[Bug]: 页面有多个iframe，iframe里面的canvas 录制失败

[Vale-sail]

Preflight Checklist

• I have searched the issue tracker for a bug report that matches the one I want to file, without success.

What package is this bug report for?

rrweb

Version

master

Expected Behavior

页面有多个iframe，iframe里面的canvas的录制应该能成功

Actual Behavior

页面有多个iframe，iframe里面的canvas的录制应该能成功

Steps to Reproduce

使用puppeteer录制一个多iframe并且iframe内有canvas的页面。

Testcase Gist URL

No response

Additional Information

canvasManager 仅仅使用window对象初始化了一次，如果页面有多个iframe。
那么getCanvas()执行会报错

我尝试使用这么修改，能够正常录制

由于我水平有限，initCanvasMutationObserver 里面我不知道怎么去改

[Vale-sail]

另外如果录制的页面有一个大的canvas，绘制时会闪烁严重

[Juice10]

Hi @Vale-sail, thank you for your excellent issue and code suggestion. Could you please create a Pull Request with these code changes? We would be more than happy to accept it

[davidleon]

After viewing the source code for a while. I think the canvasmanager constructor should have document instead of window. and the iframe walk function should automatically call up canvasmanager with corresponding document. I don't quite really understand the post fix of looping through windows. From my test cases there's always one window if i have a nested iframe canvas in browser.