cursor.java

源码为Eclipse开源开发平台桌面开发工具SWT的源代码,

 * <p>
 * The mask data is allowed to be null, but in this case the source
 * must be an ImageData representing an icon that specifies both
 * color data and mask data.
 * <p>
 * You must dispose the cursor when it is no longer required. 
 * </p>
 *
 * @param device the device on which to allocate the cursor
 * @param source the color data for the cursor
 * @param mask the mask data for the cursor (or null)
 * @param hotspotX the x coordinate of the cursor's hotspot
 * @param hotspotY the y coordinate of the cursor's hotspot
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if device is null and there is no current device</li>
 *    <li>ERROR_NULL_ARGUMENT - if the source is null</li>
 *    <li>ERROR_NULL_ARGUMENT - if the mask is null and the source does not have a mask</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the source and the mask are not the same 
 *          size, or either is not of depth one, or if the hotspot is outside 
 *          the bounds of the image</li>
 * </ul>
 * @exception SWTError <ul>
 *    <li>ERROR_NO_HANDLES - if a handle could not be obtained for cursor creation</li>
 * </ul>
 */
public Cursor(Device device, ImageData source, ImageData mask, int hotspotX, int hotspotY) {
	if (device == null) device = Device.getDevice();
	if (device == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	this.device = device;
	if (source == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (mask == null) {
		if (source.getTransparencyType() != SWT.TRANSPARENCY_MASK) {
			SWT.error(SWT.ERROR_NULL_ARGUMENT);
		}
		mask = source.getTransparencyMask();
	}
	/* Check the bounds. Mask must be the same size as source */
	if (mask.width != source.width || mask.height != source.height) {
		SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	}
	/* Check color depths */
	if (mask.depth != 1) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	if (source.depth != 1) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	/* Check the hotspots */
	if (hotspotX >= source.width || hotspotX < 0 ||
		hotspotY >= source.height || hotspotY < 0) {
		SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	}

	/* Make sure source and mask scanline pad is 2 */
	byte[] sourceData = ImageData.convertPad(source.data, source.width, source.height, source.depth, source.scanlinePad, 2);
	byte[] maskData = ImageData.convertPad(mask.data, mask.width, mask.height, mask.depth, mask.scanlinePad, 2);
	
	/* Create the cursor */
	int hInst = OS.GetModuleHandle(null);
	if (OS.IsWinCE) SWT.error (SWT.ERROR_NOT_IMPLEMENTED);
	handle = OS.CreateCursor(hInst, hotspotX, hotspotY, source.width, source.height, sourceData, maskData);
	if (handle == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	if (device.tracking) device.new_Object(this);
}

/**	 
 * Constructs a new cursor given a device, image data describing
 * the desired cursor appearance, and the x and y coordinates of
 * the <em>hotspot</em> (that is, the point within the area
 * covered by the cursor which is considered to be where the
 * on-screen pointer is "pointing").
 * <p>
 * You must dispose the cursor when it is no longer required. 
 * </p>
 *
 * @param device the device on which to allocate the cursor
 * @param source the image data for the cursor
 * @param hotspotX the x coordinate of the cursor's hotspot
 * @param hotspotY the y coordinate of the cursor's hotspot
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if device is null and there is no current device</li>
 *    <li>ERROR_NULL_ARGUMENT - if the image is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the hotspot is outside the bounds of the
 * 		 image</li>
 * </ul>
 * @exception SWTError <ul>
 *    <li>ERROR_NO_HANDLES - if a handle could not be obtained for cursor creation</li>
 * </ul>
 * 
 * @since 3.0
 */
public Cursor(Device device, ImageData source, int hotspotX, int hotspotY) {
	if (device == null) device = Device.getDevice();
	if (device == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	this.device = device;
	if (source == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	/* Check the hotspots */
	if (hotspotX >= source.width || hotspotX < 0 ||
		hotspotY >= source.height || hotspotY < 0) {
		SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	}
	ImageData mask = source.getTransparencyMask();
	int[] result = Image.init(device, null, source, mask);
	int hBitmap = result[0];
	int hMask = result[1];
	/* Create the icon */
	ICONINFO info = new ICONINFO();
	info.fIcon = true;
	info.hbmColor = hBitmap;
	info.hbmMask = hMask;
	handle = OS.CreateIconIndirect(info);
	if (handle == 0) SWT.error(SWT.ERROR_NO_HANDLES);
	OS.DeleteObject(hBitmap);
	OS.DeleteObject(hMask);
	isIcon = true;
	if (device.tracking) device.new_Object(this);
}

/**
 * Disposes of the operating system resources associated with
 * the cursor. Applications must dispose of all cursors which
 * they allocate.
 */
public void dispose () {
	if (handle == 0) return;
	if (device.isDisposed()) return;
	
	/*
	* It is an error in Windows to destroy the current
	* cursor.  Check that the cursor that is about to
	* be destroyed is the current cursor.  If so, set
	* the current cursor to be IDC_ARROW.  Note that
	* Windows shares predefined cursors so the call to
	* LoadCursor() does not leak.
	*/
	// TEMPORARY CODE
//	if (OS.GetCursor() == handle) {
//		OS.SetCursor(OS.LoadCursor(0, OS.IDC_ARROW));
//	}
	
	if (isIcon) {
		OS.DestroyIcon(handle);
	} else {
		/*
	 	* The MSDN states that one should not destroy a shared
	 	* cursor, that is, one obtained from LoadCursor.
	 	* However, it does not appear to do any harm, so rather
	 	* than keep track of how a cursor was created, we just
	 	* destroy them all. If this causes problems in the future,
	 	* put the flag back in.
		*/
		if (!OS.IsWinCE) OS.DestroyCursor(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 (object == this) return true;
	if (!(object instanceof Cursor)) return false;
	Cursor cursor = (Cursor) object;
	return device == cursor.device && handle == cursor.handle;
}

/**
 * Returns an integer hash code for the receiver. Any two 
 * objects which return <code>true</code> when passed to 
 * <code>equals</code> must return the same value for this
 * method.
 *
 * @return the receiver's hash
 *
 * @see #equals
 */
public int hashCode () {
	return handle;
}

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

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

/**	 
 * Invokes platform specific functionality to allocate a new cursor.
 * <p>
 * <b>IMPORTANT:</b> This method is <em>not</em> part of the public
 * API for <code>Cursor</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 device the device on which to allocate the color
 * @param handle the handle for the cursor
 * @return a new cursor object containing the specified device and handle
 */
public static Cursor win32_new(Device device, int handle) {
	if (device == null) device = Device.getDevice();
	Cursor cursor = new Cursor();
	cursor.handle = handle;
	cursor.device = device;
	return cursor;
}

}