1912463 - Emoji is blurred/jagged on a bugzilla comment

Status: RESOLVED WORKSFORME

(Core :: Graphics: Canvas2D, defect)

Description

[Mayank Bansal]

Go to https://bugzilla.mozilla.org/show_bug.cgi?id=1912431#c0
pinch-zoom on the emoji

AR: The emoji is blurred/jagged
ER: Not so

Bisection:
Bug 1875670 - Add a cache for rasterized COLRv1 glyphs, because fully redrawing them on each use can be expensive. r=gfx-reviewers,lsalzman
Differential Revision: https://phabricator.services.mozilla.com/D200139

I am filing this separately from bug 1912431, but feel free to dupe.

Comment 1

[Mayank Bansal]

Attachment: about:support

Comment 2

[Mayank Bansal]

Attachment: bug.png

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1875670

Comment 4

[Mayank Bansal]

FWIW, patch from bug 1912431 does not fix this issue.

Comment 5

[Jonathan Kew [:jfkthame]]

This looks like it's the same issue as bug 1908261.

Comment 6

[Jonathan Kew [:jfkthame]]

This isn't exactly the same issue as bug 1908261, as it is specifically about the pinch-zoom case (which serves to exaggerate any blurriness of the emoji).

Still, the patch that recently landed in bug 1908261 has significantly improved things here, as it increased the resolution of the cached rendering of the emoji. It won't be entirely as sharp as the rendering before the cache was added, as we were previously rendering all the components of the color glyph directly to the (zoomed) destination and so the shapes were re-rasterized at full resolution (like their surrounding text).

Now, however, we use a cached rasterization that is based on the original (un-zoomed) size, and so it will inevitably be a bit blurry when zoomed.

Still, the higher-res cache provided by bug 1908261 makes the result reasonably acceptable, I think. We can't revert to uncached "direct" rendering of these emoji because of the performance cost of individually drawing so many shapes when a page uses large numbers of emoji.

Comment 7

[Mayank Bansal]

I checked, and the emojis look much improved now.
Not sure if this bug should be closed or kept open?
(ni? you just for this question)

Comment 8

[Jonathan Kew [:jfkthame]]

Let's close this as WFM at this point; the result seems acceptable, and I don't think there's much else we can do here at present.

(Some day maybe we'll have native color-font rendering in webrender, which could further improve this....)