SWT : showing animated gif with transparent background - swt

Question

I am trying to show a animated gif which has transparent background. but the result is that the background is not transparent, below is my code, what is wrong with it?
package amarsoft.rcp.base.widgets;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Canvas;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
/**
* 负责显示各种格式的图片
*
* #author ggfan#amarsoft
*/
public class ImageViewer extends Canvas {
protected Point origin = new Point(0, 0);
protected Image image;
protected ImageData[] imageDatas;
protected Image[] images;
protected int current;
private int repeatCount;
private Runnable animationTimer;
private Color bg;
private Display display;
public ImageViewer(Composite parent) {
super(parent,SWT.NO_REDRAW_RESIZE | SWT.NO_BACKGROUND);
bg = getBackground();
display = getDisplay();
addListeners();
}
public void setImage(ImageData imageData) {
checkWidget();
stopAnimationTimer();
if(imageData != null){
this.image = new Image(display, imageData);
}
this.imageDatas = null;
this.images = null;
redraw();
}
/**
* #param repeatCount
* 0 forever
*/
public void setImages(ImageData[] imageDatas, int repeatCount) {
checkWidget();
this.image = null;
this.imageDatas = imageDatas;
this.repeatCount = repeatCount;
convertImageDatasToImages();
startAnimationTimer();
redraw();
}
#Override
public Point computeSize(int wHint, int hHint, boolean changed) {
checkWidget();
Image image = getCurrentImage();
if (image != null) {
Rectangle rect = image.getBounds();
Rectangle trim = computeTrim(0, 0, rect.width, rect.height);
return new Point(trim.width, trim.height);
}
return new Point(wHint, hHint);
}
#Override
public void dispose() {
if (image != null)
image.dispose();
if (images != null)
for (int i = 0; i < images.length; i++)
images[i].dispose();
super.dispose();
}
protected void paint(Event e) {
Image image = getCurrentImage();
if (image == null)
return;
GC gc = e.gc;
gc.drawImage(image, origin.x, origin.y);
gc.setAntialias(SWT.ON);
//gc.setBackground(bg);
Rectangle rect = image.getBounds();
Rectangle client = getClientArea();
int marginWidth = client.width - rect.width;
if (marginWidth > 0) {
//gc.fillRectangle(rect.width, 0, marginWidth, client.height);
}
int marginHeight = client.height - rect.height;
if (marginHeight > 0) {
//gc.fillRectangle(0, rect.height, client.width, marginHeight);
}
}
void addListeners() {
addListener(SWT.Paint, new Listener() {
public void handleEvent(Event e) {
paint(e);
}
});
}
void convertImageDatasToImages() {
images = new Image[imageDatas.length];
// Step 1: Determine the size of the resulting images.
int width = imageDatas[0].width;
int height = imageDatas[0].height;
// Step 2: Construct each image.
int transition = SWT.DM_FILL_BACKGROUND;
for (int i = 0; i < imageDatas.length; i++) {
ImageData id = imageDatas[i];
images[i] = new Image(display, width, height);
GC gc = new GC(images[i]);
gc.setAntialias(SWT.ON);
// Do the transition from the previous image.
switch (transition) {
case SWT.DM_FILL_NONE:
case SWT.DM_UNSPECIFIED:
// Start from last image.
gc.drawImage(images[i - 1], 0, 0);
break;
case SWT.DM_FILL_PREVIOUS:
// Start from second last image.
gc.drawImage(images[i - 2], 0, 0);
break;
default:
// DM_FILL_BACKGROUND or anything else,
// just fill with default background.
//gc.setBackground(bg);
//gc.fillRectangle(0, 0, width, height);
break;
}
// Draw the current image and clean up.
Image img = new Image(display, id);
gc.drawImage(img, 0, 0, id.width, id.height, id.x, id.y, id.width,
id.height);
img.dispose();
gc.dispose();
// Compute the next transition.
// Special case: Can't do DM_FILL_PREVIOUS on the
// second image since there is no "second last"
// image to use.
transition = id.disposalMethod;
if (i == 0 && transition == SWT.DM_FILL_PREVIOUS)
transition = SWT.DM_FILL_NONE;
}
}
Image getCurrentImage() {
if (image != null)
return image;
if (images == null)
return null;
return images[current];
}
void startAnimationTimer() {
if (images == null || images.length < 2)
return;
final int delay = imageDatas[current].delayTime * 10;
display.timerExec(delay, animationTimer = new Runnable() {
public void run() {
if (isDisposed())
return;
current = (current + 1) % images.length;
redraw();
if (current + 1 == images.length && repeatCount != 0
&& --repeatCount <= 0)
return;
display.timerExec(delay, this);
}
});
}
void stopAnimationTimer() {
if (animationTimer != null)
display.timerExec(-1, animationTimer);
}
}

Answer 1

Wow, so much work for gif animation..
Anyway, check Transparency part of article about SWT Images, it might help you.