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Do not use ideographic baseline for RenderPargraph baseline #35493

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Merged
GaryQian merged 7 commits into from
Jul 3, 2019
Merged

Do not use ideographic baseline for RenderPargraph baseline #35493

GaryQian merged 7 commits into from
Jul 3, 2019

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@GaryQian
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@GaryQian GaryQian commented Jul 2, 2019 •
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Description

#25782 Has found that using the ideographic baseline for CJK results in improper vertical centering of text. The root cause of this is that the ideographic baseline implementation in LibTxt is currently only an approximation (an existing TODO specifies fixing this), and should not be used for sensitive purposes.

Here, we override the baseline parameter and always use TextBaseline.alphabtic since it produces a much more accurate and reasonable baseline for most CJK fonts.

The long term solution is to fully support other baselines and provide accurate values for them.

Related Issues

#25782

Tests

Verify that the position of the text is as expected in a popupmenu.

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@GaryQian GaryQian mentioned this pull request Jul 2, 2019
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@goderbauer goderbauer added the framework flutter/packages/flutter repository. See also f: labels. label Jul 2, 2019
@GaryQian GaryQian added a: typography Text rendering, possibly libtxt engine flutter/engine related. See also e: labels. labels Jul 3, 2019
justinmc
justinmc approved these changes Jul 3, 2019
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LGTM. Very thorough explanation of the problem!

packages/flutter_localizations/test/text_test.dart Outdated

await tester.tap(find.byKey(targetKey));
await tester.pump();
await tester.pump(const Duration(seconds: 1)); // finish the menu animation
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Does pumpAndSettle not work here?

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Either way I would think you can get rid of the previous empty pump().

packages/flutter_localizations/test/text_test.dart Outdated
Offset bottomLeft = tester.getBottomLeft(find.text('hello, world'));
Offset bottomRight = tester.getBottomRight(find.text('hello, world'));

expect(topLeft, Offset(392.0, 298.3999996185303));
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Watch out for this failing in Cirrus. Sometimes I have to fuzzy match things like this, but hopefully it just works.

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@GaryQian GaryQian Jul 3, 2019

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I may have to disable this test on mac/windows, as those platforms read fonts slightly differently. I'll see how cirrus handles it before doing that though!

packages/flutter_localizations/test/text_test.dart Outdated

await tester.tap(find.byKey(targetKey));
await tester.pump();
await tester.pump(const Duration(seconds: 1)); // finish the menu animation
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@justinmc justinmc Jul 3, 2019

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See previous comment about pumpAndSettle.

goderbauer
goderbauer reviewed Jul 3, 2019
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packages/flutter_localizations/test/text_test.dart
expect(topRight, const Offset(477.0, 346.3999996185303));
expect(bottomLeft, const Offset(392.0, 363.3999996185303));
expect(bottomRight, const Offset(477.0, 363.3999996185303));
}, skip: !isLinux);
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@goderbauer goderbauer Jul 3, 2019

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Any way we can make the tests pass on all platforms?

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Not easily, since each platform reads the fonts differently depending on if it is using Coretext or OpenType.

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@GaryQian GaryQian Jul 3, 2019

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This is also the reason why, we only run libtxt unit tests on linux.

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Maybe add at least a comment describing that?

@GaryQian GaryQian merged commit a0c47e2 into flutter:master Jul 3, 2019
tango5614 added a commit to tango5614/flutter that referenced this pull request Jul 4, 2019
@tango5614
Merge commit 'a0c47e2216a2b50b70c478001cf5652f31a783af' into fix28096
2234ae6 
* commit 'a0c47e2216a2b50b70c478001cf5652f31a783af': (187 commits)
  Do not use ideographic baseline for RenderPargraph baseline (flutter#35493)
  Add type to StreamChannel in generated test code. (flutter#35367)
  Fix RenderFittedBox when child.size.isEmpty (flutter#35487)
  add APK build time benchmarks (flutter#35481)
  fix Selection handles position is off (flutter#34665)
  Move usage flutter create tests into memory filesystem. (flutter#35160)
  Include tags in SemanticsNode debug properties (flutter#35491)
  Re-apply 'Add currentSystemFrameTimeStamp to SchedulerBinding' (flutter#35492)
  CupertinoTextField vertical alignment (flutter#34723)
  Mark update-packages as non-experimental (flutter#35467)
  fix default artifacts to exclude ios and android (flutter#35303)
  Roll engine ffba2f6..7d3e722 (59 commits) (flutter#35489)
  Update macrobenchmarks README and app name (flutter#35477)
  mark windows and macos chrome dev mode as flaky (flutter#35495)
  Use the new service protocol message names (flutter#35482)
  Manual roll of engine 45b66b7...ffba2f6 (flutter#35464)
  more ui-as-code (flutter#35393)
  update reassemble doc (flutter#35164)
  New parameter for RawGestureDetector to customize semantics mapping (flutter#33936)
  Add --target support for Windows and Linux (flutter#34660)
  ...
@GaryQian GaryQian mentioned this pull request Jul 8, 2019
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johnsonmh pushed a commit to johnsonmh/flutter that referenced this pull request Jul 30, 2019
@GaryQian @johnsonmh
Do not use ideographic baseline for RenderPargraph baseline (flutter#…
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…35493)
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