我希望使 Canvas 区域透明,因为我想在它后面添加一张图片,以便 Canvas 操作发生在图片之上。以下是我的 Canvas 代码:
public class Panel extends SurfaceView implements SurfaceHolder.Callback {
private ViewThread mThread;
private ArrayList<Element> mElements = new ArrayList<Element>();
public Panel(Context context, AttributeSet attrs) {
super(context, attrs);
getHolder().addCallback(this);
mThread = new ViewThread(this);
}
public void doDraw(Canvas canvas) {
canvas.drawColor(Color.TRANSPARENT);
synchronized (mElements) {
for (Element element : mElements) {
element.doDraw(canvas);
}
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
// TODO Auto-generated method stub
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
if (!mThread.isAlive()) {
mThread = new ViewThread(this);
mThread.setRunning(true);
mThread.start();
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
if (mThread.isAlive()) {
mThread.setRunning(false);
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
synchronized (mElements) {
mElements.add(new Element(getResources(), (int) event.getX(), (int) event.getY()));
}
return super.onTouchEvent(event);
}
}
如何实现它,任何相关示例代码都将非常有帮助。谢谢。