/*******************************************************************************
* Copyright (c) 2000, 2011 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
* Stephan Wahlbrink - fix for bug 341702 - incorrect mixing of images with alpha channel
*******************************************************************************/
package org.eclipse.jface.resource;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.PaletteData;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.RGB;
/**
* Abstract base class for image descriptors that synthesize an image from other
* images in order to simulate the effect of custom drawing. For example, this
* could be used to superimpose a red bar dexter symbol across an image to
* indicate that something was disallowed.
* <p>
* Subclasses must implement the <code>getSize</code> and <code>fill</code>
* methods. Little or no work happens until the image descriptor's image is
* actually requested by a call to <code>createImage</code> (or to
* <code>getImageData</code> directly).
* </p>
*/
public abstract class CompositeImageDescriptor extends ImageDescriptor {
/**
* The image data for this composite image.
*/
private ImageData imageData;
/**
* Constructs an uninitialized composite image.
*/
protected CompositeImageDescriptor() {
}
/**
* Draw the composite images.
* <p>
* Subclasses must implement this framework method to paint images within
* the given bounds using one or more calls to the <code>drawImage</code>
* framework method.
* </p>
*
* @param width
* the width
* @param height
* the height
*/
protected abstract void drawCompositeImage(int width, int height);
/**
* Draws the given source image data into this composite image at the given
* position.
* <p>
* Call this internal framework method to superimpose another image atop
* this composite image.
* </p>
*
* @param src
* the source image data
* @param ox
* the x position
* @param oy
* the y position
*/
final protected void drawImage(ImageData src, int ox, int oy) {
ImageData dst = imageData;
PaletteData srcPalette = src.palette;
ImageData srcMask = null;
int alphaMask = 0, alphaShift = 0;
if (src.maskData != null) {
srcMask = src.getTransparencyMask ();
if (src.depth == 32) {
alphaMask = ~(srcPalette.redMask | srcPalette.greenMask | srcPalette.blueMask);
while (alphaMask != 0 && ((alphaMask >>> alphaShift) & 1) == 0) alphaShift++;
}
}
for (int srcY = 0, dstY = srcY + oy; srcY < src.height; srcY++, dstY++) {
for (int srcX = 0, dstX = srcX + ox; srcX < src.width; srcX++, dstX++) {
if (!(0 <= dstX && dstX < dst.width && 0 <= dstY && dstY < dst.height)) continue;
int srcPixel = src.getPixel(srcX, srcY);
int srcAlpha = 255;
if (src.maskData != null) {
if (src.depth == 32) {
srcAlpha = (srcPixel & alphaMask) >>> alphaShift;
if (srcAlpha == 0) {
srcAlpha = srcMask.getPixel(srcX, srcY) != 0 ? 255 : 0;
}
} else {
if (srcMask.getPixel(srcX, srcY) == 0) srcAlpha = 0;
}
} else if (src.transparentPixel != -1) {
if (src.transparentPixel == srcPixel) srcAlpha = 0;
} else if (src.alpha != -1) {
srcAlpha = src.alpha;
} else if (src.alphaData != null) {
srcAlpha = src.getAlpha(srcX, srcY);
}
if (srcAlpha == 0) continue;
int srcRed, srcGreen, srcBlue;
if (srcPalette.isDirect) {
srcRed = srcPixel & srcPalette.redMask;
srcRed = (srcPalette.redShift < 0) ? srcRed >>> -srcPalette.redShift : srcRed << srcPalette.redShift;
srcGreen = srcPixel & srcPalette.greenMask;
srcGreen = (srcPalette.greenShift < 0) ? srcGreen >>> -srcPalette.greenShift : srcGreen << srcPalette.greenShift;
srcBlue = srcPixel & srcPalette.blueMask;
srcBlue = (srcPalette.blueShift < 0) ? srcBlue >>> -srcPalette.blueShift : srcBlue << srcPalette.blueShift;
} else {
RGB rgb = srcPalette.getRGB(srcPixel);
srcRed = rgb.red;
srcGreen = rgb.green;
srcBlue = rgb.blue;
}
int dstRed, dstGreen, dstBlue, dstAlpha;
if (srcAlpha == 255) {
dstRed = srcRed;
dstGreen = srcGreen;
dstBlue= srcBlue;
dstAlpha = srcAlpha;
} else {
int dstPixel = dst.getPixel(dstX, dstY);
dstAlpha = dst.getAlpha(dstX, dstY);
dstRed = (dstPixel & 0xFF) >>> 0;
dstGreen = (dstPixel & 0xFF00) >>> 8;
dstBlue = (dstPixel & 0xFF0000) >>> 16;
if (dstAlpha == 255) { // simplified calculations for performance
dstRed += (srcRed - dstRed) * srcAlpha / 255;
dstGreen += (srcGreen - dstGreen) * srcAlpha / 255;
dstBlue += (srcBlue - dstBlue) * srcAlpha / 255;
} else {
// See Porter T., Duff T. 1984. "Compositing Digital Images".
// Computer Graphics 18 (3): 253�259.
dstRed = srcRed * srcAlpha * 255 + dstRed * dstAlpha * (255 - srcAlpha);
dstGreen = srcGreen * srcAlpha * 255 + dstGreen * dstAlpha * (255 - srcAlpha);
dstBlue = srcBlue * srcAlpha * 255 + dstBlue * dstAlpha * (255 - srcAlpha);
dstAlpha = srcAlpha * 255 + dstAlpha * (255 - srcAlpha);
if (dstAlpha != 0) { // if both original alphas == 0, then all colors are 0
dstRed /= dstAlpha;
dstGreen /= dstAlpha;
dstBlue /= dstAlpha;
dstAlpha /= 255;
}
}
}
dst.setPixel(dstX, dstY, ((dstRed & 0xFF) << 0) | ((dstGreen & 0xFF) << 8) | ((dstBlue & 0xFF) << 16));
dst.setAlpha(dstX, dstY, dstAlpha);
}
}
}
/*
* (non-Javadoc) Method declared on ImageDesciptor.
*/
public ImageData getImageData() {
Point size = getSize();
/* Create a 24 bit image data with alpha channel */
imageData = new ImageData(size.x, size.y, 24, new PaletteData(0xFF, 0xFF00, 0xFF0000));
imageData.alphaData = new byte[imageData.width * imageData.height];
drawCompositeImage(size.x, size.y);
/* Detect minimum transparency */
boolean transparency = false;
byte[] alphaData = imageData.alphaData;
for (int i = 0; i < alphaData.length; i++) {
int alpha = alphaData[i] & 0xFF;
if (!(alpha == 0 || alpha == 255)) {
/* Full alpha channel transparency */
return imageData;
}
if (!transparency && alpha == 0) transparency = true;
}
if (transparency) {
/* Reduce to 1-bit alpha channel transparency */
PaletteData palette = new PaletteData(new RGB[]{new RGB(0, 0, 0), new RGB(255, 255, 255)});
ImageData mask = new ImageData(imageData.width, imageData.height, 1, palette);
for (int y = 0; y < mask.height; y++) {
for (int x = 0; x < mask.width; x++) {
mask.setPixel(x, y, imageData.getAlpha(x, y) == 255 ? 1 : 0);
}
}
} else {
/* no transparency */
imageData.alphaData = null;
}
return imageData;
}
/**
* Return the transparent pixel for the receiver.
* <strong>NOTE</strong> This value is not currently in use in the
* default implementation.
* @return int
* @since 3.3
*/
protected int getTransparentPixel() {
return 0;
}
/**
* Return the size of this composite image.
* <p>
* Subclasses must implement this framework method.
* </p>
*
* @return the x and y size of the image expressed as a point object
*/
protected abstract Point getSize();
/**
* @param imageData The imageData to set.
* @since 3.3
*/
protected void setImageData(ImageData imageData) {
this.imageData = imageData;
}
}