region.java

源码为Eclipse开源开发平台桌面开发工具SWT的源代码,

/*******************************************************************************
 * 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 Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.graphics;


import org.eclipse.swt.internal.win32.*;
import org.eclipse.swt.*;

/**
 * Instances of this class represent areas of an x-y coordinate
 * system that are aggregates of the areas covered by a number
 * of rectangles.
 * <p>
 * Application code must explicitly invoke the <code>Region.dispose()</code> 
 * method to release the operating system resources managed by each instance
 * when those instances are no longer required.
 * </p>
 */

public final class Region {
	
	/**
	 * the OS resource for the region
	 * (Warning: This field is platform dependent)
	 */
	public int handle;
	
	/**
	 * the device where this region was created
	 */
	Device device;

/**
 * Constructs a new empty region.
 * 
 * @exception SWTError <ul>
 *    <li>ERROR_NO_HANDLES if a handle could not be obtained for region creation</li>
 * </ul>
 */
public Region () {
	this(null);
}

/**
 * Constructs a new empty region.
 * <p>
 * You must dispose the region when it is no longer required. 
 * </p>
 *
 * @param device the device on which to allocate the region
 *
* @exception SWTError <ul>
 *    <li>ERROR_NO_HANDLES if a handle could not be obtained for region creation</li>
 * </ul>
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if device is null and there is no current device</li>
 * </ul>
 *
 * @see #dispose
 * 
 * @since 3.0
 */
public Region (Device device) {
	if (device == null) device = Device.getDevice();
	if (device == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	this.device = device;
	handle = OS.CreateRectRgn (0, 0, 0, 0);
	if (handle == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	if (device.tracking) device.new_Object(this);
}

/**
 * Constructs a new region given a handle to the operating
 * system resources that it should represent.
 * 
 * @param handle the handle for the result
 */
Region(Device device, int handle) {
	this.device = device;
	this.handle = handle;
}

/**
 * Adds the given polygon to the collection of rectangles
 * the receiver maintains to describe its area.
 *
 * @param pointArray points that describe the polygon to merge with the receiver
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @since 3.0
*
 */
public void add (int[] pointArray) {
	if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (pointArray == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (OS.IsWinCE) SWT.error(SWT.ERROR_NOT_IMPLEMENTED);
	int polyRgn = OS.CreatePolygonRgn(pointArray, pointArray.length / 2, OS.ALTERNATE);
	OS.CombineRgn (handle, handle, polyRgn, OS.RGN_OR);
	OS.DeleteObject (polyRgn);
}

/**
 * Adds the given rectangle to the collection of rectangles
 * the receiver maintains to describe its area.
 *
 * @param rect the rectangle to merge with the receiver
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the rectangle's width or height is negative</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void add (Rectangle rect) {
	if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (rect == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (rect.width < 0 || rect.height < 0) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	
	int rectRgn = OS.CreateRectRgn (rect.x, rect.y, rect.x + rect.width, rect.y + rect.height);
	OS.CombineRgn (handle, handle, rectRgn, OS.RGN_OR);
	OS.DeleteObject (rectRgn);
}

/**
 * Adds all of the rectangles which make up the area covered
 * by the argument to the collection of rectangles the receiver
 * maintains to describe its area.
 *
 * @param region the region to merge
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the argument has been disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void add (Region region) {
	if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	if (region == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (region.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	OS.CombineRgn (handle, handle, region.handle, OS.RGN_OR);
}

/**
 * Returns <code>true</code> if the point specified by the
 * arguments is inside the area specified by the receiver,
 * and <code>false</code> otherwise.
 *
 * @param x the x coordinate of the point to test for containment
 * @param y the y coordinate of the point to test for containment
 * @return <code>true</code> if the region contains the point and <code>false</code> otherwise
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public boolean contains (int x, int y) {
	if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	return OS.PtInRegion (handle, x, y);
}

/**
 * Returns <code>true</code> if the given point is inside the
 * area specified by the receiver, and <code>false</code>
 * otherwise.
 *
 * @param pt the point to test for containment
 * @return <code>true</code> if the region contains the point and <code>false</code> otherwise
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public boolean contains (Point pt) {
	if (pt == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	return contains(pt.x, pt.y);
}

/**
 * Disposes of the operating system resources associated with
 * the region. Applications must dispose of all regions which
 * they allocate.
 */
public void dispose () {
	if (handle == 0) return;
	if (device.isDisposed()) return;
	OS.DeleteObject(handle);
	handle = 0;
	if (device.tracking) device.dispose_Object(this);
	device = null;
}

/**
 * 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
 */
public boolean equals (Object object) {
	if (this == object) return true;
	if (!(object instanceof Region)) return false;
	Region rgn = (Region)object;
	return handle == rgn.handle;
}

/**
 * Returns a rectangle which represents the rectangular
 * union of the collection of rectangles the receiver
 * maintains to describe its area.
 *
 * @return a bounding rectangle for the region
 *
 * @exception SWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 *
 * @see Rectangle#union
 */
public Rectangle getBounds() {
	if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
	RECT rect = new RECT();
	OS.GetRgnBox(handle, rect);
	return new Rectangle(rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top);
}