从canvas(非跨域)读取时出现IE9安全性错误

Question

我正在播放video标签中的视频.视频文件与index.html位于同一目录中.然后我将视频像素放在a上canvas,对它们做一些逻辑,读取它们并放在另一个上canvas.这一切在firefox和chrome中运行良好,但在IE9中不行.当我尝试从画布读取像素时,IE会出现安全性错误.如果视频源自其他某个域,那么这是可以理解的,但事实并非如此.更令人好奇的是,当我将相关代码放入setTimeout或从控制台触发它时发生错误,而不是在脚本中直接调用它时.这是相关的javascript:

$(document).ready(function(){
fun = function(){
    var main= $("#main");
    var video = $('<video autoplay="autoplay">
                <source src="orange.mp4" type="video/mp4" />
                <source src="orange.ogv" type="video/ogg" /></video>');
    video.css({"width" : 100, "height" : 200});
    var canvas1 = $('<canvas></canvas>');
    canvas1.css({"position" : "relative", "top" :0, 
                "width" : 100, "height" : 200, "background-color":"red"});
    canvas1.attr({"width" : 100, "height" : 200});
    var context1=canvas1[0].getContext("2d");

    var canvas2 = $('<canvas></canvas>');
    canvas2.css({"position" : "relative", "top" :0, 
                 "width" : 100, "height" : 200, "background-color":"purple", 
                 "margin" : "5px"});
    canvas2.attr({"width" : 100, "height" : 200});
    var context2=canvas2[0].getContext("2d");

    main.append(video);
    main.append(canvas1);
    main.append(canvas2);


    var drawFrame = function(){
            context1.drawImage(video[0],0,0,100,200);
            var data = context1.getImageData(0,0,100,200);
            context2.putImageData(data, 0, 0);
            setTimeout(drawFrame, 50);
    }

    drawFrame();
}
fun();                  // <--- this one works
var wurst = setTimeout(fun,50);     // <--- this one doesn't
});

这里发生了什么,可以做些什么来解决它？

Answer 1

嗯..这看起来很奇怪！您是否尝试过使用 requestAnimationFrame 而不是 setTimeout ？

// Polyfill for HTML5's requestAnimationFrame API.
window.requestAnimFrame = (function(){
  return  window.requestAnimationFrame       || 
          window.webkitRequestAnimationFrame || 
          window.mozRequestAnimationFrame    || 
          window.oRequestAnimationFrame      || 
          window.msRequestAnimationFrame     || 
          function( callback ){
            window.setTimeout(callback, 1000 / 60);
          };
})();

requestAnimFrame(fun);