Center iOS caret, remove constant offsets that do not scale (#31687)

bin/internal/goldens.version

-dadf2c9b8a8de8fc605e094a539410d83f700b34
+5e0cf0b9b347526d299718a4755e2d65cffacaba

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

@@ -1501,9 +1501,9 @@ class RenderEditable extends RenderBox {
   Rect get _getCaretPrototype {
     switch(defaultTargetPlatform){
       case TargetPlatform.iOS:
-        return Rect.fromLTWH(0.0, -_kCaretHeightOffset + .5, cursorWidth, preferredLineHeight + 2);
+        return Rect.fromLTWH(0.0, 0.0, cursorWidth, preferredLineHeight + 2);
       default:
-        return Rect.fromLTWH(0.0, _kCaretHeightOffset, cursorWidth, preferredLineHeight - 2.0 * _kCaretHeightOffset);
+        return Rect.fromLTWH(0.0, 0.0, cursorWidth, preferredLineHeight - 2.0 * _kCaretHeightOffset);
     }
   }
   @override
@@ -1550,19 +1550,32 @@ class RenderEditable extends RenderBox {
     if (_cursorOffset != null)
       caretRect = caretRect.shift(_cursorOffset);
 
+    if (_textPainter.getFullHeightForCaret(textPosition, _caretPrototype) != null) {
+      switch (defaultTargetPlatform) {
+        case TargetPlatform.iOS: {
+          final double heightDiff = _textPainter.getFullHeightForCaret(textPosition, _caretPrototype) - caretRect.height;
+          // Center the caret vertically along the text.
+          caretRect = Rect.fromLTWH(
+            caretRect.left,
+            caretRect.top + heightDiff / 2,
+            caretRect.width,
+            caretRect.height,
+          );
+          break;
+        }
+        default: {
           // Override the height to take the full height of the glyph at the TextPosition
           // when not on iOS. iOS has special handling that creates a taller caret.
           // TODO(garyq): See the TODO for _getCaretPrototype.
-    if (defaultTargetPlatform != TargetPlatform.iOS && _textPainter.getFullHeightForCaret(textPosition, _caretPrototype) != null) {
           caretRect = Rect.fromLTWH(
             caretRect.left,
-        // Offset by _kCaretHeightOffset to counteract the same value added in
-        // _getCaretPrototype. This prevents this from scaling poorly for small
-        // font sizes.
-        caretRect.top - _kCaretHeightOffset,
+            caretRect.top,
             caretRect.width,
             _textPainter.getFullHeightForCaret(textPosition, _caretPrototype),
           );
+          break;
+        }
+      }
     }
 
     caretRect = caretRect.shift(_getPixelPerfectCursorOffset(caretRect));

packages/flutter/test/cupertino/text_field_test.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'dart:async';
+import 'dart:io';
 
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/rendering.dart';
@@ -350,6 +351,61 @@ void main() {
     debugDefaultTargetPlatformOverride = null;
   });
 
+  testWidgets('cursor android golden', (WidgetTester tester) async {
+    final Widget widget = CupertinoApp(
+      home: Center(
+        child: RepaintBoundary(
+          key: const ValueKey<int>(1),
+          child: ConstrainedBox(
+            constraints: BoxConstraints.loose(const Size(400, 400)),
+            child: const CupertinoTextField(),
+          ),
+        ),
+      ),
+    );
+    await tester.pumpWidget(widget);
+
+    const String testValue = 'A short phrase';
+    await tester.enterText(find.byType(CupertinoTextField), testValue);
+
+    await tester.tapAt(textOffsetToPosition(tester, testValue.length));
+    await tester.pump();
+
+    await expectLater(
+      find.byKey(const ValueKey<int>(1)),
+      matchesGoldenFile('text_field_cursor_test.0.1.png'),
+    );
+  }, skip: !Platform.isLinux);
+
+  testWidgets('cursor iOS golden', (WidgetTester tester) async {
+    debugDefaultTargetPlatformOverride = TargetPlatform.iOS;
+
+    final Widget widget = CupertinoApp(
+      home: Center(
+        child: RepaintBoundary(
+          key: const ValueKey<int>(1),
+          child: ConstrainedBox(
+            constraints: BoxConstraints.loose(const Size(400, 400)),
+            child: const CupertinoTextField(),
+          ),
+        ),
+      ),
+    );
+    await tester.pumpWidget(widget);
+
+    const String testValue = 'A short phrase';
+    await tester.enterText(find.byType(CupertinoTextField), testValue);
+
+    await tester.tapAt(textOffsetToPosition(tester, testValue.length));
+    await tester.pump();
+
+    debugDefaultTargetPlatformOverride = null;
+    await expectLater(
+      find.byKey(const ValueKey<int>(1)),
+      matchesGoldenFile('text_field_cursor_test.1.1.png'),
+    );
+  }, skip: !Platform.isLinux);
+
   testWidgets(
     'can control text content via controller',
     (WidgetTester tester) async {

packages/flutter/test/material/text_field_test.dart

@@ -381,6 +381,61 @@ void main() {
     expect(textField.cursorRadius, const Radius.circular(3.0));
   });
 
+  testWidgets('cursor android golden', (WidgetTester tester) async {
+    final Widget widget = overlay(
+      child: const RepaintBoundary(
+        key: ValueKey<int>(1),
+        child: TextField(
+          cursorColor: Colors.blue,
+          cursorWidth: 15,
+          cursorRadius: Radius.circular(3.0),
+        ),
+      ),
+    );
+    await tester.pumpWidget(widget);
+
+    const String testValue = 'A short phrase';
+    await tester.enterText(find.byType(TextField), testValue);
+    await skipPastScrollingAnimation(tester);
+
+    await tester.tapAt(textOffsetToPosition(tester, testValue.length));
+    await tester.pump();
+
+    await expectLater(
+      find.byKey(const ValueKey<int>(1)),
+      matchesGoldenFile('text_field_cursor_test.0.0.png'),
+    );
+  }, skip: !Platform.isLinux);
+
+  testWidgets('cursor iOS golden', (WidgetTester tester) async {
+    debugDefaultTargetPlatformOverride = TargetPlatform.iOS;
+
+    final Widget widget = overlay(
+      child: const RepaintBoundary(
+        key: ValueKey<int>(1),
+        child: TextField(
+          cursorColor: Colors.blue,
+          cursorWidth: 15,
+          cursorRadius: Radius.circular(3.0),
+        ),
+      ),
+    );
+    await tester.pumpWidget(widget);
+
+    const String testValue = 'A short phrase';
+    await tester.enterText(find.byType(TextField), testValue);
+    await skipPastScrollingAnimation(tester);
+
+    await tester.tapAt(textOffsetToPosition(tester, testValue.length));
+    await tester.pump();
+
+    debugDefaultTargetPlatformOverride = null;
+    await expectLater(
+      find.byKey(const ValueKey<int>(1)),
+      matchesGoldenFile('text_field_cursor_test.1.0.png'),
+    );
+  }, skip: !Platform.isLinux);
+
   testWidgets('text field selection toolbar renders correctly inside opacity', (WidgetTester tester) async {
     await tester.pumpWidget(
       MaterialApp(

packages/flutter/test/widgets/editable_text_cursor_test.dart

@@ -4,6 +4,7 @@
 
 import 'dart:io';
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/material.dart';
@@ -575,6 +576,8 @@ void main() {
   });
 
   testWidgets('Floating cursor is painted on iOS', (WidgetTester tester) async {
+    debugDefaultTargetPlatformOverride = TargetPlatform.iOS;
+
     final TextEditingController controller = TextEditingController();
     const TextStyle textStyle = TextStyle();
     const String text = 'hello world this is fun and cool and awesome!';
@@ -617,14 +620,14 @@ void main() {
     expect(editable, paints
       ..rrect(
         rrect: RRect.fromRectAndRadius(
-          const Rect.fromLTRB(463.3333435058594, 0.0833332538604736, 465.3333435058594, 16.083333015441895),
+          const Rect.fromLTRB(463.3333435058594, -0.916666666666668, 465.3333435058594, 17.083333015441895),
           const Radius.circular(2.0),
         ),
         color: const Color(0xff8e8e93),
       )
       ..rrect(
         rrect: RRect.fromRectAndRadius(
-          const Rect.fromLTRB(463.8333435058594, 1.0833336114883423, 466.8333435058594, 15.083333969116211),
+          const Rect.fromLTRB(463.8333435058594, -0.916666666666668, 466.8333435058594, 19.083333969116211),
           const Radius.circular(1.0),
         ),
         color: const Color(0xbf2196f3),
@@ -642,14 +645,14 @@ void main() {
     expect(find.byType(EditableText), paints
       ..rrect(
         rrect: RRect.fromRectAndRadius(
-          const Rect.fromLTRB(191.3333282470703, 0.0833332538604736, 193.3333282470703, 16.083333015441895),
+          const Rect.fromLTRB(191.3333282470703, -0.916666666666668, 193.3333282470703, 17.083333015441895),
           const Radius.circular(2.0),
         ),
         color: const Color(0xff8e8e93),
       )
       ..rrect(
         rrect: RRect.fromRectAndRadius(
-          const Rect.fromLTRB(193.83334350585938, 1.0833336114883423, 196.83334350585938, 15.083333969116211),
+          const Rect.fromLTRB(193.83334350585938, -0.916666666666668, 196.83334350585938, 19.083333969116211),
           const Radius.circular(1.0)),
         color: const Color(0xbf2196f3),
       ),
@@ -657,5 +660,70 @@ void main() {
 
     editableTextState.updateFloatingCursor(RawFloatingCursorPoint(state: FloatingCursorDragState.End));
     await tester.pumpAndSettle();
+    debugDefaultTargetPlatformOverride = null;
+  });
+
+  testWidgets('cursor layout iOS', (WidgetTester tester) async {
+    final GlobalKey<EditableTextState> editableTextKey = GlobalKey<EditableTextState>();
+
+    debugDefaultTargetPlatformOverride = TargetPlatform.iOS;
+
+    String changedValue;
+    final Widget widget = MaterialApp(
+      theme: ThemeData(platform: TargetPlatform.iOS),
+      home: RepaintBoundary(
+        key: const ValueKey<int>(1),
+        child: Column(
+          children: <Widget>[
+            const SizedBox(width: 10, height: 10),
+            EditableText(
+              backgroundCursorColor: Colors.grey,
+              key: editableTextKey,
+              controller: TextEditingController(),
+              focusNode: FocusNode(),
+              style: Typography(platform: TargetPlatform.iOS).black.subhead,
+              cursorColor: Colors.blue,
+              selectionControls: materialTextSelectionControls,
+              keyboardType: TextInputType.text,
+              onChanged: (String value) {
+                changedValue = value;
+              },
+              cursorWidth: 15.0,
+            ),
+          ],
+        ),
+      ),
+    );
+    await tester.pumpWidget(widget);
+
+    // Populate a fake clipboard.
+    const String clipboardContent = 'Hello world!';
+    SystemChannels.platform.setMockMethodCallHandler((MethodCall methodCall) async {
+      if (methodCall.method == 'Clipboard.getData')
+        return const <String, dynamic>{'text': clipboardContent};
+      return null;
     });
+
+    // Long-press to bring up the text editing controls.
+    final Finder textFinder = find.byKey(editableTextKey);
+    await tester.longPress(textFinder);
+    tester.state<EditableTextState>(textFinder).showToolbar();
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 500));
+    await tester.pump(const Duration(milliseconds: 500));
+
+    await tester.tap(find.text('PASTE'));
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 500));
+    await tester.pump(const Duration(milliseconds: 500));
+
+    expect(changedValue, clipboardContent);
+
+    await expectLater(
+      find.byKey(const ValueKey<int>(1)),
+      matchesGoldenFile('editable_text_test.2.0.png'),
+    );
+    debugDefaultTargetPlatformOverride = null;
+  }, skip: !Platform.isLinux);
+
 }