Bug 45322 – GIF image down sampling can miss some lines

• Component: Images
• Status: RESOLVED FIXED

[Yong Li]

The bug is obvious. Patch is coming soon

[Yong Li]

Created attachment 66771 [details]
the patch

The bug is that xEnd and yEnd were calculated based on already scaled values (xBegin, yBegin). So they were scaled twice...

[Peter Kasting]

Patch itself seems fine to me (but I'm not a reviewer).

It would be nice to layout-test this with a pixel test.

[Yong Li]

(In reply to comment #2)
> Patch itself seems fine to me (but I'm not a reviewer).
> 
> It would be nice to layout-test this with a pixel test.

I didn't add a layout-test because it can be triggered by any GIF but only with certain configurations (down-sampling must be enabled, and the max pixels threshold must be some numbers)

[Peter Kasting]

That's fine, it just means you'll have different layout test results for platforms with down-sampling versus without.

Even if no down-sampling platform runs layout tests (bad!), please at least add a manual test for this (WebCore/manual-tests/).

[Yong Li]

Created attachment 66898 [details]
patch with layout test

[WebKit Commit Bot]

Comment on attachment 66898 [details]
patch with layout test

Clearing flags on attachment: 66898

Committed r67604: <http://trac.webkit.org/changeset/67604>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Satish Sampath]

This layout test fails in chromium, probably because there is no pixel test baseline to check against. I also notice that the HTML refers to the file with ".gif" extension whereas the checked in file has ".GIF" in caps. I'll try to add the baseline and fix the file name.

[Yong Li]

(In reply to comment #8)
> I also notice that the HTML refers to the file with ".gif" extension whereas the checked in file has ".GIF" in caps. I'll try to add the baseline and fix the file name.

Oops. thanks

[Dimitri Glazkov (Google)]

The test is crashing on Chromium bots sporadically. What gives?

http://test-results.appspot.com/dashboards/flakiness_dashboard.html#showExpectations=true&tests=fast%2Fimages%2Fgif-large-checkerboard.html

[Yong Li]

(In reply to comment #10)
> The test is crashing on Chromium bots sporadically. What gives?
> 
> http://test-results.appspot.com/dashboards/flakiness_dashboard.html#showExpectations=true&tests=fast%2Fimages%2Fgif-large-checkerboard.html

I cannot see anything with the URL. Is there a stack trace? Is chromium using image down sampling?

[Dimitri Glazkov (Google)]

(In reply to comment #11)
> (In reply to comment #10)
> > The test is crashing on Chromium bots sporadically. What gives?
> > 
> > http://test-results.appspot.com/dashboards/flakiness_dashboard.html#showExpectations=true&tests=fast%2Fimages%2Fgif-large-checkerboard.html
> 
> I cannot see anything with the URL. Is there a stack trace? Is chromium using image down sampling?

Click on "show results" link, you'll see some stack traces.

[Yong Li]

(In reply to comment #12)
> (In reply to comment #11)
> > (In reply to comment #10)
> > > The test is crashing on Chromium bots sporadically. What gives?
> > > 
> > > http://test-results.appspot.com/dashboards/flakiness_dashboard.html#showExpectations=true&tests=fast%2Fimages%2Fgif-large-checkerboard.html
> > 
> > I cannot see anything with the URL. Is there a stack trace? Is chromium using image down sampling?
> 
> Click on "show results" link, you'll see some stack traces.

I cannot even see "show results" link. Can you paste them here? Also the gif image in the test is super big. The bot could run out-of-memory

[Dimitri Glazkov (Google)]

(In reply to comment #13)
> (In reply to comment #12)
> > (In reply to comment #11)
> > > (In reply to comment #10)
> > > > The test is crashing on Chromium bots sporadically. What gives?
> > > > 
> > > > http://test-results.appspot.com/dashboards/flakiness_dashboard.html#showExpectations=true&tests=fast%2Fimages%2Fgif-large-checkerboard.html
> > > 
> > > I cannot see anything with the URL. Is there a stack trace? Is chromium using image down sampling?
> > 
> > Click on "show results" link, you'll see some stack traces.
> 
> I cannot even see "show results" link. Can you paste them here? Also the gif image in the test is super big. The bot could run out-of-memory

Please join discussion on bug 85073 to continue investigation of the crash.