Dispose Paragraph objects (#110627)

dev/benchmarks/macrobenchmarks/lib/src/web/bench_pageview_scroll_linethrough.dart

@@ -36,6 +36,7 @@ class _MyScrollContainerState extends State<_MyScrollContainer> {
   static const Duration stepDuration = Duration(milliseconds: 500);
 
   late PageController pageController;
+  final _CustomPainter _painter =  _CustomPainter('aa');
   int pageNumber = 0;
 
   @override
@@ -57,6 +58,7 @@ class _MyScrollContainerState extends State<_MyScrollContainer> {
   @override
   void dispose() {
     pageController.dispose();
+    _painter._textPainter.dispose();
     super.dispose();
   }
 
@@ -66,7 +68,7 @@ class _MyScrollContainerState extends State<_MyScrollContainer> {
         controller: pageController,
         itemBuilder: (BuildContext context, int position) {
           return CustomPaint(
-            painter: _CustomPainter('aa'),
+            painter: _painter,
             size: const Size(300, 500),
           );
         });

dev/integration_tests/flutter_gallery/lib/demo/transformations/transformations_demo.dart

@@ -182,6 +182,7 @@ class BoardPainter extends CustomPainter {
       );
       final Vertices vertices = board!.getVerticesForBoardPoint(boardPoint, color);
       canvas.drawVertices(vertices, BlendMode.color, Paint());
+      vertices.dispose();
     }
 
     board!.forEach(drawBoardPoint);

packages/flutter/lib/src/cupertino/date_picker.dart

@@ -482,8 +482,11 @@ class CupertinoDatePicker extends StatefulWidget {
     // because there's no other way to get the information we want without
     // laying out the text.
     painter.layout();
-
-    return painter.maxIntrinsicWidth;
+    try {
+      return painter.maxIntrinsicWidth;
+    } finally {
+      painter.dispose();
+    }
   }
 }
 
@@ -1663,6 +1666,7 @@ class _CupertinoTimerPickerState extends State<CupertinoTimerPicker> {
   @override
   void dispose() {
     PaintingBinding.instance.systemFonts.removeListener(_handleSystemFontsChange);
+    textPainter.dispose();
     super.dispose();
   }
 

packages/flutter/lib/src/material/range_slider.dart

@@ -1090,6 +1090,13 @@ class _RenderRangeSlider extends RenderBox with RelayoutWhenSystemFontsChangeMix
     super.detach();
   }
 
+  @override
+  void dispose() {
+    _startLabelPainter.dispose();
+    _endLabelPainter.dispose();
+    super.dispose();
+  }
+
   double _getValueFromVisualPosition(double visualPosition) {
     switch (textDirection) {
       case TextDirection.rtl:

packages/flutter/lib/src/material/slider.dart

@@ -1342,6 +1342,12 @@ class _RenderSlider extends RenderBox with RelayoutWhenSystemFontsChangeMixin {
     super.detach();
   }
 
+  @override
+  void dispose() {
+    _labelPainter.dispose();
+    super.dispose();
+  }
+
   double _getValueFromVisualPosition(double visualPosition) {
     switch (textDirection) {
       case TextDirection.rtl:

packages/flutter/lib/src/material/time_picker.dart

@@ -860,6 +860,17 @@ class _DialPainter extends CustomPainter {
 
   static const double _labelPadding = 28.0;
 
+  void dispose() {
+    for (final _TappableLabel label in primaryLabels) {
+      label.painter.dispose();
+    }
+    for (final _TappableLabel label in secondaryLabels) {
+      label.painter.dispose();
+    }
+    primaryLabels.clear();
+    secondaryLabels.clear();
+  }
+
   @override
   void paint(Canvas canvas, Size size) {
     final double radius = size.shortestSide / 2.0;
@@ -966,6 +977,7 @@ class _DialState extends State<_Dial> with SingleTickerProviderStateMixin {
   late ThemeData themeData;
   late MaterialLocalizations localizations;
   late MediaQueryData media;
+  _DialPainter? painter;
 
   @override
   void didChangeDependencies() {
@@ -989,6 +1001,7 @@ class _DialState extends State<_Dial> with SingleTickerProviderStateMixin {
   @override
   void dispose() {
     _thetaController.dispose();
+    painter?.dispose();
     super.dispose();
   }
 
@@ -1280,6 +1293,18 @@ class _DialState extends State<_Dial> with SingleTickerProviderStateMixin {
         break;
     }
 
+    painter?.dispose();
+    painter = _DialPainter(
+      selectedValue: selectedDialValue,
+      primaryLabels: primaryLabels,
+      secondaryLabels: secondaryLabels,
+      backgroundColor: backgroundColor,
+      accentColor: accentColor,
+      dotColor: theme.colorScheme.surface,
+      theta: _theta.value,
+      textDirection: Directionality.of(context),
+    );
+
     return GestureDetector(
       excludeFromSemantics: true,
       onPanStart: _handlePanStart,
@@ -1288,16 +1313,7 @@ class _DialState extends State<_Dial> with SingleTickerProviderStateMixin {
       onTapUp: _handleTapUp,
       child: CustomPaint(
         key: const ValueKey<String>('time-picker-dial'),
-        painter: _DialPainter(
-          selectedValue: selectedDialValue,
-          primaryLabels: primaryLabels,
-          secondaryLabels: secondaryLabels,
-          backgroundColor: backgroundColor,
-          accentColor: accentColor,
-          dotColor: theme.colorScheme.surface,
-          theta: _theta.value,
-          textDirection: Directionality.of(context),
-        ),
+        painter: painter,
       ),
     );
   }

packages/flutter/lib/src/painting/flutter_logo.dart

@@ -227,6 +227,7 @@ class _FlutterLogoPainter extends BoxPainter {
   final FlutterLogoDecoration _config;
 
   // these are configured assuming a font size of 100.0.
+  // TODO(dnfield): Figure out how to dispose this https://github.com/flutter/flutter/issues/110601
   late TextPainter _textPainter;
   late Rect _textBoundingRect;
 

packages/flutter/lib/src/painting/text_painter.dart

@@ -222,6 +222,7 @@ class TextPainter {
   bool _rebuildParagraphForPaint = true;
 
   bool get _debugAssertTextLayoutIsValid {
+    assert(!debugDisposed);
     if (_paragraph == null) {
       throw FlutterError.fromParts(<DiagnosticsNode>[
         ErrorSummary('Text layout not available'),
@@ -247,6 +248,7 @@ class TextPainter {
       }
       return true;
     }());
+    _paragraph?.dispose();
     _paragraph = null;
     _lineMetricsCache = null;
     _previousCaretPosition = null;
@@ -271,6 +273,7 @@ class TextPainter {
       return;
     }
     if (_text?.style != value?.style) {
+      _layoutTemplate?.dispose();
       _layoutTemplate = null;
     }
 
@@ -329,6 +332,7 @@ class TextPainter {
     }
     _textDirection = value;
     markNeedsLayout();
+    _layoutTemplate?.dispose();
     _layoutTemplate = null; // Shouldn't really matter, but for strict correctness...
   }
 
@@ -347,6 +351,7 @@ class TextPainter {
     }
     _textScaleFactor = value;
     markNeedsLayout();
+    _layoutTemplate?.dispose();
     _layoutTemplate = null;
   }
 
@@ -1060,4 +1065,33 @@ class TextPainter {
     assert(_debugAssertTextLayoutIsValid);
     return  _lineMetricsCache ??= _paragraph!.computeLineMetrics();
   }
+
+  bool _disposed = false;
+
+  /// Whether this object has been disposed or not.
+  ///
+  /// Only for use when asserts are enabled.
+  bool get debugDisposed {
+    bool? disposed;
+    assert(() {
+      disposed = _disposed;
+      return true;
+    }());
+    return disposed ?? (throw StateError('debugDisposed only available when asserts are on.'));
+  }
+
+  /// Releases the resources associated with this painter.
+  ///
+  /// After disposal this painter is unusable.
+  void dispose() {
+    assert(() {
+      _disposed = true;
+      return true;
+    }());
+    _layoutTemplate?.dispose();
+    _layoutTemplate = null;
+    _paragraph?.dispose();
+    _paragraph = null;
+    _text = null;
+  }
 }

packages/flutter/lib/src/rendering/debug_overflow_indicator.dart

@@ -114,6 +114,14 @@ mixin DebugOverflowIndicatorMixin on RenderObject {
     TextPainter(textDirection: TextDirection.ltr), // This label is in English.
   );
 
+  @override
+  void dispose() {
+    for (final TextPainter painter in _indicatorLabel) {
+      painter.dispose();
+    }
+    super.dispose();
+  }
+
   // Set to true to trigger a debug message in the console upon
   // the next paint call. Will be reset after each paint.
   bool _overflowReportNeeded = true;

packages/flutter/lib/src/rendering/editable.dart

@@ -388,6 +388,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     _autocorrectHighlightPainter.dispose();
     _selectionPainter.dispose();
     _caretPainter.dispose();
+    _textPainter.dispose();
     super.dispose();
   }
 

packages/flutter/lib/src/rendering/paragraph.dart

@@ -256,6 +256,7 @@ class RenderParagraph extends RenderBox
     // _lastSelectableFragments may hold references to this RenderParagraph.
     // Release them manually to avoid retain cycles.
     _lastSelectableFragments = null;
+    _textPainter.dispose();
     super.dispose();
   }
 
@@ -864,6 +865,7 @@ class RenderParagraph extends RenderBox
               <Color>[const Color(0xFFFFFFFF), const Color(0x00FFFFFF)],
             );
           }
+          fadeSizePainter.dispose();
           break;
       }
     } else {

packages/flutter/lib/src/rendering/proxy_box.dart

@@ -1515,6 +1515,13 @@ abstract class _RenderCustomClip<T> extends RenderProxyBox {
       return true;
     }());
   }
+
+  @override
+  void dispose() {
+    _debugText?.dispose();
+    _debugText = null;
+    super.dispose();
+  }
 }
 
 /// Clips its child using a rectangle.

packages/flutter/lib/src/widgets/banner.dart

@@ -117,14 +117,23 @@ class BannerPainter extends CustomPainter {
   );
 
   bool _prepared = false;
-  late TextPainter _textPainter;
+  TextPainter? _textPainter;
   late Paint _paintShadow;
   late Paint _paintBanner;
 
+  /// Release resources held by this painter.
+  ///
+  /// After calling this method, this object is no longer usable.
+  void dispose() {
+    _textPainter?.dispose();
+    _textPainter = null;
+  }
+
   void _prepare() {
     _paintShadow = _shadow.toPaint();
     _paintBanner = Paint()
       ..color = color;
+    _textPainter?.dispose();
     _textPainter = TextPainter(
       text: TextSpan(style: textStyle, text: message),
       textAlign: TextAlign.center,
@@ -144,8 +153,8 @@ class BannerPainter extends CustomPainter {
       ..drawRect(_kRect, _paintShadow)
       ..drawRect(_kRect, _paintBanner);
     const double width = _kOffset * 2.0;
-    _textPainter.layout(minWidth: width, maxWidth: width);
-    _textPainter.paint(canvas, _kRect.topLeft + Offset(0.0, (_kRect.height - _textPainter.height) / 2.0));
+    _textPainter!.layout(minWidth: width, maxWidth: width);
+    _textPainter!.paint(canvas, _kRect.topLeft + Offset(0.0, (_kRect.height - _textPainter!.height) / 2.0));
   }
 
   @override

packages/flutter/lib/src/widgets/semantics_debugger.dart

@@ -339,6 +339,7 @@ class _SemanticsDebuggerPainter extends CustomPainter {
       ..layout(maxWidth: rect.width);
 
     textPainter.paint(canvas, Alignment.center.inscribe(textPainter.size, rect).topLeft);
+    textPainter.dispose();
     canvas.restore();
   }
 

packages/flutter/lib/src/widgets/widget_inspector.dart

@@ -2777,6 +2777,13 @@ class _InspectorOverlayLayer extends Layer {
   TextPainter? _textPainter;
   double? _textPainterMaxWidth;
 
+  @override
+  void dispose() {
+    _textPainter?.dispose();
+    _textPainter = null;
+    super.dispose();
+  }
+
   @override
   void addToScene(ui.SceneBuilder builder) {
     if (!selection.active) {
@@ -2878,6 +2885,7 @@ class _InspectorOverlayLayer extends Layer {
     final TextSpan? textSpan = _textPainter?.text as TextSpan?;
     if (_textPainter == null || textSpan!.text != message || _textPainterMaxWidth != maxWidth) {
       _textPainterMaxWidth = maxWidth;
+      _textPainter?.dispose();
       _textPainter = TextPainter()
         ..maxLines = _kMaxTooltipLines
         ..ellipsis = '...'

packages/flutter/test/painting/text_painter_rtl_test.dart

@@ -32,6 +32,7 @@ void main() {
       painter.getWordBoundary(const TextPosition(offset: 9)),
       const TextRange(start: 8, end: 11),
     );
+    painter.dispose();
   });
 
   test('TextPainter - bidi overrides in LTR', () {
@@ -164,6 +165,7 @@ void main() {
       // The list currently has one extra bogus entry (the last entry, for the
       // trailing U+202C PDF, should be empty but is one-pixel-wide instead).
     ], skip: skipExpectsWithKnownBugs); // https://github.com/flutter/flutter/issues/87536
+    painter.dispose();
   }, skip: skipTestsWithKnownBugs); // https://github.com/flutter/flutter/issues/87536
 
   test('TextPainter - bidi overrides in RTL', () {
@@ -255,6 +257,7 @@ void main() {
       // The list is currently in the wrong order (so selection boxes will paint in the wrong order).
       skip: skipExpectsWithKnownBugs, // https://github.com/flutter/flutter/issues/87536
     );
+    painter.dispose();
   }, skip: skipTestsWithKnownBugs); // https://github.com/flutter/flutter/issues/87536
 
   test('TextPainter - forced line-wrapping with bidi', () {
@@ -322,6 +325,7 @@ void main() {
         TextBox.fromLTRBD(0.0, 10.0, 10.0, 20.0, TextDirection.rtl), // Alef
       ],
     );
+    painter.dispose();
   }, skip: isBrowser); // https://github.com/flutter/flutter/issues/32238
 
   test('TextPainter - line wrap mid-word', () {
@@ -356,6 +360,7 @@ void main() {
       // horizontal offsets are one pixel off in places; vertical offsets are good
       skip: skipExpectsWithKnownBugs, // https://github.com/flutter/flutter/issues/87536
     );
+    painter.dispose();
   }, skip: skipTestsWithKnownBugs); // https://github.com/flutter/flutter/issues/87536
 
   test('TextPainter - line wrap mid-word, bidi - LTR base', () {
@@ -412,6 +417,7 @@ void main() {
       <TextBox>[TextBox.fromLTRBD(70.0, 28.0, 80.0, 38.0, TextDirection.ltr)],
       <TextBox>[TextBox.fromLTRBD(80.0, 28.0, 90.0, 38.0, TextDirection.ltr)],
     ]);
+    painter.dispose();
   }, skip: skipTestsWithKnownBugs); // https://github.com/flutter/flutter/issues/87536
 
   test('TextPainter - line wrap mid-word, bidi - RTL base', () {
@@ -447,6 +453,7 @@ void main() {
       // The list is currently in the wrong order (so selection boxes will paint in the wrong order).
       skip: skipExpectsWithKnownBugs, // https://github.com/flutter/flutter/issues/87536
     );
+    painter.dispose();
   }, skip: skipTestsWithKnownBugs); // https://github.com/flutter/flutter/issues/87536
 
   test('TextPainter - multiple levels', () {
@@ -478,6 +485,7 @@ void main() {
       // Also currently there's an extraneous box at the start of the list.
       skip: skipExpectsWithKnownBugs, // https://github.com/flutter/flutter/issues/87536
     );
+    painter.dispose();
   }, skip: skipTestsWithKnownBugs); // https://github.com/flutter/flutter/issues/87536
 
   test('TextPainter - getPositionForOffset - RTL in LTR', () {
@@ -561,6 +569,7 @@ void main() {
       painter.getPositionForOffset(const Offset(100.0, 5.0)).toString(),
       const TextPosition(offset: 9, affinity: TextAffinity.upstream).toString(),
     );
+    painter.dispose();
   }, skip: skipTestsWithKnownBugs); // https://github.com/flutter/flutter/issues/87536
 
   test('TextPainter - getPositionForOffset - LTR in RTL', () {
@@ -606,6 +615,7 @@ void main() {
       painter.getPositionForOffset(const Offset(62.0, 5.0)).toString(),
       const TextPosition(offset: 3, affinity: TextAffinity.upstream).toString(),
     );
+    painter.dispose();
   }, skip: skipTestsWithKnownBugs); // https://github.com/flutter/flutter/issues/87536
 
   test('TextPainter - Spaces', () {
@@ -667,6 +677,7 @@ void main() {
       // Horizontal offsets are currently one pixel off in places; vertical offsets are good.
       skip: skipExpectsWithKnownBugs, // https://github.com/flutter/flutter/issues/87536
     );
+    painter.dispose();
   }, skip: skipTestsWithKnownBugs); // https://github.com/flutter/flutter/issues/87536
 
   test('TextPainter - empty text baseline', () {
@@ -678,6 +689,7 @@ void main() {
     );
     painter.layout();
     expect(painter.computeDistanceToActualBaseline(TextBaseline.alphabetic), moreOrLessEquals(80.0, epsilon: 0.001));
+    painter.dispose();
   });
 }
 

packages/flutter/test/painting/text_painter_test.dart

@@ -35,6 +35,7 @@ void main() {
     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', () {
@@ -53,6 +54,7 @@ void main() {
     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', () {
@@ -78,6 +80,7 @@ void main() {
     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', () {
@@ -144,6 +147,7 @@ void main() {
     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 center space test', () {
@@ -166,6 +170,7 @@ void main() {
     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', () {
@@ -180,6 +185,7 @@ void main() {
       e.toString(),
       contains('TextPainter.paint called when text geometry was not yet calculated'),
     );
+    painter.dispose();
   });
 
   test('TextPainter requires textDirection', () {
@@ -203,6 +209,7 @@ void main() {
     );
     painter.layout();
     expect(painter.size, const Size(123.0, 123.0));
+    painter.dispose();
   });
 
   test('TextPainter textScaleFactor test', () {
@@ -220,6 +227,7 @@ void main() {
     );
     painter.layout();
     expect(painter.size, const Size(20.0, 20.0));
+    painter.dispose();
   });
 
   test('TextPainter textScaleFactor null style test', () {
@@ -232,6 +240,7 @@ void main() {
     );
     painter.layout();
     expect(painter.size, const Size(28.0, 28.0));
+    painter.dispose();
   });
 
   test('TextPainter default text height is 14 pixels', () {
@@ -242,6 +251,7 @@ void main() {
     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', () {
@@ -252,6 +262,7 @@ void main() {
     painter.layout();
     expect(painter.preferredLineHeight, 100.0);
     expect(painter.size, const Size(100.0, 100.0));
+    painter.dispose();
   });
 
   test('TextPainter intrinsic dimensions', () {
@@ -273,6 +284,7 @@ void main() {
     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(
@@ -286,6 +298,7 @@ void main() {
     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(
@@ -299,6 +312,7 @@ void main() {
     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(
@@ -312,6 +326,7 @@ void main() {
     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(
@@ -325,6 +340,7 @@ void main() {
     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(
@@ -338,6 +354,7 @@ void main() {
     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', () {
@@ -679,6 +696,7 @@ void main() {
     );
     expect(caretOffset.dx, moreOrLessEquals(0.0, epsilon: 0.0001));
     expect(caretOffset.dy, moreOrLessEquals(0.0, epsilon: 0.0001));
+    painter.dispose();
   });
 
   test('TextPainter widget span', () {
@@ -773,6 +791,7 @@ void main() {
     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
@@ -782,6 +801,7 @@ void main() {
 
     painter.textHeightBehavior = const TextHeightBehavior();
     painter.textHeightBehavior = null;
+    painter.dispose();
   });
 
   test('TextPainter line metrics', () {
@@ -846,6 +866,7 @@ void main() {
     expect(lines[1].lineNumber, 1);
     expect(lines[2].lineNumber, 2);
     expect(lines[3].lineNumber, 3);
+    painter.dispose();
   }, skip: true); // https://github.com/flutter/flutter/issues/62819
 
   test('TextPainter caret height and line height', () {
@@ -862,6 +883,7 @@ void main() {
       ui.Rect.zero,
     )!;
     expect(caretHeight, 50.0);
+    painter.dispose();
   }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308
 
   group('TextPainter line-height', () {
@@ -886,6 +908,7 @@ void main() {
       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', () {
@@ -910,6 +933,7 @@ void main() {
       // 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', () {
@@ -935,6 +959,7 @@ void main() {
       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', () {
@@ -955,6 +980,7 @@ void main() {
       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', () {
@@ -978,6 +1004,7 @@ void main() {
         const TextSelection(baseOffset: 0, extentOffset: 1),
       ).first.toRect();
       expect(glyphBox, newGlyphBox);
+      painter.dispose();
     });
   }, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/87543
 
@@ -997,6 +1024,7 @@ void main() {
     // 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', () {
@@ -1013,6 +1041,7 @@ void main() {
             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', () {
@@ -1033,6 +1062,7 @@ void main() {
 
     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', () {
@@ -1068,6 +1098,7 @@ void main() {
 
     expect(exception?.message, contains('The calls that first invalidated the text layout were:'));
     exception = null;
+    painter.dispose();
   });
 
   test('TextPainter requires layout after providing different placeholder dimensions', () {
@@ -1105,6 +1136,7 @@ void main() {
       e.toString(),
       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', () {
@@ -1143,7 +1175,15 @@ void main() {
       e.toString(),
       isNot(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);
+  });
 }
 
 class MockCanvas extends Fake implements Canvas {

packages/flutter/test/widgets/text_test.dart

@@ -1070,6 +1070,7 @@ void main() {
     final ui.Paragraph paragraph = builder.build();
     paragraph.layout(const ui.ParagraphConstraints(width: 1000));
     expect(paragraph.getBoxesForRange(2, 2), isEmpty);
+    paragraph.dispose();
   });
 
   // Regression test for https://github.com/flutter/flutter/issues/65818