跨域资源共享策略拒绝跨域图像加载 [英] Cross-origin image load denied by Cross-Origin Resource Sharing policy

问题描述

我使用html2canvas(来自html2canvas.hertzen.com)捕获屏幕截图.我收到这样的奇怪错误: 我网页的代码放在一个主机上，例如主机A. 如果我的网页包含另一个主机(例如主机B)上的图像，则出现此错误: 跨域资源共享策略拒绝跨域图像加载

I use html2canvas (from html2canvas.hertzen.com) to capture screenshot. I got this strange error like this: The code of my webpage is put on one host, say Host A. If my webpage contains an image on another host, say Host B, then I hit this error: Cross-origin image load denied by Cross-Origin Resource Sharing policy

但是，令人困惑的部分是，如果主机B是facebook(我的图像是指向Facebook的直接链接

However, the confusing part is that if Host B is facebook (my image is a direct link to facebook https://fbcdn-profile-a.akamaihd.net/hprofile-ak-ash4/372701_100000684388457_1551561655_q.jpg) then the error disappear.

我的功能

html2canvas([document.body], {
                    useCORS : true,
                    logging : true,
                    onrendered : function(canvas) {
                        document.body.appendChild(canvas);
                        var myImage = canvas.toDataURL("image/png");
                        window.open(myImage);
                    }

有人给小费吗? Tks

Anyone got a tip? Tks

解决方案

 html2canvas([document.body], {
                                    useCORS: true,
                                    proxy: "Server",
                                    onrendered : function(canvas) {                               
                                        ListUCapture = canvas.toDataURL("image/png");                                                           
                                    }
                     });
Server is server of node.js

推荐答案

如果希望将跨域图像加载到画布上，则需要使用跨域标头或在相同的源下提供该图像. Facebook下的该图片带有以下标头选项集:

If you wish to load cross-origin images to a canvas, you need to either serve the image with cross-origin headers or under the same origin. That image under Facebook is served with the following header option set:

Access-Control-Allow-Origin:*

表示，可以使用useCORS选项进行跨域加载.但是，您的主机B似乎没有为其设置跨域标头来为它们提供服务.

Meaning, it can be cross-origin loaded with the useCORS option. However, it would appear that your Host B isn't serving them with cross-origin headers set.

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