Android canvas使用canvas.scale翻转

Question

I have a little question. :) In my new live wallpaper I am flipping the canvas horizontally with:

c.scale(-1f, 1f, screenWidth* 0.5f, screenHeight* 0.5f);
drawFlipped();
c.scale(-1f, 1f, screenWidth* 0.5f, screenHeight* 0.5f);

This all works great but I also happen to have an ontouch event where the user can click the different moving object defined as a Rect.

But when the rect is drawn on the flipped canvas the x,y coordinates are not correct. Its still in mirror and I understand that because I flip the canvas back after drawing the sprites.

My question is: How can I calculate the on touch event from the right side of the screen? I tried: Screenwidth - object.x - object.width but it did not help much :(

Answer 1

This works for me:

int screenWidth = getScreenWidth();
Rect newCoordinates = new Rect(object.getRect()); //copies old coordinates
newCoordinates.right = screenWidth - object.getRect().left; //switch right and left since the Rect is being mirrored
newCoordinates.left = screenWidth - object.getRect().right;
object.setRect(newCoordinates);