Reland "Remove single-view assumption from widgets library (#117480)" (#117549)

* Revert "Revert "Remove single-view assumption from widgets library (#117480)" (#117545)"

This reverts commit b8d5d9c4.

* check for mounted

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

@@ -43,6 +43,7 @@ import 'text_editing_intents.dart';
 import 'text_selection.dart';
 import 'text_selection_toolbar_anchors.dart';
 import 'ticker_provider.dart';
+import 'view.dart';
 import 'widget_span.dart';
 
 export 'package:flutter/services.dart' show SelectionChangedCause, SmartDashesType, SmartQuotesType, TextEditingValue, TextInputType, TextSelection;
@@ -3303,17 +3304,21 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
 
   @override
   void didChangeMetrics() {
-    if (_lastBottomViewInset != WidgetsBinding.instance.window.viewInsets.bottom) {
+    if (!mounted) {
+      return;
+    }
+    final ui.FlutterView view = View.of(context);
+    if (_lastBottomViewInset != view.viewInsets.bottom) {
       SchedulerBinding.instance.addPostFrameCallback((Duration _) {
         _selectionOverlay?.updateForScroll();
       });
-      if (_lastBottomViewInset < WidgetsBinding.instance.window.viewInsets.bottom) {
+      if (_lastBottomViewInset < view.viewInsets.bottom) {
         // Because the metrics change signal from engine will come here every frame
         // (on both iOS and Android). So we don't need to show caret with animation.
         _scheduleShowCaretOnScreen(withAnimation: false);
       }
     }
-    _lastBottomViewInset = WidgetsBinding.instance.window.viewInsets.bottom;
+    _lastBottomViewInset = view.viewInsets.bottom;
   }
 
   Future<void> _performSpellCheck(final String text) async {
@@ -3516,7 +3521,7 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
     if (_hasFocus) {
       // Listen for changing viewInsets, which indicates keyboard showing up.
       WidgetsBinding.instance.addObserver(this);
-      _lastBottomViewInset = WidgetsBinding.instance.window.viewInsets.bottom;
+      _lastBottomViewInset = View.of(context).viewInsets.bottom;
       if (!widget.readOnly) {
         _scheduleShowCaretOnScreen(withAnimation: true);
       }

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

@@ -14,6 +14,7 @@ import 'framework.dart';
 import 'overscroll_indicator.dart';
 import 'scroll_metrics.dart';
 import 'scroll_simulation.dart';
+import 'view.dart';
 
 export 'package:flutter/physics.dart' show ScrollSpringSimulation, Simulation, Tolerance;
 
@@ -252,7 +253,7 @@ class ScrollPhysics {
     assert(metrics != null);
     assert(context != null);
     if (parent == null) {
-      final double maxPhysicalPixels = WidgetsBinding.instance.window.physicalSize.longestSide;
+      final double maxPhysicalPixels = View.of(context).physicalSize.longestSide;
       return velocity.abs() > maxPhysicalPixels;
     }
     return parent!.recommendDeferredLoading(velocity, metrics, context);

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

@@ -12,6 +12,7 @@ import 'basic.dart';
 import 'binding.dart';
 import 'framework.dart';
 import 'gesture_detector.dart';
+import 'view.dart';
 
 /// A widget that visualizes the semantics for the child.
 ///
@@ -96,7 +97,7 @@ class _SemanticsDebuggerState extends State<SemanticsDebugger> with WidgetsBindi
   Offset? _lastPointerDownLocation;
   void _handlePointerDown(PointerDownEvent event) {
     setState(() {
-      _lastPointerDownLocation = event.position * WidgetsBinding.instance.window.devicePixelRatio;
+      _lastPointerDownLocation = event.position * View.of(context).devicePixelRatio;
     });
     // TODO(ianh): Use a gesture recognizer so that we can reset the
     // _lastPointerDownLocation when none of the other gesture recognizers win.
@@ -159,7 +160,7 @@ class _SemanticsDebuggerState extends State<SemanticsDebugger> with WidgetsBindi
         _pipelineOwner,
         _client.generation,
         _lastPointerDownLocation, // in physical pixels
-        WidgetsBinding.instance.window.devicePixelRatio,
+        View.of(context).devicePixelRatio,
         widget.labelStyle,
       ),
       child: GestureDetector(

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

@@ -10,6 +10,7 @@ import 'dart:math' as math;
 import 'dart:ui' as ui
     show
         ClipOp,
+        FlutterView,
         Image,
         ImageByteFormat,
         Paragraph,
@@ -30,6 +31,7 @@ import 'debug.dart';
 import 'framework.dart';
 import 'gesture_detector.dart';
 import 'service_extensions.dart';
+import 'view.dart';
 
 /// Signature for the builder callback used by
 /// [WidgetInspector.selectButtonBuilder].
@@ -2726,7 +2728,8 @@ class _WidgetInspectorState extends State<WidgetInspector>
     // on the edge of the display. If the pointer is being dragged off the edge
     // of the display we do not want to select anything. A user can still select
     // a widget that is only at the exact screen margin by tapping.
-    final Rect bounds = (Offset.zero & (WidgetsBinding.instance.window.physicalSize / WidgetsBinding.instance.window.devicePixelRatio)).deflate(_kOffScreenMargin);
+    final ui.FlutterView view = View.of(context);
+    final Rect bounds = (Offset.zero & (view.physicalSize / view.devicePixelRatio)).deflate(_kOffScreenMargin);
     if (!bounds.contains(_lastPointerLocation!)) {
       setState(() {
         selection.clear();

packages/flutter/test/widgets/editable_text_test.dart

@@ -14398,6 +14398,28 @@ testWidgets('Floating cursor ending with selection', (WidgetTester tester) async
 
     expect(tester.takeException(), null);
   });
+
+  testWidgets('does not crash when didChangeMetrics is called after unmounting', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      MaterialApp(
+        home: EditableText(
+          controller: controller,
+          focusNode: FocusNode(),
+          style: Typography.material2018().black.titleMedium!,
+          cursorColor: Colors.blue,
+          backgroundCursorColor: Colors.grey,
+        ),
+      ),
+    );
+
+    final EditableTextState state = tester.state<EditableTextState>(find.byType(EditableText));
+
+    // Disposes the EditableText.
+    await tester.pumpWidget(const Placeholder());
+
+    // Shouldn't crash.
+    state.didChangeMetrics();
+  });
 }
 
 class UnsettableController extends TextEditingController {