Android: rotate canvas around the center of the screen

I'm trying to rotate the canvas around the center of the screen, to get the (0,0) coordinates at the bottom right.

This is how I do it:

Display display = getWindowManager().getDefaultDisplay(); 
int width = display.getWidth();
int height = display.getHeight();
canvas.rotate(180, width/2, height/2);

It does rotate correctly, and everything is perfect at the AVD with API level 17. But on the AVD with API level 8 the (0,0) coordinate appears at the wrong place. Before rotation the picture was fitting the whole screen at this device too, but now it looks like this:

what is causing the problem?

*EDIT!

The problem is resolved by rotating the canvas around its own middle point:

canvas.rotate(180,canvas.getWidth()/2,canvas.getHeight()/2);

But still, why doesn't the previous version work with older APIs?