您可以选择“屏幕截图”的页面使用Canvas？ [英] Can you take a "screenshot" of the page using Canvas?
问题描述
我有一个页面，其中我们使用CSS定位一堆元素，并使用JS更改它们的顶部和左侧位置。
报告这些东西已经失调，但用户有动机谎言这是欺骗，所以我不能确定他们是否说实话。我试图找出一个方法来弄清楚他们是否撒谎，并有一些证据。
我知道Canvas有一个方法从一个图像元素或另一个canvas元素（一种BitBlt操作）复制图像信息。
可能以某种方式，使用Canvas Flash，无论什么），拍一张页面的图片？
同样，我不是试图从< image>获取信息。我试图复制用户看到的内容，它由几个HTML元素组成，绝对定位（我主要关心这些位置），并以某种方式将其上传到服务器。
任何想法？
有人问过一个问题，有点类似于这个。滚动到Youtube底部，然后点击报告错误链接。 Google的反馈工具（基于Javascript驱动）基本上是你所描述的。根据我看到的代码，它使用画布，并有一个基于JavaScript的JPEG编码器，构建一个JPG图像发送给Google。
是很多工作，但我相信你可以完成类似的事情。
I have a page where we're positioning a bunch of elements using CSS, and changing their "top and left" positions using JS.
I've had reports that these things have been misaligned, but a user has motive to lie about this to "cheat", so i'm not exactly sure whether they're telling the truth. I'm trying to find a way to figure out whether they're lying or not, and to have some "proof".
I know that Canvas has a method to copy image information from an image element, or another canvas element (kind of a BitBlt operation).
Would it be possible to somehow, with Canvas (or with something else, Flash, whatever), take a "picture" of a piece of the page?
Again, i'm not trying to take information from an <image>. I'm trying to copy what the user sees, which is comprised of several HTML elements positioned absolutely (and I care mostly about those positions), and somehow upload that to the server.
I understand this can't be done, but maybe i'm missing something.
Any ideas?
Somebody asked a question earlier that's somewhat similar to this. Scroll to the bottom of Youtube and click the "Report a Bug" link. Google's Feedback Tool (Javascript driven), essentially does what you described. Judging by what I looked at of its code, it uses canvas and has a JavaScript-based JPEG encoder which builds a JPG image to send off to Google.
It would definitely be a lot of work, but I'm sure you could accomplish something similar.
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