SWT：顯示帶有透明背景的動畫gif

我想要顯示具有透明背景的動畫gif。但結果是背景不透明，下面是我的代碼，它有什麼問題？SWT：顯示帶有透明背景的動畫gif
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; 

/** 
* 負責顯示各種格式的圖片 
* 
* @author [email protected] 
*/ 
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); 
    } 
}
enter image description here