Speed up bitmap animation in custom View

Speed up bitmap animation in custom View

In my custom view i have 1 animation that i need to run at demand (on tile
click). Currently i am using this method:
public boolean onTouchEvent(MotionEvent event) {
switch(event.getAction()){
case MotionEvent.ACTION_DOWN:
//check what tile for clicked
getHandler().removeCallbacks(explosionThread);
getHandler().post(explosionThread);
}
}
break;
}
return super.onTouchEvent(event);
}
So i am calling (or sending to view thread, to be specific) a Runnable
that calls it self until it comes to an end of an image...
private Runnable explosionThread=new Runnable(){
@Override
public void run() {
invalidate();
if(expCount<15){
getHandler().postDelayed(this, 10);
}
}
};
In my onDraw() method i implemented logic to go threw bitmap and draw it
on screen ( using cnavas.drawBitmap(bitmap,srcRect,destRect,paint)....
Now, I want to avoid using SurfaceView (i have only 1 animation and View
uses less resources). I think the animation is slow because onDraw needs
to draw whole screen each time invalidate() is called witch can be slow (
drawing 64 tiles with png images). I know that there is an overload of
invalidate method, invalidate(Rect dirty) but i don't really know how to
use it. If u think that that is the answer please write how to avoid
drawing whole onDraw method ( or what method can I overwrite that is used
by invalidate(Rect) method, if there is any).
If you have any other better way to speed up animation post it plz. Thanks
in advance....