From e9753328dd5ee63117a95b54f0015656b77965ab Mon Sep 17 00:00:00 2001
From: Chun-Heng Tai <chtai@google.com>
Date: Mon, 15 May 2023 10:11:45 -0700
Subject: [PATCH] Overrides accessibilityScrollToVisible

---
 .../ios/framework/Source/SemanticsObject.mm   | 16 ++++++++
 .../framework/Source/SemanticsObjectTest.mm   | 39 ++++++++++++++++++-
 2 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/shell/platform/darwin/ios/framework/Source/SemanticsObject.mm b/shell/platform/darwin/ios/framework/Source/SemanticsObject.mm
index 68f1beb7c31bc..a12f60c538540 100644
--- a/shell/platform/darwin/ios/framework/Source/SemanticsObject.mm
+++ b/shell/platform/darwin/ios/framework/Source/SemanticsObject.mm
@@ -569,6 +569,22 @@ - (id)_accessibilityHitTest:(CGPoint)point withEvent:(UIEvent*)event {
   return [self search:point];
 }
 
+// A private API iOS called when an item is swipe-to-focusd in VoiceOver.
+- (BOOL)accessibilityScrollToVisible {
+  [self bridge]->DispatchSemanticsAction([self uid], flutter::SemanticsAction::kShowOnScreen);
+  // There is no documentation on the return value. It doesn't appear
+  // to make a difference whether it returns YES or NO. Use Yes for now.
+  return YES;
+}
+
+// A private API iOS called when an item is swipe-to-focusd VoiceOver.
+//
+// There isn't a documentation on the input child, and the `child` appears always
+// the same object of `self`.
+- (BOOL)accessibilityScrollToVisibleWithChild:(id)child {
+  return [child accessibilityScrollToVisible];
+}
+
 - (NSAttributedString*)accessibilityAttributedLabel {
   NSString* label = [self accessibilityLabel];
   if (label.length == 0) {
diff --git a/shell/platform/darwin/ios/framework/Source/SemanticsObjectTest.mm b/shell/platform/darwin/ios/framework/Source/SemanticsObjectTest.mm
index cc2e29a126a92..48ebd0063563a 100644
--- a/shell/platform/darwin/ios/framework/Source/SemanticsObjectTest.mm
+++ b/shell/platform/darwin/ios/framework/Source/SemanticsObjectTest.mm
@@ -93,7 +93,8 @@ @interface SemanticsObjectTest : XCTestCase
 @end
 
 @interface SemanticsObject (Tests)
-
+- (BOOL)accessibilityScrollToVisible;
+- (BOOL)accessibilityScrollToVisibleWithChild:(id)child;
 - (id)_accessibilityHitTest:(CGPoint)point withEvent:(UIEvent*)event;
 @end
 
@@ -202,6 +203,42 @@ - (void)testAccessibilityHitTestNoFocusableItem {
   XCTAssertNil(hitTestResult);
 }
 
+- (void)testAccessibilityScrollToVisible {
+  fml::WeakPtrFactory<flutter::MockAccessibilityBridge> factory(
+      new flutter::MockAccessibilityBridge());
+  fml::WeakPtr<flutter::MockAccessibilityBridge> bridge = factory.GetWeakPtr();
+  SemanticsObject* object3 = [[SemanticsObject alloc] initWithBridge:bridge uid:3];
+
+  flutter::SemanticsNode node3;
+  node3.id = 3;
+  node3.rect = SkRect::MakeXYWH(0, 0, 200, 200);
+  [object3 setSemanticsNode:&node3];
+
+  [object3 accessibilityScrollToVisible];
+
+  XCTAssertTrue(bridge->observations.size() == 1);
+  XCTAssertTrue(bridge->observations[0].id == 3);
+  XCTAssertTrue(bridge->observations[0].action == flutter::SemanticsAction::kShowOnScreen);
+}
+
+- (void)testAccessibilityScrollToVisibleWithChild {
+  fml::WeakPtrFactory<flutter::MockAccessibilityBridge> factory(
+      new flutter::MockAccessibilityBridge());
+  fml::WeakPtr<flutter::MockAccessibilityBridge> bridge = factory.GetWeakPtr();
+  SemanticsObject* object3 = [[SemanticsObject alloc] initWithBridge:bridge uid:3];
+
+  flutter::SemanticsNode node3;
+  node3.id = 3;
+  node3.rect = SkRect::MakeXYWH(0, 0, 200, 200);
+  [object3 setSemanticsNode:&node3];
+
+  [object3 accessibilityScrollToVisibleWithChild:object3];
+
+  XCTAssertTrue(bridge->observations.size() == 1);
+  XCTAssertTrue(bridge->observations[0].id == 3);
+  XCTAssertTrue(bridge->observations[0].action == flutter::SemanticsAction::kShowOnScreen);
+}
+
 - (void)testAccessibilityHitTestOutOfRect {
   fml::WeakPtrFactory<flutter::AccessibilityBridgeIos> factory(
       new flutter::MockAccessibilityBridge());