bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Canvas.java - platform/eclipse.platform.swt - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2018 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
  * which accompanies this distribution, and is available at
  * https://www.eclipse.org/legal/epl-2.0/
  *
  * SPDX-License-Identifier: EPL-2.0
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.swt.widgets;


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

 /**
  * Instances of this class provide a surface for drawing
  * arbitrary graphics.
  * <dl>
  * <dt><b>Styles:</b></dt>
  * <dd>(none)</dd>
  * <dt><b>Events:</b></dt>
  * <dd>(none)</dd>
  * </dl>
  * <p>
  * This class may be subclassed by custom control implementors
  * who are building controls that are <em>not</em> constructed
  * from aggregates of other controls. That is, they are either
  * painted using SWT graphics calls or are handled by native
  * methods.
  * </p>
  *
  * @see Composite
  * @see <a href="http://www.eclipse.org/swt/snippets/#canvas">Canvas snippets</a>
  * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: ControlExample</a>
  * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
  */
 public class Canvas extends Composite {
 	Caret caret;
 	IME ime;
 	boolean blink, drawFlag;

 Canvas () {}

 /**
  * Constructs a new instance of this class given its parent
  * and a style value describing its behavior and appearance.
  * <p>
  * The style value is either one of the style constants defined in
  * class <code>SWT</code> which is applicable to instances of this
  * class, or must be built by <em>bitwise OR</em>'ing together
  * (that is, using the <code>int</code> "|" operator) two or more
  * of those <code>SWT</code> style constants. The class description
  * lists the style constants that are applicable to the class.
  * Style bits are also inherited from superclasses.
  * </p>
  *
  * @param parent a composite control which will be the parent of the new instance (cannot be null)
  * @param style the style of control to construct
  *
  * @exception IllegalArgumentException <ul>
  *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
  * </ul>
  * @exception SWTException <ul>
  *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
  * </ul>
  *
  * @see SWT
  * @see Widget#getStyle
  */
 public Canvas (Composite parent, int style) {
 	super (parent, checkStyle (style));
 }

 /**
  * Fills the interior of the rectangle specified by the arguments,
  * with the receiver's background.
  *
  * @param gc the gc where the rectangle is to be filled
  * @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 IllegalArgumentException <ul>
  *    <li>ERROR_NULL_ARGUMENT - if the gc is null</li>
  *    <li>ERROR_INVALID_ARGUMENT - if the gc has been disposed</li>
  * </ul>
  * @exception SWTException <ul>
  *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
  *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
  * </ul>
  *
  * @since 3.2
  */
 public void drawBackground (GC gc, int x, int y, int width, int height) {
 	drawBackground (gc, x, y, width, height, 0, 0);
 }

 /**
  * Returns the caret.
  * <p>
  * The caret for the control is automatically hidden
  * and shown when the control is painted or resized,
  * when focus is gained or lost and when an the control
  * is scrolled.  To avoid drawing on top of the caret,
  * the programmer must hide and show the caret when
  * drawing in the window any other time.
  * </p>
  *
  * @return the caret for the receiver, may be null
  *
  * @exception SWTException <ul>
  *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
  *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
  * </ul>
  */
 public Caret getCaret () {
 	checkWidget();
 	return caret;
 }

 @Override
 Point getIMCaretPos () {
 	if (caret == null) return super.getIMCaretPos ();
 	return new Point (caret.x, caret.y);
 }

 /**
  * Returns the IME.
  *
  * @return the IME
  *
  * @exception SWTException <ul>
  *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
  *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
  * </ul>
  *
  * @since 3.4
  */
 public IME getIME () {
 	checkWidget ();
 	return ime;
 }

 @Override
 long gtk_button_press_event (long widget, long event) {
 	if (ime != null) {
 		long result = ime.gtk_button_press_event (widget, event);
 		if (result != 0) return result;
 	}
 	return  super.gtk_button_press_event (widget, event);
 }

 @Override
 long gtk_commit (long imcontext, long text) {
 	if (ime != null) {
 		long result = ime.gtk_commit (imcontext, text);
 		if (result != 0) return result;
 	}
 	return super.gtk_commit (imcontext, text);
 }

 @Override
 long gtk_draw (long widget, long cairo) {
 	if ((state & OBSCURED) != 0) return 0;
 	long result;
 	if ( GTK.GTK_VERSION < OS.VERSION(3, 22, 0)) {
 		boolean isFocus = caret != null && caret.isFocusCaret ();
 		if (isFocus) caret.killFocus ();
 		result = super.gtk_draw (widget, cairo);
 		if (isFocus) caret.setFocus ();
 	} else {
 		result = super.gtk_draw (widget, cairo);
 		/*
 		 *  blink is needed to be checked as gtk_draw() signals sent from other parts of the canvas
 		 *  can interfere with the blinking state. This will ensure that we are only draw/redrawing the
 		 *  caret when it is intended to. See Bug 517487.
 		 *
 		 *  Additionally, only draw the caret if it has focus. See bug 528819.
 		 */
 		if (caret != null && blink == true && caret.isFocusCaret()) {
 			drawCaret(widget,cairo);
 			blink = false;
 		}
 	}
 	return result;
 }

 private void drawCaret (long widget, long cairo) {
 	if(this.isDisposed()) return;
 	if (cairo == 0) error(SWT.ERROR_NO_HANDLES);
 	if (drawFlag) {
 		Cairo.cairo_save(cairo);
 		if (caret.image != null && !caret.image.isDisposed() && caret.image.mask == 0) {
 			Cairo.cairo_set_source_rgb(cairo, 1, 1, 1);
 			Cairo.cairo_set_operator(cairo, Cairo.CAIRO_OPERATOR_DIFFERENCE);
 			long surface = Cairo.cairo_get_target(cairo);
 			int nWidth = 0;
 			switch (Cairo.cairo_surface_get_type(surface)) {
 				case Cairo.CAIRO_SURFACE_TYPE_IMAGE:
 					nWidth = Cairo.cairo_image_surface_get_width(surface);
 					break;
 				case Cairo.CAIRO_SURFACE_TYPE_XLIB:
 					nWidth = Cairo.cairo_xlib_surface_get_width(surface);
 					break;
 			}
 			int nX = caret.x;
 			if ((style & SWT.MIRRORED) != 0) nX = getClientWidth () - nWidth - nX;
 			Cairo.cairo_translate(cairo, nX, caret.y);
 			Cairo.cairo_set_source_surface(cairo, caret.image.surface, 0, 0);
 			Cairo.cairo_paint(cairo);
 		} else {
 			Cairo.cairo_set_source_rgb(cairo, 1, 1, 1);
 			Cairo.cairo_set_operator(cairo, Cairo.CAIRO_OPERATOR_DIFFERENCE);
 			int nWidth = caret.width, nHeight = caret.height;
 			if (nWidth <= 0) nWidth = Caret.DEFAULT_WIDTH;
 			int nX = caret.x;
 			if ((style & SWT.MIRRORED) != 0) nX = getClientWidth () - nWidth - nX;
 			Cairo.cairo_rectangle(cairo, nX, caret.y, nWidth, nHeight);
 			}
 		Cairo.cairo_fill(cairo);
 		Cairo.cairo_restore(cairo);
 		drawFlag = false;
 	} else {
 		drawFlag = true;
 		}
 	return;
 }

 @Override
 long gtk_focus_in_event (long widget, long event) {
 	long result = super.gtk_focus_in_event (widget, event);
 	if (caret != null) caret.setFocus ();
 	return result;
 }

 @Override
 long gtk_focus_out_event (long widget, long event) {
 	long result = super.gtk_focus_out_event (widget, event);
 	if (caret != null) caret.killFocus ();
 	return result;
 }

 @Override
 long gtk_preedit_changed (long imcontext) {
 	if (ime != null) {
 		long result = ime.gtk_preedit_changed (imcontext);
 		if (result != 0) return result;
 	}
 	return super.gtk_preedit_changed (imcontext);
 }

 @Override
 void redrawWidget (int x, int y, int width, int height, boolean redrawAll, boolean all, boolean trim) {
 	boolean isFocus = caret != null && caret.isFocusCaret ();
 	if (isFocus) caret.killFocus ();
 	super.redrawWidget (x, y, width, height, redrawAll, all, trim);
 	if (isFocus) caret.setFocus ();
 }

 @Override
 void releaseChildren (boolean destroy) {
 	if (caret != null) {
 		caret.release (false);
 		caret = null;
 	}
 	if (ime != null) {
 		ime.release (false);
 		ime = null;
 	}
 	super.releaseChildren (destroy);
 }

 @Override
 void reskinChildren (int flags) {
 	if (caret != null) caret.reskin (flags);
 	if (ime != null)  ime.reskin (flags);
 	super.reskinChildren (flags);
 }

 /**
  * Scrolls a rectangular area of the receiver by first copying
  * the source area to the destination and then causing the area
  * of the source which is not covered by the destination to
  * be repainted. Children that intersect the rectangle are
  * optionally moved during the operation. In addition, all outstanding
  * paint events are flushed before the source area is copied to
  * ensure that the contents of the canvas are drawn correctly.
  *
  * @param destX the x coordinate of the destination
  * @param destY the y coordinate of the destination
  * @param x the x coordinate of the source
  * @param y the y coordinate of the source
  * @param width the width of the area
  * @param height the height of the area
  * @param all <code>true</code>if children should be scrolled, and <code>false</code> otherwise
  *
  * @exception SWTException <ul>
  *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
  *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
  * </ul>
  */
 public void scroll (int destX, int destY, int x, int y, int width, int height, boolean all) {
 	checkWidget();
 	if (width <= 0 || height <= 0) return;
 	/*
 	 * scrollInPixels() doesn't seem to be needed on GTK4, so we can return early.
 	 * In fact it doesn't seem to be needed on GTK3 either, but it's been left
 	 * here for stability on older GTK3 versions. The investigation
 	 * as to why it's unneeded is left as a TODO. See bug 546274.
 	 */
 	if (GTK.GTK4) return;
 	Point destination = DPIUtil.autoScaleUp (new Point (destX, destY));
 	Rectangle srcRect = DPIUtil.autoScaleUp (new Rectangle (x, y, width, height));
 	scrollInPixels(destination.x, destination.y, srcRect.x, srcRect.y, srcRect.width, srcRect.height, all);
 }

 void scrollInPixels (int destX, int destY, int x, int y, int width, int height, boolean all) {
 	if ((style & SWT.MIRRORED) != 0) {
 		int clientWidth = getClientWidth ();
 		x = clientWidth - width - x;
 		destX = clientWidth - width - destX;
 	}
 	int deltaX = destX - x, deltaY = destY - y;
 	if (deltaX == 0 && deltaY == 0) return;
 	if (!isVisible ()) return;
 	boolean isFocus = caret != null && caret.isFocusCaret ();
 	if (isFocus) caret.killFocus ();
 	long window = paintWindow ();
 	long visibleRegion = GDK.gdk_window_get_visible_region (window);
 	cairo_rectangle_int_t srcRect = new cairo_rectangle_int_t ();
 	srcRect.x = x;
 	srcRect.y = y;
 	/*
 	 * Feature in GTK: for 3.16+ the "visible" region in Canvas includes
 	 * the scrollbar dimensions in its calculations. This means the "previous"
 	 * location the scrollbars are re-painted when scrolling, causing the
 	 * hopping effect. See bug 480458.
 	 */
 	long hBarHandle = 0;
 	long vBarHandle = 0;
 	if (GTK.GTK_IS_SCROLLED_WINDOW(scrolledHandle)) {
 		hBarHandle = GTK.gtk_scrolled_window_get_hscrollbar (scrolledHandle);
 		vBarHandle = GTK.gtk_scrolled_window_get_vscrollbar (scrolledHandle);
 	}
 	GtkRequisition requisition = new GtkRequisition();
 	if (hBarHandle != 0) {
 		gtk_widget_get_preferred_size (hBarHandle, requisition);
 		if (requisition.height > 0) {
 			srcRect.y = y - requisition.height;
 		}
 	}
 	if (vBarHandle != 0) {
 		gtk_widget_get_preferred_size (vBarHandle, requisition);
 		if (requisition.width > 0) {
 			srcRect.x = x - requisition.width;
 		}
 	}
 	srcRect.width = width;
 	srcRect.height = height;
 	long copyRegion = Cairo.cairo_region_create_rectangle (srcRect);
 	Cairo.cairo_region_intersect(copyRegion, visibleRegion);
 	long invalidateRegion = Cairo.cairo_region_create_rectangle (srcRect);
 	Cairo.cairo_region_subtract (invalidateRegion, visibleRegion);
 	Cairo.cairo_region_translate (invalidateRegion, deltaX, deltaY);
 	cairo_rectangle_int_t copyRect = new cairo_rectangle_int_t();
 	Cairo.cairo_region_get_extents (copyRegion, copyRect);
 	if (copyRect.width != 0 && copyRect.height != 0) {
 		update ();
 	}
 	Control control = findBackgroundControl ();
 	if (control == null) control = this;
 	if (control.backgroundImage != null) {
 		redrawWidget (x, y, width, height, false, false, false);
 		redrawWidget (destX, destY, width, height, false, false, false);
 	} else {
 		long cairo = GDK.gdk_cairo_create(window);
 		if (Cairo.cairo_version() < Cairo.CAIRO_VERSION_ENCODE(1, 12, 0)) {
 			GDK.gdk_cairo_set_source_window(cairo, window, 0, 0);
 		} else {
 			Cairo.cairo_push_group(cairo);
 			GDK.gdk_cairo_set_source_window(cairo, window, 0, 0);
 			Cairo.cairo_paint(cairo);
 			Cairo.cairo_pop_group_to_source(cairo);
 		}
 		double[] matrix = {1, 0, 0, 1, -deltaX, -deltaY};
 		Cairo.cairo_pattern_set_matrix(Cairo.cairo_get_source(cairo), matrix);
 		Cairo.cairo_rectangle(cairo, copyRect.x + deltaX, copyRect.y + deltaY, copyRect.width, copyRect.height);
 		Cairo.cairo_clip(cairo);
 		Cairo.cairo_paint(cairo);
 		Cairo.cairo_destroy(cairo);
 		boolean disjoint = (destX + width < x) || (x + width < destX) || (destY + height < y) || (y + height < destY);
 		if (disjoint) {
 			cairo_rectangle_int_t rect = new cairo_rectangle_int_t();
 			rect.x = x;
 			rect.y = y;
 			rect.width = width;
 			rect.height = height;
 			Cairo.cairo_region_union_rectangle (invalidateRegion, rect);
 		} else {
 			cairo_rectangle_int_t rect = new cairo_rectangle_int_t();
 			if (deltaX != 0) {
 				int newX = destX - deltaX;
 				if (deltaX < 0) newX = destX + width;
 				rect.x = newX;
 				rect.y = y;
 				rect.width = Math.abs(deltaX);
 				rect.height = height;
 				Cairo.cairo_region_union_rectangle (invalidateRegion, rect);
 			}
 			if (deltaY != 0) {
 				int newY = destY - deltaY;
 				if (deltaY < 0) newY = destY + height;
 				rect.x = x;
 				rect.y = newY;
 				rect.width = width;
 				rect.height = Math.abs(deltaY);
 				Cairo.cairo_region_union_rectangle (invalidateRegion, rect);
 			}
 		}
 		GDK.gdk_window_invalidate_region(window, invalidateRegion, all);
 	}
 	Cairo.cairo_region_destroy (visibleRegion);
 	Cairo.cairo_region_destroy (copyRegion);
 	Cairo.cairo_region_destroy (invalidateRegion);
 	if (all) {
 		Control [] children = _getChildren ();
 		for (int i=0; i<children.length; i++) {
 			Control child = children [i];
 			Rectangle rect = child.getBoundsInPixels ();
 			if (Math.min(x + width, rect.x + rect.width) >= Math.max (x, rect.x) &&
 				Math.min(y + height, rect.y + rect.height) >= Math.max (y, rect.y)) {
 					child.setLocationInPixels (rect.x + deltaX, rect.y + deltaY);
 			}
 		}
 	}
 	if (isFocus) caret.setFocus ();
 	/*
 	 * Due to overlay drawing of scrollbars current method of scrolling leaves scrollbar and notifiers for them inside the canvas
 	 * after scroll. Fix is to redraw once done.
 	 */
 	redraw(false);
 }

 @Override
 int setBounds (int x, int y, int width, int height, boolean move, boolean resize) {
 	boolean isFocus = caret != null && caret.isFocusCaret ();
 	if (isFocus) caret.killFocus ();
 	int result = super.setBounds (x, y, width, height, move, resize);
 	if (isFocus) caret.setFocus ();
 	return result;
 }

 /**
  * Sets the receiver's caret.
  * <p>
  * The caret for the control is automatically hidden
  * and shown when the control is painted or resized,
  * when focus is gained or lost and when an the control
  * is scrolled.  To avoid drawing on top of the caret,
  * the programmer must hide and show the caret when
  * drawing in the window any other time.
  * </p>
  * @param caret the new caret for the receiver, may be null
  *
  * @exception IllegalArgumentException <ul>
  *    <li>ERROR_INVALID_ARGUMENT - if the caret has been disposed</li>
  * </ul>
  * @exception SWTException <ul>
  *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
  *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
  * </ul>
  */
 public void setCaret (Caret caret) {
 	checkWidget();
 	Caret newCaret = caret;
 	Caret oldCaret = this.caret;
 	this.caret = newCaret;
 	if (hasFocus ()) {
 		if (oldCaret != null) oldCaret.killFocus ();
 		if (newCaret != null) {
 			if (newCaret.isDisposed()) error(SWT.ERROR_INVALID_ARGUMENT);
 			newCaret.setFocus ();
 		}
 	}
 }

 @Override
 public void setFont (Font font) {
 	checkWidget();
 	if (caret != null) caret.setFont (font);
 	super.setFont (font);
 }

 /**
  * Sets the receiver's IME.
  *
  * @param ime the new IME for the receiver, may be null
  *
  * @exception IllegalArgumentException <ul>
  *    <li>ERROR_INVALID_ARGUMENT - if the IME has been disposed</li>
  * </ul>
  * @exception SWTException <ul>
  *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
  *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
  * </ul>
  *
  * @since 3.4
  */
 public void setIME (IME ime) {
 	checkWidget ();
 	if (ime != null && ime.isDisposed()) error(SWT.ERROR_INVALID_ARGUMENT);
 	this.ime = ime;
 }

 void updateCaret () {
 	long imHandle = imHandle ();
 	if (imHandle == 0) return;
 	GdkRectangle rect = new GdkRectangle ();
 	rect.x = caret.x;
 	rect.y = caret.y;
 	rect.width = caret.width;
 	rect.height = caret.height;
 	GTK.gtk_im_context_set_cursor_location (imHandle, rect);
 }

 }
	/*******************************************************************************
	* Copyright (c) 2000, 2018 IBM Corporation and others.
	*
	* This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License 2.0
	* which accompanies this distribution, and is available at
	* https://www.eclipse.org/legal/epl-2.0/
	*
	* SPDX-License-Identifier: EPL-2.0
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/
	package org.eclipse.swt.widgets;


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

	/**
	* Instances of this class provide a surface for drawing
	* arbitrary graphics.
	* <dl>
	* <dt><b>Styles:</b></dt>
	* <dd>(none)</dd>
	* <dt><b>Events:</b></dt>
	* <dd>(none)</dd>
	* </dl>
	* <p>
	* This class may be subclassed by custom control implementors
	* who are building controls that are <em>not</em> constructed
	* from aggregates of other controls. That is, they are either
	* painted using SWT graphics calls or are handled by native
	* methods.
	* </p>
	*
	* @see Composite
	* @see <a href="http://www.eclipse.org/swt/snippets/#canvas">Canvas snippets</a>
	* @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: ControlExample</a>
	* @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
	*/
	public class Canvas extends Composite {
	Caret caret;
	IME ime;
	boolean blink, drawFlag;

	Canvas () {}

	/**
	* Constructs a new instance of this class given its parent
	* and a style value describing its behavior and appearance.
	* <p>
	* The style value is either one of the style constants defined in
	* class <code>SWT</code> which is applicable to instances of this
	* class, or must be built by <em>bitwise OR</em>'ing together
	* (that is, using the <code>int</code> "\|" operator) two or more
	* of those <code>SWT</code> style constants. The class description
	* lists the style constants that are applicable to the class.
	* Style bits are also inherited from superclasses.
	* </p>
	*
	* @param parent a composite control which will be the parent of the new instance (cannot be null)
	* @param style the style of control to construct
	*
	* @exception IllegalArgumentException <ul>
	* <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
	* </ul>
	* @exception SWTException <ul>
	* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
	* </ul>
	*
	* @see SWT
	* @see Widget#getStyle
	*/
	public Canvas (Composite parent, int style) {
	super (parent, checkStyle (style));
	}

	/**
	* Fills the interior of the rectangle specified by the arguments,
	* with the receiver's background.
	*
	* @param gc the gc where the rectangle is to be filled
	* @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 IllegalArgumentException <ul>
	* <li>ERROR_NULL_ARGUMENT - if the gc is null</li>
	* <li>ERROR_INVALID_ARGUMENT - if the gc has been disposed</li>
	* </ul>
	* @exception SWTException <ul>
	* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
	* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
	* </ul>
	*
	* @since 3.2
	*/
	public void drawBackground (GC gc, int x, int y, int width, int height) {
	drawBackground (gc, x, y, width, height, 0, 0);
	}

	/**
	* Returns the caret.
	* <p>
	* The caret for the control is automatically hidden
	* and shown when the control is painted or resized,
	* when focus is gained or lost and when an the control
	* is scrolled. To avoid drawing on top of the caret,
	* the programmer must hide and show the caret when
	* drawing in the window any other time.
	* </p>
	*
	* @return the caret for the receiver, may be null
	*
	* @exception SWTException <ul>
	* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
	* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
	* </ul>
	*/
	public Caret getCaret () {
	checkWidget();
	return caret;
	}

	@Override
	Point getIMCaretPos () {
	if (caret == null) return super.getIMCaretPos ();
	return new Point (caret.x, caret.y);
	}

	/**
	* Returns the IME.
	*
	* @return the IME
	*
	* @exception SWTException <ul>
	* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
	* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
	* </ul>
	*
	* @since 3.4
	*/
	public IME getIME () {
	checkWidget ();
	return ime;
	}

	@Override
	long gtk_button_press_event (long widget, long event) {
	if (ime != null) {
	long result = ime.gtk_button_press_event (widget, event);
	if (result != 0) return result;
	}
	return super.gtk_button_press_event (widget, event);
	}

	@Override
	long gtk_commit (long imcontext, long text) {
	if (ime != null) {
	long result = ime.gtk_commit (imcontext, text);
	if (result != 0) return result;
	}
	return super.gtk_commit (imcontext, text);
	}

	@Override
	long gtk_draw (long widget, long cairo) {
	if ((state & OBSCURED) != 0) return 0;
	long result;
	if ( GTK.GTK_VERSION < OS.VERSION(3, 22, 0)) {
	boolean isFocus = caret != null && caret.isFocusCaret ();
	if (isFocus) caret.killFocus ();
	result = super.gtk_draw (widget, cairo);
	if (isFocus) caret.setFocus ();
	} else {
	result = super.gtk_draw (widget, cairo);
	/*
	* blink is needed to be checked as gtk_draw() signals sent from other parts of the canvas
	* can interfere with the blinking state. This will ensure that we are only draw/redrawing the
	* caret when it is intended to. See Bug 517487.
	*
	* Additionally, only draw the caret if it has focus. See bug 528819.
	*/
	if (caret != null && blink == true && caret.isFocusCaret()) {
	drawCaret(widget,cairo);
	blink = false;
	}
	}
	return result;
	}

	private void drawCaret (long widget, long cairo) {
	if(this.isDisposed()) return;
	if (cairo == 0) error(SWT.ERROR_NO_HANDLES);
	if (drawFlag) {
	Cairo.cairo_save(cairo);
	if (caret.image != null && !caret.image.isDisposed() && caret.image.mask == 0) {
	Cairo.cairo_set_source_rgb(cairo, 1, 1, 1);
	Cairo.cairo_set_operator(cairo, Cairo.CAIRO_OPERATOR_DIFFERENCE);
	long surface = Cairo.cairo_get_target(cairo);
	int nWidth = 0;
	switch (Cairo.cairo_surface_get_type(surface)) {
	case Cairo.CAIRO_SURFACE_TYPE_IMAGE:
	nWidth = Cairo.cairo_image_surface_get_width(surface);
	break;
	case Cairo.CAIRO_SURFACE_TYPE_XLIB:
	nWidth = Cairo.cairo_xlib_surface_get_width(surface);
	break;
	}
	int nX = caret.x;
	if ((style & SWT.MIRRORED) != 0) nX = getClientWidth () - nWidth - nX;
	Cairo.cairo_translate(cairo, nX, caret.y);
	Cairo.cairo_set_source_surface(cairo, caret.image.surface, 0, 0);
	Cairo.cairo_paint(cairo);
	} else {
	Cairo.cairo_set_source_rgb(cairo, 1, 1, 1);
	Cairo.cairo_set_operator(cairo, Cairo.CAIRO_OPERATOR_DIFFERENCE);
	int nWidth = caret.width, nHeight = caret.height;
	if (nWidth <= 0) nWidth = Caret.DEFAULT_WIDTH;
	int nX = caret.x;
	if ((style & SWT.MIRRORED) != 0) nX = getClientWidth () - nWidth - nX;
	Cairo.cairo_rectangle(cairo, nX, caret.y, nWidth, nHeight);
	}
	Cairo.cairo_fill(cairo);
	Cairo.cairo_restore(cairo);
	drawFlag = false;
	} else {
	drawFlag = true;
	}
	return;
	}

	@Override
	long gtk_focus_in_event (long widget, long event) {
	long result = super.gtk_focus_in_event (widget, event);
	if (caret != null) caret.setFocus ();
	return result;
	}

	@Override
	long gtk_focus_out_event (long widget, long event) {
	long result = super.gtk_focus_out_event (widget, event);
	if (caret != null) caret.killFocus ();
	return result;
	}

	@Override
	long gtk_preedit_changed (long imcontext) {
	if (ime != null) {
	long result = ime.gtk_preedit_changed (imcontext);
	if (result != 0) return result;
	}
	return super.gtk_preedit_changed (imcontext);
	}

	@Override
	void redrawWidget (int x, int y, int width, int height, boolean redrawAll, boolean all, boolean trim) {
	boolean isFocus = caret != null && caret.isFocusCaret ();
	if (isFocus) caret.killFocus ();
	super.redrawWidget (x, y, width, height, redrawAll, all, trim);
	if (isFocus) caret.setFocus ();
	}

	@Override
	void releaseChildren (boolean destroy) {
	if (caret != null) {
	caret.release (false);
	caret = null;
	}
	if (ime != null) {
	ime.release (false);
	ime = null;
	}
	super.releaseChildren (destroy);
	}

	@Override
	void reskinChildren (int flags) {
	if (caret != null) caret.reskin (flags);
	if (ime != null) ime.reskin (flags);
	super.reskinChildren (flags);
	}

	/**
	* Scrolls a rectangular area of the receiver by first copying
	* the source area to the destination and then causing the area
	* of the source which is not covered by the destination to
	* be repainted. Children that intersect the rectangle are
	* optionally moved during the operation. In addition, all outstanding
	* paint events are flushed before the source area is copied to
	* ensure that the contents of the canvas are drawn correctly.
	*
	* @param destX the x coordinate of the destination
	* @param destY the y coordinate of the destination
	* @param x the x coordinate of the source
	* @param y the y coordinate of the source
	* @param width the width of the area
	* @param height the height of the area
	* @param all <code>true</code>if children should be scrolled, and <code>false</code> otherwise
	*
	* @exception SWTException <ul>
	* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
	* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
	* </ul>
	*/
	public void scroll (int destX, int destY, int x, int y, int width, int height, boolean all) {
	checkWidget();
	if (width <= 0 \|\| height <= 0) return;
	/*
	* scrollInPixels() doesn't seem to be needed on GTK4, so we can return early.
	* In fact it doesn't seem to be needed on GTK3 either, but it's been left
	* here for stability on older GTK3 versions. The investigation
	* as to why it's unneeded is left as a TODO. See bug 546274.
	*/
	if (GTK.GTK4) return;
	Point destination = DPIUtil.autoScaleUp (new Point (destX, destY));
	Rectangle srcRect = DPIUtil.autoScaleUp (new Rectangle (x, y, width, height));
	scrollInPixels(destination.x, destination.y, srcRect.x, srcRect.y, srcRect.width, srcRect.height, all);
	}

	void scrollInPixels (int destX, int destY, int x, int y, int width, int height, boolean all) {
	if ((style & SWT.MIRRORED) != 0) {
	int clientWidth = getClientWidth ();
	x = clientWidth - width - x;
	destX = clientWidth - width - destX;
	}
	int deltaX = destX - x, deltaY = destY - y;
	if (deltaX == 0 && deltaY == 0) return;
	if (!isVisible ()) return;
	boolean isFocus = caret != null && caret.isFocusCaret ();
	if (isFocus) caret.killFocus ();
	long window = paintWindow ();
	long visibleRegion = GDK.gdk_window_get_visible_region (window);
	cairo_rectangle_int_t srcRect = new cairo_rectangle_int_t ();
	srcRect.x = x;
	srcRect.y = y;
	/*
	* Feature in GTK: for 3.16+ the "visible" region in Canvas includes
	* the scrollbar dimensions in its calculations. This means the "previous"
	* location the scrollbars are re-painted when scrolling, causing the
	* hopping effect. See bug 480458.
	*/
	long hBarHandle = 0;
	long vBarHandle = 0;
	if (GTK.GTK_IS_SCROLLED_WINDOW(scrolledHandle)) {
	hBarHandle = GTK.gtk_scrolled_window_get_hscrollbar (scrolledHandle);
	vBarHandle = GTK.gtk_scrolled_window_get_vscrollbar (scrolledHandle);
	}
	GtkRequisition requisition = new GtkRequisition();
	if (hBarHandle != 0) {
	gtk_widget_get_preferred_size (hBarHandle, requisition);
	if (requisition.height > 0) {
	srcRect.y = y - requisition.height;
	}
	}
	if (vBarHandle != 0) {
	gtk_widget_get_preferred_size (vBarHandle, requisition);
	if (requisition.width > 0) {
	srcRect.x = x - requisition.width;
	}
	}
	srcRect.width = width;
	srcRect.height = height;
	long copyRegion = Cairo.cairo_region_create_rectangle (srcRect);
	Cairo.cairo_region_intersect(copyRegion, visibleRegion);
	long invalidateRegion = Cairo.cairo_region_create_rectangle (srcRect);
	Cairo.cairo_region_subtract (invalidateRegion, visibleRegion);
	Cairo.cairo_region_translate (invalidateRegion, deltaX, deltaY);
	cairo_rectangle_int_t copyRect = new cairo_rectangle_int_t();
	Cairo.cairo_region_get_extents (copyRegion, copyRect);
	if (copyRect.width != 0 && copyRect.height != 0) {
	update ();
	}
	Control control = findBackgroundControl ();
	if (control == null) control = this;
	if (control.backgroundImage != null) {
	redrawWidget (x, y, width, height, false, false, false);
	redrawWidget (destX, destY, width, height, false, false, false);
	} else {
	long cairo = GDK.gdk_cairo_create(window);
	if (Cairo.cairo_version() < Cairo.CAIRO_VERSION_ENCODE(1, 12, 0)) {
	GDK.gdk_cairo_set_source_window(cairo, window, 0, 0);
	} else {
	Cairo.cairo_push_group(cairo);
	GDK.gdk_cairo_set_source_window(cairo, window, 0, 0);
	Cairo.cairo_paint(cairo);
	Cairo.cairo_pop_group_to_source(cairo);
	}
	double[] matrix = {1, 0, 0, 1, -deltaX, -deltaY};
	Cairo.cairo_pattern_set_matrix(Cairo.cairo_get_source(cairo), matrix);
	Cairo.cairo_rectangle(cairo, copyRect.x + deltaX, copyRect.y + deltaY, copyRect.width, copyRect.height);
	Cairo.cairo_clip(cairo);
	Cairo.cairo_paint(cairo);
	Cairo.cairo_destroy(cairo);
	boolean disjoint = (destX + width < x) \|\| (x + width < destX) \|\| (destY + height < y) \|\| (y + height < destY);
	if (disjoint) {
	cairo_rectangle_int_t rect = new cairo_rectangle_int_t();
	rect.x = x;
	rect.y = y;
	rect.width = width;
	rect.height = height;
	Cairo.cairo_region_union_rectangle (invalidateRegion, rect);
	} else {
	cairo_rectangle_int_t rect = new cairo_rectangle_int_t();
	if (deltaX != 0) {
	int newX = destX - deltaX;
	if (deltaX < 0) newX = destX + width;
	rect.x = newX;
	rect.y = y;
	rect.width = Math.abs(deltaX);
	rect.height = height;
	Cairo.cairo_region_union_rectangle (invalidateRegion, rect);
	}
	if (deltaY != 0) {
	int newY = destY - deltaY;
	if (deltaY < 0) newY = destY + height;
	rect.x = x;
	rect.y = newY;
	rect.width = width;
	rect.height = Math.abs(deltaY);
	Cairo.cairo_region_union_rectangle (invalidateRegion, rect);
	}
	}
	GDK.gdk_window_invalidate_region(window, invalidateRegion, all);
	}
	Cairo.cairo_region_destroy (visibleRegion);
	Cairo.cairo_region_destroy (copyRegion);
	Cairo.cairo_region_destroy (invalidateRegion);
	if (all) {
	Control [] children = _getChildren ();
	for (int i=0; i<children.length; i++) {
	Control child = children [i];
	Rectangle rect = child.getBoundsInPixels ();
	if (Math.min(x + width, rect.x + rect.width) >= Math.max (x, rect.x) &&
	Math.min(y + height, rect.y + rect.height) >= Math.max (y, rect.y)) {
	child.setLocationInPixels (rect.x + deltaX, rect.y + deltaY);
	}
	}
	}
	if (isFocus) caret.setFocus ();
	/*
	* Due to overlay drawing of scrollbars current method of scrolling leaves scrollbar and notifiers for them inside the canvas
	* after scroll. Fix is to redraw once done.
	*/
	redraw(false);
	}

	@Override
	int setBounds (int x, int y, int width, int height, boolean move, boolean resize) {
	boolean isFocus = caret != null && caret.isFocusCaret ();
	if (isFocus) caret.killFocus ();
	int result = super.setBounds (x, y, width, height, move, resize);
	if (isFocus) caret.setFocus ();
	return result;
	}

	/**
	* Sets the receiver's caret.
	* <p>
	* The caret for the control is automatically hidden
	* and shown when the control is painted or resized,
	* when focus is gained or lost and when an the control
	* is scrolled. To avoid drawing on top of the caret,
	* the programmer must hide and show the caret when
	* drawing in the window any other time.
	* </p>
	* @param caret the new caret for the receiver, may be null
	*
	* @exception IllegalArgumentException <ul>
	* <li>ERROR_INVALID_ARGUMENT - if the caret has been disposed</li>
	* </ul>
	* @exception SWTException <ul>
	* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
	* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
	* </ul>
	*/
	public void setCaret (Caret caret) {
	checkWidget();
	Caret newCaret = caret;
	Caret oldCaret = this.caret;
	this.caret = newCaret;
	if (hasFocus ()) {
	if (oldCaret != null) oldCaret.killFocus ();
	if (newCaret != null) {
	if (newCaret.isDisposed()) error(SWT.ERROR_INVALID_ARGUMENT);
	newCaret.setFocus ();
	}
	}
	}

	@Override
	public void setFont (Font font) {
	checkWidget();
	if (caret != null) caret.setFont (font);
	super.setFont (font);
	}

	/**
	* Sets the receiver's IME.
	*
	* @param ime the new IME for the receiver, may be null
	*
	* @exception IllegalArgumentException <ul>
	* <li>ERROR_INVALID_ARGUMENT - if the IME has been disposed</li>
	* </ul>
	* @exception SWTException <ul>
	* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
	* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
	* </ul>
	*
	* @since 3.4
	*/
	public void setIME (IME ime) {
	checkWidget ();
	if (ime != null && ime.isDisposed()) error(SWT.ERROR_INVALID_ARGUMENT);
	this.ime = ime;
	}

	void updateCaret () {
	long imHandle = imHandle ();
	if (imHandle == 0) return;
	GdkRectangle rect = new GdkRectangle ();
	rect.x = caret.x;
	rect.y = caret.y;
	rect.width = caret.width;
	rect.height = caret.height;
	GTK.gtk_im_context_set_cursor_location (imHandle, rect);
	}

	}