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Many of the widgets that use CustomPaint were spamming repaints because CustomPaint repaints when the identity of the onPaint callback changes, which it does every build for StatelessComponents. This patch changes CustomPaint to use a CustomPainter, similar to the new custom layout widgets. The CustomPainter has a `shouldRepaint` function along with its `paint` function. This function gives clients explicit control over when the custom paint object repaints.
68 lines
1.5 KiB
Dart
68 lines
1.5 KiB
Dart
import 'package:flutter/rendering.dart';
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const Size _kTestViewSize = const Size(800.0, 600.0);
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class TestRenderView extends RenderView {
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TestRenderView() {
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attach();
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rootConstraints = new ViewConstraints(size: _kTestViewSize);
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scheduleInitialLayout();
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scheduleInitialPaint(new TransformLayer(transform: new Matrix4.identity()));
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}
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}
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enum EnginePhase {
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layout,
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paint,
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composite
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}
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RenderView _renderView;
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RenderView get renderView => _renderView;
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void layout(RenderBox box, { BoxConstraints constraints, EnginePhase phase: EnginePhase.layout }) {
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assert(box != null); // if you want to just repump the last box, call pumpFrame().
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if (renderView == null)
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_renderView = new TestRenderView();
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if (renderView.child != null)
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renderView.child = null;
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if (constraints != null) {
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box = new RenderPositionedBox(
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child: new RenderConstrainedBox(
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additionalConstraints: constraints,
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child: box
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)
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);
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}
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renderView.child = box;
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pumpFrame(phase: phase);
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}
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void pumpFrame({ EnginePhase phase: EnginePhase.layout }) {
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RenderObject.flushLayout();
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if (phase == EnginePhase.layout)
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return;
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renderView.updateCompositingBits();
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RenderObject.flushPaint();
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if (phase == EnginePhase.paint)
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return;
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renderView.compositeFrame();
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}
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class TestCallbackPainter extends CustomPainter {
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const TestCallbackPainter({ this.onPaint });
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final VoidCallback onPaint;
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void paint(Canvas canvas, Size size) {
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onPaint();
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}
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bool shouldRepaint(TestCallbackPainter oldPainter) => true;
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}
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