Disable cursor opacity animation on macOS, make iOS cursor animation discrete (#104335)

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

@@ -1168,7 +1168,7 @@ class _TextFieldState extends State<TextField> with RestorationMixin implements
         forcePressEnabled = false;
         textSelectionControls ??= cupertinoDesktopTextSelectionControls;
         paintCursorAboveText = true;
-        cursorOpacityAnimates = true;
+        cursorOpacityAnimates = false;
         cursorColor = widget.cursorColor ?? selectionStyle.cursorColor ?? cupertinoTheme.primaryColor;
         selectionColor = selectionStyle.selectionColor ?? cupertinoTheme.primaryColor.withOpacity(0.40);
         cursorRadius ??= const Radius.circular(2.0);

packages/flutter/test/cupertino/text_field_test.dart

@@ -702,40 +702,6 @@ void main() {
     expect(editableText.cursorOffset, const Offset(-2.0 / 3.0, 0));
   });
 
-  testWidgets('Cursor animates', (WidgetTester tester) async {
-    await tester.pumpWidget(
-      const CupertinoApp(
-        home: CupertinoTextField(),
-      ),
-    );
-
-    final Finder textFinder = find.byType(CupertinoTextField);
-    await tester.tap(textFinder);
-    await tester.pump();
-
-    final EditableTextState editableTextState = tester.firstState(find.byType(EditableText));
-    final RenderEditable renderEditable = editableTextState.renderEditable;
-
-    expect(renderEditable.cursorColor!.alpha, 255);
-
-    await tester.pump(const Duration(milliseconds: 100));
-    await tester.pump(const Duration(milliseconds: 400));
-
-    expect(renderEditable.cursorColor!.alpha, 255);
-
-    await tester.pump(const Duration(milliseconds: 200));
-    await tester.pump(const Duration(milliseconds: 100));
-
-    expect(renderEditable.cursorColor!.alpha, 110);
-
-    await tester.pump(const Duration(milliseconds: 100));
-
-    expect(renderEditable.cursorColor!.alpha, 16);
-    await tester.pump(const Duration(milliseconds: 50));
-
-    expect(renderEditable.cursorColor!.alpha, 0);
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.iOS, TargetPlatform.macOS }));
-
   testWidgets('Cursor radius is 2.0', (WidgetTester tester) async {
     await tester.pumpWidget(
       const CupertinoApp(

packages/flutter/test/material/text_field_test.dart

@@ -609,42 +609,6 @@ void main() {
     await checkCursorToggle();
   });
 
-  testWidgets('Cursor animates', (WidgetTester tester) async {
-    await tester.pumpWidget(
-      const MaterialApp(
-        home: Material(
-          child: TextField(),
-        ),
-      ),
-    );
-
-    final Finder textFinder = find.byType(TextField);
-    await tester.tap(textFinder);
-    await tester.pump();
-
-    final EditableTextState editableTextState = tester.firstState(find.byType(EditableText));
-    final RenderEditable renderEditable = editableTextState.renderEditable;
-
-    expect(renderEditable.cursorColor!.alpha, 255);
-
-    await tester.pump(const Duration(milliseconds: 100));
-    await tester.pump(const Duration(milliseconds: 400));
-
-    expect(renderEditable.cursorColor!.alpha, 255);
-
-    await tester.pump(const Duration(milliseconds: 200));
-    await tester.pump(const Duration(milliseconds: 100));
-
-    expect(renderEditable.cursorColor!.alpha, 110);
-
-    await tester.pump(const Duration(milliseconds: 100));
-
-    expect(renderEditable.cursorColor!.alpha, 16);
-    await tester.pump(const Duration(milliseconds: 50));
-
-    expect(renderEditable.cursorColor!.alpha, 0);
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.iOS,  TargetPlatform.macOS }));
-
   // Regression test for https://github.com/flutter/flutter/issues/78918.
   testWidgets('RenderEditable sets correct text editing value', (WidgetTester tester) async {
     final TextEditingController controller = TextEditingController(text: 'how are you');
@@ -1328,7 +1292,7 @@ void main() {
 
     editText = (findRenderEditable(tester).text! as TextSpan).text!;
     expect(editText.substring(editText.length - 1), '\u2022');
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.iOS, TargetPlatform.android }));
+  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android }));
 
   testWidgets('desktop obscureText control test', (WidgetTester tester) async {
     await tester.pumpWidget(

packages/flutter/test/widgets/editable_text_cursor_test.dart

@@ -166,61 +166,75 @@ void main() {
     );
   });
 
-  testWidgets('Cursor animates', (WidgetTester tester) async {
-    const Widget widget = MaterialApp(
-      home: Material(
-        child: TextField(
-          maxLines: 3,
+  testWidgets('Cursor animates on iOS', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const MaterialApp(
+        home: Material(
+          child: TextField(),
         ),
       ),
     );
-    await tester.pumpWidget(widget);
 
-    await tester.tap(find.byType(TextField));
+    final Finder textFinder = find.byType(TextField);
+    await tester.tap(textFinder);
     await tester.pump();
 
     final EditableTextState editableTextState = tester.firstState(find.byType(EditableText));
     final RenderEditable renderEditable = editableTextState.renderEditable;
 
-    expect(renderEditable.cursorColor!.alpha, 255);
+    expect(renderEditable.cursorColor!.opacity, 1.0);
+
+    int walltimeMicrosecond = 0;
+    double lastVerifiedOpacity = 1.0;
+
+    Future<void> verifyKeyFrame({ required double opacity, required int at }) async {
+      const int delta = 1;
+      assert(at - delta > walltimeMicrosecond);
+      await tester.pump(Duration(microseconds: at - delta - walltimeMicrosecond));
+
+      // Instead of verifying the opacity at each key frame, this function
+      // verifies the opacity immediately *before* each key frame to avoid
+      // fp precision issues.
+      expect(
+        renderEditable.cursorColor!.opacity,
+        closeTo(lastVerifiedOpacity, 0.01),
+        reason: 'opacity at ${at-delta} microseconds',
+      );
+
+      walltimeMicrosecond = at - delta;
+      lastVerifiedOpacity = opacity;
+    }
+
+    await verifyKeyFrame(opacity: 1.0,  at: 500000);
+    await verifyKeyFrame(opacity: 0.75, at: 537500);
+    await verifyKeyFrame(opacity: 0.5,  at: 575000);
+    await verifyKeyFrame(opacity: 0.25, at: 612500);
+    await verifyKeyFrame(opacity: 0.0,  at: 650000);
+    await verifyKeyFrame(opacity: 0.0,  at: 850000);
+    await verifyKeyFrame(opacity: 0.25, at: 887500);
+    await verifyKeyFrame(opacity: 0.5,  at: 925000);
+    await verifyKeyFrame(opacity: 0.75, at: 962500);
+    await verifyKeyFrame(opacity: 1.0,  at: 1000000);
+  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.iOS }));
+
+  testWidgets('Cursor does not animate on non-iOS platforms', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const MaterialApp(
+        home: Material(child: TextField(maxLines: 3)),
+      ),
+    );
 
-    // Trigger initial timer. When focusing the first time, the cursor shows
-    // for slightly longer than the average on time.
+    await tester.tap(find.byType(TextField));
     await tester.pump();
-    await tester.pump(const Duration(milliseconds: 200));
-    // Start timing standard cursor show period.
-    expect(renderEditable.cursorColor!.alpha, 255);
-    expect(renderEditable, paints..rrect(color: const Color(0xff2196f3)));
-
-    await tester.pump(const Duration(milliseconds: 500));
-    // Start to animate the cursor away.
-    expect(renderEditable.cursorColor!.alpha, 255);
-    expect(renderEditable, paints..rrect(color: const Color(0xff2196f3)));
-
-    await tester.pump(const Duration(milliseconds: 100));
-    expect(renderEditable.cursorColor!.alpha, 110);
-    expect(renderEditable, paints..rrect(color: const Color(0x6e2196f3)));
-
-    await tester.pump(const Duration(milliseconds: 100));
-    expect(renderEditable.cursorColor!.alpha, 16);
-    expect(renderEditable, paints..rrect(color: const Color(0x102196f3)));
-
-    await tester.pump(const Duration(milliseconds: 100));
-    expect(renderEditable.cursorColor!.alpha, 0);
-    // Don't try to draw the cursor.
-    expect(renderEditable, paintsExactlyCountTimes(#drawRRect, 0));
-
-    // Wait some more while the cursor is gone. It'll trigger the cursor to
-    // start animating in again.
-    await tester.pump(const Duration(milliseconds: 300));
-    expect(renderEditable.cursorColor!.alpha, 0);
-    expect(renderEditable, paintsExactlyCountTimes(#drawRRect, 0));
+    // Wait for the current animation to finish. If the cursor never stops its
+    // blinking animation the test will timeout.
+    await tester.pumpAndSettle();
 
-    await tester.pump(const Duration(milliseconds: 50));
-    // Cursor starts coming back.
-    expect(renderEditable.cursorColor!.alpha, 79);
-    expect(renderEditable, paints..rrect(color: const Color(0x4f2196f3)));
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.iOS,  TargetPlatform.macOS }));
+    for (int i = 0; i < 40; i += 1) {
+      await tester.pump(const Duration(milliseconds: 100));
+      expect(tester.hasRunningAnimations, false);
+    }
+  }, variant: TargetPlatformVariant(TargetPlatform.values.toSet()..remove(TargetPlatform.iOS)));
 
   testWidgets('Cursor does not animate on Android', (WidgetTester tester) async {
     final Color defaultCursorColor = Color(ThemeData.fallback().colorScheme.primary.value);
@@ -956,4 +970,40 @@ void main() {
     );
     EditableText.debugDeterministicCursor = false;
   }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.iOS,  TargetPlatform.macOS }));
+
+  testWidgets('password briefly does not show last character when disabled by system', (WidgetTester tester) async {
+    final bool debugDeterministicCursor = EditableText.debugDeterministicCursor;
+    EditableText.debugDeterministicCursor = false;
+    addTearDown(() {
+      EditableText.debugDeterministicCursor = debugDeterministicCursor;
+    });
+
+    await tester.pumpWidget(MaterialApp(
+      home: EditableText(
+        backgroundCursorColor: Colors.grey,
+        controller: controller,
+        obscureText: true,
+        focusNode: focusNode,
+        style: textStyle,
+        cursorColor: cursorColor,
+      ),
+    ));
+
+    await tester.enterText(find.byType(EditableText), 'AA');
+    await tester.pump();
+    await tester.enterText(find.byType(EditableText), 'AAA');
+    await tester.pump();
+
+    tester.binding.platformDispatcher.brieflyShowPasswordTestValue = false;
+    addTearDown(() {
+      tester.binding.platformDispatcher.brieflyShowPasswordTestValue = true;
+    });
+    expect((findRenderEditable(tester).text! as TextSpan).text, '••A');
+    await tester.pump(const Duration(milliseconds: 500));
+    expect((findRenderEditable(tester).text! as TextSpan).text, '•••');
+    await tester.pump(const Duration(milliseconds: 500));
+    await tester.pump(const Duration(milliseconds: 500));
+    await tester.pump(const Duration(milliseconds: 500));
+    expect((findRenderEditable(tester).text! as TextSpan).text, '•••');
+  });
 }

packages/flutter/test/widgets/editable_text_test.dart

@@ -3943,42 +3943,6 @@ void main() {
     expect((findRenderEditable(tester).text! as TextSpan).text, '•••');
   });
 
-  testWidgets('password briefly does not show last character on Android if turned off', (WidgetTester tester) async {
-    final bool debugDeterministicCursor = EditableText.debugDeterministicCursor;
-    EditableText.debugDeterministicCursor = false;
-    addTearDown(() {
-      EditableText.debugDeterministicCursor = debugDeterministicCursor;
-    });
-
-    await tester.pumpWidget(MaterialApp(
-      home: EditableText(
-        backgroundCursorColor: Colors.grey,
-        controller: controller,
-        obscureText: true,
-        focusNode: focusNode,
-        style: textStyle,
-        cursorColor: cursorColor,
-      ),
-    ));
-
-    await tester.enterText(find.byType(EditableText), 'AA');
-    await tester.pump();
-    await tester.enterText(find.byType(EditableText), 'AAA');
-    await tester.pump();
-
-    tester.binding.platformDispatcher.brieflyShowPasswordTestValue = false;
-    addTearDown(() {
-      tester.binding.platformDispatcher.brieflyShowPasswordTestValue = true;
-    });
-    expect((findRenderEditable(tester).text! as TextSpan).text, '••A');
-    await tester.pump(const Duration(milliseconds: 500));
-    expect((findRenderEditable(tester).text! as TextSpan).text, '•••');
-    await tester.pump(const Duration(milliseconds: 500));
-    await tester.pump(const Duration(milliseconds: 500));
-    await tester.pump(const Duration(milliseconds: 500));
-    expect((findRenderEditable(tester).text! as TextSpan).text, '•••');
-  });
-
   group('a11y copy/cut/paste', () {
     Future<void> buildApp(MockTextSelectionControls controls, WidgetTester tester) {
       return tester.pumpWidget(MaterialApp(