Question

I’m having a sprite (canvas) which is being scaled. The canvas has a mask. The problem is that simple scaling (scaleX=newScale; scaleY=newScale;) takes the part of canvas under mask beyound the mask. So I need to move canvas after scaling in such a way that point of canvas under mask remain in the same place. I’m trying to do something like the following:

var deltaScale = newScale / scale;
//w and h are width and height of mask
canvas.scaleX = newScale;
canvas.scaleY = newScale;
canvas.x += (canvas.x + w/2) - (canvas.x + w/2) / deltaScale;
canvas.y += (canvas.y + h/2) - (canvas.y + h/2) / deltaScale;

still after that central point do not remain on the same place. Can somebody prompt me how should I move canvas after scaling?

PS: width and height of canvas is extremely big (some of 25000) if that helps.

UPD: Canvas with it’s mask are added on Sprite, mask is having the same sizes as that parent sprite, canvas.x and canvas.y are negative.

Answer 1

The way I did something similar before was to put the canvas sprite inside another sprite eg. zoom which has its reg point in the centre of the screen (or where ever needed). You can then move canvas around inside the zoom sprite (in my case it was draggable) and scale the outer sprite so the centre is zoomed into.
Scaling and positioning different sprites I found much easier than doing an offset.