Shift tap on an unfocused field (#97543)

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

@@ -951,17 +951,20 @@ class TextSelectionGestureDetectorBuilder {
   // Either base or extent will be moved to the last tapped position, whichever
   // is closest. The selection will never shrink or pivot, only grow.
   //
+  // If fromSelection is given, will expand from that selection instead of the
+  // current selection in renderEditable.
+  //
   // See also:
   //
   //   * [_extendSelection], which is similar but pivots the selection around
   //     the base.
-  void _expandSelection(Offset offset, SelectionChangedCause cause) {
+  void _expandSelection(Offset offset, SelectionChangedCause cause, [TextSelection? fromSelection]) {
     assert(cause != null);
     assert(offset != null);
     assert(renderEditable.selection?.baseOffset != null);
 
     final TextPosition tappedPosition = renderEditable.getPositionForPoint(offset);
-    final TextSelection selection = renderEditable.selection!;
+    final TextSelection selection = fromSelection ?? renderEditable.selection!;
     final bool baseIsCloser =
         (tappedPosition.offset - selection.baseOffset).abs()
         < (tappedPosition.offset - selection.extentOffset).abs();
@@ -1069,7 +1072,16 @@ class TextSelectionGestureDetectorBuilder {
       switch (defaultTargetPlatform) {
         case TargetPlatform.iOS:
         case TargetPlatform.macOS:
-          _expandSelection(details.globalPosition, SelectionChangedCause.tap);
+          // On these platforms, a shift-tapped unfocused field expands from 0,
+          // not from the previous selection.
+          final TextSelection? fromSelection = renderEditable.hasFocus
+              ? null
+              : const TextSelection.collapsed(offset: 0);
+          _expandSelection(
+            details.globalPosition,
+            SelectionChangedCause.tap,
+            fromSelection,
+          );
           break;
         case TargetPlatform.android:
         case TargetPlatform.fuchsia:

packages/flutter/test/cupertino/text_field_test.dart

@@ -5053,6 +5053,62 @@ void main() {
     expect(controller.selection.extentOffset, 4);
   }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android, TargetPlatform.fuchsia, TargetPlatform.linux, TargetPlatform.windows }));
 
+  testWidgets('shift tapping an unfocused field', (WidgetTester tester) async {
+    final TextEditingController controller = TextEditingController(
+      text: 'Atwater Peel Sherbrooke Bonaventure',
+    );
+    final FocusNode focusNode = FocusNode();
+    await tester.pumpWidget(
+      CupertinoApp(
+        home: Center(
+          child: CupertinoTextField(
+            controller: controller,
+            focusNode: focusNode,
+          ),
+        ),
+      ),
+    );
+
+    expect(focusNode.hasFocus, isFalse);
+
+    // Put the cursor at the end of the field.
+    await tester.tapAt(textOffsetToPosition(tester, controller.text.length));
+    await tester.pump(kDoubleTapTimeout);
+    await tester.pumpAndSettle();
+    expect(focusNode.hasFocus, isTrue);
+    expect(controller.selection.baseOffset, 35);
+    expect(controller.selection.extentOffset, 35);
+
+    // Unfocus the field, but the selection remains.
+    focusNode.unfocus();
+    await tester.pumpAndSettle();
+    expect(focusNode.hasFocus, isFalse);
+    expect(controller.selection.baseOffset, 35);
+    expect(controller.selection.extentOffset, 35);
+
+    // Shift tap in the middle of the field.
+    await tester.sendKeyDownEvent(LogicalKeyboardKey.shift);
+    await tester.tapAt(textOffsetToPosition(tester, 20));
+    await tester.pumpAndSettle();
+    expect(focusNode.hasFocus, isTrue);
+    switch (defaultTargetPlatform) {
+      // Apple platforms start the selection from 0.
+      case TargetPlatform.iOS:
+      case TargetPlatform.macOS:
+        expect(controller.selection.baseOffset, 0);
+        break;
+
+      // Other platforms start from the previous selection.
+      case TargetPlatform.android:
+      case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
+        expect(controller.selection.baseOffset, 35);
+        break;
+    }
+    expect(controller.selection.extentOffset, 20);
+  }, variant: TargetPlatformVariant.all());
+
   testWidgets('can shift + tap + drag to select with a keyboard (Apple platforms)', (WidgetTester tester) async {
     final TextEditingController controller = TextEditingController(
       text: 'Atwater Peel Sherbrooke Bonaventure',

packages/flutter/test/material/text_field_test.dart

@@ -10560,6 +10560,63 @@ void main() {
     expect(controller.selection.extentOffset, 4);
   }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android, TargetPlatform.fuchsia, TargetPlatform.linux, TargetPlatform.windows }));
 
+  testWidgets('shift tapping an unfocused field', (WidgetTester tester) async {
+    final TextEditingController controller = TextEditingController(
+      text: 'Atwater Peel Sherbrooke Bonaventure',
+    );
+    final FocusNode focusNode = FocusNode();
+    await tester.pumpWidget(
+      MaterialApp(
+        home:  Material(
+          child: Center(
+            child: TextField(
+              controller: controller,
+              focusNode: focusNode,
+            ),
+          ),
+        ),
+      ),
+    );
+    expect(focusNode.hasFocus, isFalse);
+
+    // Put the cursor at the end of the field.
+    await tester.tapAt(textOffsetToPosition(tester, controller.text.length));
+    await tester.pump(kDoubleTapTimeout);
+    await tester.pumpAndSettle();
+    expect(focusNode.hasFocus, isTrue);
+    expect(controller.selection.baseOffset, 35);
+    expect(controller.selection.extentOffset, 35);
+
+    // Unfocus the field, but the selection remains.
+    focusNode.unfocus();
+    await tester.pumpAndSettle();
+    expect(focusNode.hasFocus, isFalse);
+    expect(controller.selection.baseOffset, 35);
+    expect(controller.selection.extentOffset, 35);
+
+    // Shift tap in the middle of the field.
+    await tester.sendKeyDownEvent(LogicalKeyboardKey.shift);
+    await tester.tapAt(textOffsetToPosition(tester, 20));
+    await tester.pumpAndSettle();
+    expect(focusNode.hasFocus, isTrue);
+    switch (defaultTargetPlatform) {
+      // Apple platforms start the selection from 0.
+      case TargetPlatform.iOS:
+      case TargetPlatform.macOS:
+        expect(controller.selection.baseOffset, 0);
+        break;
+
+      // Other platforms start from the previous selection.
+      case TargetPlatform.android:
+      case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
+        expect(controller.selection.baseOffset, 35);
+        break;
+    }
+    expect(controller.selection.extentOffset, 20);
+  }, variant: TargetPlatformVariant.all());
+
   testWidgets('can shift + tap + drag to select with a keyboard (Apple platforms)', (WidgetTester tester) async {
     final TextEditingController controller = TextEditingController(
       text: 'Atwater Peel Sherbrooke Bonaventure',