packages/flutter/test/rendering/baseline_test.dart

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

import 'package:flutter/rendering.dart';
import 'package:flutter_test/flutter_test.dart';

import 'rendering_tester.dart';

void main() {
  TestRenderingFlutterBinding.ensureInitialized();

  test('RenderBaseline', () {
    RenderBaseline parent;
    RenderSizedBox child;
    final RenderBox root = RenderPositionedBox(
      alignment: Alignment.topLeft,
      child: parent = RenderBaseline(
        baseline: 0.0,
        baselineType: TextBaseline.alphabetic,
        child: child = RenderSizedBox(const Size(100.0, 100.0)),
      ),
    );
    final BoxParentData childParentData = child.parentData! as BoxParentData;

    layout(root);
    expect(childParentData.offset.dx, equals(0.0));
    expect(childParentData.offset.dy, equals(-100.0));
    expect(parent.size, equals(const Size(100.0, 0.0)));

    parent.baseline = 25.0;
    pumpFrame();
    expect(childParentData.offset.dx, equals(0.0));
    expect(childParentData.offset.dy, equals(-75.0));
    expect(parent.size, equals(const Size(100.0, 25.0)));

    parent.baseline = 90.0;
    pumpFrame();
    expect(childParentData.offset.dx, equals(0.0));
    expect(childParentData.offset.dy, equals(-10.0));
    expect(parent.size, equals(const Size(100.0, 90.0)));

    parent.baseline = 100.0;
    pumpFrame();
    expect(childParentData.offset.dx, equals(0.0));
    expect(childParentData.offset.dy, equals(0.0));
    expect(parent.size, equals(const Size(100.0, 100.0)));

    parent.baseline = 110.0;
    pumpFrame();
    expect(childParentData.offset.dx, equals(0.0));
    expect(childParentData.offset.dy, equals(10.0));
    expect(parent.size, equals(const Size(100.0, 110.0)));
  });

  test('RenderFlex and RenderIgnoreBaseline (control test -- with baseline)', () {
    final RenderBox a, b;
    final RenderBox root = RenderFlex(
      crossAxisAlignment: CrossAxisAlignment.baseline,
      textBaseline: TextBaseline.alphabetic,
      textDirection: TextDirection.ltr,
      children: <RenderBox>[
        a = RenderParagraph(
          const TextSpan(text: 'a', style: TextStyle(fontSize: 128.0, fontFamily: 'FlutterTest')), // places baseline at y=96
          textDirection: TextDirection.ltr,
        ),
        b = RenderParagraph(
          const TextSpan(text: 'b', style: TextStyle(fontSize: 32.0, fontFamily: 'FlutterTest')), // 24 above baseline, 8 below baseline
          textDirection: TextDirection.ltr,
        ),
      ],
    );
    layout(root);

    final Offset aPos = a.localToGlobal(Offset.zero);
    final Offset bPos = b.localToGlobal(Offset.zero);
    expect(aPos.dy, 0.0);
    expect(bPos.dy, 96.0 - 24.0);
  });

  test('RenderFlex and RenderIgnoreBaseline (with ignored baseline)', () {
    final RenderBox a, b;
    final RenderBox root = RenderFlex(
      crossAxisAlignment: CrossAxisAlignment.baseline,
      textBaseline: TextBaseline.alphabetic,
      textDirection: TextDirection.ltr,
      children: <RenderBox>[
        RenderIgnoreBaseline(
          child: a = RenderParagraph(
            const TextSpan(text: 'a', style: TextStyle(fontSize: 128.0, fontFamily: 'FlutterTest')),
            textDirection: TextDirection.ltr,
          ),
        ),
        b = RenderParagraph(
          const TextSpan(text: 'b', style: TextStyle(fontSize: 32.0, fontFamily: 'FlutterTest')),
          textDirection: TextDirection.ltr,
        ),
      ],
    );
    layout(root);

    final Offset aPos = a.localToGlobal(Offset.zero);
    final Offset bPos = b.localToGlobal(Offset.zero);
    expect(aPos.dy, 0.0);
    expect(bPos.dy, 0.0);
  });
}