);
		PangoAttribute attribute = new PangoAttribute();
		OS.memmove(attribute, attr, PangoAttribute.sizeof);
		attribute.start_index = buffer1.length;
		attribute.end_index = buffer1.length + 1;
		OS.memmove(attr, attribute, PangoAttribute.sizeof);
		OS.pango_attr_list_insert(attr_list, attr);
		OS.pango_layout_set_attributes(layout, attr_list);
		OS.pango_attr_list_unref(attr_list);
	} else {
		buffer = Converter.wcsToMbcs(text, false);
		OS.pango_layout_set_attributes(layout, 0);
	}
	OS.pango_layout_set_text(layout, buffer, buffer.length);
	OS.pango_layout_set_single_paragraph_mode(layout, (flags & SWT.DRAW_DELIMITER) == 0);
	OS.pango_layout_set_tabs(layout, (flags & SWT.DRAW_TAB) != 0 ? 0 : data.device.emptyTab);
	data.string = string;
	data.stringWidth = data.stringHeight = -1;
	data.drawFlags = flags;
}

/**
 * Sets the receiver's text anti-aliasing value to the parameter,
 * which must be one of <code>SWT.DEFAULT</code>, <code>SWT.OFF</code>
 * or <code>SWT.ON</code>. Note that this controls anti-aliasing only
 * for all <em>text drawing</em> operations.
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 *
 * @param antialias the anti-aliasing setting
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the parameter is not one of <code>SWT.DEFAULT</code>,
 *                                 <code>SWT.OFF</code> or <code>SWT.ON</code></li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 *
 * @see #getAdvanced
 * @see #setAdvanced
 * @see #setAntialias
 *
 * @since 3.1
 */
public void setTextAntialias(int antialias) {
    if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (data.cairo == 0 && antialias == SWT.DEFAULT) return;
	int mode = 0;
	switch (antialias) {
		case SWT.DEFAULT: mode = Cairo.CAIRO_ANTIALIAS_DEFAULT; break;
		case SWT.OFF: mode = Cairo.CAIRO_ANTIALIAS_NONE; break;
		case SWT.ON: mode = Cairo.CAIRO_ANTIALIAS_GRAY;
            break;
		default:
			SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	}
    initCairo();
    long /*int*/ options = Cairo.cairo_font_options_create();
    Cairo.cairo_font_options_set_antialias(options, mode);
	if (data.context == 0) createLayout();
	OS.pango_cairo_context_set_font_options(data.context, options);
    Cairo.cairo_font_options_destroy(options);
}

/**
 * Sets the transform that is currently being used by the receiver. If
 * the argument is <code>null</code>, the current transform is set to
 * the identity transform.
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 *
 * @param transform the transform to set
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the parameter has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 *
 * @see Transform
 * @see #getAdvanced
 * @see #setAdvanced
 *
 * @since 3.1
 */
public void setTransform(Transform transform) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (transform != null && transform.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	if (data.cairo == 0 && transform == null) return;
	initCairo();
	long /*int*/ cairo = data.cairo;
	if (GTK.GTK_VERSION >= OS.VERSION (3, 14, 0)) {
		// Re-set the original Cairo transformation matrix: it contains a translation relative to the parent widget.
		if (currentTransform != null) {
			Cairo.cairo_set_matrix(cairo, cairoTransformationMatrix);
			currentTransform = null;
		}
		// Apply user transform on top of the current transformation matrix (and remember it)
		if (transform != null) {
			currentTransform = transform.handle.clone();
			double[] transformMatrix = identity();
			Cairo.cairo_matrix_multiply(transformMatrix, transform.handle, transformMatrix);
			Cairo.cairo_transform(cairo, transformMatrix);
		}
	} else {
		double[] identity = identity();
		if (transform != null) {
			Cairo.cairo_matrix_multiply(identity, transform.handle, identity);
		}
		Cairo.cairo_set_matrix(cairo, identity);
	}
	data.state &= ~DRAW_OFFSET;
}

/**
 * If the argument is <code>true</code>, puts the receiver
 * in a drawing mode where the resulting color in the destination
 * is the <em>exclusive or</em> of the color values in the source
 * and the destination, and if the argument is <code>false</code>,
 * puts the receiver in a drawing mode where the destination color
 * is replaced with the source color value.
 * <p>
 * Note that this mode in fundamentally unsupportable on certain
 * platforms, notably Carbon (Mac OS X). Clients that want their
 * code to run on all platforms need to avoid this method.
 * </p>
 *
 * @param xor if <code>true</code>, then <em>xor</em> mode is used, otherwise <em>source copy</em> mode is used
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @deprecated this functionality is not supported on some platforms
 */
@Deprecated
public void setXORMode(boolean xor) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (Cairo.cairo_version() >= Cairo.CAIRO_VERSION_ENCODE(1, 10, 0)) {
		Cairo.cairo_set_operator(handle, xor ? Cairo.CAIRO_OPERATOR_DIFFERENCE : Cairo.CAIRO_OPERATOR_OVER);
	}
	data.xorMode = xor;
}
/**
 * Returns the extent of the given string. No tab
 * expansion or carriage return processing will be performed.
 * <p>
 * The <em>extent</em> of a string is the width and height of
 * the rectangular area it would cover if drawn in a particular
 * font (in this case, the current font in the receiver).
 * </p>
 *
 * @param string the string to measure
 * @return a point containing the extent of the string
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public Point stringExtent(String string) {
	return DPIUtil.autoScaleDown(drawable, stringExtentInPixels(string));
}
Point stringExtentInPixels(String string) {
	return textExtentInPixels(string, 0);
}

/**
 * Returns the extent of the given string. Tab expansion and
 * carriage return processing are performed.
 * <p>
 * The <em>extent</em> of a string is the width and height of
 * the rectangular area it would cover if drawn in a particular
 * font (in this case, the current font in the receiver).
 * </p>
 *
 * @param string the string to measure
 * @return a point containing the extent of the string
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public Point textExtent(String string) {
	return DPIUtil.autoScaleDown(drawable, textExtentInPixels(string));
}

Point textExtentInPixels(String string) {
	return textExtentInPixels(string, SWT.DRAW_DELIMITER | SWT.DRAW_TAB);
}

/**
 * Returns the extent of the given string. Tab expansion, line
 * delimiter and mnemonic processing are performed according to
 * the specified flags, which can be a combination of:
 * <dl>
 * <dt><b>DRAW_DELIMITER</b></dt>
 * <dd>draw multiple lines</dd>
 * <dt><b>DRAW_TAB</b></dt>
 * <dd>expand tabs</dd>
 * <dt><b>DRAW_MNEMONIC</b></dt>
 * <dd>underline the mnemonic character</dd>
 * <dt><b>DRAW_TRANSPARENT</b></dt>
 * <dd>transparent background</dd>
 * </dl>
 * <p>
 * The <em>extent</em> of a string is the width and height of
 * the rectangular area it would cover if drawn in a particular
 * font (in this case, the current font in the receiver).
 * </p>
 *
 * @param string the string to measure
 * @param flags the flags specifying how to process the text
 * @return a point containing the extent of the string
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public Point textExtent(String string, int flags) {
	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (string == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	return DPIUtil.autoScaleDown(drawable, textExtentInPixels(string, flags));
}
Point textExtentInPixels(String string, int flags) {
	setString(string, flags);
	checkGC(FONT);
	if (data.stringWidth == -1) {
		computeStringSize();
	}
	return new Point(data.stringWidth, data.stringHeight);
}

/**
 * Returns a string containing a concise, human-readable
 * description of the receiver.
 *
 * @return a string representation of the receiver
 */
@Override
public String toString () {
	if (isDisposed()) return "GC {*DISPOSED*}";
	return "GC {" + handle + "}";
}

}