Apply dpr transform to fuchsia accessibility bridge (#21364)

* Apply dpr transform to fuchsia accessibility bridge

* fix format

* addressing comment

* fix typo

Author: chunhtai

shell/platform/fuchsia/flutter/accessibility_bridge.cc

@@ -56,9 +56,14 @@ fuchsia::ui::gfx::BoundingBox AccessibilityBridge::GetNodeLocation(
 
 fuchsia::ui::gfx::mat4 AccessibilityBridge::GetNodeTransform(
     const flutter::SemanticsNode& node) const {
+  return ConvertSkiaTransformToMat4(node.transform);
+}
+
+fuchsia::ui::gfx::mat4 AccessibilityBridge::ConvertSkiaTransformToMat4(
+    const SkM44 transform) const {
   fuchsia::ui::gfx::mat4 value;
   float* m = value.matrix.data();
-  node.transform.getColMajor(m);
+  transform.getColMajor(m);
   return value;
 }
 
@@ -248,7 +253,8 @@ static void PrintNodeSizeError(uint32_t node_id) {
 }
 
 void AccessibilityBridge::AddSemanticsNodeUpdate(
-    const flutter::SemanticsNodeUpdates update) {
+    const flutter::SemanticsNodeUpdates update,
+    float view_pixel_ratio) {
   if (update.empty()) {
     return;
   }
@@ -259,7 +265,7 @@ void AccessibilityBridge::AddSemanticsNodeUpdate(
 
   std::vector<fuchsia::accessibility::semantics::Node> nodes;
   size_t current_size = 0;
-
+  bool has_root_node_update = false;
   // TODO(MI4-2498): Actions, Roles, hit test children, additional
   // flags/states/attr
 
@@ -268,6 +274,14 @@ void AccessibilityBridge::AddSemanticsNodeUpdate(
   for (const auto& value : update) {
     size_t this_node_size = sizeof(fuchsia::accessibility::semantics::Node);
     const auto& flutter_node = value.second;
+    // We handle root update separately in GetRootNodeUpdate.
+    // TODO(chunhtai): remove this special case after we remove the inverse
+    // view pixel ratio transformation in scenic view.
+    if (flutter_node.id == kRootNodeId) {
+      root_flutter_semantics_node_ = flutter_node;
+      has_root_node_update = true;
+      continue;
+    }
     // Store the nodes for later hit testing.
     nodes_[flutter_node.id] = {
         .id = flutter_node.id,
@@ -302,7 +316,6 @@ void AccessibilityBridge::AddSemanticsNodeUpdate(
       PrintNodeSizeError(flutter_node.id);
       return;
     }
-
     current_size += this_node_size;
 
     // If we would exceed the max FIDL message size by appending this node,
@@ -319,6 +332,29 @@ void AccessibilityBridge::AddSemanticsNodeUpdate(
     PrintNodeSizeError(nodes.back().node_id());
   }
 
+  // Handles root node update.
+  if (has_root_node_update || last_seen_view_pixel_ratio_ != view_pixel_ratio) {
+    last_seen_view_pixel_ratio_ = view_pixel_ratio;
+    size_t root_node_size;
+    fuchsia::accessibility::semantics::Node root_update =
+        GetRootNodeUpdate(root_node_size);
+    // TODO(MI4-2531, FIDL-718): Remove this
+    // This is defensive. If, despite our best efforts, we ended up with a node
+    // that is larger than the max fidl size, we send no updates.
+    if (root_node_size >= kMaxMessageSize) {
+      PrintNodeSizeError(kRootNodeId);
+      return;
+    }
+    current_size += root_node_size;
+    // If we would exceed the max FIDL message size by appending this node,
+    // we should delete/update/commit now.
+    if (current_size >= kMaxMessageSize) {
+      tree_ptr_->UpdateSemanticNodes(std::move(nodes));
+      nodes.clear();
+    }
+    nodes.push_back(std::move(root_update));
+  }
+
   PruneUnreachableNodes();
   UpdateScreenRects();
 
@@ -328,6 +364,45 @@ void AccessibilityBridge::AddSemanticsNodeUpdate(
   tree_ptr_->CommitUpdates([]() {});
 }
 
+fuchsia::accessibility::semantics::Node AccessibilityBridge::GetRootNodeUpdate(
+    size_t& node_size) {
+  fuchsia::accessibility::semantics::Node root_fuchsia_node;
+  std::vector<uint32_t> child_ids;
+  node_size = sizeof(fuchsia::accessibility::semantics::Node);
+  for (int32_t flutter_child_id :
+       root_flutter_semantics_node_.childrenInTraversalOrder) {
+    child_ids.push_back(FlutterIdToFuchsiaId(flutter_child_id));
+  }
+  // Applies the inverse view pixel ratio transformation to the root node.
+  float inverse_view_pixel_ratio = 1.f / last_seen_view_pixel_ratio_;
+  SkM44 inverse_view_pixel_ratio_transform;
+  inverse_view_pixel_ratio_transform.setScale(inverse_view_pixel_ratio,
+                                              inverse_view_pixel_ratio, 1.f);
+
+  SkM44 result = root_flutter_semantics_node_.transform *
+                 inverse_view_pixel_ratio_transform;
+  nodes_[root_flutter_semantics_node_.id] = {
+      .id = root_flutter_semantics_node_.id,
+      .flags = root_flutter_semantics_node_.flags,
+      .rect = root_flutter_semantics_node_.rect,
+      .transform = result,
+      .children_in_hit_test_order =
+          root_flutter_semantics_node_.childrenInHitTestOrder,
+  };
+  root_fuchsia_node.set_node_id(root_flutter_semantics_node_.id)
+      .set_role(GetNodeRole(root_flutter_semantics_node_))
+      .set_location(GetNodeLocation(root_flutter_semantics_node_))
+      .set_transform(ConvertSkiaTransformToMat4(result))
+      .set_attributes(
+          GetNodeAttributes(root_flutter_semantics_node_, &node_size))
+      .set_states(GetNodeStates(root_flutter_semantics_node_, &node_size))
+      .set_actions(GetNodeActions(root_flutter_semantics_node_, &node_size))
+      .set_child_ids(child_ids);
+  node_size += kNodeIdSize *
+               root_flutter_semantics_node_.childrenInTraversalOrder.size();
+  return root_fuchsia_node;
+}
+
 void AccessibilityBridge::UpdateScreenRects() {
   std::unordered_set<int32_t> visited_nodes;
   UpdateScreenRects(kRootNodeId, SkM44{}, &visited_nodes);

shell/platform/fuchsia/flutter/accessibility_bridge.h

@@ -82,7 +82,8 @@ class AccessibilityBridge
   void SetSemanticsEnabled(bool enabled);
 
   // Adds a semantics node update to the buffer of node updates to apply.
-  void AddSemanticsNodeUpdate(const flutter::SemanticsNodeUpdates update);
+  void AddSemanticsNodeUpdate(const flutter::SemanticsNodeUpdates update,
+                              float view_pixel_ratio);
 
   // Notifies the bridge of a 'hover move' touch exploration event.
   zx_status_t OnHoverMove(double x, double y);
@@ -115,6 +116,8 @@ class AccessibilityBridge
   AccessibilityBridge::Delegate& delegate_;
 
   static constexpr int32_t kRootNodeId = 0;
+  flutter::SemanticsNode root_flutter_semantics_node_;
+  float last_seen_view_pixel_ratio_ = 1.f;
   fidl::Binding<fuchsia::accessibility::semantics::SemanticListener> binding_;
   fuchsia::accessibility::semantics::SemanticsManagerPtr
       fuchsia_semantics_manager_;
@@ -124,15 +127,21 @@ class AccessibilityBridge
   // Assists with pruning unreachable nodes and hit testing.
   std::unordered_map<int32_t, SemanticsNode> nodes_;
 
+  fuchsia::accessibility::semantics::Node GetRootNodeUpdate(size_t& node_size);
+
   // Derives the BoundingBox of a Flutter semantics node from its
   // rect and elevation.
   fuchsia::ui::gfx::BoundingBox GetNodeLocation(
       const flutter::SemanticsNode& node) const;
 
-  // Converts a Flutter semantics node's transformation to a mat4.
+  // Gets mat4 transformation from a Flutter semantics node.
   fuchsia::ui::gfx::mat4 GetNodeTransform(
       const flutter::SemanticsNode& node) const;
 
+  // Converts a Flutter semantics node's transformation to a mat4.
+  fuchsia::ui::gfx::mat4 ConvertSkiaTransformToMat4(
+      const SkM44 transform) const;
+
   // Derives the attributes for a Fuchsia semantics node from a Flutter
   // semantics node.
   fuchsia::accessibility::semantics::Attributes GetNodeAttributes(