问题：
Google's "Report a Bug" or "Feedback Tool" lets you select an area of your browser window to create a screenshot that is submitted with your feedback about a bug. 利用Google的“报告错误”或“反馈工具”，您可以选择浏览器窗口的区域来创建屏幕截图，并在屏幕上提交有关错误的反馈。
Screenshot by Jason Small, posted in a duplicate question . Jason Small的屏幕截图，张贴在一个重复的问题中 。
How are they doing this? 他们是如何做到的？ Google's JavaScript feedback API is loaded from here and their overview of the feedback module will demonstrate the screenshot capability. Google的JavaScript反馈API从此处加载， 它们对反馈模块的概述将演示屏幕截图功能。
解决方案：
参考一： https://stackoom.com/question/KbrI/使用HTML-Canvas-JavaScript拍摄浏览器内屏幕截图参考二： https://oldbug.net/q/KbrI/Using-HTML5-Canvas-JavaScript-to-take-in-browser-screenshots
来源：oschina
链接：https://my.oschina.net/stackoom/blog/4319679