Scale selection handles for rich text on iOS (#85789)

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

@@ -67,13 +67,13 @@ class _CupertinoDesktopTextSelectionControls extends TextSelectionControls {
 
   /// Builds the text selection handles, but desktop has none.
   @override
-  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textLineHeight, [VoidCallback? onTap]) {
+  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textLineHeight, [VoidCallback? onTap, double? startGlyphHeight, double? endGlyphHeight]) {
     return const SizedBox.shrink();
   }
 
   /// Gets the position for the text selection handles, but desktop has none.
   @override
-  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight) {
+  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight, [double? startGlyphHeight, double? endGlyphHeight]) {
     return Offset.zero;
   }
 }

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

@@ -247,18 +247,19 @@ class CupertinoTextSelectionControls extends TextSelectionControls {
 
   /// Builder for iOS text selection edges.
   @override
-  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textLineHeight, [VoidCallback? onTap]) {
+  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textLineHeight, [VoidCallback? onTap, double? startGlyphHeight, double? endGlyphHeight]) {
     // iOS selection handles do not respond to taps.
 
     // We want a size that's a vertical line the height of the text plus a 18.0
     // padding in every direction that will constitute the selection drag area.
-    final Size desiredSize = getHandleSize(textLineHeight);
+    startGlyphHeight = startGlyphHeight ?? textLineHeight;
+    endGlyphHeight = endGlyphHeight ?? textLineHeight;
 
-    final Widget handle = SizedBox.fromSize(
-      size: desiredSize,
-      child: CustomPaint(
+    final Size desiredSize;
+    final Widget handle;
+
+    final Widget customPaint = CustomPaint(
       painter: _TextSelectionHandlePainter(CupertinoTheme.of(context).primaryColor),
-      ),
     );
 
     // [buildHandle]'s widget is positioned at the selection cursor's bottom
@@ -266,9 +267,18 @@ class CupertinoTextSelectionControls extends TextSelectionControls {
     // on top of the text selection endpoints.
     switch (type) {
       case TextSelectionHandleType.left:
+        desiredSize = getHandleSize(startGlyphHeight);
+        handle = SizedBox.fromSize(
+          size: desiredSize,
+          child: customPaint,
+        );
         return handle;
       case TextSelectionHandleType.right:
-        // Right handle is a vertical mirror of the left.
+        desiredSize = getHandleSize(endGlyphHeight);
+        handle = SizedBox.fromSize(
+          size: desiredSize,
+          child: customPaint,
+        );
         return Transform(
           transform: Matrix4.identity()
             ..translate(desiredSize.width / 2, desiredSize.height / 2)
@@ -286,12 +296,17 @@ class CupertinoTextSelectionControls extends TextSelectionControls {
   ///
   /// See [TextSelectionControls.getHandleAnchor].
   @override
-  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight) {
-    final Size handleSize = getHandleSize(textLineHeight);
+  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight, [double? startGlyphHeight, double? endGlyphHeight]) {
+    startGlyphHeight = startGlyphHeight ?? textLineHeight;
+    endGlyphHeight = endGlyphHeight ?? textLineHeight;
+
+    final Size handleSize;
+
     switch (type) {
       // The circle is at the top for the left handle, and the anchor point is
       // all the way at the bottom of the line.
       case TextSelectionHandleType.left:
+        handleSize = getHandleSize(startGlyphHeight);
         return Offset(
           handleSize.width / 2,
           handleSize.height,
@@ -299,12 +314,14 @@ class CupertinoTextSelectionControls extends TextSelectionControls {
       // The right handle is vertically flipped, and the anchor point is near
       // the top of the circle to give slight overlap.
       case TextSelectionHandleType.right:
+        handleSize = getHandleSize(endGlyphHeight);
         return Offset(
           handleSize.width / 2,
           handleSize.height - 2 * _kSelectionHandleRadius + _kSelectionHandleOverlap,
         );
       // A collapsed handle anchors itself so that it's centered.
       case TextSelectionHandleType.collapsed:
+        handleSize = getHandleSize(textLineHeight);
         return Offset(
           handleSize.width / 2,
           textLineHeight + (handleSize.height - textLineHeight) / 2,

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

@@ -53,13 +53,13 @@ class _DesktopTextSelectionControls extends TextSelectionControls {
 
   /// Builds the text selection handles, but desktop has none.
   @override
-  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textLineHeight, [VoidCallback? onTap]) {
+  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textLineHeight, [VoidCallback? onTap, double? startGlyphHeight, double? endGlyphHeight]) {
     return const SizedBox.shrink();
   }
 
   /// Gets the position for the text selection handles, but desktop has none.
   @override
-  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight) {
+  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight, [double? startGlyphHeight, double? endGlyphHeight]) {
     return Offset.zero;
   }
 

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

@@ -54,7 +54,7 @@ class MaterialTextSelectionControls extends TextSelectionControls {
 
   /// Builder for material-style text selection handles.
   @override
-  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textHeight, [VoidCallback? onTap]) {
+  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textHeight, [VoidCallback? onTap, double? startGlyphHeight, double? endGlyphHeight]) {
     final ThemeData theme = Theme.of(context);
     final Color handleColor = TextSelectionTheme.of(context).selectionHandleColor ?? theme.colorScheme.primary;
     final Widget handle = SizedBox(
@@ -94,7 +94,7 @@ class MaterialTextSelectionControls extends TextSelectionControls {
   ///
   /// See [TextSelectionControls.getHandleAnchor].
   @override
-  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight) {
+  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight, [double? startGlyphHeight, double? endGlyphHeight]) {
     switch (type) {
       case TextSelectionHandleType.left:
         return const Offset(_kHandleSize, 0);

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

@@ -3088,7 +3088,7 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     final Offset paintOffset = _paintOffset;
 
     final List<ui.TextBox> boxes = selection.isCollapsed ?
-        <ui.TextBox>[] : _textPainter.getBoxesForSelection(selection);
+        <ui.TextBox>[] : _textPainter.getBoxesForSelection(selection, boxHeightStyle: selectionHeightStyle, boxWidthStyle: selectionWidthStyle);
     if (boxes.isEmpty) {
       // TODO(mpcomplete): This doesn't work well at an RTL/LTR boundary.
       final Offset caretOffset = _textPainter.getOffsetForCaret(selection.extent, _caretPrototype);
@@ -3119,6 +3119,8 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
 
     final List<ui.TextBox> boxes = _textPainter.getBoxesForSelection(
       TextSelection(baseOffset: range.start, extentOffset: range.end),
+      boxHeightStyle: selectionHeightStyle,
+      boxWidthStyle: selectionWidthStyle,
     );
 
     return boxes.fold(

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

@@ -5,6 +5,7 @@
 import 'dart:async';
 import 'dart:math' as math;
 
+import 'package:characters/characters.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
@@ -119,12 +120,12 @@ abstract class TextSelectionControls {
   /// interaction is allowed. As a counterexample, the default selection handle
   /// on iOS [cupertinoTextSelectionControls] does not call [onTap] at all,
   /// since its handles are not meant to be tapped.
-  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textLineHeight, [VoidCallback? onTap]);
+  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textLineHeight, [VoidCallback? onTap, double? startGlyphHeight, double? endGlyphHeight]);
 
   /// Get the anchor point of the handle relative to itself. The anchor point is
   /// the point that is aligned with a specific point in the text. A handle
   /// often visually "points to" that location.
-  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight);
+  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight, [double? startGlyphHeight, double? endGlyphHeight]);
 
   /// Builds a toolbar near a text selection.
   ///
@@ -824,9 +825,47 @@ class _TextSelectionHandleOverlayState
         break;
     }
 
+    // On some platforms we may want to calculate the start and end handles
+    // separately so they scale for the selected content.
+    //
+    // For the start handle we compute the rectangles that encompass the range
+    // of the first full selected grapheme cluster at the beginning of the selection.
+    //
+    // For the end handle we compute the rectangles that encompass the range
+    // of the last full selected grapheme cluster at the end of the selection.
+    final InlineSpan span = widget.renderObject.text!;
+    final String text = span.toPlainText();
+    final int firstSelectedGraphemeExtent;
+    final int lastSelectedGraphemeExtent;
+    final TextSelection? selection = widget.renderObject.selection;
+
+    if (selection != null && selection.isValid && !selection.isCollapsed) {
+      final String selectedGraphemes = selection.textInside(text);
+      firstSelectedGraphemeExtent = selectedGraphemes.characters.first.length;
+      lastSelectedGraphemeExtent = selectedGraphemes.characters.last.length;
+      assert(firstSelectedGraphemeExtent <= selectedGraphemes.length && lastSelectedGraphemeExtent <= selectedGraphemes.length);
+    } else {
+      // The call to selectedGraphemes.characters.first/last will throw a state
+      // error if the given text is empty, so fall back to first/last character
+      // range in this case.
+      //
+      // The call to widget.selection.textInside(text) will return a RangeError
+      // for a collapsed selection, fall back to this case when that happens.
+      firstSelectedGraphemeExtent = 0;
+      lastSelectedGraphemeExtent = 0;
+    }
+
+    final Rect? startHandleRect = widget.renderObject.getRectForComposingRange(TextRange(start: widget.selection.start, end: widget.selection.start + firstSelectedGraphemeExtent));
+    final Rect? endHandleRect = widget.renderObject.getRectForComposingRange(TextRange(start: widget.selection.end - lastSelectedGraphemeExtent, end: widget.selection.end));
+
+    assert(!(firstSelectedGraphemeExtent > 0 && widget.selection.isValid && !widget.selection.isCollapsed) || startHandleRect != null);
+    assert(!(lastSelectedGraphemeExtent > 0 && widget.selection.isValid && !widget.selection.isCollapsed) || endHandleRect != null);
+
     final Offset handleAnchor = widget.selectionControls.getHandleAnchor(
       type,
       widget.renderObject.preferredLineHeight,
+      startHandleRect?.height ?? widget.renderObject.preferredLineHeight,
+      endHandleRect?.height ?? widget.renderObject.preferredLineHeight,
     );
     final Size handleSize = widget.selectionControls.getHandleSize(
       widget.renderObject.preferredLineHeight,
@@ -877,6 +916,8 @@ class _TextSelectionHandleOverlayState
                 type,
                 widget.renderObject.preferredLineHeight,
                 widget.onSelectionHandleTapped,
+                startHandleRect?.height ?? widget.renderObject.preferredLineHeight,
+                endHandleRect?.height ?? widget.renderObject.preferredLineHeight,
               ),
             ),
           ),

packages/flutter/test/cupertino/text_field_test.dart

@@ -35,7 +35,7 @@ class MockClipboard {
 
 class MockTextSelectionControls extends TextSelectionControls {
   @override
-  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textLineHeight, [VoidCallback? onTap]) {
+  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textLineHeight, [VoidCallback? onTap, double? startGlyphHeight, double? endGlyphHeight]) {
     throw UnimplementedError();
   }
 
@@ -54,7 +54,7 @@ class MockTextSelectionControls extends TextSelectionControls {
   }
 
   @override
-  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight) {
+  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight, [double? startGlyphHeight, double? endGlyphHeight]) {
     throw UnimplementedError();
   }
 

packages/flutter/test/material/text_field_test.dart

@@ -833,13 +833,28 @@ void main() {
         ),
       ),
     );
+    final EditableTextState editableTextState = tester.state(find.byType(EditableText));
 
-    final Offset textfieldStart = tester.getTopLeft(find.byKey(const Key('field0')));
-
-    await tester.longPressAt(textfieldStart + const Offset(50.0, 2.0));
+    // Double tap to select the first word.
+    const int index = 4;
+    await tester.tapAt(textOffsetToPosition(tester, index));
     await tester.pump(const Duration(milliseconds: 50));
-    await tester.tapAt(textfieldStart + const Offset(100.0, 107.0));
-    await tester.pump(const Duration(milliseconds: 300));
+    await tester.tapAt(textOffsetToPosition(tester, index));
+    await tester.pumpAndSettle();
+    expect(editableTextState.selectionOverlay!.handlesAreVisible, isTrue);
+    expect(controller.selection.baseOffset, 0);
+    expect(controller.selection.extentOffset, 7);
+
+    // Use toolbar to select all text.
+    if (isContextMenuProvidedByPlatform) {
+      controller.selection = TextSelection(baseOffset: 0, extentOffset: controller.text.length);
+      expect(controller.selection.extentOffset, controller.text.length);
+    } else {
+      await tester.tap(find.text('Select all'));
+      await tester.pump();
+      expect(controller.selection.baseOffset, 0);
+      expect(controller.selection.extentOffset, controller.text.length);
+    }
 
     await expectLater(
       find.byType(MaterialApp),

packages/flutter/test/widgets/editable_text_test.dart

@@ -7797,7 +7797,7 @@ class MockTextSelectionControls extends Fake implements TextSelectionControls {
   }
 
   @override
-  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textLineHeight, [VoidCallback? onTap]) {
+  Widget buildHandle(BuildContext context, TextSelectionHandleType type, double textLineHeight, [VoidCallback? onTap, double? startGlyphHeight, double? endGlyphHeight]) {
     return Container();
   }
 
@@ -7807,7 +7807,7 @@ class MockTextSelectionControls extends Fake implements TextSelectionControls {
   }
 
   @override
-  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight) {
+  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight, [double? startGlyphHeight, double? endGlyphHeight]) {
     return Offset.zero;
   }