Positioning an imageview inside a FrameLayout with layout?! (changing ImageResource)

Question

I have an ImageView with absolute size and position (in the FrameLayout):

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    layout((int)left, (int)(bottom-width), (int)(left+width), (int)bottom);
}

now when I change my ImageResource with:

setImageResource(...);

the position of all Images is set to top left for one second.. and then switches back to normal!

i also use:

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    setMeasuredDimension((int)width, (int)width);
}