custom_single_child_layout_test.dart 5.7 KB
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// Copyright 2014 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/widgets.dart';
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import 'package:flutter_test/flutter_test.dart';
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class TestSingleChildLayoutDelegate extends SingleChildLayoutDelegate {
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  late BoxConstraints constraintsFromGetSize;
  BoxConstraints? constraintsFromGetConstraintsForChild;
  late Size sizeFromGetPositionForChild;
  late Size childSizeFromGetPositionForChild;
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  @override
  Size getSize(BoxConstraints constraints) {
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    if (!RenderObject.debugCheckingIntrinsics) {
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      constraintsFromGetSize = constraints;
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    }
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    return const Size(200.0, 300.0);
  }

  @override
  BoxConstraints getConstraintsForChild(BoxConstraints constraints) {
    assert(!RenderObject.debugCheckingIntrinsics);
    constraintsFromGetConstraintsForChild = constraints;
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    return const BoxConstraints(minWidth: 100.0, maxWidth: 150.0, minHeight: 200.0, maxHeight: 400.0);
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  }

  @override
  Offset getPositionForChild(Size size, Size childSize) {
    assert(!RenderObject.debugCheckingIntrinsics);
    sizeFromGetPositionForChild = size;
    childSizeFromGetPositionForChild = childSize;
    return Offset.zero;
  }

  bool shouldRelayoutCalled = false;
  bool shouldRelayoutValue = false;

  @override
  bool shouldRelayout(_) {
    assert(!RenderObject.debugCheckingIntrinsics);
    shouldRelayoutCalled = true;
    return shouldRelayoutValue;
  }
}

class FixedSizeLayoutDelegate extends SingleChildLayoutDelegate {
  FixedSizeLayoutDelegate(this.size);

  final Size size;

  @override
  Size getSize(BoxConstraints constraints) => size;

  @override
  BoxConstraints getConstraintsForChild(BoxConstraints constraints) {
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    return BoxConstraints.tight(size);
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  }

  @override
  bool shouldRelayout(FixedSizeLayoutDelegate oldDelegate) {
    return size != oldDelegate.size;
  }
}

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class NotifierLayoutDelegate extends SingleChildLayoutDelegate {
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  NotifierLayoutDelegate(this.size) : super(relayout: size);
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  final ValueNotifier<Size> size;

  @override
  Size getSize(BoxConstraints constraints) => size.value;

  @override
  BoxConstraints getConstraintsForChild(BoxConstraints constraints) {
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    return BoxConstraints.tight(size.value);
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  }

  @override
  bool shouldRelayout(NotifierLayoutDelegate oldDelegate) {
    return size != oldDelegate.size;
  }
}

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Widget buildFrame(SingleChildLayoutDelegate delegate) {
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  return Center(
    child: CustomSingleChildLayout(
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      delegate: delegate,
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      child: Container(),
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    ),
  );
}

void main() {
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  testWidgets('Control test for CustomSingleChildLayout', (WidgetTester tester) async {
    final TestSingleChildLayoutDelegate delegate = TestSingleChildLayoutDelegate();
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    await tester.pumpWidget(buildFrame(delegate));

    expect(delegate.constraintsFromGetSize.minWidth, 0.0);
    expect(delegate.constraintsFromGetSize.maxWidth, 800.0);
    expect(delegate.constraintsFromGetSize.minHeight, 0.0);
    expect(delegate.constraintsFromGetSize.maxHeight, 600.0);

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    expect(delegate.constraintsFromGetConstraintsForChild!.minWidth, 0.0);
    expect(delegate.constraintsFromGetConstraintsForChild!.maxWidth, 800.0);
    expect(delegate.constraintsFromGetConstraintsForChild!.minHeight, 0.0);
    expect(delegate.constraintsFromGetConstraintsForChild!.maxHeight, 600.0);
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    expect(delegate.sizeFromGetPositionForChild.width, 200.0);
    expect(delegate.sizeFromGetPositionForChild.height, 300.0);

    expect(delegate.childSizeFromGetPositionForChild.width, 150.0);
    expect(delegate.childSizeFromGetPositionForChild.height, 400.0);
  });

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  testWidgets('Test SingleChildDelegate shouldRelayout method', (WidgetTester tester) async {
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    TestSingleChildLayoutDelegate delegate =
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        TestSingleChildLayoutDelegate();
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    await tester.pumpWidget(buildFrame(delegate));

    // Layout happened because the delegate was set.
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    expect(delegate.constraintsFromGetConstraintsForChild, isNotNull); // i.e. layout happened
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    expect(delegate.shouldRelayoutCalled, isFalse);

    // Layout did not happen because shouldRelayout() returned false.
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    delegate = TestSingleChildLayoutDelegate();
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    delegate.shouldRelayoutValue = false;
    await tester.pumpWidget(buildFrame(delegate));
    expect(delegate.shouldRelayoutCalled, isTrue);
    expect(delegate.constraintsFromGetConstraintsForChild, isNull);

    // Layout happened because shouldRelayout() returned true.
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    delegate = TestSingleChildLayoutDelegate();
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    delegate.shouldRelayoutValue = true;
    await tester.pumpWidget(buildFrame(delegate));
    expect(delegate.shouldRelayoutCalled, isTrue);
    expect(delegate.constraintsFromGetConstraintsForChild, isNotNull);
  });

  testWidgets('Delegate can change size', (WidgetTester tester) async {
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    await tester.pumpWidget(buildFrame(FixedSizeLayoutDelegate(const Size(100.0, 200.0))));
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    RenderBox box = tester.renderObject(find.byType(CustomSingleChildLayout));
    expect(box.size, equals(const Size(100.0, 200.0)));

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    await tester.pumpWidget(buildFrame(FixedSizeLayoutDelegate(const Size(150.0, 240.0))));
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    box = tester.renderObject(find.byType(CustomSingleChildLayout));
    expect(box.size, equals(const Size(150.0, 240.0)));
  });
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  testWidgets('Can use listener for relayout', (WidgetTester tester) async {
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    final ValueNotifier<Size> size = ValueNotifier<Size>(const Size(100.0, 200.0));
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    await tester.pumpWidget(buildFrame(NotifierLayoutDelegate(size)));
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    RenderBox box = tester.renderObject(find.byType(CustomSingleChildLayout));
    expect(box.size, equals(const Size(100.0, 200.0)));

    size.value = const Size(150.0, 240.0);
    await tester.pump();

    box = tester.renderObject(find.byType(CustomSingleChildLayout));
    expect(box.size, equals(const Size(150.0, 240.0)));
  });
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}