Bug 59540 – REGRESSION: white overlay scrollbars on apple.com/startpage

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[Jon Lee]

<rdar://problem/9338653>

[Jon Lee]

Created attachment 91185 [details]
Patch

[WebKit Review Bot]

Attachment 91185 [details] did not pass style-queue:

Failed to run "['Tools/Scripts/check-webkit-style', '--diff-files', u'Source/WebCore/ChangeLog', u'Source/WebCor..." exit_code: 1

Source/WebCore/ChangeLog:1:  ChangeLog entry has no bug number  [changelog/bugnumber] [5]
Total errors found: 1 in 2 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Jon Lee]

Created attachment 91191 [details]
Patch

fix ChangeLog

[Simon Fraser (smfr)]

Comment on attachment 91191 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=91191&action=review

> Source/WebCore/page/Frame.cpp:510
> +    // <https://bugs.webkit.org/show_bug.cgi?id=59540> To find the aggregate background color
> +    // of the document, we look at the background color of the document and the body, and blend
> +    // them against the base background color of the frame view. Ideally we should include
> +    // background images, but including them in this calculation is time-intensive,
> +    // and would lead to unpredictable results.

I think this is too verbose (imagine if every change had such comments!).

> Source/WebCore/page/Frame.cpp:530
> +        return htmlBackgroundColor;

What if htmlBackgroundColor is transparent? Shouldn't this return the base background color?

> Source/WebCore/page/Frame.cpp:534
> +    if (!htmlBackgroundColor.isValid())
> +        return bodyBackgroundColor;

bodyBackgroundColor may be transparent here also, so you you'd need to return the baseBackgroundColor.

> Source/WebCore/page/Frame.cpp:543
> +    return view()->baseBackgroundColor().blend(htmlBackgroundColor.blend(bodyBackgroundColor));

Blend does linear interpolation, which is not the same as what is used for compositing. I think you want to combine them using the "normal" blend mode (aka Porter Duff's "source over"): R = S + D*(1 - Sa)

[Jon Lee]

Created attachment 91386 [details]
Patch

Including the base background for short-circuit tests, and adding a comment in Color.h re: blend() function.

[WebKit Commit Bot]

The commit-queue encountered the following flaky tests while processing attachment 91386 [details]:

http/tests/inspector/console-websocket-error.html bug 57392 (authors: [e-mail] and [e-mail])
The commit-queue is continuing to process your patch.

[WebKit Commit Bot]

Comment on attachment 91386 [details]
Patch

Clearing flags on attachment: 91386

Committed r85171: <http://trac.webkit.org/changeset/85171>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.