在CSS缩放画布中获取正确的鼠标位置

Question

我一直试图采取几个简单的MooTools操作的逻辑，并将其转换为使用jQuery。

我想要的逻辑就是为了这个jsfiddle它允许的是通过css调整大小来在canvas元素上获得准确的鼠标位置。

我发现answer here，所以我已经工作了几个小时都无济于事

我想我明白他的逻辑，但拟合由于某种原因，我没有看到结果

这里是我有什么从他answer与阿拜的逻辑迄今所做注释掉

// Get the change ratio for the new css set size 
//var cssScale = [canvas.getSize().x/canvas.get('width'), canvas.getSize().y/canvas.get('height')]; 
var cssScale = [$('canvas').height()/$('canvas').attr('height'), $('canvas').width()/$('canvas').attr('$('canvas').height()/$('canvas').attr('height'),')] 

//Create an object of the dimensions 
// I think from my looking at the jsfiddle x&y is the position of the rect in his canvas 
// and w&h are the height and width of that rect so it's not really necessary for my problem which 
// is just getting mouse cords accuratly. 
//this.setDims(x*cssScale[0], y*cssScale[1], w*cssScale[0], h*cssScale[1]); 

// This is the offset of the clickable square in his code. 
//this.offset = [x - this.dims[0], y - this.dims[1]]; 

// Now I do not know what this is 
// If the offset is just for position in their code why is it used here 
// How can you display just scaled mouse position 
this.x = (x - this.offset[0])/cssScale[0] + w * .5; 
this.y = (y - this.offset[1])/cssScale[1] + h * .5; 

Answer 1

我用普通的JavaScript了一个小demo。我有一个blog post解释过程。

查看示例，特别注意使用变量sx和sy的位置。他们是你的缩放比例。您基本上需要将此应用于画布内的任何偏移量（即屏幕上的鼠标位置减去画布偏移量）。