Note that if you are looking for how to draw this Image, whilst rotated, then you should look at the 'drawRotatedImage' function. This method alters the transformation matrix used when drawing to this Image.
All rotations are clockwise, and all angles are in radians.
Rotates the drawing matrix inside this Image by the angle given. If 'isCentred' is false, then this is performed around the origin. This means it will rotate around the pixel at 0x0, which is at the top left corner of the screen. If 'isCentred' is true, then it will rotate around the centre of the screen.
After applying this rotation, items will be drawn rotated, when they are drawn to this Image.
This rotates the screen around the x and y location given.