Adds a mechanism for announce events to be forwarded to a11y. (#23499)

shell/platform/fuchsia/flutter/BUILD.gn

@@ -111,6 +111,7 @@ template("runner_sources") {
       "//flutter/lib/ui",
       "//flutter/runtime",
       "//flutter/shell/common",
+      "//flutter/shell/platform/common/cpp/client_wrapper:client_wrapper",
     ]
     flutter_deps = [
       ":fuchsia_gpu_configuration",

shell/platform/fuchsia/flutter/accessibility_bridge.cc

@@ -431,6 +431,15 @@ fuchsia::accessibility::semantics::Node AccessibilityBridge::GetRootNodeUpdate(
   return root_fuchsia_node;
 }
 
+void AccessibilityBridge::RequestAnnounce(const std::string message) {
+  fuchsia::accessibility::semantics::SemanticEvent semantic_event;
+  fuchsia::accessibility::semantics::AnnounceEvent announce_event;
+  announce_event.set_message(message);
+  semantic_event.set_announce(std::move(announce_event));
+
+  tree_ptr_->SendSemanticEvent(std::move(semantic_event), []() {});
+}
+
 void AccessibilityBridge::UpdateScreenRects() {
   std::unordered_set<int32_t> visited_nodes;
   UpdateScreenRects(kRootNodeId, SkM44{}, &visited_nodes);

shell/platform/fuchsia/flutter/accessibility_bridge.h

@@ -85,6 +85,9 @@ class AccessibilityBridge
   void AddSemanticsNodeUpdate(const flutter::SemanticsNodeUpdates update,
                               float view_pixel_ratio);
 
+  // Requests a message announcement from the accessibility TTS system.
+  void RequestAnnounce(const std::string message);
+
   // Notifies the bridge of a 'hover move' touch exploration event.
   zx_status_t OnHoverMove(double x, double y);
 

shell/platform/fuchsia/flutter/accessibility_bridge_unittest.cc

@@ -103,6 +103,16 @@ TEST_F(AccessibilityBridgeTest, EnableDisable) {
   EXPECT_TRUE(accessibility_delegate_.enabled());
 }
 
+TEST_F(AccessibilityBridgeTest, RequestAnnounce) {
+  accessibility_bridge_->RequestAnnounce("message");
+  RunLoopUntilIdle();
+
+  auto& last_events = semantics_manager_.GetLastEvents();
+  ASSERT_EQ(last_events.size(), 1u);
+  ASSERT_TRUE(last_events[0].is_announce());
+  EXPECT_EQ(last_events[0].announce().message(), "message");
+}
+
 TEST_F(AccessibilityBridgeTest, UpdatesNodeRoles) {
   flutter::SemanticsNodeUpdates updates;
 

shell/platform/fuchsia/flutter/flutter_runner_fakes.h

@@ -90,6 +90,18 @@ class MockSemanticsManager
     commit_count_++;
   }
 
+  void SendSemanticEvent(
+      fuchsia::accessibility::semantics::SemanticEvent semantic_event,
+      SendSemanticEventCallback callback) override {
+    last_events_.emplace_back(std::move(semantic_event));
+    callback();
+  }
+
+  std::vector<fuchsia::accessibility::semantics::SemanticEvent>&
+  GetLastEvents() {
+    return last_events_;
+  }
+
  private:
   bool has_view_ref_ = false;
   fidl::BindingSet<SemanticsManager> bindings_;
@@ -102,6 +114,7 @@ class MockSemanticsManager
   bool delete_overflowed_;
   std::vector<uint32_t> last_deleted_node_ids_;
   int commit_count_;
+  std::vector<fuchsia::accessibility::semantics::SemanticEvent> last_events_;
 };
 
 }  // namespace flutter_runner_test

shell/platform/fuchsia/flutter/platform_view.cc

@@ -15,6 +15,8 @@
 #include "flutter/fml/logging.h"
 #include "flutter/lib/ui/window/pointer_data.h"
 #include "flutter/lib/ui/window/window.h"
+#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/encodable_value.h"
+#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/standard_message_codec.h"
 #include "third_party/rapidjson/include/rapidjson/document.h"
 #include "third_party/rapidjson/include/rapidjson/stringbuffer.h"
 #include "third_party/rapidjson/include/rapidjson/writer.h"
@@ -658,6 +660,25 @@ void PlatformView::UpdateSemantics(
 void PlatformView::HandleAccessibilityChannelPlatformMessage(
     fml::RefPtr<flutter::PlatformMessage> message) {
   FML_DCHECK(message->channel() == kAccessibilityChannel);
+
+  const flutter::StandardMessageCodec& standard_message_codec =
+      flutter::StandardMessageCodec::GetInstance(nullptr);
+  std::unique_ptr<flutter::EncodableValue> decoded =
+      standard_message_codec.DecodeMessage(message->data());
+
+  flutter::EncodableMap map = std::get<flutter::EncodableMap>(*decoded);
+  std::string type =
+      std::get<std::string>(map.at(flutter::EncodableValue("type")));
+  if (type == "announce") {
+    flutter::EncodableMap data_map = std::get<flutter::EncodableMap>(
+        map.at(flutter::EncodableValue("data")));
+    std::string text =
+        std::get<std::string>(data_map.at(flutter::EncodableValue("message")));
+
+    accessibility_bridge_->RequestAnnounce(text);
+  }
+
+  message->response()->CompleteEmpty();
 }
 
 // Channel handler for kFlutterPlatformChannel