if use css set canvas to half of it,and then can't drag,how to fixed this?

[xmcase]

code like this, if I set canvas width 300px,height 300px, like this " ",and then can't drag again.

[caleb531]

@xmcase How are you setting the canvas width? It will skew the canvas coordinate system if you try to change the canvas width/height with CSS; that is probably why your drag is skewed.

Instead, you need to set the canvas width/height using jQuery's attr() or prop() methods:

$('#my-canvas').prop({
    width: 300,
    height: 300
});