[a11y] : set isFocused will update isFocusable to true (flutter#170935)

the isFocused and isFocusable flags should be more consistent,

this is also to prepare for
flutter#170696 ,


So all EditableText and TextField widgets will have isFocusable flag set
to true now. (because they set isFocused).



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- [ ] I listed at least one issue that this PR fixes in the description
above.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [ ] I added new tests to check the change I am making, or this PR is
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Fixes] where supported.
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---------

Co-authored-by: chunhtai <[email protected]>

Author: hannah-hyj

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

@@ -953,7 +953,7 @@ class RenderCustomPaint extends RenderProxyBox {
       config.isFocusable = properties.focusable!;
     }
     if (properties.focused != null) {
-      config.isFocused = properties.focused!;
+      config.isFocused = properties.focused;
     }
     if (properties.enabled != null) {
       config.isEnabled = properties.enabled;

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

@@ -4857,7 +4857,7 @@ mixin SemanticsAnnotationsMixin on RenderObject {
       config.isFocusable = _properties.focusable!;
     }
     if (_properties.focused != null) {
-      config.isFocused = _properties.focused!;
+      config.isFocused = _properties.focused;
     }
     if (_properties.inMutuallyExclusiveGroup != null) {
       config.isInMutuallyExclusiveGroup = _properties.inMutuallyExclusiveGroup!;

packages/flutter/lib/src/semantics/semantics.dart

@@ -1472,6 +1472,11 @@ class SemanticsProperties extends DiagnosticableTree {
     this.slider,
     this.keyboardKey,
     this.readOnly,
+    @Deprecated(
+      'Use focused instead. '
+      'Setting focused automatically set focusable. '
+      'This feature was deprecated after v3.36.0-0.0.pre.',
+    )
     this.focusable,
     this.focused,
     this.inMutuallyExclusiveGroup,
@@ -1656,10 +1661,17 @@ class SemanticsProperties extends DiagnosticableTree {
   /// to be confused with accessibility focus. Accessibility focus is the
   /// green/black rectangular highlight that TalkBack/VoiceOver draws around the
   /// element it is reading, and is separate from input focus.
+  @Deprecated(
+    'Use focused instead. '
+    'Setting focused automatically set focusable. '
+    'This feature was deprecated after v3.36.0-0.0.pre.',
+  )
   final bool? focusable;
 
   /// If non-null, whether the node currently holds input focus.
   ///
+  /// If null, the node is not fosusable.
+  ///
   /// At most one node in the tree should hold input focus at any point in time,
   /// and it should not be set to true if [focusable] is false.
   ///
@@ -5589,16 +5601,30 @@ class SemanticsConfiguration {
   }
 
   /// Whether the owning [RenderObject] can hold the input focus.
+  @Deprecated(
+    'Check if isFocused is null instead. '
+    'This feature was deprecated after v3.36.0-0.0.pre.',
+  )
   bool get isFocusable => _flags.isFocusable;
+
+  @Deprecated(
+    'Setting isFocused automatically set this to true. '
+    'This feature was deprecated after v3.36.0-0.0.pre.',
+  )
   set isFocusable(bool value) {
     _flags = _flags.copyWith(isFocusable: value);
     _hasBeenAnnotated = true;
   }
 
   /// Whether the owning [RenderObject] currently holds the input focus.
-  bool get isFocused => _flags.isFocused;
-  set isFocused(bool value) {
-    _flags = _flags.copyWith(isFocused: value);
+  /// If the value is `null`, it's not focusable.
+  bool? get isFocused => _flags.isFocusable ? _flags.isFocused : null;
+  set isFocused(bool? value) {
+    if (value != null) {
+      _flags = _flags.copyWith(isFocusable: true, isFocused: value);
+    } else {
+      _flags = _flags.copyWith(isFocusable: false, isFocused: false);
+    }
     _hasBeenAnnotated = true;
   }
 

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

@@ -724,7 +724,7 @@ class _FocusState extends State<Focus> {
             ? focusNode.requestFocus
             : null,
         focusable: _couldRequestFocus,
-        focused: _hadPrimaryFocus,
+        focused: _couldRequestFocus ? _hadPrimaryFocus : null,
         child: widget.child,
       );
     }

packages/flutter/test/semantics/semantics_test.dart

@@ -937,7 +937,7 @@ void main() {
     expect(config.isChecked, null);
     expect(config.isSelected, isFalse);
     expect(config.isBlockingSemanticsOfPreviouslyPaintedNodes, isFalse);
-    expect(config.isFocused, isFalse);
+    expect(config.isFocused, null);
     expect(config.isTextField, isFalse);
 
     expect(config.onShowOnScreen, isNull);