Repository: flutter
Issue: `TextPainter.getFullHeightForCaret` reports incorrect results for a space as the last character
Labels: framework,d: api docs,has reproducible steps,P2,team-text-input,triaged-text-input,found in release: 3.24,found in release: 3.26

### Steps to reproduce

1. Run the provided sample code

### Expected results

The caret at the end should be the same size as the other two.

### Actual results

The caret at the end is shorter than the other two.

### Code sample

<details open><summary>Code sample</summary>

```dart
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

void main() {
  runApp(const MainApp());
}

class MainApp extends StatefulWidget {
  const MainApp({super.key});

  @override
  State<MainApp> createState() => _MainAppState();
}

class _MainAppState extends State<MainApp> {
  final _textKey = GlobalKey();

  final _sampleText = 'ABC DEFGH '; // Length is 10

  final _startTextPosition = const TextPosition(offset: 0);
  Offset? _startCaretOffset;
  double _startCaretHeight = 0;

  final _middleTextPosition = const TextPosition(offset: 4);
  Offset? _middleCaretOffset;
  double _middleCaretHeight = 0;

  /// The position immediately after the last character (the space character).
  final _endTextPosition = const TextPosition(offset: 10);
  Offset? _endCaretOffset;
  double _endCaretHeight = 0;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((duration) {
      if (!mounted) {
        return;
      }

      final renderParagraph = _textKey.currentContext!.findRenderObject() as RenderParagraph;

      setState(() {
        _startCaretOffset = renderParagraph.getOffsetForCaret(_startTextPosition, Rect.zero);
        _startCaretHeight = renderParagraph.getFullHeightForCaret(_startTextPosition);

        _middleCaretOffset = renderParagraph.getOffsetForCaret(_middleTextPosition, Rect.zero);
        _middleCaretHeight = renderParagraph.getFullHeightForCaret(_middleTextPosition);

        _endCaretOffset = renderParagraph.getOffsetForCaret(_endTextPosition, Rect.zero);
        _endCaretHeight = renderParagraph.getFullHeightForCaret(_endTextPosition);
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              Stack(
                clipBehavior: Clip.none,
                children: [
                  Container(
                    color: Colors.yellow,
                    child: Text(
                      _sampleText,
                      key: _textKey,
                      style: const TextStyle(
                        fontSize: 40,
                        color: Colors.black,
                      ),
                    ),
                  ),
                  if (_startCaretOffset != null)
                    Positioned(
                      left: _startCaretOffset!.dx,
                      top: _startCaretOffset!.dy,
                      child: Container(
                        width: 2,
                        height: _startCaretHeight,
                        color: Colors.red,
                      ),
                    ),
                  if (_middleCaretOffset != null)
                    Positioned(
                      left: _middleCaretOffset!.dx,
                      top: _middleCaretOffset!.dy,
                      child: Container(
                        width: 2,
                        height: _middleCaretHeight,
                        color: Colors.red,
                      ),
                    ),
                  if (_endCaretOffset != null)
                    Positioned(
                      left: _endCaretOffset!.dx,
                      top: _endCaretOffset!.dy,
                      child: Container(
                        width: 2,
                        height: _endCaretHeight,
                        color: Colors.red,
                      ),
                    ),
                ],
              ),
              if (_startCaretOffset != null) Text('Letter "B" caret height: $_startCaretHeight'),
              if (_middleCaretOffset != null) Text('Letter "F" caret height: $_middleCaretHeight'),
              if (_endCaretOffset != null) Text('Space caret height: $_endCaretHeight'),
            ],
          ),
        ),
      ),
    );
  }
}

```

</details>


### Screenshots or Video

<details open>
<summary>Screenshots / Video demonstration</summary>

![image](https://github.com/user-attachments/assets/6d9010d7-6007-4e08-bde6-e3df43243336)

</details>


### Logs

<details open><summary>Logs</summary>

No relevant info.

</details>


### Flutter Doctor output

<details><summary>Doctor output</summary>

```console
$ flutter doctor -v
[✓] Flutter (Channel master, 3.25.0-1.0.pre.153, on macOS 15.0 24A335
    darwin-arm64, locale en-BR)
    • Flutter version 3.25.0-1.0.pre.153 on channel master at
      /Users/angelosilvestre/dev/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 17f63272a0 (3 weeks ago), 2024-08-27 19:30:17 +0000
    • Engine revision 7d751acc81
    • Dart version 3.6.0 (build 3.6.0-175.0.dev)
    • DevTools version 2.39.0-dev.15

[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
    • Android SDK at /Users/angelosilvestre/Library/Android/sdk
    • Platform android-35, build-tools 34.0.0
    • Java binary at: /Applications/Android
      Studio.app/Contents/jbr/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build
      17.0.6+0-17.0.6b829.9-10027231)
    • All Android licenses accepted.

[!] Xcode - develop for iOS and macOS (Xcode 16.0)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 16A242d
    ! iOS 18.0 Simulator not installed; this may be necessary for iOS and macOS
      development.
      To download and install the platform, open Xcode, select Xcode > Settings
      > Platforms,
      and click the GET button for the required platform.

      For more information, please visit:
        https://developer.apple.com/documentation/xcode/installing-additional-si
        mulator-runtimes
    ! CocoaPods 1.12.1 out of date (1.13.0 is recommended).
        CocoaPods is a package manager for iOS or macOS platform code.
        Without CocoaPods, plugins will not work on iOS or macOS.
        For more info, see https://flutter.dev/to/platform-plugins
      To update CocoaPods, see
      https://guides.cocoapods.org/using/getting-started.html#updating-cocoapods

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2022.3)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build
      17.0.6+0-17.0.6b829.9-10027231)

[✓] VS Code (version 1.93.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.96.0

[✓] Connected device (3 available)
    • macOS (desktop)                 • macos                 • darwin-arm64   • macOS 15.0 24A335
      darwin-arm64
    • Mac Designed for iPad (desktop) • mac-designed-for-ipad • darwin         • macOS 15.0 24A335
      darwin-arm64
    • Chrome (web)                    • chrome                • web-javascript • Google Chrome 129.0.6668.58

[✓] Network resources
    • All expected network resources are available.

! Doctor found issues in 1 category.
```

</details>