Selection area right click behavior should match native (#128224)

This change updates `SelectableRegion`s right-click gesture to match native platform behavior.

Before: Right-click gesture selects word at position and opens context menu (All Platforms)
After: 
- Linux, toggles context menu on/off, and collapses selection when click was not on an active selection (uncollapsed).
- Windows, Android, Fuchsia, shows context menu at right-clicked position (unless the click is at an active selection).
- macOS, toggles the context menu if right click was at the same position as the previous / or selects word at position and opens context menu.
- iOS, selects word at position and opens context menu.

This change also prevents the `copy` menu button from being shown when there is a collapsed selection (nothing to copy).

Fixes #117561

examples/api/lib/material/selectable_region/selectable_region.0.dart

@@ -157,6 +157,7 @@ class _RenderSelectableAdapter extends RenderProxyBox with Selectable, Selection
         hasContent: true,
         startSelectionPoint: isReversed ? secondSelectionPoint : firstSelectionPoint,
         endSelectionPoint: isReversed ? firstSelectionPoint : secondSelectionPoint,
+        selectionRects: <Rect>[selectionRect],
       );
     }
   }

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

@@ -1335,6 +1335,14 @@ class _SelectableFragment with Selectable, ChangeNotifier implements TextLayoutM
       : paragraph._getOffsetForPosition(TextPosition(offset: selectionEnd));
     final bool flipHandles = isReversed != (TextDirection.rtl == paragraph.textDirection);
     final Matrix4 paragraphToFragmentTransform = getTransformToParagraph()..invert();
+    final TextSelection selection = TextSelection(
+      baseOffset: selectionStart,
+      extentOffset: selectionEnd,
+    );
+    final List<Rect> selectionRects = <Rect>[];
+    for (final TextBox textBox in paragraph.getBoxesForSelection(selection)) {
+      selectionRects.add(textBox.toRect());
+    }
     return SelectionGeometry(
       startSelectionPoint: SelectionPoint(
         localPosition: MatrixUtils.transformPoint(paragraphToFragmentTransform, startOffsetInParagraphCoordinates),
@@ -1346,6 +1354,7 @@ class _SelectableFragment with Selectable, ChangeNotifier implements TextLayoutM
         lineHeight: paragraph._textPainter.preferredLineHeight,
         handleType: flipHandles ? TextSelectionHandleType.left : TextSelectionHandleType.right,
       ),
+      selectionRects: selectionRects,
       status: _textSelectionStart!.offset == _textSelectionEnd!.offset
         ? SelectionStatus.collapsed
         : SelectionStatus.uncollapsed,

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

@@ -576,8 +576,8 @@ enum SelectionStatus {
 /// The geometry of the current selection.
 ///
 /// This includes details such as the locations of the selection start and end,
-/// line height, etc. This information is used for drawing selection controls
-/// for mobile platforms.
+/// line height, the rects that encompass the selection, etc. This information
+/// is used for drawing selection controls for mobile platforms.
 ///
 /// The positions in geometry are in local coordinates of the [SelectionHandler]
 /// or [Selectable].
@@ -590,6 +590,7 @@ class SelectionGeometry {
   const SelectionGeometry({
     this.startSelectionPoint,
     this.endSelectionPoint,
+    this.selectionRects = const <Rect>[],
     required this.status,
     required this.hasContent,
   }) : assert((startSelectionPoint == null && endSelectionPoint == null) || status != SelectionStatus.none);
@@ -627,6 +628,10 @@ class SelectionGeometry {
   /// The status of ongoing selection in the [Selectable] or [SelectionHandler].
   final SelectionStatus status;
 
+  /// The rects in the local coordinates of the containing [Selectable] that
+  /// represent the selection if there is any.
+  final List<Rect> selectionRects;
+
   /// Whether there is any selectable content in the [Selectable] or
   /// [SelectionHandler].
   final bool hasContent;
@@ -638,12 +643,14 @@ class SelectionGeometry {
   SelectionGeometry copyWith({
     SelectionPoint? startSelectionPoint,
     SelectionPoint? endSelectionPoint,
+    List<Rect>? selectionRects,
     SelectionStatus? status,
     bool? hasContent,
   }) {
     return SelectionGeometry(
       startSelectionPoint: startSelectionPoint ?? this.startSelectionPoint,
       endSelectionPoint: endSelectionPoint ?? this.endSelectionPoint,
+      selectionRects: selectionRects ?? this.selectionRects,
       status: status ?? this.status,
       hasContent: hasContent ?? this.hasContent,
     );
@@ -660,6 +667,7 @@ class SelectionGeometry {
     return other is SelectionGeometry
         && other.startSelectionPoint == startSelectionPoint
         && other.endSelectionPoint == endSelectionPoint
+        && other.selectionRects == selectionRects
         && other.status == status
         && other.hasContent == hasContent;
   }
@@ -669,6 +677,7 @@ class SelectionGeometry {
     return Object.hash(
       startSelectionPoint,
       endSelectionPoint,
+      selectionRects,
       status,
       hasContent,
     );

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

@@ -263,7 +263,7 @@ class SelectableRegion extends StatefulWidget {
     required final VoidCallback onCopy,
     required final VoidCallback onSelectAll,
   }) {
-    final bool canCopy = selectionGeometry.hasSelection;
+    final bool canCopy = selectionGeometry.status == SelectionStatus.uncollapsed;
     final bool canSelectAll = selectionGeometry.hasContent;
 
     // Determine which buttons will appear so that the order and total number is
@@ -489,12 +489,62 @@ class SelectableRegionState extends State<SelectableRegion> with TextSelectionDe
     _updateSelectedContentIfNeeded();
   }
 
+  bool _positionIsOnActiveSelection({required Offset globalPosition}) {
+    for (final Rect selectionRect in _selectionDelegate.value.selectionRects) {
+      final Matrix4 transform = _selectable!.getTransformTo(null);
+      final Rect globalRect = MatrixUtils.transformRect(transform, selectionRect);
+      if (globalRect.contains(globalPosition)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
   void _handleRightClickDown(TapDownDetails details) {
+    final Offset? previousSecondaryTapDownPosition = lastSecondaryTapDownPosition;
+    final bool toolbarIsVisible = _selectionOverlay?.toolbarIsVisible ?? false;
     lastSecondaryTapDownPosition = details.globalPosition;
     widget.focusNode.requestFocus();
-    _selectWordAt(offset: details.globalPosition);
+    switch (defaultTargetPlatform) {
+      case TargetPlatform.android:
+      case TargetPlatform.fuchsia:
+      case TargetPlatform.windows:
+        // If lastSecondaryTapDownPosition is within the current selection then
+        // keep the current selection, if not then collapse it.
+        final bool lastSecondaryTapDownPositionWasOnActiveSelection = _positionIsOnActiveSelection(globalPosition: details.globalPosition);
+        if (!lastSecondaryTapDownPositionWasOnActiveSelection) {
+          _selectStartTo(offset: lastSecondaryTapDownPosition!);
+          _selectEndTo(offset: lastSecondaryTapDownPosition!);
+        }
         _showHandles();
-    _showToolbar(location: details.globalPosition);
+        _showToolbar(location: lastSecondaryTapDownPosition);
+      case TargetPlatform.iOS:
+        _selectWordAt(offset: lastSecondaryTapDownPosition!);
+        _showHandles();
+        _showToolbar(location: lastSecondaryTapDownPosition);
+      case TargetPlatform.macOS:
+        if (previousSecondaryTapDownPosition == lastSecondaryTapDownPosition && toolbarIsVisible) {
+          hideToolbar();
+          return;
+        }
+        _selectWordAt(offset: lastSecondaryTapDownPosition!);
+        _showHandles();
+        _showToolbar(location: lastSecondaryTapDownPosition);
+      case TargetPlatform.linux:
+        if (toolbarIsVisible) {
+          hideToolbar();
+          return;
+        }
+        // If lastSecondaryTapDownPosition is within the current selection then
+        // keep the current selection, if not then collapse it.
+        final bool lastSecondaryTapDownPositionWasOnActiveSelection = _positionIsOnActiveSelection(globalPosition: details.globalPosition);
+        if (!lastSecondaryTapDownPositionWasOnActiveSelection) {
+          _selectStartTo(offset: lastSecondaryTapDownPosition!);
+          _selectEndTo(offset: lastSecondaryTapDownPosition!);
+        }
+        _showHandles();
+        _showToolbar(location: lastSecondaryTapDownPosition);
+    }
     _updateSelectedContentIfNeeded();
   }
 
@@ -1770,9 +1820,30 @@ abstract class MultiSelectableSelectionContainerDelegate extends SelectionContai
       }
     }
 
+    // Need to collect selection rects from selectables ranging from the
+    // currentSelectionStartIndex to the currentSelectionEndIndex.
+    final List<Rect> selectionRects = <Rect>[];
+    final Rect? drawableArea = hasSize ? Rect
+      .fromLTWH(0, 0, containerSize.width, containerSize.height) : null;
+    for (int index = currentSelectionStartIndex; index <= currentSelectionEndIndex; index++) {
+      final List<Rect> currSelectableSelectionRects = selectables[index].value.selectionRects;
+      final List<Rect> selectionRectsWithinDrawableArea = currSelectableSelectionRects.map((Rect selectionRect) {
+        final Matrix4 transform = getTransformFrom(selectables[index]);
+        final Rect localRect = MatrixUtils.transformRect(transform, selectionRect);
+        if (drawableArea != null) {
+          return drawableArea.intersect(localRect);
+        }
+        return localRect;
+      }).where((Rect selectionRect) {
+        return selectionRect.isFinite && !selectionRect.isEmpty;
+      }).toList();
+      selectionRects.addAll(selectionRectsWithinDrawableArea);
+    }
+
     return SelectionGeometry(
       startSelectionPoint: startPoint,
       endSelectionPoint: endPoint,
+      selectionRects: selectionRects,
       status: startGeometry != endGeometry
         ? SelectionStatus.uncollapsed
         : startGeometry.status,

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

@@ -562,15 +562,13 @@ class TextSelectionOverlay {
   /// Whether the handles are currently visible.
   bool get handlesAreVisible => _selectionOverlay._handles != null && handlesVisible;
 
-  /// Whether the toolbar is currently visible.
-  ///
-  /// Includes both the text selection toolbar and the spell check menu.
+  /// {@macro flutter.widgets.SelectionOverlay.toolbarIsVisible}
   ///
   /// See also:
   ///
   ///   * [spellCheckToolbarIsVisible], which is only whether the spell check menu
   ///     specifically is visible.
-  bool get toolbarIsVisible => _selectionOverlay._toolbarIsVisible;
+  bool get toolbarIsVisible => _selectionOverlay.toolbarIsVisible;
 
   /// Whether the magnifier is currently visible.
   bool get magnifierIsVisible => _selectionOverlay._magnifierController.shown;
@@ -984,7 +982,12 @@ class SelectionOverlay {
   /// {@macro flutter.widgets.magnifier.TextMagnifierConfiguration.details}
   final TextMagnifierConfiguration magnifierConfiguration;
 
-  bool get _toolbarIsVisible {
+  /// {@template flutter.widgets.SelectionOverlay.toolbarIsVisible}
+  /// Whether the toolbar is currently visible.
+  ///
+  /// Includes both the text selection toolbar and the spell check menu.
+  /// {@endtemplate}
+  bool get toolbarIsVisible {
     return selectionControls is TextSelectionHandleControls
         ? _contextMenuController.isShown || _spellCheckToolbarController.isShown
         : _toolbar != null || _spellCheckToolbarController.isShown;
@@ -1001,7 +1004,7 @@ class SelectionOverlay {
   /// [MagnifierController.shown].
   /// {@endtemplate}
   void showMagnifier(MagnifierInfo initialMagnifierInfo) {
-    if (_toolbarIsVisible) {
+    if (toolbarIsVisible) {
       hideToolbar();
     }