edde746
b08b3b846a
Skia's dithered gradient shaders cost ~10ms per full-screen pass on Mali-class TV GPUs: the two spotlight scrims alone were ~20ms of a 27ms raster frame, while flat blended quads at the same coverage are ~free. Bake axis-aligned LinearGradients once into cached 1x1024 premultiplied strip textures drawn as stretched quads (shader fallback for unsupported shapes and the first frame). Converted the spotlight, TV detail backdrop, app-bar scrims, rail bleed, person-card overlay, and the video-controls scrim, which now also keeps one widget type across hasFrame flips so the controls subtree survives in-place source switches. Scripted-browse on a Mali-G31 box: draw p50 27.5ms -> 7.1ms, swap block 20.3ms -> 0.9ms, janky draws 69% -> 2%; screenshots pixel-identical.
97 lines
3.4 KiB
Dart
97 lines
3.4 KiB
Dart
import 'dart:typed_data';
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import 'dart:ui' as ui;
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import 'package:flutter/material.dart';
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import 'package:flutter/rendering.dart';
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import 'package:flutter_test/flutter_test.dart';
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import 'package:plezy/widgets/rasterized_gradient.dart';
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/// The strip texture must composite identically to Skia's gradient shader.
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/// Translucent non-black ramps are the regression case: rgba8888 strips are
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/// consumed premultiplied, so straight-alpha baking renders them far too
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/// bright (a white fade-to-transparent scrim becomes an opaque sheet).
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void main() {
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Future<ui.Image> capture(WidgetTester tester, Key key) async {
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final boundary = tester.renderObject<RenderRepaintBoundary>(find.byKey(key));
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late ui.Image image;
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await tester.runAsync(() async => image = await boundary.toImage());
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return image;
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}
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Future<List<int>> centerColumn(WidgetTester tester, ui.Image image) async {
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late ByteData bytes;
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await tester.runAsync(() async => bytes = (await image.toByteData())!);
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final x = image.width ~/ 2;
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final column = <int>[];
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for (var y = 0; y < image.height; y += 8) {
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final offset = (y * image.width + x) * 4;
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column.addAll([bytes.getUint8(offset), bytes.getUint8(offset + 1), bytes.getUint8(offset + 2)]);
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}
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return column;
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}
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testWidgets('strip path matches the gradient shader over a colored background', (tester) async {
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final gradient = LinearGradient(
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begin: Alignment.topCenter,
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end: Alignment.bottomCenter,
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colors: [
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Colors.white.withValues(alpha: 0.8),
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Colors.white.withValues(alpha: 0.4),
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Colors.white.withValues(alpha: 0.0),
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],
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stops: const [0.0, 0.4, 1.0],
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);
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// Bake ahead of the build so RasterizedGradient paints the strip from
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// its first frame instead of the (trivially identical) shader fallback.
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late ui.Image? strip;
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await tester.runAsync(() async => strip = await RasterizedGradient.prebake(gradient));
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expect(strip, isNotNull, reason: 'axis-aligned gradient must bake to a strip');
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const rasterizedKey = Key('rasterized');
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const shaderKey = Key('shader');
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Widget sample(Key key, Widget gradientBox) => RepaintBoundary(
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key: key,
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child: SizedBox(
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width: 64,
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height: 256,
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child: Stack(
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fit: StackFit.expand,
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children: [
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const ColoredBox(color: Color(0xFF406080)),
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gradientBox,
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],
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),
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),
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);
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await tester.pumpWidget(
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Directionality(
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textDirection: TextDirection.ltr,
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child: Center(
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child: Row(
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mainAxisSize: MainAxisSize.min,
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children: [
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sample(rasterizedKey, RasterizedGradient(gradient: gradient)),
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sample(shaderKey, DecoratedBox(decoration: BoxDecoration(gradient: gradient))),
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],
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),
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),
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),
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);
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final rasterized = await centerColumn(tester, await capture(tester, rasterizedKey));
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final shader = await centerColumn(tester, await capture(tester, shaderKey));
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for (var i = 0; i < shader.length; i++) {
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// Skia dithers its gradient shader; the strip doesn't. Allow a couple
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// of levels of noise — the premul bug is off by 50+ on this ramp.
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expect(
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(rasterized[i] - shader[i]).abs(),
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lessThanOrEqualTo(3),
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reason: 'channel ${i % 3} at sample ${i ~/ 3}: strip=${rasterized[i]} shader=${shader[i]}',
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);
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}
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});
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}
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