How can I draw an animated view in android?

Question

I created a custom view from scratch. Extended View and overrided onDraw(). When comes down in animating the view i generate a custom animation usi

Answer 1

Since this question has some interest I will reply.

The best way to to that is to have a separate canvas thread. A "separate" canvas can only be achieved with a SurfaceView. LunarLanding is an excelent example of that use. Each frame is calculated separately than the main view sharing only CPU time, not drawing time. Therefore is faster, even with the combination of for e.g a regular view at the top and an animating view at the bottom.

But you have to set an interval if you are in that shared environment. That interval is used for the FPS cap. If you don't set FPS cap then the CPU will running wild managing to get good animation to the SurfaceView if it was alone. Capping it at 60fps or even less will do the trick to draw all views efficiently with no CPU overload.

So see the drawing thread of the Lunar Landing from the API demos and set a FPS cap.

private long timeNow;
    private long timeDelta;
    private long timePrevFrame;

    private void capFps(int fps) {  
            timeNow = System.currentTimeMillis();
            timeDelta = timeNow - timePrevFrame;        

            try {

//ps you can always set 16 instead of 1000/fps for 60FPS to avoid the calculation every time

Thread.sleep((1000 / fps) - timeDelta);
            } catch (InterruptedException e) {

            }   

            timePrevFrame = System.currentTimeMillis();
    }

and then the drawing thread will look something like this:

@Override
    public void run() {
        Canvas c;

        while (run) {
            c = null;
            sleepFps(60, false);
            try {
                synchronized (surfaceHolder) {
                    c = surfaceHolder.lockCanvas(null);
                    widgetView.doDraw(c);
                }
            } finally {
                if (c != null) {
                    surfaceHolder.unlockCanvasAndPost(c);
                }
            }

        }
    }