在画布边界范围内移动对象 [英] Move object within canvas boundary limit

问题描述

我试图将移动对象限制在画布中，但是我在移动具有顶部和左侧限制区域的对象时遇到了一些困难，当我缩放具有较大尺寸的对象时，我也无法限制对象的移动.画布左侧和顶部的移动对象

I am trying to limit the moving object within the canvas but i am getting some difficulty to moving object with limit area on top and left side and when i scale the object with big size that time also i am not able to limit the moving object on left and top side of the canvas

canvas.observe("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;
        }

        var halfw = obj.currentWidth/2;
        var halfh = obj.currentHeight/2;
        var bounds = {tl: {x: halfw, y:halfh},
            br: {x: obj.canvas.width-halfw, y: obj.canvas.height-halfh}
        };

        // top-left  corner
        if(obj.top < bounds.tl.y || obj.left < bounds.tl.x){
            obj.top = Math.max(obj.top, bounds.tl.y);
            obj.left = Math.max(obj.left, bounds.tl.x )
        }


        // bot-right corner
        if(obj.top > bounds.br.y || obj.left > bounds.br.x){
            obj.top = Math.min(obj.top, bounds.br.y);
            obj.left = Math.min(obj.left, bounds.br.x)
        }
});

推荐答案

只需在您的js文件中添加以下代码，并根据画布的高度和宽度更改比例X(左)和Y(上)的值. /p>

Just add the below code in your js file and change the value of scale X(left) and Y(top) according to your canvas height and width.

// canvas moving limit 

canvas.observe("object:moving", function(e){
      var obj = e.target;
         // if object is too big ignore

        var halfw = obj.currentWidth/2;
        var halfh = obj.currentHeight/2;
        var bounds = {tl: {x: halfw, y:halfh},
            br: {x: obj.canvas.width , y: obj.canvas.height }
        };

        // top-left  corner



            // alert("text");
        if(obj.top < bounds.tl.y || obj.left < bounds.tl.x){
            obj.top = Math.max(obj.top, '10'  );
            obj.left = Math.max(obj.left , '50' ) 
        }


        // bot-right corner
        if(obj.top > bounds.br.y || obj.left > bounds.br.x ){
            obj.top = Math.min(obj.top, '360'  );  
            obj.left = Math.min(obj.left, '470' )  
        }

});
// end canvas moving limit

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