/******************************************************************************* * 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.*;/** * Instances of this class describe the color data used by an image. * <p> * Depending on the depth of the image, the PaletteData can take one * of two forms, indicated by the isDirect field: * </p> * <dl> * <dt> * <em>isDirect is false</em> * </dt> * <dd> * If isDirect is <code>false</code>, this palette is an indexed * palette which maps pixel values to RGBs. The actual RGB values * may be retrieved by using the getRGBs() method. * </dd> * <dt> * <em>isDirect is true</em> * </dt> * <dd> * If isDirect is <code>true</code>, this palette is a direct color * palette. Instead of containing RGB values, it contains red, * green and blue mask and shift information which indicates how * the color components may be extracted from a given pixel. * This means that the RGB value is actually encoded in the pixel value. * <p> * In this case, the shift data is the number of bits required to shift * the RGB value to the left in order to align the high bit of the * corresponding mask with the high bit of the first byte. This number * may be negative, so care must be taken when shifting. For example, * with a red mask of 0xFF0000, the red shift would be -16. With a red * mask of 0x1F, the red shift would be 3. * </p> * </dd> * </dl> * * @see Image * @see RGB */ public final class PaletteData {		/**	 * true if the receiver is a direct palette, 	 * and false otherwise	 */	public boolean isDirect;		/**	 * the RGB values for an indexed palette, where the	 * indices of the array correspond to pixel values	 */	public RGB[] colors;		/**	 * the red mask for a direct palette	 */	public int redMask;		/**	 * the green mask for a direct palette	 */	public int greenMask;		/**	 * the blue mask for a direct palette	 */	public int blueMask;		/**	 * the red shift for a direct palette	 */	public int redShift;		/**	 * the green shift for a direct palette	 */	public int greenShift;		/**	 * the blue shift for a direct palette	 */	public int blueShift;/** * Constructs a new indexed palette given an array of RGB values. * * @param colors the array of <code>RGB</code>s for the palette * * @exception IllegalArgumentException <ul> *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li> * </ul> */public PaletteData(RGB[] colors) {	if (colors == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);	this.colors = colors;	this.isDirect = false;}/** * Constructs a new direct palette given the red, green and blue masks. * * @param redMask the red mask * @param greenMask the green mask * @param blueMask the blue mask */public PaletteData(int redMask, int greenMask, int blueMask) {	this.redMask = redMask;	this.greenMask = greenMask;	this.blueMask = blueMask;	this.isDirect = true;	this.redShift = shiftForMask(redMask);	this.greenShift = shiftForMask(greenMask);	this.blueShift = shiftForMask(blueMask);}/** * Returns the pixel value corresponding to the given <code>RBG</code>. * * @param rgb the RGB to get the pixel value for * @return the pixel value for the given RGB *  * @exception IllegalArgumentException <ul> *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li> *    <li>ERROR_INVALID_ARGUMENT - if the RGB is not found in the palette</li> * </ul> */public int getPixel(RGB rgb) {	if (rgb == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);	if (isDirect) {		int pixel = 0;		pixel |= (redShift < 0 ? rgb.red << -redShift : rgb.red >>> redShift) & redMask;		pixel |= (greenShift < 0 ? rgb.green << -greenShift : rgb.green >>> greenShift) & greenMask;		pixel |= (blueShift < 0 ? rgb.blue << -blueShift : rgb.blue >>> blueShift) & blueMask;		return pixel;	} else {		for (int i = 0; i < colors.length; i++) {			if (colors[i].equals(rgb)) return i;		}		/* The RGB did not exist in the palette */		SWT.error(SWT.ERROR_INVALID_ARGUMENT);		return 0;	}}/** * Returns an <code>RGB</code> corresponding to the given pixel value. * * @param pixel the pixel to get the RGB value for * @return the RGB value for the given pixel * * @exception IllegalArgumentException <ul> *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li> *    <li>ERROR_INVALID_ARGUMENT - if the pixel does not exist in the palette</li> * </ul> */public RGB getRGB(int pixel) {	if (isDirect) {		int r = pixel & redMask;		r = (redShift < 0) ? r >>> -redShift : r << redShift;		int g = pixel & greenMask;		g = (greenShift < 0) ? g >>> -greenShift : g << greenShift;		int b = pixel & blueMask;		b = (blueShift < 0) ? b >>> -blueShift : b << blueShift;		return new RGB(r, g, b);	} else {		if (pixel < 0 || pixel >= colors.length) {			SWT.error(SWT.ERROR_INVALID_ARGUMENT);		}		return colors[pixel];	}}/** * Returns all the RGB values in the receiver if it is an * indexed palette, or null if it is a direct palette. * * @return the <code>RGB</code>s for the receiver or null */public RGB[] getRGBs() {	return colors;}/** * Computes the shift value for a given mask. * * @param mask the mask to compute the shift for * @return the shift amount * * @see PaletteData */int shiftForMask(int mask) {	for (int i = 31; i >= 0; i--) { 		if (((mask >> i) & 0x1) != 0) return 7 - i;	}	return 32;}}