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非服务器模式下运行getImageData函数出现 the operation is insecure

2021-10-01 11:06:37 作者：互联网

我在非服务器模式下运行了一个获取图片像素数据的函数。报错。
报错为the operation is insecure.
解决思路为：打开服务器，将运行由：file:///D:/wamp64/www/js_programme/canvas_pixel.html
改为：http://localhost/js_programme/canvas_pixel.html
问题解决，结果图片：
问题解决后的结果下面放上自己的代码：

<!DOCTYPE html>
<html lang="en">
<head>
     <meta charset="UTF-8">
     <title>Canvas-像素操作</title>
     </head>
     <body>
          <canvas id="canvas" width="300" height="227"></canvas>
          <canvas id="canvas2" width="300" height="200"></canvas>
          <canvas id="canvas3" width="300" height="200"></canvas>


     </body>

          <script>
               
               var canvas=document.getElementById("canvas");
               var ctx=canvas.getContext("2d");
               var img=new Image();// 创建一个<img>元素
               img.crossOrigin='anonymous';
               img.src='./rhino.jpg';
               img.onload=function(){
                  ctx.drawImage(img,0,0);
                  img.style.display='none';  
               };
               
               canvas.addEventListener('click',function(e){
                   var x=e.offsetX;
                   var y=e.offsetY;
                   console.log(ctx.getImageData(100,150,5,5));
                   console.log(ctx.getImageData(x,y,1,1).data);
               });
               
               
               /*
               var img=new Image();
               img.src='./rhino.jpg';
               img.crossOrigin='anonymous';//这行代码不能够要；
               var canvas=document.getElementById('canvas');
               var ctx=canvas.getContext('2d');
               img.οnlοad=function(){
                    ctx.drawImage(img,0,0);
                    img.style.display='none';
               };
               var hoveredColor=document.getElementById('canvas2').getContext('2d');
               var selectedColor=document.getElementById('canvas3').getContext('2d');
               hoveredColor.rect(0,0,300,200);
               selectedColor.rect(0,0,300,200);
               function pick(event,destination){
                    var x=event.layerX;//鼠标的x，y数值；
                    var y=event.layerY;
                    console.log('mouse position of x,y is ',x,y);
                    var imagedata=ctx.getImageData(x,y,2,2).data;
                    //console.log('pixel is =',pixel);
                    //var data=pixel.data;
                    console.log('data is equal to ',imagedata);
                    const rgba='rgba(data[0],data[1],data[2],data[3]/255})';
                    destination.style.background=rgba;
                    destination.textContext=rgba;
                    return rgba;
               }
               canvas.addEventListener('mousemove',function(event){
                    pick(event,hoveredColor);
               });
               canvas.addEventListener('click',function(event){
                    pick(event,selectedColor);
               });
               */

          </script>
     </html>

标签：canvas,img,insecure,ctx,getImageData,var,operation,data,event
来源： https://blog.csdn.net/weixin_47024922/article/details/120576180