Subpixel positioning fails since ac5525a #8166

paulrouget · 2015-10-23T07:20:10Z

When an iframe is present in the document, top:0.5px is drawn at 1px.

It's started with ac5525a.

<style>

  div {
    position: absolute;
    left: 0;
    top: 10.5px;
    width: 200px;
    height: 200px;
    background: red;
  }

  iframe {
    border: none;
  }

  .foo { display: none; }

</style>

<script>
  setInterval(() => {
    document.querySelector('iframe').classList.toggle('foo');
  }, 1000);
</script>

<body>
  <div></div>
  <iframe></iframe>
</body>

paulrouget · 2015-10-23T07:24:18Z

/cc @mrobinson

paulrouget · 2015-10-23T07:45:36Z

Using to_nearest_pixel instead of to_nearest_px in components/gfx/paint_task.rs appears to solve the issue. I'll submit a PR.

paulrouget · 2015-10-23T08:41:38Z

I don't know how to get the pixel density in build_layer_properties. Usually, we use page_rect and screen_screen, but here, I don't know how to get this info.

mrobinson · 2015-10-27T22:32:06Z

I think one issue here is that the layer boundaries are rounded instead of expanded to pixel boundaries. I have a fix for this which depends on servo/app_units#3 (though I don't have a readily accessible hidpi screen to test it on).

glennw · 2015-10-27T23:00:57Z

@mrobinson Depending on what you're testing, you may be able to use --device-pixel-ratio=2 even on a non-hidpi monitor to test with.


        Expand DisplayList layer bounds to whole pixel

Before passing these layers to the paint task, expand them to pixel boundaries. This ensures that subpixel edges of the layer will not be clipped away and helps prevent rounding issues with layer contents. Fixes servo#8166.


        Expand DisplayList layer bounds to whole pixels

Before passing these layers to the paint task, expand them to pixel boundaries. This ensures that subpixel edges of the layer will not be clipped away and helps prevent rounding issues with layer contents. Fixes servo#8166.


        Auto merge of #8244 - mrobinson:layer-size, r=pcwalton

Expand DisplayList layer bounds to whole pixels Before passing these layers to the paint task, expand them to pixel boundaries. This ensures that subpixel edges of the layer will not be clipped away and helps prevent rounding issues with layer contents. Fixes #8166.  [<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/servo/8244)

paulrouget mentioned this issue Oct 23, 2015

Servo + Browser.html: webplatform bugs browserhtml/browserhtml#562

Closed

62 of 92 tasks complete

jdm added the A-gfx/rendering label Oct 23, 2015

mrobinson mentioned this issue Oct 27, 2015

Mix stacking contexts into the positioned content list #8174

Closed

mrobinson mentioned this issue Oct 29, 2015

Expand DisplayList layer bounds to whole pixels #8244

Merged

bors-servo closed this in #8244 Oct 29, 2015

paulrouget added the A-browserhtml/P3 label Jan 26, 2016

servo / servo

Subpixel positioning fails since ac5525a #8166

Subpixel positioning fails since ac5525a #8166

paulrouget commented Oct 23, 2015

paulrouget commented Oct 23, 2015

paulrouget commented Oct 23, 2015

paulrouget commented Oct 23, 2015

mrobinson commented Oct 27, 2015

glennw commented Oct 27, 2015

servo / servo

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Subpixel positioning fails since ac5525a #8166

Subpixel positioning fails since ac5525a #8166

Comments

paulrouget commented Oct 23, 2015

paulrouget commented Oct 23, 2015

paulrouget commented Oct 23, 2015

paulrouget commented Oct 23, 2015

mrobinson commented Oct 27, 2015

glennw commented Oct 27, 2015