FlipY

For example, if the bottom edge of the surface is constrained, the gravity is 'bottom' and the anchor is 'bottom', change the gravity to 'top' and the anchor to 'top'. The adjusted position is calculated given the original anchor rectangle and offset, but with the new flipped anchor and gravity values. If the adjusted position also ends up being constrained, the resulting position of the FlipY adjustment will be the one before the adjustment.