Use a separate TextPainter for intrinsics calculation in RenderEditable and RenderParagraph (#144577)

Use a dedicated `TextPainter` for intrinsic size calculation in `RenderEditable` and `RenderParagraph`.

This is an implementation detail so the change should be covered by existing tests.  Performance wise this shouldn't be significantly slower since SkParagraph [caches the result of slower operations across different paragraphs](9c62e7b382/modules/skparagraph/src/ParagraphCache.cpp (L254-L272)). Existing benchmarks should be able to catch potential regressions (??).

The reason for making this change is to make sure that intrinsic size computations don't destroy text layout artifacts, so I can expose the text layout as a stream of immutable `TextLayout` objects, to signify other render objects that text-layout-dependent-cache (such as caches for `getBoxesForRange` which can be relatively slow to compute) should be invalidated and  `markNeedsPaint` needs to be called if the painting logic depended on text layout.
Without this change, the intrinsics/dry layout calculations will add additional events to the text layout stream, which violates the "dry"/non-destructive contract.

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

@@ -410,6 +410,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     _selectionPainter.dispose();
     _caretPainter.dispose();
     _textPainter.dispose();
+    _textIntrinsicsCache?.dispose();
     if (_disposeShowCursor) {
       _showCursor.dispose();
       _disposeShowCursor = false;
@@ -510,18 +511,6 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     );
   }
 
-  double? _textLayoutLastMaxWidth;
-  double? _textLayoutLastMinWidth;
-
-  /// Assert that the last layout still matches the constraints.
-  void debugAssertLayoutUpToDate() {
-    assert(
-      _textLayoutLastMaxWidth == constraints.maxWidth &&
-      _textLayoutLastMinWidth == constraints.minWidth,
-      'Last width ($_textLayoutLastMinWidth, $_textLayoutLastMaxWidth) not the same as max width constraint (${constraints.minWidth}, ${constraints.maxWidth}).',
-    );
-  }
-
   /// Whether the [handleEvent] will propagate pointer events to selection
   /// handlers.
   ///
@@ -542,7 +531,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       return;
     }
     _textPainter.textHeightBehavior = value;
-    markNeedsTextLayout();
+    markNeedsLayout();
   }
 
   /// {@macro flutter.painting.textPainter.textWidthBasis}
@@ -552,7 +541,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       return;
     }
     _textPainter.textWidthBasis = value;
-    markNeedsTextLayout();
+    markNeedsLayout();
   }
 
   /// The pixel ratio of the current device.
@@ -565,7 +554,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       return;
     }
     _devicePixelRatio = value;
-    markNeedsTextLayout();
+    markNeedsLayout();
   }
 
   /// Character used for obscuring text if [obscureText] is true.
@@ -655,7 +644,6 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
   /// {@macro flutter.services.TextLayoutMetrics.getLineAtOffset}
   @override
   TextSelection getLineAtOffset(TextPosition position) {
-    debugAssertLayoutUpToDate();
     final TextRange line = _textPainter.getLineBoundary(position);
     // If text is obscured, the entire string should be treated as one line.
     if (obscureText) {
@@ -761,23 +749,10 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     _backgroundRenderObject?.markNeedsPaint();
   }
 
-  /// Marks the render object as needing to be laid out again and have its text
-  /// metrics recomputed.
-  ///
-  /// Implies [markNeedsLayout].
-  @protected
-  void markNeedsTextLayout() {
-    _textLayoutLastMaxWidth = null;
-    _textLayoutLastMinWidth = null;
-    markNeedsLayout();
-  }
-
   @override
   void systemFontsDidChange() {
     super.systemFontsDidChange();
     _textPainter.markNeedsLayout();
-    _textLayoutLastMaxWidth = null;
-    _textLayoutLastMinWidth = null;
   }
 
   /// Returns a plain text version of the text in [TextPainter].
@@ -803,10 +778,25 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     _cachedAttributedValue = null;
     _cachedCombinedSemanticsInfos = null;
     _canComputeIntrinsicsCached = null;
-    markNeedsTextLayout();
+    markNeedsLayout();
     markNeedsSemanticsUpdate();
   }
 
+  TextPainter? _textIntrinsicsCache;
+  TextPainter get _textIntrinsics {
+    return (_textIntrinsicsCache ??= TextPainter())
+      ..text = _textPainter.text
+      ..textAlign = _textPainter.textAlign
+      ..textDirection = _textPainter.textDirection
+      ..textScaler = _textPainter.textScaler
+      ..maxLines = _textPainter.maxLines
+      ..ellipsis = _textPainter.ellipsis
+      ..locale = _textPainter.locale
+      ..strutStyle = _textPainter.strutStyle
+      ..textWidthBasis = _textPainter.textWidthBasis
+      ..textHeightBehavior = _textPainter.textHeightBehavior;
+  }
+
   /// How the text should be aligned horizontally.
   TextAlign get textAlign => _textPainter.textAlign;
   set textAlign(TextAlign value) {
@@ -814,7 +804,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       return;
     }
     _textPainter.textAlign = value;
-    markNeedsTextLayout();
+    markNeedsLayout();
   }
 
   /// The directionality of the text.
@@ -837,7 +827,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       return;
     }
     _textPainter.textDirection = value;
-    markNeedsTextLayout();
+    markNeedsLayout();
     markNeedsSemanticsUpdate();
   }
 
@@ -857,7 +847,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       return;
     }
     _textPainter.locale = value;
-    markNeedsTextLayout();
+    markNeedsLayout();
   }
 
   /// The [StrutStyle] used by the renderer's internal [TextPainter] to
@@ -868,7 +858,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       return;
     }
     _textPainter.strutStyle = value;
-    markNeedsTextLayout();
+    markNeedsLayout();
   }
 
   /// The color to use when painting the cursor.
@@ -977,7 +967,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     // height of the first line in case there are hard line breaks in the text.
     // See the `_preferredHeight` method.
     _textPainter.maxLines = value == 1 ? 1 : null;
-    markNeedsTextLayout();
+    markNeedsLayout();
   }
 
   /// {@macro flutter.widgets.editableText.minLines}
@@ -990,7 +980,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       return;
     }
     _minLines = value;
-    markNeedsTextLayout();
+    markNeedsLayout();
   }
 
   /// {@macro flutter.widgets.editableText.expands}
@@ -1001,7 +991,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       return;
     }
     _expands = value;
-    markNeedsTextLayout();
+    markNeedsLayout();
   }
 
   /// The color to use when painting the selection.
@@ -1039,7 +1029,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       return;
     }
     _textPainter.textScaler = value;
-    markNeedsTextLayout();
+    markNeedsLayout();
   }
 
   /// The region of text that is selected, if any.
@@ -1215,7 +1205,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       return;
     }
     _enableInteractiveSelection = value;
-    markNeedsTextLayout();
+    markNeedsLayout();
     markNeedsSemanticsUpdate();
   }
 
@@ -1841,12 +1831,12 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     if (!_canComputeIntrinsics) {
       return 0.0;
     }
-    _textPainter.setPlaceholderDimensions(layoutInlineChildren(
+    final List<PlaceholderDimensions> placeholderDimensions = layoutInlineChildren(double.infinity, (RenderBox child, BoxConstraints constraints) => Size(child.getMinIntrinsicWidth(double.infinity), 0.0));
-      double.infinity,
+    final (double minWidth, double maxWidth) = _adjustConstraints();
-      (RenderBox child, BoxConstraints constraints) => Size(child.getMinIntrinsicWidth(double.infinity), 0.0),
+    return (_textIntrinsics
-    ));
+      ..setPlaceholderDimensions(placeholderDimensions)
-    _layoutText();
+      ..layout(minWidth: minWidth, maxWidth: maxWidth))
-    return _textPainter.minIntrinsicWidth;
+      .minIntrinsicWidth;
   }
 
   @override
@@ -1854,14 +1844,17 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     if (!_canComputeIntrinsics) {
       return 0.0;
     }
-    _textPainter.setPlaceholderDimensions(layoutInlineChildren(
+    final List<PlaceholderDimensions> placeholderDimensions = layoutInlineChildren(
       double.infinity,
       // Height and baseline is irrelevant as all text will be laid
       // out in a single line. Therefore, using 0.0 as a dummy for the height.
       (RenderBox child, BoxConstraints constraints) => Size(child.getMaxIntrinsicWidth(double.infinity), 0.0),
-    ));
+    );
-    _layoutText();
+    final (double minWidth, double maxWidth) = _adjustConstraints();
-    return _textPainter.maxIntrinsicWidth + _caretMargin;
+    return (_textIntrinsics
+      ..setPlaceholderDimensions(placeholderDimensions)
+      ..layout(minWidth: minWidth, maxWidth: maxWidth))
+      .maxIntrinsicWidth + _caretMargin;
   }
 
   /// An estimate of the height of a line in the text. See [TextPainter.preferredLineHeight].
@@ -1869,8 +1862,6 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
   double get preferredLineHeight => _textPainter.preferredLineHeight;
 
   int? _cachedLineBreakCount;
-  // TODO(LongCatIsLooong): see if we can let ui.Paragraph estimate the number
-  // of lines
   int _countHardLineBreaks(String text) {
     final int? cachedValue = _cachedLineBreakCount;
     if (cachedValue != null) {
@@ -1895,14 +1886,15 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     final int? maxLines = this.maxLines;
     final int? minLines = this.minLines ?? maxLines;
     final double minHeight = preferredLineHeight * (minLines ?? 0);
+    assert(maxLines != 1 || _textIntrinsics.maxLines == 1);
 
     if (maxLines == null) {
       final double estimatedHeight;
       if (width == double.infinity) {
         estimatedHeight = preferredLineHeight * (_countHardLineBreaks(plainText) + 1);
       } else {
-        _layoutText(maxWidth: width);
+        final (double minWidth, double maxWidth) = _adjustConstraints(maxWidth: width);
-        estimatedHeight = _textPainter.height;
+        estimatedHeight = (_textIntrinsics..layout(minWidth: minWidth, maxWidth: maxWidth)).height;
       }
       return math.max(estimatedHeight, minHeight);
     }
@@ -1914,16 +1906,19 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       // The _layoutText call lays out the paragraph using infinite width when
       // maxLines == 1. Also _textPainter.maxLines will be set to 1 so should
       // there be any line breaks only the first line is shown.
-      assert(_textPainter.maxLines == 1);
+      final (double minWidth, double maxWidth) = _adjustConstraints(maxWidth: width);
-      _layoutText(maxWidth: width);
+      return (_textIntrinsics..layout(minWidth: minWidth, maxWidth: maxWidth)).height;
-      return _textPainter.height;
     }
     if (minLines == maxLines) {
       return minHeight;
     }
-    _layoutText(maxWidth: width);
     final double maxHeight = preferredLineHeight * maxLines;
-    return clampDouble(_textPainter.height, minHeight, maxHeight);
+    final (double minWidth, double maxWidth) = _adjustConstraints(maxWidth: width);
+    return clampDouble(
+      (_textIntrinsics..layout(minWidth: minWidth, maxWidth: maxWidth)).height,
+      minHeight,
+      maxHeight,
+    );
   }
 
   @override
@@ -1934,7 +1929,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     if (!_canComputeIntrinsics) {
       return 0.0;
     }
-    _textPainter.setPlaceholderDimensions(layoutInlineChildren(width, ChildLayoutHelper.dryLayoutChild));
+    _textIntrinsics.setPlaceholderDimensions(layoutInlineChildren(width, ChildLayoutHelper.dryLayoutChild));
     return _preferredHeight(width);
   }
 
@@ -2075,7 +2070,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
   /// [from] corresponds to the [TextSelection.baseOffset], and [to] corresponds
   /// to the [TextSelection.extentOffset].
   void selectPositionAt({ required Offset from, Offset? to, required SelectionChangedCause cause }) {
-    _layoutText(minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
+    _computeTextMetricsIfNeeded();
     final TextPosition fromPosition = _textPainter.getPositionForOffset(globalToLocal(from - _paintOffset));
     final TextPosition? toPosition = to == null
       ? null
@@ -2150,7 +2145,6 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
   /// [TextPosition].
   @visibleForTesting
   TextSelection getWordAtOffset(TextPosition position) {
-    debugAssertLayoutUpToDate();
     // When long-pressing past the end of the text, we want a collapsed cursor.
     if (position.offset >= plainText.length) {
       return TextSelection.fromPosition(
@@ -2229,17 +2223,13 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
   // restored to the original values before final layout and painting.
   List<PlaceholderDimensions>? _placeholderDimensions;
 
-  void _layoutText({ double minWidth = 0.0, double maxWidth = double.infinity }) {
+  (double minWidth, double maxWidth) _adjustConstraints({ double minWidth = 0.0, double maxWidth = double.infinity }) {
     final double availableMaxWidth = math.max(0.0, maxWidth - _caretMargin);
     final double availableMinWidth = math.min(minWidth, availableMaxWidth);
-    final double textMaxWidth = _isMultiline ? availableMaxWidth : double.infinity;
+    return (
-    final double textMinWidth = forceLine ? availableMaxWidth : availableMinWidth;
+      forceLine ? availableMaxWidth : availableMinWidth,
-    _textPainter.layout(
+      _isMultiline ? availableMaxWidth : double.infinity,
-        minWidth: textMinWidth,
-        maxWidth: textMaxWidth,
     );
-    _textLayoutLastMinWidth = minWidth;
-    _textLayoutLastMaxWidth = maxWidth;
   }
 
   // Computes the text metrics if `_textPainter`'s layout information was marked
@@ -2262,7 +2252,8 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
   // the constraints used to layout the `_textPainter` is different. See
   // `TextPainter.layout`.
   void _computeTextMetricsIfNeeded() {
-    _layoutText(minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
+    final (double minWidth, double maxWidth) = _adjustConstraints(minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
+    _textPainter.layout(minWidth: minWidth, maxWidth: maxWidth);
   }
 
   late Rect _caretPrototype;
@@ -2325,10 +2316,14 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       ));
       return Size.zero;
     }
-    _textPainter.setPlaceholderDimensions(layoutInlineChildren(constraints.maxWidth, ChildLayoutHelper.dryLayoutChild));
+
-    _layoutText(minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
+    final (double minWidth, double maxWidth) = _adjustConstraints(minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
-    final double width = forceLine ? constraints.maxWidth : constraints
+    _textIntrinsics
-        .constrainWidth(_textPainter.size.width + _caretMargin);
+      ..setPlaceholderDimensions(layoutInlineChildren(constraints.maxWidth, ChildLayoutHelper.dryLayoutChild))
+      ..layout(minWidth: minWidth, maxWidth: maxWidth);
+    final double width = forceLine
+      ? constraints.maxWidth
+      : constraints.constrainWidth(_textIntrinsics.size.width + _caretMargin);
     return Size(width, constraints.constrainHeight(_preferredHeight(constraints.maxWidth)));
   }
 
@@ -2336,8 +2331,10 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
   void performLayout() {
     final BoxConstraints constraints = this.constraints;
     _placeholderDimensions = layoutInlineChildren(constraints.maxWidth, ChildLayoutHelper.layoutChild);
-    _textPainter.setPlaceholderDimensions(_placeholderDimensions);
+    final (double minWidth, double maxWidth) = _adjustConstraints(minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
-    _computeTextMetricsIfNeeded();
+    _textPainter
+      ..setPlaceholderDimensions(_placeholderDimensions)
+      ..layout(minWidth: minWidth, maxWidth: maxWidth);
     positionInlineChildren(_textPainter.inlinePlaceholderBoxes!);
     _computeCaretPrototype();
     // We grab _textPainter.size here because assigning to `size` on the next
@@ -2349,9 +2346,20 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     // though we currently don't use those here.
     // See also RenderParagraph which has a similar issue.
     final Size textPainterSize = _textPainter.size;
-    final double width = forceLine ? constraints.maxWidth : constraints
+    final double width = forceLine
-        .constrainWidth(_textPainter.size.width + _caretMargin);
+      ? constraints.maxWidth
-    final double preferredHeight = _preferredHeight(constraints.maxWidth);
+      : constraints.constrainWidth(_textPainter.size.width + _caretMargin);
+    assert(maxLines != 1 || _textPainter.maxLines == 1);
+    final double preferredHeight = switch (maxLines) {
+      null => math.max(_textPainter.height, preferredLineHeight * (minLines ?? 0)),
+      1    => _textPainter.height,
+      final int maxLines => clampDouble(
+        _textPainter.height,
+        preferredLineHeight * (minLines ?? maxLines),
+        preferredLineHeight * maxLines,
+      ),
+    };
+
     size = Size(width, constraints.constrainHeight(preferredHeight));
     final Size contentSize = Size(textPainterSize.width + _caretMargin, textPainterSize.height);
 
@@ -2521,7 +2529,6 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
   }
 
   void _paintContents(PaintingContext context, Offset offset) {
-    debugAssertLayoutUpToDate();
     final Offset effectiveOffset = offset + _paintOffset;
 
     if (selection != null && !_floatingCursorOn) {

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

@@ -306,6 +306,27 @@ class RenderParagraph extends RenderBox with ContainerRenderObjectMixin<RenderBo
 
   final TextPainter _textPainter;
 
+  // Currently, computing min/max intrinsic width/height will destroy state
+  // inside the painter. Instead of calling _layout again to get back the correct
+  // state, use a separate TextPainter for intrinsics calculation.
+  //
+  // TODO(abarth): Make computing the min/max intrinsic width/height a
+  //  non-destructive operation.
+  TextPainter? _textIntrinsicsCache;
+  TextPainter get _textIntrinsics {
+    return (_textIntrinsicsCache ??= TextPainter())
+      ..text = _textPainter.text
+      ..textAlign = _textPainter.textAlign
+      ..textDirection = _textPainter.textDirection
+      ..textScaler = _textPainter.textScaler
+      ..maxLines = _textPainter.maxLines
+      ..ellipsis = _textPainter.ellipsis
+      ..locale = _textPainter.locale
+      ..strutStyle = _textPainter.strutStyle
+      ..textWidthBasis = _textPainter.textWidthBasis
+      ..textHeightBehavior = _textPainter.textHeightBehavior;
+  }
+
   List<AttributedString>? _cachedAttributedLabels;
 
   List<InlineSpanSemanticsInformation>? _cachedCombinedSemanticsInfos;
@@ -448,6 +469,7 @@ class RenderParagraph extends RenderBox with ContainerRenderObjectMixin<RenderBo
     _removeSelectionRegistrarSubscription();
     _disposeSelectableFragments();
     _textPainter.dispose();
+    _textIntrinsicsCache?.dispose();
     super.dispose();
   }
 
@@ -630,21 +652,17 @@ class RenderParagraph extends RenderBox with ContainerRenderObjectMixin<RenderBo
     return getOffsetForCaret(position, Rect.zero) + Offset(0, getFullHeightForCaret(position) ?? 0.0);
   }
 
-  List<ui.LineMetrics> _computeLineMetrics() {
-    return _textPainter.computeLineMetrics();
-  }
-
   @override
   double computeMinIntrinsicWidth(double height) {
     if (!_canComputeIntrinsics()) {
       return 0.0;
     }
-    _textPainter.setPlaceholderDimensions(layoutInlineChildren(
+    final List<PlaceholderDimensions> placeholderDimensions = layoutInlineChildren(
       double.infinity,
       (RenderBox child, BoxConstraints constraints) => Size(child.getMinIntrinsicWidth(double.infinity), 0.0),
-    ));
+    );
-    _layoutText(); // layout with infinite width.
+    return (_textIntrinsics..setPlaceholderDimensions(placeholderDimensions)..layout())
-    return _textPainter.minIntrinsicWidth;
+      .minIntrinsicWidth;
   }
 
   @override
@@ -652,23 +670,24 @@ class RenderParagraph extends RenderBox with ContainerRenderObjectMixin<RenderBo
     if (!_canComputeIntrinsics()) {
       return 0.0;
     }
-    _textPainter.setPlaceholderDimensions(layoutInlineChildren(
+    final List<PlaceholderDimensions> placeholderDimensions = layoutInlineChildren(
       double.infinity,
       // Height and baseline is irrelevant as all text will be laid
       // out in a single line. Therefore, using 0.0 as a dummy for the height.
       (RenderBox child, BoxConstraints constraints) => Size(child.getMaxIntrinsicWidth(double.infinity), 0.0),
-    ));
+    );
-    _layoutText(); // layout with infinite width.
+    return (_textIntrinsics..setPlaceholderDimensions(placeholderDimensions)..layout())
-    return _textPainter.maxIntrinsicWidth;
+      .maxIntrinsicWidth;
   }
 
   double _computeIntrinsicHeight(double width) {
     if (!_canComputeIntrinsics()) {
       return 0.0;
     }
-    _textPainter.setPlaceholderDimensions(layoutInlineChildren(width, ChildLayoutHelper.dryLayoutChild));
+    return (_textIntrinsics
-    _layoutText(minWidth: width, maxWidth: width);
+      ..setPlaceholderDimensions(layoutInlineChildren(width, ChildLayoutHelper.dryLayoutChild))
-    return _textPainter.height;
+      ..layout(minWidth: width, maxWidth: _adjustMaxWidth(width)))
+      .height;
   }
 
   @override
@@ -761,14 +780,6 @@ class RenderParagraph extends RenderBox with ContainerRenderObjectMixin<RenderBo
   @visibleForTesting
   bool get debugHasOverflowShader => _overflowShader != null;
 
-  void _layoutText({ double minWidth = 0.0, double maxWidth = double.infinity }) {
-    final bool widthMatters = softWrap || overflow == TextOverflow.ellipsis;
-    _textPainter.layout(
-      minWidth: minWidth,
-      maxWidth: widthMatters ? maxWidth : double.infinity,
-    );
-  }
-
   @override
   void systemFontsDidChange() {
     super.systemFontsDidChange();
@@ -782,9 +793,13 @@ class RenderParagraph extends RenderBox with ContainerRenderObjectMixin<RenderBo
   // restored to the original values before final layout and painting.
   List<PlaceholderDimensions>? _placeholderDimensions;
 
+  double _adjustMaxWidth(double maxWidth) {
+    return softWrap || overflow == TextOverflow.ellipsis ? maxWidth : double.infinity;
+  }
   void _layoutTextWithConstraints(BoxConstraints constraints) {
-    _textPainter.setPlaceholderDimensions(_placeholderDimensions);
+    _textPainter
-    _layoutText(minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
+      ..setPlaceholderDimensions(_placeholderDimensions)
+      ..layout(minWidth: constraints.minWidth, maxWidth: _adjustMaxWidth(constraints.maxWidth));
   }
 
   @override
@@ -796,9 +811,11 @@ class RenderParagraph extends RenderBox with ContainerRenderObjectMixin<RenderBo
       ));
       return Size.zero;
     }
-    _textPainter.setPlaceholderDimensions(layoutInlineChildren(constraints.maxWidth, ChildLayoutHelper.dryLayoutChild));
+    final Size size = (_textIntrinsics
-    _layoutText(minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
+     ..setPlaceholderDimensions(layoutInlineChildren(constraints.maxWidth, ChildLayoutHelper.dryLayoutChild))
-    return constraints.constrain(_textPainter.size);
+     ..layout(minWidth: constraints.minWidth, maxWidth: _adjustMaxWidth(constraints.maxWidth)))
+     .size;
+    return constraints.constrain(size);
   }
 
   @override
@@ -876,18 +893,10 @@ class RenderParagraph extends RenderBox with ContainerRenderObjectMixin<RenderBo
 
   @override
   void paint(PaintingContext context, Offset offset) {
-    // Ideally we could compute the min/max intrinsic width/height with a
+    // Text alignment only triggers repaint so it's possible the text layout has
-    // non-destructive operation. However, currently, computing these values
+    // been invalidated but performLayout wasn't called at this point. Make sure
-    // will destroy state inside the painter. If that happens, we need to get
+    // the TextPainter has a valid layout.
-    // back the correct state by calling _layout again.
-    //
-    // TODO(abarth): Make computing the min/max intrinsic width/height a
-    //  non-destructive operation.
-    //
-    // If you remove this call, make sure that changing the textAlign still
-    // works properly.
     _layoutTextWithConstraints(constraints);
-
     assert(() {
       if (debugRepaintTextRainbowEnabled) {
         final Paint paint = Paint()
@@ -1919,7 +1928,7 @@ class _SelectableFragment with Selectable, Diagnosticable, ChangeNotifier implem
   }
 
   MapEntry<TextPosition, SelectionResult> _handleVerticalMovement(TextPosition position, {required double horizontalBaselineInParagraphCoordinates, required bool below}) {
-    final List<ui.LineMetrics> lines = paragraph._computeLineMetrics();
+    final List<ui.LineMetrics> lines = paragraph._textPainter.computeLineMetrics();
     final Offset offset = paragraph.getOffsetForCaret(position, Rect.zero);
     int currentLine = lines.length - 1;
     for (final ui.LineMetrics lineMetrics in lines) {

packages/flutter/test/rendering/editable_intrinsics_test.dart

@@ -0,0 +1,147 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  final TextSelectionDelegate delegate = _FakeEditableTextState();
+
+  test('editable intrinsics', () {
+    final RenderEditable editable = RenderEditable(
+      text: const TextSpan(
+        style: TextStyle(height: 1.0, fontSize: 10.0),
+        text: '12345',
+      ),
+      startHandleLayerLink: LayerLink(),
+      endHandleLayerLink: LayerLink(),
+      textDirection: TextDirection.ltr,
+      locale: const Locale('ja', 'JP'),
+      offset: ViewportOffset.zero(),
+      textSelectionDelegate: delegate,
+    );
+    expect(editable.getMinIntrinsicWidth(double.infinity), 50.0);
+    // The width includes the width of the cursor (1.0).
+    expect(editable.getMaxIntrinsicWidth(double.infinity), 52.0);
+    expect(editable.getMinIntrinsicHeight(double.infinity), 10.0);
+    expect(editable.getMaxIntrinsicHeight(double.infinity), 10.0);
+
+    expect(
+      editable.toStringDeep(minLevel: DiagnosticLevel.info),
+      equalsIgnoringHashCodes(
+        'RenderEditable#00000 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE DETACHED\n'
+        ' │ parentData: MISSING\n'
+        ' │ constraints: MISSING\n'
+        ' │ size: MISSING\n'
+        ' │ cursorColor: null\n'
+        ' │ showCursor: ValueNotifier<bool>#00000(false)\n'
+        ' │ maxLines: 1\n'
+        ' │ minLines: null\n'
+        ' │ selectionColor: null\n'
+        ' │ locale: ja_JP\n'
+        ' │ selection: null\n'
+        ' │ offset: _FixedViewportOffset#00000(offset: 0.0)\n'
+        ' ╘═╦══ text ═══\n'
+        '   ║ TextSpan:\n'
+        '   ║   inherit: true\n'
+        '   ║   size: 10.0\n'
+        '   ║   height: 1.0x\n'
+        '   ║   "12345"\n'
+        '   ╚═══════════\n',
+      ),
+    );
+  });
+
+  test('textScaler affects intrinsics', () {
+    final RenderEditable editable = RenderEditable(
+      text: const TextSpan(
+        style: TextStyle(fontSize: 10),
+        text: 'Hello World',
+      ),
+      textDirection: TextDirection.ltr,
+      startHandleLayerLink: LayerLink(),
+      endHandleLayerLink: LayerLink(),
+      offset: ViewportOffset.zero(),
+      textSelectionDelegate: delegate,
+    );
+
+    expect(editable.getMaxIntrinsicWidth(double.infinity), 110 + 2);
+
+    editable.textScaler = const TextScaler.linear(2);
+    expect(editable.getMaxIntrinsicWidth(double.infinity), 220 + 2);
+  });
+
+  test('maxLines affects intrinsics', () {
+    final RenderEditable editable = RenderEditable(
+      text: TextSpan(
+        style: const TextStyle(fontSize: 10),
+        text: List<String>.filled(5, 'A').join('\n'),
+      ),
+      textDirection: TextDirection.ltr,
+      startHandleLayerLink: LayerLink(),
+      endHandleLayerLink: LayerLink(),
+      offset: ViewportOffset.zero(),
+      textSelectionDelegate: delegate,
+      maxLines: null,
+    );
+
+    expect(editable.getMaxIntrinsicHeight(double.infinity), 50);
+
+    editable.maxLines = 1;
+    expect(editable.getMaxIntrinsicHeight(double.infinity), 10);
+  });
+
+  test('strutStyle affects intrinsics', () {
+    final RenderEditable editable = RenderEditable(
+      text: const TextSpan(
+        style: TextStyle(fontSize: 10),
+        text: 'Hello World',
+      ),
+      textDirection: TextDirection.ltr,
+      startHandleLayerLink: LayerLink(),
+      endHandleLayerLink: LayerLink(),
+      offset: ViewportOffset.zero(),
+      textSelectionDelegate: delegate,
+    );
+
+    expect(editable.getMaxIntrinsicHeight(double.infinity), 10);
+
+    editable.strutStyle = const StrutStyle(fontSize: 100, forceStrutHeight: true);
+    expect(editable.getMaxIntrinsicHeight(double.infinity), 100);
+  }, skip: kIsWeb && !isCanvasKit); // [intended] strut spport for HTML renderer https://github.com/flutter/flutter/issues/32243.
+}
+
+class _FakeEditableTextState with TextSelectionDelegate {
+  @override
+  TextEditingValue textEditingValue = TextEditingValue.empty;
+
+  TextSelection? selection;
+
+  @override
+  void hideToolbar([bool hideHandles = true]) { }
+
+  @override
+  void userUpdateTextEditingValue(TextEditingValue value, SelectionChangedCause cause) {
+    selection = value.selection;
+  }
+
+  @override
+  void bringIntoView(TextPosition position) { }
+
+  @override
+  void cutSelection(SelectionChangedCause cause) { }
+
+  @override
+  Future<void> pasteText(SelectionChangedCause cause) {
+    return Future<void>.value();
+  }
+
+  @override
+  void selectAll(SelectionChangedCause cause) { }
+
+  @override
+  void copySelection(SelectionChangedCause cause) { }
+}

packages/flutter/test/rendering/editable_test.dart

@@ -201,52 +201,6 @@ void main() {
     expect(leaderLayers.single.offset, endpoint + paintOffset, reason: 'offset should respect paintOffset');
   });
 
-  test('editable intrinsics', () {
-    final TextSelectionDelegate delegate = _FakeEditableTextState();
-    final RenderEditable editable = RenderEditable(
-      text: const TextSpan(
-        style: TextStyle(height: 1.0, fontSize: 10.0),
-        text: '12345',
-      ),
-      startHandleLayerLink: LayerLink(),
-      endHandleLayerLink: LayerLink(),
-      textDirection: TextDirection.ltr,
-      locale: const Locale('ja', 'JP'),
-      offset: ViewportOffset.zero(),
-      textSelectionDelegate: delegate,
-    );
-    expect(editable.getMinIntrinsicWidth(double.infinity), 50.0);
-    // The width includes the width of the cursor (1.0).
-    expect(editable.getMaxIntrinsicWidth(double.infinity), 52.0);
-    expect(editable.getMinIntrinsicHeight(double.infinity), 10.0);
-    expect(editable.getMaxIntrinsicHeight(double.infinity), 10.0);
-
-    expect(
-      editable.toStringDeep(minLevel: DiagnosticLevel.info),
-      equalsIgnoringHashCodes(
-        'RenderEditable#00000 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE DETACHED\n'
-        ' │ parentData: MISSING\n'
-        ' │ constraints: MISSING\n'
-        ' │ size: MISSING\n'
-        ' │ cursorColor: null\n'
-        ' │ showCursor: ValueNotifier<bool>#00000(false)\n'
-        ' │ maxLines: 1\n'
-        ' │ minLines: null\n'
-        ' │ selectionColor: null\n'
-        ' │ locale: ja_JP\n'
-        ' │ selection: null\n'
-        ' │ offset: _FixedViewportOffset#00000(offset: 0.0)\n'
-        ' ╘═╦══ text ═══\n'
-        '   ║ TextSpan:\n'
-        '   ║   inherit: true\n'
-        '   ║   size: 10.0\n'
-        '   ║   height: 1.0x\n'
-        '   ║   "12345"\n'
-        '   ╚═══════════\n',
-      ),
-    );
-  });
-
   // Test that clipping will be used even when the text fits within the visible
   // region if the start position of the text is offset (e.g. during scrolling
   // animation).

packages/flutter/test/rendering/paragraph_intrinsics_test.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
 
@@ -66,4 +67,49 @@ void main() {
     expect(testBlock.getMinIntrinsicHeight(0.0), equals(manyLinesTextHeight));
     expect(testBlock.getMaxIntrinsicHeight(0.0), equals(manyLinesTextHeight));
   });
+
+  test('textScaler affects intrinsics', () {
+    final RenderParagraph paragraph = RenderParagraph(
+      const TextSpan(
+        style: TextStyle(fontSize: 10),
+        text: 'Hello World',
+      ),
+      textDirection: TextDirection.ltr,
+    );
+
+    expect(paragraph.getMaxIntrinsicWidth(double.infinity), 110);
+
+    paragraph.textScaler = const TextScaler.linear(2);
+    expect(paragraph.getMaxIntrinsicWidth(double.infinity), 220);
+  });
+
+  test('maxLines affects intrinsics', () {
+    final RenderParagraph paragraph = RenderParagraph(
+      TextSpan(
+        style: const TextStyle(fontSize: 10),
+        text: List<String>.filled(5, 'A').join('\n'),
+      ),
+      textDirection: TextDirection.ltr,
+    );
+
+    expect(paragraph.getMaxIntrinsicHeight(double.infinity), 50);
+
+    paragraph.maxLines = 1;
+    expect(paragraph.getMaxIntrinsicHeight(double.infinity), 10);
+  });
+
+  test('strutStyle affects intrinsics', () {
+    final RenderParagraph paragraph = RenderParagraph(
+      const TextSpan(
+        style: TextStyle(fontSize: 10),
+        text: 'Hello World',
+      ),
+      textDirection: TextDirection.ltr,
+    );
+
+    expect(paragraph.getMaxIntrinsicHeight(double.infinity), 10);
+
+    paragraph.strutStyle = const StrutStyle(fontSize: 100, forceStrutHeight: true);
+    expect(paragraph.getMaxIntrinsicHeight(double.infinity), 100);
+  }, skip: kIsWeb && !isCanvasKit); // [intended] strut spport for HTML renderer https://github.com/flutter/flutter/issues/32243.
 }

packages/flutter/test/rendering/paragraph_test.dart

@@ -375,6 +375,27 @@ void main() {
     expect(paragraph.size.height, 30.0);
   }, skip: isBrowser); // https://github.com/flutter/flutter/issues/61018
 
+  test('textAlign triggers TextPainter relayout in the paint method', () {
+    final RenderParagraph paragraph = RenderParagraph(
+      const TextSpan(text: 'A', style: TextStyle(fontSize: 10.0)),
+      textDirection: TextDirection.ltr,
+      textAlign: TextAlign.left,
+    );
+
+    Rect getRectForA() => paragraph.getBoxesForSelection(const TextSelection(baseOffset: 0, extentOffset: 1)).single.toRect();
+
+    layout(paragraph, constraints: const BoxConstraints.tightFor(width: 100.0));
+
+    expect(getRectForA(), const Rect.fromLTWH(0, 0, 10, 10));
+
+    paragraph.textAlign = TextAlign.right;
+    expect(paragraph.debugNeedsLayout, isFalse);
+    expect(paragraph.debugNeedsPaint, isTrue);
+
+    paragraph.paint(MockPaintingContext(), Offset.zero);
+    expect(getRectForA(), const Rect.fromLTWH(90, 0, 10, 10));
+  });
+
   group('didExceedMaxLines', () {
     RenderParagraph createRenderParagraph({
       int? maxLines,