Canvas contents does not render when discarding file download
Reported by
pa...@werl.cz,
Jul 17 2016
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Issue description
UserAgent: Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.106 Safari/537.36
Example URL:
N/A
Steps to reproduce the problem:
1. Open the attached file in a new Chrome tab
2. Open another tab, and use the address bar to directly download some file (the bottom download bar must pop up, so you might want to use some .exe setup file download URL for that)
3. Don't close the download bar, but switch back to the tab you opened in step 1.
4. Discard the download
What is the expected behavior?
The canvas should still render its contents after discarding the download.
What went wrong?
Canvas no longer renders its contents. Surprisingly, if I use getContext('2d').getImageData, I can still read the image stored in the canvas. It just doesn't render on the page.
Does it occur on multiple sites: Yes
Is it a problem with a plugin? No
Did this work before? N/A
Does this work in other browsers? Yes
Chrome version: 51.0.2704.106 Channel: stable
OS Version: 6.3
Flash Version:
I have discovered this behavior on quite complex website, where the canvas MIGHT stop rendering (it doesn't always happen) when:
1) the download bar pops up
2) the download bar is discarded
3) other tab is closed
,
Jul 17 2016
So there is kind of a workaround, using a piece of javascript code below. The code makes it very rare for the bug to happen, but if you are persistent enough and keep trying, you should be able to reproduce the bug eventually.
Anyway, another "workaround" when you experience this bug is to switch to another tab and then back to the buggy tab, and the canvas should render correctly again.
var isChrome = !!window.chrome
if (isChrome === true)
{
var canvasContext = canvas.getContext('2d');
setInterval(function() {
canvasContext.clearRect(0, 0, 1, 1);
}, 0);
}
,
Jul 18 2016
,
Jul 18 2016
pavel@Could you please provide the sample file for step 2 with actual and expected behavior screencast for better understanding the issue to triage it further.
,
Jul 19 2016
Thank you for providing more feedback. Adding requester "ssamanoori@chromium.org" for another review and adding "Needs-Review" label for tracking. For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot
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Jul 20 2016
Hi pavel@, could you please try chrome canary: https://www.google.com/chrome/browser/canary.html I tried on a win10 desktop, and I can reproduce the bug on chrome 51 (stable version). When I tried on chrome canary, I can no longer reproduce it. Looks like it is fixed on canary. Feel free to re-open the bug if you found that this is reproducible on canary.
,
Jul 20 2016
Hi, I have tested it on canary and can't reproduce it either. Great! Looking forward to this being pushed to the stable line. Cheers. |
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