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Issue metadata

Status: WontFix
Owner: ----
Closed: Sep 10
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: ----
Pri: 3
Type: Bug



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Overflow clipping border radius

Project Member Reported by r...@igalia.com, Sep 10

Issue description


Check the attached example and expected output.
The example is:
  <div style="background: green; border-radius: 50%; height: 50px; width: 100px; padding: 25px 0; overflow: hidden;">
    <div style="background: green; width: 200px; height: 200px;"></div>
  </div>

The reference is:
  <div style="background: green; border-radius: 50%; height: 100px; width: 100px; overflow: hidden;">
  </div>

Without the inner DIV there are no differences in rendering,
but with it there are.

I believe both should be equivalent.
 
border-radius.html
265 bytes View Download
border-radius-expected.html
124 bytes View Download
border-radious-diff.png
4.6 KB View Download
Components: Blink>Paint
Status: WontFix (was: Untriaged)
In theory they are equivalent, but the div with a child and overflow requires clipping for the overflow, which changes the code paths and results in different rendering.
And, possibly more importantly, the inner div will render on-top of the outer div, meaning you can get accumulated coverage on the edges depending on characteristics of the specific rasterizer. I.e if you want to have a chance of working you should avoid overlap between the inner and outer divs (at the very least where the border edges will be.)
Thank you very much for the very quick feedback.

So I guess it's expected that some tests fail due to this:
* http://w3c-test.org/css/css-contain/contain-paint-clip-015.html
* http://w3c-test.org/css/css-contain/contain-paint-clip-016.html

Is there any way to mark them as "fuzzy"?
Support for "fuzzyness" is discussed in https://github.com/web-platform-tests/wpt/issues/7543

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