text_painter_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 'dart:ui' as ui;

import 'package:flutter/foundation.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';

void _checkCaretOffsetsLtrAt(String text, List<int> boundaries) {
  expect(boundaries.first, 0);
  expect(boundaries.last, text.length);

  final TextPainter painter = TextPainter()
    ..textDirection = TextDirection.ltr;

  // Lay out the string up to each boundary, and record the width.
  final List<double> prefixWidths = <double>[];
  for (final int boundary in boundaries) {
    painter.text = TextSpan(text: text.substring(0, boundary));
    painter.layout();
    prefixWidths.add(painter.width);
  }

  // The painter has the full text laid out.  Check the caret offsets.
  double caretOffset(int offset) {
    final TextPosition position = ui.TextPosition(offset: offset);
    return painter.getOffsetForCaret(position, ui.Rect.zero).dx;
  }
  expect(boundaries.map(caretOffset).toList(), prefixWidths);
  double lastOffset = caretOffset(0);
  for (int i = 1; i <= text.length; i++) {
    final double offset = caretOffset(i);
    expect(offset, greaterThanOrEqualTo(lastOffset));
    lastOffset = offset;
  }
  painter.dispose();
}

/// Check the caret offsets are accurate for the given single line of LTR text.
///
/// This lays out the given text as a single line with [TextDirection.ltr]
/// and checks the following invariants, which should always hold if the text
/// is made up of LTR characters:
///  * The caret offsets go monotonically from 0.0 to the width of the text.
///  * At each character (that is, grapheme cluster) boundary, the caret
///    offset equals the width that the text up to that point would have
///    if laid out on its own.
///
/// If you have a [TextSpan] instead of a plain [String],
/// see [caretOffsetsForTextSpan].
void checkCaretOffsetsLtr(String text) {
  final List<int> characterBoundaries = <int>[];
  final CharacterRange range = CharacterRange.at(text, 0);
  while (true) {
    characterBoundaries.add(range.current.length);
    if (range.stringAfterLength <= 0) {
      break;
    }
    range.expandNext();
  }
  _checkCaretOffsetsLtrAt(text, characterBoundaries);
}

/// Check the caret offsets are accurate for the given single line of LTR text,
/// ignoring character boundaries within each given cluster.
///
/// This concatenates [clusters] into a string and then performs the same
/// checks as [checkCaretOffsetsLtr], except that instead of checking the
/// offset-equals-prefix-width invariant at every character boundary,
/// it does so only at the boundaries between the elements of [clusters].
///
/// The elements of [clusters] should be composed of whole characters: each
/// element should be a valid character range in the concatenated string.
///
/// Consider using [checkCaretOffsetsLtr] instead of this function.  If that
/// doesn't pass, you may have an instance of <https://github.com/flutter/flutter/issues/122478>.
void checkCaretOffsetsLtrFromPieces(List<String> clusters) {
  final StringBuffer buffer = StringBuffer();
  final List<int> boundaries = <int>[];
  boundaries.add(buffer.length);
  for (final String cluster in clusters) {
    buffer.write(cluster);
    boundaries.add(buffer.length);
  }
  _checkCaretOffsetsLtrAt(buffer.toString(), boundaries);
}

/// Compute the caret offsets for the given single line of text, a [TextSpan].
///
/// This lays out the given text as a single line with the given [textDirection]
/// and returns a full list of caret offsets, one at each code unit boundary.
///
/// This also checks that the offset at the very start or very end, if the text
/// direction is RTL or LTR respectively, equals the line's width.
///
/// If you have a [String] instead of a nontrivial [TextSpan],
/// consider using [checkCaretOffsetsLtr] instead.
List<double> caretOffsetsForTextSpan(TextDirection textDirection, TextSpan text) {
  final TextPainter painter = TextPainter()
    ..textDirection = textDirection
    ..text = text
    ..layout();
  final int length = text.toPlainText().length;
  final List<double> result = List<double>.generate(length + 1, (int offset) {
    final TextPosition position = ui.TextPosition(offset: offset);
    return painter.getOffsetForCaret(position, ui.Rect.zero).dx;
  });
  switch (textDirection) {
    case TextDirection.ltr: expect(result[length], painter.width);
    case TextDirection.rtl: expect(result[0], painter.width);
  }
  painter.dispose();
  return result;
}

void main() {
  test('TextPainter caret test', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    String text = 'A';
    checkCaretOffsetsLtr(text);

    painter.text = TextSpan(text: text);
    painter.layout();

    Offset caretOffset = painter.getOffsetForCaret(
      const ui.TextPosition(offset: 0),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, 0);
    caretOffset = painter.getOffsetForCaret(ui.TextPosition(offset: text.length), ui.Rect.zero);
    expect(caretOffset.dx, painter.width);

    // Check that getOffsetForCaret handles a character that is encoded as a
    // surrogate pair.
    text = 'A\u{1F600}';
    checkCaretOffsetsLtr(text);
    painter.text = TextSpan(text: text);
    painter.layout();
    caretOffset = painter.getOffsetForCaret(ui.TextPosition(offset: text.length), ui.Rect.zero);
    expect(caretOffset.dx, painter.width);
    painter.dispose();
  });

  test('TextPainter caret test with WidgetSpan', () {
    // Regression test for https://github.com/flutter/flutter/issues/98458.
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    painter.text = const TextSpan(children: <InlineSpan>[
      TextSpan(text: 'before'),
      WidgetSpan(child: Text('widget')),
      TextSpan(text: 'after'),
    ]);
    painter.setPlaceholderDimensions(const <PlaceholderDimensions>[
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
    ]);
    painter.layout();
    final Offset caretOffset = painter.getOffsetForCaret(ui.TextPosition(offset: painter.text!.toPlainText().length), ui.Rect.zero);
    expect(caretOffset.dx, painter.width);
    painter.dispose();
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308

  test('TextPainter null text test', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    List<TextSpan> children = <TextSpan>[const TextSpan(text: 'B'), const TextSpan(text: 'C')];
    painter.text = TextSpan(children: children);
    painter.layout();

    Offset caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 0), ui.Rect.zero);
    expect(caretOffset.dx, 0);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 1), ui.Rect.zero);
    expect(caretOffset.dx, painter.width / 2);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 2), ui.Rect.zero);
    expect(caretOffset.dx, painter.width);

    children = <TextSpan>[];
    painter.text = TextSpan(children: children);
    painter.layout();

    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 0), ui.Rect.zero);
    expect(caretOffset.dx, 0);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 1), ui.Rect.zero);
    expect(caretOffset.dx, 0);
    painter.dispose();
  });

  test('TextPainter caret emoji test', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    // Format: '👩‍<zwj>👩‍<zwj>👦👩‍<zwj>👩‍<zwj>👧‍<zwj>👧👏<modifier>'
    // One three-person family, one four-person family, one clapping hands (medium skin tone).
    const String text = '👩‍👩‍👦👩‍👩‍👧‍👧👏🏽';
    checkCaretOffsetsLtr(text);

    painter.text = const TextSpan(text: text);
    painter.layout(maxWidth: 10000);

    expect(text.length, 23);

    Offset caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 0), ui.Rect.zero);
    expect(caretOffset.dx, 0); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: text.length), ui.Rect.zero);
    expect(caretOffset.dx, painter.width);

    // Two UTF-16 codepoints per emoji, one codepoint per zwj
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 1), ui.Rect.zero);
    expect(caretOffset.dx, 42); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 2), ui.Rect.zero);
    expect(caretOffset.dx, 42); // <zwj>
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 3), ui.Rect.zero);
    expect(caretOffset.dx, 42); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 4), ui.Rect.zero);
    expect(caretOffset.dx, 42); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 5), ui.Rect.zero);
    expect(caretOffset.dx, 42); // <zwj>
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 6), ui.Rect.zero);
    expect(caretOffset.dx, 42); // 👦
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 7), ui.Rect.zero);
    expect(caretOffset.dx, 42); // 👦
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 8), ui.Rect.zero);
    expect(caretOffset.dx, 42); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 9), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 10), ui.Rect.zero);
    expect(caretOffset.dx, 98); // <zwj>
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 11), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 12), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 13), ui.Rect.zero);
    expect(caretOffset.dx, 98); // <zwj>
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 14), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👧‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 15), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👧‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 16), ui.Rect.zero);
    expect(caretOffset.dx, 98); // <zwj>
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 17), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👧
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 18), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👧
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 19), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👏
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 20), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👏
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 21), ui.Rect.zero);
    expect(caretOffset.dx, 98); // <medium skin tone modifier>
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 22), ui.Rect.zero);
    expect(caretOffset.dx, 98); // <medium skin tone modifier>
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 23), ui.Rect.zero);
    expect(caretOffset.dx, 126); // end of string
    painter.dispose();
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308

  test('TextPainter caret emoji tests: single, long emoji', () {
    // Regression test for https://github.com/flutter/flutter/issues/50563
    checkCaretOffsetsLtr('👩‍🚀');
    checkCaretOffsetsLtr('👩‍❤️‍💋‍👩');
    checkCaretOffsetsLtr('👨‍👩‍👦‍👦');
    checkCaretOffsetsLtr('👨🏾‍🤝‍👨🏻');
    checkCaretOffsetsLtr('👨‍👦');
    checkCaretOffsetsLtr('👩‍👦');
    checkCaretOffsetsLtr('🏌🏿‍♀️');
    checkCaretOffsetsLtr('🏊‍♀️');
    checkCaretOffsetsLtr('🏄🏻‍♂️');

    // These actually worked even before #50563 was fixed (because
    // their lengths in code units are powers of 2, namely 4 and 8).
    checkCaretOffsetsLtr('🇺🇳');
    checkCaretOffsetsLtr('👩‍❤️‍👨');
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308

  test('TextPainter caret emoji test: letters, then 1 emoji of 5 code units', () {
    // Regression test for https://github.com/flutter/flutter/issues/50563
    checkCaretOffsetsLtr('a👩‍🚀');
    checkCaretOffsetsLtr('ab👩‍🚀');
    checkCaretOffsetsLtr('abc👩‍🚀');
    checkCaretOffsetsLtr('abcd👩‍🚀');
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308

  test('TextPainter caret zalgo test', () {
    // Regression test for https://github.com/flutter/flutter/issues/98516
    checkCaretOffsetsLtr('Z͉̳̺ͥͬ̾a̴͕̲̒̒͌̋ͪl̨͎̰̘͉̟ͤ̀̈̚͜g͕͔̤͖̟̒͝ͅo̵̡̡̼͚̐ͯ̅ͪ̆ͣ̚');
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308

  test('TextPainter caret Devanagari test', () {
    // Regression test for https://github.com/flutter/flutter/issues/118403
    checkCaretOffsetsLtrFromPieces(
        <String>['प्रा', 'प्त', ' ', 'व', 'र्ण', 'न', ' ', 'प्र', 'व्रु', 'ति']);
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308

  test('TextPainter caret Devanagari test, full strength', () {
    // Regression test for https://github.com/flutter/flutter/issues/118403
    checkCaretOffsetsLtr('प्राप्त वर्णन प्रव्रुति');
  }, skip: true); // https://github.com/flutter/flutter/issues/122478

  test('TextPainter caret emoji test LTR: letters next to emoji, as separate TextBoxes', () {
    // Regression test for https://github.com/flutter/flutter/issues/122477
    // The trigger for this bug was to have SkParagraph report separate
    // TextBoxes for the emoji and for the characters next to it.
    // In normal usage on a real device, this can happen by simply typing
    // letters and then an emoji, presumably because they get different fonts.
    // In these tests, our single test font covers both letters and emoji,
    // so we provoke the same effect by adding styles.
    expect(caretOffsetsForTextSpan(
        TextDirection.ltr,
        const TextSpan(children: <TextSpan>[
          TextSpan(text: '👩‍🚀', style: TextStyle()),
          TextSpan(text: ' words', style: TextStyle(fontWeight: FontWeight.bold)),
        ])),
        <double>[0, 28, 28, 28, 28, 28, 42, 56, 70, 84, 98, 112]);
    expect(caretOffsetsForTextSpan(
        TextDirection.ltr,
        const TextSpan(children: <TextSpan>[
          TextSpan(text: 'words ', style: TextStyle(fontWeight: FontWeight.bold)),
          TextSpan(text: '👩‍🚀', style: TextStyle()),
        ])),
        <double>[0, 14, 28, 42, 56, 70, 84, 84, 84, 84, 84, 112]);
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308

  test('TextPainter caret emoji test RTL: letters next to emoji, as separate TextBoxes', () {
    // Regression test for https://github.com/flutter/flutter/issues/122477
    expect(caretOffsetsForTextSpan(
        TextDirection.rtl,
        const TextSpan(children: <TextSpan>[
          TextSpan(text: '👩‍🚀', style: TextStyle()),
          TextSpan(text: ' מילים', style: TextStyle(fontWeight: FontWeight.bold)),
        ])),
        <double>[112, 84, 84, 84, 84, 84, 70, 56, 42, 28, 14, 0]);
    expect(caretOffsetsForTextSpan(
        TextDirection.rtl,
        const TextSpan(children: <TextSpan>[
          TextSpan(text: 'מילים ', style: TextStyle(fontWeight: FontWeight.bold)),
          TextSpan(text: '👩‍🚀', style: TextStyle()),
        ])),
        <double>[112, 98, 84, 70, 56, 42, 28, 28, 28, 28, 28, 0]);
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308

  test('TextPainter caret center space test', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    const String text = 'test text with space at end   ';
    painter.text = const TextSpan(text: text);
    painter.textAlign = TextAlign.center;
    painter.layout();

    Offset caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 0), ui.Rect.zero);
    expect(caretOffset.dx, 21);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: text.length), ui.Rect.zero);
    // The end of the line is 441, but the width is only 420, so the cursor is
    // stopped there without overflowing.
    expect(caretOffset.dx, painter.width);

    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 1), ui.Rect.zero);
    expect(caretOffset.dx, 35);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 2), ui.Rect.zero);
    expect(caretOffset.dx, 49);
    painter.dispose();
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308

  test('TextPainter error test', () {
    final TextPainter painter = TextPainter(textDirection: TextDirection.ltr);

    expect(
      () => painter.paint(MockCanvas(), Offset.zero),
      throwsA(isA<StateError>().having(
        (StateError error) => error.message,
        'message',
        contains('TextPainter.paint called when text geometry was not yet calculated'),
      )),
    );
    painter.dispose();
  });

  test('TextPainter requires textDirection', () {
    final TextPainter painter1 = TextPainter(text: const TextSpan(text: ''));
    expect(painter1.layout, throwsStateError);
    final TextPainter painter2 = TextPainter(text: const TextSpan(text: ''), textDirection: TextDirection.rtl);
    expect(painter2.layout, isNot(throwsStateError));
  });

  test('TextPainter size test', () {
    final TextPainter painter = TextPainter(
      text: const TextSpan(
        text: 'X',
        style: TextStyle(inherit: false, fontSize: 123.0),
      ),
      textDirection: TextDirection.ltr,
    );
    painter.layout();
    expect(painter.size, const Size(123.0, 123.0));
    painter.dispose();
  });

  test('TextPainter textScaler test', () {
    final TextPainter painter = TextPainter(
      text: const TextSpan(
        text: 'X',
        style: TextStyle(inherit: false, fontSize: 10.0),
      ),
      textDirection: TextDirection.ltr,
      textScaler: const TextScaler.linear(2.0),
    );
    painter.layout();
    expect(painter.size, const Size(20.0, 20.0));
    painter.dispose();
  });

  test('TextPainter textScaler null style test', () {
    final TextPainter painter = TextPainter(
      text: const TextSpan(
        text: 'X',
      ),
      textDirection: TextDirection.ltr,
      textScaler: const TextScaler.linear(2.0),
    );
    painter.layout();
    expect(painter.size, const Size(28.0, 28.0));
    painter.dispose();
  });

  test('TextPainter default text height is 14 pixels', () {
    final TextPainter painter = TextPainter(
      text: const TextSpan(text: 'x'),
      textDirection: TextDirection.ltr,
    );
    painter.layout();
    expect(painter.preferredLineHeight, 14.0);
    expect(painter.size, const Size(14.0, 14.0));
    painter.dispose();
  });

  test('TextPainter sets paragraph size from root', () {
    final TextPainter painter = TextPainter(
      text: const TextSpan(text: 'x', style: TextStyle(fontSize: 100.0)),
      textDirection: TextDirection.ltr,
    );
    painter.layout();
    expect(painter.preferredLineHeight, 100.0);
    expect(painter.size, const Size(100.0, 100.0));
    painter.dispose();
  });

  test('TextPainter intrinsic dimensions', () {
    const TextStyle style = TextStyle(
      inherit: false,
      fontSize: 10.0,
    );
    TextPainter painter;

    painter = TextPainter(
      text: const TextSpan(
        text: 'X X X',
        style: style,
      ),
      textDirection: TextDirection.ltr,
    );
    painter.layout();
    expect(painter.size, const Size(50.0, 10.0));
    expect(painter.minIntrinsicWidth, 10.0);
    expect(painter.maxIntrinsicWidth, 50.0);
    painter.dispose();

    painter = TextPainter(
      text: const TextSpan(
        text: 'X X X',
        style: style,
      ),
      textDirection: TextDirection.ltr,
      ellipsis: 'e',
    );
    painter.layout();
    expect(painter.size, const Size(50.0, 10.0));
    expect(painter.minIntrinsicWidth, 50.0);
    expect(painter.maxIntrinsicWidth, 50.0);
    painter.dispose();

    painter = TextPainter(
      text: const TextSpan(
        text: 'X X XXXX',
        style: style,
      ),
      textDirection: TextDirection.ltr,
      maxLines: 2,
    );
    painter.layout();
    expect(painter.size, const Size(80.0, 10.0));
    expect(painter.minIntrinsicWidth, 40.0);
    expect(painter.maxIntrinsicWidth, 80.0);
    painter.dispose();

    painter = TextPainter(
      text: const TextSpan(
        text: 'X X XXXX XX',
        style: style,
      ),
      textDirection: TextDirection.ltr,
      maxLines: 2,
    );
    painter.layout();
    expect(painter.size, const Size(110.0, 10.0));
    expect(painter.minIntrinsicWidth, 70.0);
    expect(painter.maxIntrinsicWidth, 110.0);
    painter.dispose();

    painter = TextPainter(
      text: const TextSpan(
        text: 'XXXXXXXX XXXX XX X',
        style: style,
      ),
      textDirection: TextDirection.ltr,
      maxLines: 2,
    );
    painter.layout();
    expect(painter.size, const Size(180.0, 10.0));
    expect(painter.minIntrinsicWidth, 90.0);
    expect(painter.maxIntrinsicWidth, 180.0);
    painter.dispose();

    painter = TextPainter(
      text: const TextSpan(
        text: 'X XX XXXX XXXXXXXX',
        style: style,
      ),
      textDirection: TextDirection.ltr,
      maxLines: 2,
    );
    painter.layout();
    expect(painter.size, const Size(180.0, 10.0));
    expect(painter.minIntrinsicWidth, 90.0);
    expect(painter.maxIntrinsicWidth, 180.0);
    painter.dispose();
  }, skip: true); // https://github.com/flutter/flutter/issues/13512

  test('TextPainter handles newlines properly', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    const double SIZE_OF_A = 14.0; // square size of "a" character
    String text = 'aaa';
    painter.text = TextSpan(text: text);
    painter.layout();

    // getOffsetForCaret in a plain one-line string is the same for either affinity.
    int offset = 0;
    painter.text = TextSpan(text: text);
    painter.layout();
    Offset caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(SIZE_OF_A * offset, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(SIZE_OF_A * offset, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    offset = 1;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(SIZE_OF_A * offset, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(SIZE_OF_A * offset, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    offset = 2;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(SIZE_OF_A * offset, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(SIZE_OF_A * offset, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    offset = 3;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(SIZE_OF_A * offset, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(SIZE_OF_A * offset, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));

    // For explicit newlines, getOffsetForCaret places the caret at the location
    // indicated by offset regardless of affinity.
    text = '\n\n';
    painter.text = TextSpan(text: text);
    painter.layout();
    offset = 0;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    offset = 1;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A, epsilon: 0.0001));
    offset = 2;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A * 2, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A * 2, epsilon: 0.0001));

    // getOffsetForCaret in an unwrapped string with explicit newlines is the
    // same for either affinity.
    text = '\naaa';
    painter.text = TextSpan(text: text);
    painter.layout();
    offset = 0;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    offset = 1;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A, epsilon: 0.0001));

    // When text wraps on its own, getOffsetForCaret disambiguates between the
    // end of one line and start of next using affinity.
    text = 'aaaaaaaa'; // Just enough to wrap one character down to second line
    painter.text = TextSpan(text: text);
    painter.layout(maxWidth: 100); // SIZE_OF_A * text.length > 100, so it wraps
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: text.length - 1),
      ui.Rect.zero,
    );
    // When affinity is downstream, cursor is at beginning of second line
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: text.length - 1, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    // When affinity is upstream, cursor is at end of first line
    expect(caretOffset.dx, moreOrLessEquals(98.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));

    // When given a string with a newline at the end, getOffsetForCaret puts
    // the cursor at the start of the next line regardless of affinity
    text = 'aaa\n';
    painter.text = TextSpan(text: text);
    painter.layout();
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: text.length),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A, epsilon: 0.0001));
    offset = text.length;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A, epsilon: 0.0001));

    // Given a one-line right aligned string, positioning the cursor at offset 0
    // means that it appears at the "end" of the string, after the character
    // that was typed first, at x=0.
    painter.textAlign = TextAlign.right;
    text = 'aaa';
    painter.text = TextSpan(text: text);
    painter.layout();
    offset = 0;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    painter.textAlign = TextAlign.left;

    // When given an offset after a newline in the middle of a string,
    // getOffsetForCaret returns the start of the next line regardless of
    // affinity.
    text = 'aaa\naaa';
    painter.text = TextSpan(text: text);
    painter.layout();
    offset = 4;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A, epsilon: 0.0001));

    // When given a string with multiple trailing newlines, places the caret
    // in the position given by offset regardless of affinity.
    text = 'aaa\n\n\n';
    offset = 3;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(SIZE_OF_A * 3, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(SIZE_OF_A * 3, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));

    offset = 4;
    painter.text = TextSpan(text: text);
    painter.layout();
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A, epsilon: 0.001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A, epsilon: 0.0001));

    offset = 5;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A * 2, epsilon: 0.001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A * 2, epsilon: 0.0001));

    offset = 6;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A * 3, epsilon: 0.0001));

    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A * 3, epsilon: 0.0001));

    // When given a string with multiple leading newlines, places the caret in
    // the position given by offset regardless of affinity.
    text = '\n\n\naaa';
    offset = 3;
    painter.text = TextSpan(text: text);
    painter.layout();
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A * 3, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A * 3, epsilon: 0.0001));

    offset = 2;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A * 2, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A * 2, epsilon: 0.0001));

    offset = 1;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy,moreOrLessEquals(SIZE_OF_A, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(SIZE_OF_A, epsilon: 0.0001));

    offset = 0;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
    expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
    painter.dispose();
  });

  test('TextPainter widget span', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    const String text = 'test';
    painter.text = const TextSpan(
      text: text,
      children: <InlineSpan>[
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
        TextSpan(text: text),
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
        TextSpan(text: text),
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
        WidgetSpan(child: SizedBox(width: 50, height: 30)),
      ],
    );

    // We provide dimensions for the widgets
    painter.setPlaceholderDimensions(const <PlaceholderDimensions>[
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(51, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
    ]);

    painter.layout(maxWidth: 500);

    // Now, each of the WidgetSpans will have their own placeholder 'hole'.
    Offset caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 1), ui.Rect.zero);
    expect(caretOffset.dx, 14);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 4), ui.Rect.zero);
    expect(caretOffset.dx, 56);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 5), ui.Rect.zero);
    expect(caretOffset.dx, 106);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 6), ui.Rect.zero);
    expect(caretOffset.dx, 120);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 10), ui.Rect.zero);
    expect(caretOffset.dx, 212);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 11), ui.Rect.zero);
    expect(caretOffset.dx, 262);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 12), ui.Rect.zero);
    expect(caretOffset.dx, 276);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 13), ui.Rect.zero);
    expect(caretOffset.dx, 290);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 14), ui.Rect.zero);
    expect(caretOffset.dx, 304);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 15), ui.Rect.zero);
    expect(caretOffset.dx, 318);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 16), ui.Rect.zero);
    expect(caretOffset.dx, 368);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 17), ui.Rect.zero);
    expect(caretOffset.dx, 418);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 18), ui.Rect.zero);
    expect(caretOffset.dx, 0);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 19), ui.Rect.zero);
    expect(caretOffset.dx, 50);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 23), ui.Rect.zero);
    expect(caretOffset.dx, 250);

    expect(painter.inlinePlaceholderBoxes!.length, 14);
    expect(painter.inlinePlaceholderBoxes![0], const TextBox.fromLTRBD(56, 0, 106, 30, TextDirection.ltr));
    expect(painter.inlinePlaceholderBoxes![2], const TextBox.fromLTRBD(212, 0, 262, 30, TextDirection.ltr));
    expect(painter.inlinePlaceholderBoxes![3], const TextBox.fromLTRBD(318, 0, 368, 30, TextDirection.ltr));
    expect(painter.inlinePlaceholderBoxes![4], const TextBox.fromLTRBD(368, 0, 418, 30, TextDirection.ltr));
    expect(painter.inlinePlaceholderBoxes![5], const TextBox.fromLTRBD(418, 0, 468, 30, TextDirection.ltr));
    // line should break here
    expect(painter.inlinePlaceholderBoxes![6], const TextBox.fromLTRBD(0, 30, 50, 60, TextDirection.ltr));
    expect(painter.inlinePlaceholderBoxes![7], const TextBox.fromLTRBD(50, 30, 100, 60, TextDirection.ltr));
    expect(painter.inlinePlaceholderBoxes![10], const TextBox.fromLTRBD(200, 30, 250, 60, TextDirection.ltr));
    expect(painter.inlinePlaceholderBoxes![11], const TextBox.fromLTRBD(250, 30, 300, 60, TextDirection.ltr));
    expect(painter.inlinePlaceholderBoxes![12], const TextBox.fromLTRBD(300, 30, 351, 60, TextDirection.ltr));
    expect(painter.inlinePlaceholderBoxes![13], const TextBox.fromLTRBD(351, 30, 401, 60, TextDirection.ltr));
    painter.dispose();
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/87540

  // Null values are valid. See https://github.com/flutter/flutter/pull/48346#issuecomment-584839221
  test('TextPainter set TextHeightBehavior null test', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    painter.textHeightBehavior = const TextHeightBehavior();
    painter.textHeightBehavior = null;
    painter.dispose();
  });

  test('TextPainter line metrics', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    const String text = 'test1\nhello line two really long for soft break\nfinal line 4';
    painter.text = const TextSpan(
      text: text,
    );

    painter.layout(maxWidth: 300);

    expect(painter.text, const TextSpan(text: text));
    expect(painter.preferredLineHeight, 14);

    final List<ui.LineMetrics> lines = painter.computeLineMetrics();

    expect(lines.length, 4);

    expect(lines[0].hardBreak, true);
    expect(lines[1].hardBreak, false);
    expect(lines[2].hardBreak, true);
    expect(lines[3].hardBreak, true);

    expect(lines[0].ascent, 10.5);
    expect(lines[1].ascent, 10.5);
    expect(lines[2].ascent, 10.5);
    expect(lines[3].ascent, 10.5);

    expect(lines[0].descent, 3.5);
    expect(lines[1].descent, 3.5);
    expect(lines[2].descent, 3.5);
    expect(lines[3].descent, 3.5);

    expect(lines[0].unscaledAscent, 10.5);
    expect(lines[1].unscaledAscent, 10.5);
    expect(lines[2].unscaledAscent, 10.5);
    expect(lines[3].unscaledAscent, 10.5);

    expect(lines[0].baseline, 10.5);
    expect(lines[1].baseline, 24.5);
    expect(lines[2].baseline, 38.5);
    expect(lines[3].baseline, 52.5);

    expect(lines[0].height, 14);
    expect(lines[1].height, 14);
    expect(lines[2].height, 14);
    expect(lines[3].height, 14);

    expect(lines[0].width, 70);
    expect(lines[1].width, 294);
    expect(lines[2].width, 266);
    expect(lines[3].width, 168);

    expect(lines[0].left, 0);
    expect(lines[1].left, 0);
    expect(lines[2].left, 0);
    expect(lines[3].left, 0);

    expect(lines[0].lineNumber, 0);
    expect(lines[1].lineNumber, 1);
    expect(lines[2].lineNumber, 2);
    expect(lines[3].lineNumber, 3);
    painter.dispose();
  }, skip: kIsWeb && !isCanvasKit); // https://github.com/flutter/flutter/issues/122066

  test('TextPainter caret height and line height', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr
      ..strutStyle = const StrutStyle(fontSize: 50.0);

    const String text = 'A';
    painter.text = const TextSpan(text: text, style: TextStyle(height: 1.0));
    painter.layout();

    final double caretHeight = painter.getFullHeightForCaret(
      const ui.TextPosition(offset: 0),
      ui.Rect.zero,
    )!;
    expect(caretHeight, 50.0);
    painter.dispose();
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308

  group('TextPainter line-height', () {
    test('half-leading', () {
      const TextStyle style = TextStyle(
        height: 20,
        fontSize: 1,
        leadingDistribution: TextLeadingDistribution.even,
      );

      final TextPainter painter = TextPainter()
        ..textDirection = TextDirection.ltr
        ..text = const TextSpan(text: 'A', style: style)
        ..layout();

      final Rect glyphBox = painter.getBoxesForSelection(
        const TextSelection(baseOffset: 0, extentOffset: 1),
      ).first.toRect();

      final RelativeRect insets = RelativeRect.fromSize(glyphBox, painter.size);
      // The glyph box is centered.
      expect(insets.top, insets.bottom);
      // The glyph box is exactly 1 logical pixel high.
      expect(insets.top, (20 - 1) / 2);
      painter.dispose();
    });

    test('half-leading with small height', () {
      const TextStyle style = TextStyle(
        height: 0.1,
        fontSize: 10,
        leadingDistribution: TextLeadingDistribution.even,
      );

      final TextPainter painter = TextPainter()
        ..textDirection = TextDirection.ltr
        ..text = const TextSpan(text: 'A', style: style)
        ..layout();

      final Rect glyphBox = painter.getBoxesForSelection(
        const TextSelection(baseOffset: 0, extentOffset: 1),
      ).first.toRect();

      final RelativeRect insets = RelativeRect.fromSize(glyphBox, painter.size);
      // The glyph box is still centered.
      expect(insets.top, insets.bottom);
      // The glyph box is exactly 10 logical pixel high (the height multiplier
      // does not scale the glyph). Negative leading.
      expect(insets.top, (1 - 10) / 2);
      painter.dispose();
    });

    test('half-leading with leading trim', () {
      const TextStyle style = TextStyle(
        height: 0.1,
        fontSize: 10,
        leadingDistribution: TextLeadingDistribution.even,
      );

      final TextPainter painter = TextPainter()
        ..textDirection = TextDirection.ltr
        ..text = const TextSpan(text: 'A', style: style)
        ..textHeightBehavior = const TextHeightBehavior(
            applyHeightToFirstAscent: false,
            applyHeightToLastDescent: false,
          )
        ..layout();

      final Rect glyphBox = painter.getBoxesForSelection(
        const TextSelection(baseOffset: 0, extentOffset: 1),
      ).first.toRect();

      expect(painter.size, glyphBox.size);
      // The glyph box is still centered.
      expect(glyphBox.topLeft, Offset.zero);
      painter.dispose();
    });

    test('TextLeadingDistribution falls back to paragraph style', () {
      const TextStyle style = TextStyle(height: 20, fontSize: 1);
      final TextPainter painter = TextPainter()
        ..textDirection = TextDirection.ltr
        ..text = const TextSpan(text: 'A', style: style)
        ..textHeightBehavior = const TextHeightBehavior(
            leadingDistribution: TextLeadingDistribution.even,
          )
        ..layout();

      final Rect glyphBox = painter.getBoxesForSelection(
        const TextSelection(baseOffset: 0, extentOffset: 1),
      ).first.toRect();

      // Still uses half-leading.
      final RelativeRect insets = RelativeRect.fromSize(glyphBox, painter.size);
      expect(insets.top, insets.bottom);
      expect(insets.top, (20 - 1) / 2);
      painter.dispose();
    });

    test('TextLeadingDistribution does nothing if height multiplier is null', () {
      const TextStyle style = TextStyle(fontSize: 1);
      final TextPainter painter = TextPainter()
        ..textDirection = TextDirection.ltr
        ..text = const TextSpan(text: 'A', style: style)
        ..textHeightBehavior = const TextHeightBehavior(
            leadingDistribution: TextLeadingDistribution.even,
          )
        ..layout();

      final Rect glyphBox = painter.getBoxesForSelection(
        const TextSelection(baseOffset: 0, extentOffset: 1),
      ).first.toRect();

      painter.textHeightBehavior = const TextHeightBehavior();
      painter.layout();

      final Rect newGlyphBox = painter.getBoxesForSelection(
        const TextSelection(baseOffset: 0, extentOffset: 1),
      ).first.toRect();
      expect(glyphBox, newGlyphBox);
      painter.dispose();
    });
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/87543

  test('TextPainter handles invalid UTF-16', () {
    Object? exception;
    FlutterError.onError = (FlutterErrorDetails details) {
      exception = details.exception;
    };

    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    const String text = 'Hello\uD83DWorld';
    const double fontSize = 20.0;
    painter.text = const TextSpan(text: text, style: TextStyle(fontSize: fontSize));
    painter.layout();
    // The layout should include one replacement character.
    expect(painter.width, equals(fontSize));
    expect(exception, isNotNull);
    painter.dispose();
  }, skip: kIsWeb); // https://github.com/flutter/flutter/issues/87544

  test('Diacritic', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    // Two letters followed by a diacritic
    const String text = 'ฟห้';
    painter.text = const TextSpan(text: text);
    painter.layout();

    final ui.Offset caretOffset = painter.getOffsetForCaret(
        const ui.TextPosition(
            offset: text.length, affinity: TextAffinity.upstream),
        ui.Rect.zero);
    expect(caretOffset.dx, painter.width);
    painter.dispose();
  }, skip: kIsWeb && !isCanvasKit); // https://github.com/flutter/flutter/issues/87545

  test('TextPainter line metrics update after layout', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    const String text = 'word1 word2 word3';
    painter.text = const TextSpan(
      text: text,
    );

    painter.layout(maxWidth: 80);

    List<ui.LineMetrics> lines = painter.computeLineMetrics();
    expect(lines.length, 3);

    painter.layout(maxWidth: 1000);

    lines = painter.computeLineMetrics();
    expect(lines.length, 1);
    painter.dispose();
  }, skip: kIsWeb && !isCanvasKit); // https://github.com/flutter/flutter/issues/62819

  test('TextPainter throws with stack trace when accessing text layout', () {
    final TextPainter painter = TextPainter()
      ..text = const TextSpan(text: 'TEXT')
      ..textDirection = TextDirection.ltr;

    expect(
      () => painter.getPositionForOffset(Offset.zero),
      throwsA(isA<FlutterError>().having(
        (FlutterError error) => error.message,
        'message',
        contains('The TextPainter has never been laid out.'),
      )),
    );

    expect(
      () {
        painter.layout();
        painter.getPositionForOffset(Offset.zero);
      },
      returnsNormally,
    );

    expect(
      () {
        painter.markNeedsLayout();
        painter.getPositionForOffset(Offset.zero);
      },
      throwsA(isA<FlutterError>().having(
        (FlutterError error) => error.message,
        'message',
        contains('The calls that first invalidated the text layout were:'),
      )),
    );
    painter.dispose();
  });

  test('TextPainter requires layout after providing different placeholder dimensions', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    painter.text = const TextSpan(children: <InlineSpan>[
      TextSpan(text: 'before'),
      WidgetSpan(child: Text('widget1')),
      WidgetSpan(child: Text('widget2')),
      WidgetSpan(child: Text('widget3')),
      TextSpan(text: 'after'),
    ]);

    painter.setPlaceholderDimensions(const <PlaceholderDimensions>[
      PlaceholderDimensions(size: Size(30, 30), alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(40, 30), alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), alignment: ui.PlaceholderAlignment.bottom),
    ]);
    painter.layout();

    painter.setPlaceholderDimensions(const <PlaceholderDimensions>[
      PlaceholderDimensions(size: Size(30, 30), alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(40, 20), alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), alignment: ui.PlaceholderAlignment.bottom),
    ]);

    expect(
      () => painter.paint(MockCanvas(), Offset.zero),
      throwsA(isA<StateError>().having(
        (StateError error) => error.message,
        'message',
        contains('TextPainter.paint called when text geometry was not yet calculated'),
      )),
    );
    painter.dispose();
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308

  test('TextPainter does not require layout after providing identical placeholder dimensions', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    painter.text = const TextSpan(children: <InlineSpan>[
      TextSpan(text: 'before'),
      WidgetSpan(child: Text('widget1')),
      WidgetSpan(child: Text('widget2')),
      WidgetSpan(child: Text('widget3')),
      TextSpan(text: 'after'),
    ]);

    painter.setPlaceholderDimensions(const <PlaceholderDimensions>[
      PlaceholderDimensions(size: Size(30, 30), alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(40, 30), alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), alignment: ui.PlaceholderAlignment.bottom),
    ]);
    painter.layout();

    painter.setPlaceholderDimensions(const <PlaceholderDimensions>[
      PlaceholderDimensions(size: Size(30, 30), alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(40, 30), alignment: ui.PlaceholderAlignment.bottom),
      PlaceholderDimensions(size: Size(50, 30), alignment: ui.PlaceholderAlignment.bottom),
    ]);

    // In tests, paint() will throw an UnimplementedError due to missing drawParagraph method.
    expect(
      () => painter.paint(MockCanvas(), Offset.zero),
      isNot(throwsA(isA<StateError>().having(
        (StateError error) => error.message,
        'message',
        contains('TextPainter.paint called when text geometry was not yet calculated'),
      ))),
    );
    painter.dispose();
  }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308

  test('TextPainter - debugDisposed', () {
    final TextPainter painter = TextPainter();
    expect(painter.debugDisposed, false);
    painter.dispose();
    expect(painter.debugDisposed, true);
  });

  test('TextPainter computeWidth', () {
    const InlineSpan text = TextSpan(text: 'foobar');
    final TextPainter painter = TextPainter(text: text, textDirection: TextDirection.ltr);
    painter.layout();
    expect(painter.width, TextPainter.computeWidth(text: text, textDirection: TextDirection.ltr));

    painter.layout(minWidth: 500);
    expect(painter.width, TextPainter.computeWidth(text: text, textDirection: TextDirection.ltr, minWidth: 500));

    painter.dispose();
  });

  test('TextPainter computeMaxIntrinsicWidth', () {
    const InlineSpan text = TextSpan(text: 'foobar');
    final TextPainter painter = TextPainter(text: text, textDirection: TextDirection.ltr);
    painter.layout();
    expect(painter.maxIntrinsicWidth, TextPainter.computeMaxIntrinsicWidth(text: text, textDirection: TextDirection.ltr));

    painter.layout(minWidth: 500);
    expect(painter.maxIntrinsicWidth, TextPainter.computeMaxIntrinsicWidth(text: text, textDirection: TextDirection.ltr, minWidth: 500));

    painter.dispose();
  });

  test('TextPainter.getWordBoundary works', (){
    // Regression test for https://github.com/flutter/flutter/issues/93493 .
    const String testCluster = '👨‍👩‍👦👨‍👩‍👦👨‍👩‍👦'; // 8 * 3
    final TextPainter textPainter = TextPainter(
      text: const TextSpan(text: testCluster),
      textDirection: TextDirection.ltr,
    );

     textPainter.layout();
     expect(
       textPainter.getWordBoundary(const TextPosition(offset: 8)),
       const TextRange(start: 8, end: 16),
     );
   }, skip: isBrowser); // https://github.com/flutter/flutter/issues/61017

  test('TextHeightBehavior with strut on empty paragraph', () {
    // Regression test for https://github.com/flutter/flutter/issues/112123
    const TextStyle style = TextStyle(height: 11, fontSize: 7);
    const TextSpan simple = TextSpan(text: 'x', style: style);
    const TextSpan emptyString = TextSpan(text: '', style: style);
    const TextSpan emptyParagraph = TextSpan(style: style);

    final TextPainter painter = TextPainter(
      textDirection: TextDirection.ltr,
      strutStyle: StrutStyle.fromTextStyle(style, forceStrutHeight: true),
      textHeightBehavior: const TextHeightBehavior(applyHeightToFirstAscent: false, applyHeightToLastDescent: false),
    );

    painter.text = simple;
    painter.layout();
    final double height = painter.height;
    for (final TextSpan span in <TextSpan>[simple, emptyString, emptyParagraph]) {
      painter.text = span;
      painter.layout();
      expect(painter.height, height, reason: '$span is expected to have a height of $height');
      expect(painter.preferredLineHeight, height, reason: '$span is expected to have a height of $height');
    }
  });

  test('TextPainter plainText getter', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    expect(painter.plainText, '');

    painter.text = const TextSpan(children: <InlineSpan>[
      TextSpan(text: 'before\n'),
      WidgetSpan(child: Text('widget')),
      TextSpan(text: 'after'),
    ]);
    expect(painter.plainText, 'before\n\uFFFCafter');

    painter.setPlaceholderDimensions(const <PlaceholderDimensions>[
      PlaceholderDimensions(size: Size(50, 30), alignment: ui.PlaceholderAlignment.bottom),
    ]);
    painter.layout();
    expect(painter.plainText, 'before\n\uFFFCafter');

    painter.text = const TextSpan(children: <InlineSpan>[
      TextSpan(text: 'be\nfo\nre\n'),
      WidgetSpan(child: Text('widget')),
      TextSpan(text: 'af\nter'),
    ]);
    expect(painter.plainText, 'be\nfo\nre\n\uFFFCaf\nter');
    painter.layout();
    expect(painter.plainText, 'be\nfo\nre\n\uFFFCaf\nter');

    painter.dispose();
  });

  test('TextPainter infinite width - centered', () {
    final TextPainter painter = TextPainter()
      ..textAlign = TextAlign.center
      ..textDirection = TextDirection.ltr;
    painter.text = const TextSpan(text: 'A', style: TextStyle(fontSize: 10));
    MockCanvasWithDrawParagraph mockCanvas = MockCanvasWithDrawParagraph();

    painter.layout(minWidth: double.infinity);
    expect(painter.width, double.infinity);
    expect(() => painter.paint(mockCanvas = MockCanvasWithDrawParagraph(), Offset.zero), returnsNormally);
    expect(mockCanvas.centerX, isNull);

    painter.layout();
    expect(painter.width, 10);
    expect(() => painter.paint(mockCanvas = MockCanvasWithDrawParagraph(), Offset.zero), returnsNormally);
    expect(mockCanvas.centerX, 5);

    painter.layout(minWidth: 100);
    expect(painter.width, 100);
    expect(() => painter.paint(mockCanvas = MockCanvasWithDrawParagraph(), Offset.zero), returnsNormally);
    expect(mockCanvas.centerX, 50);

    painter.dispose();
  });

  test('TextPainter infinite width - LTR justified', () {
    final TextPainter painter = TextPainter()
      ..textAlign = TextAlign.justify
      ..textDirection = TextDirection.ltr;
    painter.text = const TextSpan(text: 'A', style: TextStyle(fontSize: 10));
    MockCanvasWithDrawParagraph mockCanvas = MockCanvasWithDrawParagraph();

    painter.layout(minWidth: double.infinity);
    expect(painter.width, double.infinity);
    expect(() => painter.paint(mockCanvas = MockCanvasWithDrawParagraph(), Offset.zero), returnsNormally);
    expect(mockCanvas.offsetX, 0);

    painter.layout();
    expect(painter.width, 10);
    expect(() => painter.paint(mockCanvas = MockCanvasWithDrawParagraph(), Offset.zero), returnsNormally);
    expect(mockCanvas.offsetX, 0);

    painter.layout(minWidth: 100);
    expect(painter.width, 100);
    expect(() => painter.paint(mockCanvas = MockCanvasWithDrawParagraph(), Offset.zero), returnsNormally);
    expect(mockCanvas.offsetX, 0);

    painter.dispose();
  });

  test('TextPainter line breaking does not round to integers', () {
    if (!ui.ParagraphBuilder.shouldDisableRoundingHack) {
      return;
    }
    const double fontSize = 1.25;
    const String text = '12345';
    assert((fontSize * text.length).truncate() != fontSize * text.length);
    final TextPainter painter = TextPainter(
      textDirection: TextDirection.ltr,
      text: const TextSpan(text: text, style: TextStyle(fontSize: fontSize)),
    )..layout(maxWidth: text.length * fontSize);

    expect(painter.maxIntrinsicWidth, text.length * fontSize);
    switch (painter.computeLineMetrics()) {
      case [ui.LineMetrics(width: final double width)]:
        expect(width, text.length * fontSize);
      case final List<ui.LineMetrics> metrics:
        expect(metrics, hasLength(1));
    }
  }, skip: kIsWeb && !isCanvasKit); // [intended] Browsers seem to always round font/glyph metrics.
}

class MockCanvas extends Fake implements Canvas {
}

class MockCanvasWithDrawParagraph extends Fake implements Canvas {
  double? centerX;
  double? offsetX;
  @override
  void drawParagraph(ui.Paragraph paragraph, Offset offset) {
    offsetX = offset.dx;
    centerX = offset.dx + paragraph.width / 2;
  }
}