因為SWT的ImageLoader支持讀寫以上所有格式的圖片，所以實現起來比較簡單。主要解決了兩個問題。第一個問題是播放GIF動畫，通過ImageLoader讀入GIF的所有幀以及間隔時間，然后用Display.timerExec實現Timer播放。第二個問題是對圖片的Scrollbar支持以及pack支持。SWT.H_SCROLL和SWT.V_SCROLL
雖然加上了滾動條，但是不起作用，需要監聽滾動條的SWT.Selection事件。另外，加上滾動條后，pack無法得到大小，不能正確的pack。需要重載computeSize。
/**
* 負責顯示各種格式的圖片
*
* @author 喜來樂哈哈
*/
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 ScrollBar hBar;
private ScrollBar vBar;
private Color bg;
private Display display;
public ImageViewer(Composite parent) {
super(parent, SWT.NO_BACKGROUND | SWT.NO_REDRAW_RESIZE | SWT.V_SCROLL
| SWT.H_SCROLL);
hBar = getHorizontalBar();
vBar = getVerticalBar();
bg = getBackground();
display = getDisplay();
addListeners();
}
public void setImage(ImageData imageData) {
checkWidget();
stopAnimationTimer();
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.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() {
hBar.addListener(SWT.Selection, new Listener() {
public void handleEvent(Event arg0) {
hscroll();
}
});
vBar.addListener(SWT.Selection, new Listener() {
public void handleEvent(Event arg0) {
vscroll();
}
});
addListener(SWT.Resize, new Listener() {
public void handleEvent(Event e) {
resize();
}
});
addListener(SWT.Paint, new Listener() {
public void handleEvent(Event e) {
paint(e);
}
});
}
void hscroll() {
Image image = getCurrentImage();
if (image != null) {
int hSelection = hBar.getSelection();
int destX = -hSelection - origin.x;
Rectangle rect = image.getBounds();
scroll(destX, 0, 0, 0, rect.width, rect.height, false);
origin.x = -hSelection;
}
}
void vscroll() {
Image image = getCurrentImage();
if (image != null) {
int vSelection = vBar.getSelection();
int destY = -vSelection - origin.y;
Rectangle rect = image.getBounds();
scroll(0, destY, 0, 0, rect.width, rect.height, false);
origin.y = -vSelection;
}
}
void resize() {
Image image = getCurrentImage();
if (image == null)
return;
Rectangle rect = image.getBounds();
Rectangle client = getClientArea();
hBar.setMaximum(rect.width);
vBar.setMaximum(rect.height);
hBar.setThumb(Math.min(rect.width, client.width));
vBar.setThumb(Math.min(rect.height, client.height));
int hPage = rect.width - client.width;
int vPage = rect.height - client.height;
int hSelection = hBar.getSelection();
int vSelection = vBar.getSelection();
if (hSelection >= hPage) {
if (hPage <= 0)
hSelection = 0;
origin.x = -hSelection;
}
if (vSelection >= vPage) {
if (vPage <= 0)
vSelection = 0;
origin.y = -vSelection;
}
redraw();
}
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]);
// 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);
}
}
測試程序
public class ImageCanvasTest {
public static void main(String[] args) {
Display display = new Display();
final Shell shell = new Shell(display);
ImageViewer ic = new ImageViewer(shell);
shell.setLayout(new FillLayout());
FileDialog dialog = new FileDialog(shell, SWT.OPEN);
dialog.setText("Open an image file or cancel");
String string = dialog.open();
ImageLoader loader = new ImageLoader();
ImageData[] imageDatas = loader.load(string);
if (imageDatas.length == 0)
return;
else if (imageDatas.length == 1) {
ic.setImage(imageDatas[0]);
} else {
ic.setImages(imageDatas, loader.repeatCount);
}
ic.pack();
shell.pack();
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch())
display.sleep();
}
display.dispose();
}
}
在對GIF圖片的支持上，Swing要做的好很多，一句label.setIcon(new ImageIcon(name))就搞定GIF動畫了。
轉載請保留
http://www.aygfsteel.com/xilaile/archive/2007/04/10/109547.html