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haikuwebkit/LayoutTests/fast/text/emoji-with-joiner.html

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[Cocoa] LastResort in the font family list causes emoji with joiners to be rendered as multiple .notdef characters https://bugs.webkit.org/show_bug.cgi?id=187209 <rdar://problem/40920785> Reviewed by Darin Adler. Source/WebCore: Inside our complex text codepath, we perform our own font fallback, which includes a function that asks "can this font support this grapheme cluster?" Because of the mechanics of how fonts work, the implementation of this function is "Does the font's cmap table support every character of the cluster?" We were using Font::glyphForCharacter() to determine this; however, this function maps certain control characters to the zero width space character (with the intention that these control characters shouldn't be visible in the fast text codepath). That replacement, however, was causing us to get false negatives, because Apple Color Emoji doesn't support zero width space. Therefore, Apple Color Emoji was looking like it didn't support emoji combining sequences. The best solution to this would be to get Font::glyphForCharacter() to stop performing these replacements (see https://bugs.webkit.org/show_bug.cgi?id=187166). However, that is too risky of a change to be making right now. Instead, a more localized solution is to implement a version of "Does the font's cmap table support every character of the cluster" that doesn't perform the substitutions. This patch does exactly that, and uses a bit vector to cache the results. In order to not have a giant bit vector, we take the old code path if we know the substitutions won't affect us (and uses ASSERT()s to validate this) so the bit vector only holds at maximum 3 words of storage. Test: fast/text/emoji-with-joiner.html * platform/graphics/Font.cpp: (WebCore::codePointSupportIndex): (WebCore::createAndFillGlyphPage): (WebCore::Font::platformSupportsCodePoint const): (WebCore::Font::supportsCodePoint const): (WebCore::Font::canRenderCombiningCharacterSequence const): * platform/graphics/Font.h: * platform/graphics/cocoa/FontCocoa.mm: (WebCore::Font::platformSupportsCodePoint const): Source/WTF: * wtf/unicode/CharacterNames.h: LayoutTests: * fast/text/emoji-with-joiner-expected.txt: Added. * fast/text/emoji-with-joiner.html: Added. Canonical link: https://commits.webkit.org/202498@main git-svn-id: https://svn.webkit.org/repository/webkit/trunk@233413 268f45cc-cd09-0410-ab3c-d52691b4dbfc
2018-07-02 01:36:43 +00:00
<!DOCTYPE html>
<html>
<head>
<script src="../../resources/js-test-pre.js"></script>
<style>
.ib {
font: 48px 'Apple Color Emoji', 'LastResort';
display: inline-block;
}
</style>
</head>
<body>
<div class="ib">&#x1F471;&zwj;&#x2642;&#xFE0F;</div>
<div class="ib">&#x1F471;&#x1F3FB;&zwj;&#x2642;&#xFE0F;</div>
<div class="ib">&#x1F471;&#x1F3FC;&zwj;&#x2642;&#xFE0F;</div>
<div class="ib">&#x1F471;&#x1F3FD;&zwj;&#x2642;&#xFE0F;</div>
<div class="ib">&#x1F471;&#x1F3FE;&zwj;&#x2642;&#xFE0F;</div>
<div class="ib">&#x1F471;&#x1F3FF;&zwj;&#x2642;&#xFE0F;</div>
<script>
var elements = document.querySelectorAll(".ib");
for (var element of elements) {
shouldBe("element.offsetWidth", "48");
}
</script>
<script src="../../resources/js-test-post.js"></script>
</body>
</html>