Bug 95875 – [Chromium] Regression: Web Inspector tool-tips pixellated with --force-device-scale-factor=2

• Component: Web Inspector (Deprecated)
• Status: RESOLVED FIXED

[Jeff Timanus]

The web inspector tool-tip UI is pixelated when viewed in ChromeOS with a non-1 device scale factor applied.

This was potentially introduced by r127240. (wkbug.com/95456)  The tool-tip boundary was previously drawn via native calls to skia, but it is now rendered with a web-ui, using a canvas2d element.  Canvas2D elements do not change resolution under page scale operations, and as a result the UI becomes chunky.

Repro Steps:
  - Build ChromeOS (use_aura=1 chromeos=1)
  - Run Chrome:  out/Debug/chrome --force-compositing-mode --force-device-scale-factor=2
  - Use the web-inspector to highlight dom elements on a page.

See attached screen shot for an example.

[Jeff Timanus]

Created attachment 162294 [details]
Fuzzy tool tip screen shot.

[Pavel Feldman]

What would people do to canvas code in such cases? Multiply things by devicePixelRatio?

[Alexander Pavlov (apavlov)]

(In reply to comment #2)
> What would people do to canvas code in such cases? Multiply things by devicePixelRatio?

Found a context-scaling solution: http://blog.iwalt.com/2010/08/generating-highresolution-graphics-with-html5s-canvas-element.html

[Alexander Pavlov (apavlov)]

(In reply to comment #0)

> Repro Steps:
>   - Build ChromeOS (use_aura=1 chromeos=1)
>   - Run Chrome:  out/Debug/chrome --force-compositing-mode --force-device-scale-factor=2
>   - Use the web-inspector to highlight dom elements on a page.

Are there any other ways to reproduce the issue other than using ChromeOS? I'm failing to get the device scale factor override in desktop Chromium on Linux.

[Alexander Pavlov (apavlov)]

Created attachment 162472 [details]
Patch

[Jeff Timanus]

(In reply to comment #4)
> (In reply to comment #0)
> 
> > Repro Steps:
> >   - Build ChromeOS (use_aura=1 chromeos=1)
> >   - Run Chrome:  out/Debug/chrome --force-compositing-mode --force-device-scale-factor=2
> >   - Use the web-inspector to highlight dom elements on a page.
> 
> Are there any other ways to reproduce the issue other than using ChromeOS? I'm failing to get the device scale factor override in desktop Chromium on Linux.

From my understanding --force-device-scale-factor only works in ChromeOS.

I had a quick look at the patch, and I think it is the correct approach.

[Alexander Pavlov (apavlov)]

Committed r127833: <http://trac.webkit.org/changeset/127833>