/*******************************************************************************
 * Copyright (c) 2000, 2004 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.widgets;


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

/**
 * Instances of this class provide an i-beam that is typically used
 * as the insertion point for text.
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>(none)</dd>
 * <dt><b>Events:</b></dt>
 * <dd>(none)</dd>
 * </dl>
 * <p>
 * IMPORTANT: This class is intended to be subclassed <em>only</em>
 * within the SWT implementation.
 * </p>
 */
public class Caret extends Widget {
	Canvas parent;
	int x, y, width, height;
	boolean isVisible, isShowing;
	int blinkRate;
	Image image;
	Font font;

/**
 * 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>
 *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
 * </ul>
 *
 * @see SWT
 * @see Widget#checkSubclass
 * @see Widget#getStyle
 */
public Caret (Canvas parent, int style) {
	super (parent, style);
	this.parent = parent;
	createWidget (0);
}

boolean blinkCaret () {
	if (!isVisible) return true;
	if (!isShowing) return showCaret ();
	if (blinkRate == 0) return true;
	return hideCaret ();
}

void createWidget (int index) {
	super.createWidget (index);
	blinkRate = display.getCaretBlinkTime ();
	isVisible = true;
	if (parent.getCaret () == null) {
		parent.setCaret (this);
	}
}

boolean drawCaret () {
	if (parent == null) return false;
	if (parent.isDisposed ()) return false;
	int /*long*/ window = parent.paintWindow ();
	int /*long*/ gc = OS.gdk_gc_new (window);
	GdkColor color = new GdkColor ();
	color.red = (short) 0xffff;
	color.green = (short) 0xffff;
	color.blue = (short) 0xffff;
	int /*long*/ colormap = OS.gdk_colormap_get_system ();
	OS.gdk_colormap_alloc_color (colormap, color, true, true);
	OS.gdk_gc_set_foreground (gc, color);
	OS.gdk_gc_set_function (gc, OS.GDK_XOR);
	if (image != null && !image.isDisposed() && image.mask == 0) {
		int[] width = new int[1]; int[] height = new int[1];
	 	OS.gdk_drawable_get_size(image.pixmap, width, height);
		OS.gdk_draw_drawable(window, gc, image.pixmap, 0, 0, x, y, width[0], height[0]);
	} else {
		int nWidth = width, nHeight = height;
		if (nWidth <= 0) nWidth = 1;
		OS.gdk_draw_rectangle (window, gc, 1, x, y, nWidth, nHeight);
	}
	OS.g_object_unref (gc);
	OS.gdk_colormap_free_colors (colormap, color, 1);
	return true;
}

/**
 * Returns a rectangle describing the receiver's size and location
 * relative to its parent (or its display if its parent is null).
 *
 * @return the receiver's bounding rectangle
 *
 * @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 Rectangle getBounds () {
	checkWidget();
	if (image != null) {
		Rectangle rect = image.getBounds ();
		return new Rectangle (x, y, rect.width, rect.height);
	}
	return new Rectangle (x, y, width, height);
}

/**
 * Returns the font that the receiver will use to paint textual information.
 *
 * @return the receiver's font
 *
 * @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 Font getFont () {
	checkWidget();
	if (font != null) return font;
	return parent.getFont ();
}

/**
 * Returns the image that the receiver will use to paint the caret.
 *
 * @return the receiver's image
 *
 * @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 Image getImage () {
	checkWidget();
	return image;
}

/**
 * Returns a point describing the receiver's location relative
 * to its parent (or its display if its parent is null).
 *
 * @return the receiver's location
 *
 * @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 Point getLocation () {
	checkWidget();
	return new Point (x, y);
}

/**
 * Returns the receiver's parent, which must be a <code>Canvas</code>.
 *
 * @return the receiver's parent
 *
 * @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 Canvas getParent () {
	checkWidget();
	return parent;
}

/**
 * Returns a point describing the receiver's size.
 *
 * @return the receiver's size
 *
 * @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 Point getSize () {
	checkWidget();
	if (image != null) {
		Rectangle rect = image.getBounds ();
		return new Point (rect.width, rect.height);
	}
	return new Point (width, height);
}

/**
 * Returns <code>true</code> if the receiver is visible, and
 * <code>false</code> otherwise.
 * <p>
 * If one of the receiver's ancestors is not visible or some
 * other condition makes the receiver not visible, this method
 * may still indicate that it is considered visible even though
 * it may not actually be showing.
 * </p>
 *
 * @return the receiver's visibility state
 *
 * @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 boolean getVisible () {
	checkWidget();
	return isVisible;
}

boolean hideCaret () {
	if (!isShowing) return true;
	isShowing = false;
	return drawCaret ();
}

/**
 * Returns <code>true</code> if the receiver is visible and all
 * of the receiver's ancestors are visible and <code>false</code>
 * otherwise.
 *
 * @return the receiver's visibility state
 *
 * @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>
 *
 * @see #getVisible
 */
public boolean isVisible () {
	checkWidget();
	return isVisible && parent.isVisible () && parent.hasFocus ();
}

boolean isFocusCaret () {
	return this == display.currentCaret;
}

void killFocus () {
	if (display.currentCaret != this) return;
	display.setCurrentCaret (null);
	if (isVisible) hideCaret ();
}

void releaseChild () {
	super.releaseChild ();
	if (this == parent.getCaret ()) parent.setCaret (null);
}

void releaseWidget () {
	super.releaseWidget ();
	if (display.currentCaret == this) {
		hideCaret ();
		display.setCurrentCaret (null);
	}
	parent = null;
	image = null;
}

/**
 * Sets the receiver's size and location to the rectangular
 * area specified by the arguments. The <code>x</code> and 
 * <code>y</code> arguments are relative to the receiver's
 * parent (or its display if its parent is null).
 *
 * @param x the new x coordinate for the receiver
 * @param y the new y coordinate for the receiver
 * @param width the new width for the receiver
 * @param height the new height for the receiver
 *
 * @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 setBounds (int x, int y, int width, int height) {
	checkWidget();
	if (this.x == x && this.y == y && this.width == width && this.height == height) return;
	boolean isFocus = isFocusCaret ();
	if (isFocus && isVisible) hideCaret ();
	this.x = x; this.y = y;
	this.width = width; this.height = height;
	parent.updateCaret ();
	if (isFocus && isVisible) showCaret ();
}

/**
 * Sets the receiver's size and location to the rectangular
 * area specified by the argument. The <code>x</code> and 
 * <code>y</code> fields of the rectangle are relative to
 * the receiver's parent (or its display if its parent is null).
 *
 * @param rect the new bounds for the receiver
 *
 * @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 setBounds (Rectangle rect) {
	checkWidget();
	if (rect == null) error (SWT.ERROR_NULL_ARGUMENT);
	setBounds (rect.x, rect.y, rect.width, rect.height);
}

void setFocus () {
	if (display.currentCaret == this) return;
	display.setCurrentCaret (this);
	if (isVisible) showCaret ();
}

/**
 * Sets the font that the receiver will use to paint textual information
 * to the font specified by the argument, or to the default font for that
 * kind of control if the argument is null.
 *
 * @param font the new font (or null)
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the font 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 setFont (Font font) {
	checkWidget();
	if (font != null && font.isDisposed ()) {
		error (SWT.ERROR_INVALID_ARGUMENT);
	}
	this.font = font;
}

/**
 * Sets the image that the receiver will use to paint the caret
 * to the image specified by the argument, or to the default
 * which is a filled rectangle if the argument is null
 *
 * @param image the new image (or null)
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the image 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 setImage (Image image) {
	checkWidget();
	if (image != null && image.isDisposed ()) {
		error (SWT.ERROR_INVALID_ARGUMENT);
	}
	boolean isFocus = isFocusCaret ();
	if (isFocus && isVisible) hideCaret ();
	this.image = image;
	if (isFocus && isVisible) showCaret ();
}

/**
 * Sets the receiver's location to the point specified by
 * the arguments which are relative to the receiver's
 * parent (or its display if its parent is null).
 *
 * @param x the new x coordinate for the receiver
 * @param y the new y coordinate for the receiver
 *
 * @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 setLocation (int x, int y) {
	checkWidget();
	setBounds (x, y, width, height);
}

/**
 * Sets the receiver's location to the point specified by
 * the argument which is relative to the receiver's
 * parent (or its display if its parent is null).
 *
 * @param location the new location for the receiver
 *
 * @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 setLocation (Point location) {
	checkWidget();
	if (location == null) error (SWT.ERROR_NULL_ARGUMENT);
	setLocation (location.x, location.y);
}

/**
 * Sets the receiver's size to the point specified by the arguments.
 *
 * @param width the new width for the receiver
 * @param height the new height for the receiver
 *
 * @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 setSize (int width, int height) {
	checkWidget();
	setBounds (x, y, width, height);
}

/**
 * Sets the receiver's size to the point specified by the argument.
 *
 * @param size the new extent for the receiver
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the point is null</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 setSize (Point size) {
	checkWidget();
	if (size == null) error (SWT.ERROR_NULL_ARGUMENT);
	setSize (size.x, size.y);
}

/**
 * Marks the receiver as visible if the argument is <code>true</code>,
 * and marks it invisible otherwise. 
 * <p>
 * If one of the receiver's ancestors is not visible or some
 * other condition makes the receiver not visible, marking
 * it visible may not actually cause it to be displayed.
 * </p>
 *
 * @param visible the new visibility state
 *
 * @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 setVisible (boolean visible) {
	checkWidget();
	if (visible == isVisible) return;
	isVisible = visible;
	if (!isFocusCaret ()) return;
	if (isVisible) {
		showCaret ();
	} else {
		hideCaret ();
	}
}

boolean showCaret () {
	if (isShowing) return true;
	isShowing = true;
	return drawCaret ();
}

}