如何防止画布对象仅移动X轴左方向（FabricJS）

Question

我正在尝试的是在画布画布中绑定画布对象。通常在创建一个obejct时，它可以移动到画布之外，如下所示：

但我想只在画布内移动它。它不能在外面。这是我的代码：

  var canvas = new fabric.Canvas('c');
  var SampleText = new fabric.Text(Text, {
    left: canvas.getWidth() / 2,
    top: canvas.getHeight() / 2       
  });
  SampleText.on('moving', function(e) {     
       // need to immplement the logic here
    });
  canvas.add(SampleText);
  canvas.renderAll();

我已经看过选项canvas.item(0).lockMovementX = true;但我认为这不会解决我的问题。

Answer 1

有很多解决方案：

JS Part：

$(document).ready(function() {
    var canvas=new fabric.Canvas('demo');
    canvas.on('object:moving', function (e) {
        var obj = e.target;
         // if object is too big ignore
        if(obj.currentHeight > obj.canvas.height || obj.currentWidth > obj.canvas.width){
            return;
        }        
        obj.setCoords();        
        // top-left  corner
        if(obj.getBoundingRect().top < 0 || obj.getBoundingRect().left < 0){
            obj.top = Math.max(obj.top, obj.top-obj.getBoundingRect().top);
            obj.left = Math.max(obj.left, obj.left-obj.getBoundingRect().left);
        }
        // bot-right corner
        if(obj.getBoundingRect().top+obj.getBoundingRect().height  > obj.canvas.height || obj.getBoundingRect().left+obj.getBoundingRect().width  > obj.canvas.width){
            obj.top = Math.min(obj.top, obj.canvas.height-obj.getBoundingRect().height+obj.top-obj.getBoundingRect().top);
            obj.left = Math.min(obj.left, obj.canvas.width-obj.getBoundingRect().width+obj.left-obj.getBoundingRect().left);
        }
    });
    var text=new fabric.IText('Jayesh');
    canvas.add(text);
});

看看这个JsFiddle