How do I properly transform entire canvas in fabric.js / change fabric's origin?

问题

I'm trying to set fabric up so the origin is bottom left instead of top left. Currently I'm using setViewportTransform and it transforms everything as I want, except for the selection box. (doesn't seem to get the transformation) I made a fiddle & you can see how if you rotate the rectangle, the selection box rotates the wrong way.

So my question is, how do I set fabric.js' origin to the bottom left?

http://jsfiddle.net/39up3jcm/105/

回答1:

The simplest solution I found was to:

1. Change the view by adding transform: scaleY(-1) to the canvas CSS
2. Change the inputs by redefining fabric.Canvas.prototype.getPointer but replace pointer.y = pointer.y - this._offset.top with pointer.y = bounds.height - pointer.y + this._offset.top

** Fabric version 1.7.20

来源：https://stackoverflow.com/questions/50283319/how-do-i-properly-transform-entire-canvas-in-fabric-js-change-fabrics-origin