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base repository: flutter/engine
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  • 3 commits
  • 11 files changed
  • 2 contributors

Commits on Aug 31, 2023

  1. Roll Skia from bf6b239838d3 to e1b27dcecd0a (1 revision) (#45349) 

    https://skia.googlesource.com/skia.git/+log/bf6b239838d3..e1b27dcecd0a

2023-08-31 [email protected] Roll HarfBuzz from f380a328 to 4cfc6d8e (4 commits)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/skia-flutter-autoroll
Please CC [email protected],[email protected],[email protected],[email protected] on the revert to ensure that a human
is aware of the problem.

To file a bug in Skia: https://bugs.chromium.org/p/skia/issues/entry
To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
    @skia-flutter-autoroll
    skia-flutter-autoroll authored Aug 31, 2023
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  2. Roll Dart SDK from ac3bc9f6351a to 9f9bd8cddfb0 (1 revision) (#45352) 

    https://dart.googlesource.com/sdk.git/+log/ac3bc9f6351a..9f9bd8cddfb0

2023-08-31 [email protected] Version 3.2.0-127.0.dev

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/dart-sdk-flutter-engine
Please CC [email protected],[email protected] on the revert to ensure that a human
is aware of the problem.

To file a bug in Flutter Engine: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
    @skia-flutter-autoroll
    skia-flutter-autoroll authored Aug 31, 2023
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  3. [web] More efficient fallback font selection (#44526) 

    The PR improves the code size and runtime performance of fallback font selection.

### Performance improvements

Initialization of the data structures to support fallback font selection has been moved from creating the FallbackFontManager (first frame) to the first use, i.e. the first frame actually needing a fallback font.

The numbers reported below are for a lightly edited version of the counter demo that appends to the counter about ~300 missing code points that need ~25 fallback fonts to cover the missing code points. Timings taken from a few profiles on my performance workstation.

|  |  Before | After  | 
| --- | ---: | ---: |
| FallbackFontManager() |~100ms | <2ms |
| First need | 0ms | 12ms |
| Subsequent need | 20-30ms | <1ms |

### Size improvements

|  |  Before | After  | � |
| --- | ---: | ---: | ---: |
| main.dart.js | 1586405 | 1477319 | -109086 (-6.87%) |
| brotli -9 | 427304 | 401611 | -25693 (-6.01%) |

### Algorithm notes

#### Startup

The old algorithm built an interval tree from the code point ranges of the ~140 fallback fonts and uses the interval tree to build a list of fonts that support each missing code point. The new algorithm uses a binary search map that directly produces the list of fonts. There are fewer binary search ranges (~22k) than the aggregate ranges for all the fonts (~26k).
Most of the startup time gain comes from using a data unpacks directly into a useful form rather than needing processing to build an interval tree (~12ms vs ~100ms).

#### Running

The runtime for font selection is greatly improved for several reasons

- The code point space is partitioned into components so that code point counting can be batched.
- When a font is selected, the counts are updated incrementally rather than being recomputed.
- The counts are held in fields of the NotoFont and component objects rather than in Maps or Sets.

Batching, incremental update and avoiding hash tables are roughly multiplicative in effect.

## Issues

- flutter/flutter#131440

*If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].*

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style
    @rakudrama
    rakudrama authored Aug 31, 2023
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