embedder_semantics_update.h

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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#ifndef FLUTTER_SHELL_PLATFORM_EMBEDDER_EMBEDDER_SEMANTICS_UPDATE_H_
#define FLUTTER_SHELL_PLATFORM_EMBEDDER_EMBEDDER_SEMANTICS_UPDATE_H_
 
#include "flutter/lib/ui/semantics/custom_accessibility_action.h"
#include "flutter/lib/ui/semantics/semantics_node.h"
#include "flutter/shell/platform/embedder/embedder.h"
 
namespace flutter {
 
// A semantic update, used by the embedder API's v1 and v2 semantic update
// callbacks.
class EmbedderSemanticsUpdate {
 public:
  EmbedderSemanticsUpdate(const SemanticsNodeUpdates& nodes,
                          const CustomAccessibilityActionUpdates& actions);
 
  ~EmbedderSemanticsUpdate();
 
  // Get the semantic update. The pointer is only valid while
  // |EmbedderSemanticsUpdate| exists.
  FlutterSemanticsUpdate* get() { return &update_; }
 
 private:
  FlutterSemanticsUpdate update_;
  std::vector<FlutterSemanticsNode> nodes_;
  std::vector<FlutterSemanticsCustomAction> actions_;
 
  // Translates engine semantic nodes to embedder semantic nodes.
  void AddNode(const SemanticsNode& node);
 
  // Translates engine semantic custom actions to embedder semantic custom
  // actions.
  void AddAction(const CustomAccessibilityAction& action);
 
  FML_DISALLOW_COPY_AND_ASSIGN(EmbedderSemanticsUpdate);
};
 
// A semantic update, used by the embedder API's v3 semantic update callback.
//
// This holds temporary embedder-specific objects that are translated from
// the engine's internal representation and passed back to the semantics
// update callback. Once the callback finishes, this object is destroyed
// and the temporary embedder-specific objects are automatically cleaned up.
class EmbedderSemanticsUpdate2 {
 public:
  EmbedderSemanticsUpdate2(const SemanticsNodeUpdates& nodes,
                           const CustomAccessibilityActionUpdates& actions);
 
  ~EmbedderSemanticsUpdate2();
 
  // Get the semantic update. The pointer is only valid while
  // |EmbedderSemanticsUpdate2| exists.
  FlutterSemanticsUpdate2* get() { return &update_; }
 
 private:
  // These fields hold temporary embedder-specific objects that
  // must remain valid for the duration of the semantics update callback.
  // They are automatically cleaned up when |EmbedderSemanticsUpdate2| is
  // destroyed.
  FlutterSemanticsUpdate2 update_;
  std::vector<FlutterSemanticsNode2> nodes_;
  std::vector<FlutterSemanticsNode2*> node_pointers_;
  std::vector<FlutterSemanticsCustomAction2> actions_;
  std::vector<FlutterSemanticsCustomAction2*> action_pointers_;
 
  std::vector<std::unique_ptr<std::vector<const FlutterStringAttribute*>>>
      node_string_attributes_;
  std::vector<std::unique_ptr<FlutterStringAttribute>> string_attributes_;
  std::vector<std::unique_ptr<FlutterLocaleStringAttribute>> locale_attributes_;
  std::unique_ptr<FlutterSpellOutStringAttribute> spell_out_attribute_;
 
  // Translates engine semantic nodes to embedder semantic nodes.
  void AddNode(const SemanticsNode& node);
 
  // Translates engine semantic custom actions to embedder semantic custom
  // actions.
  void AddAction(const CustomAccessibilityAction& action);
 
  // A helper struct for |CreateStringAttributes|.
  struct EmbedderStringAttributes {
    // The number of string attribute pointers in |attributes|.
    size_t count;
    // An array of string attribute pointers.
    const FlutterStringAttribute** attributes;
  };
 
  // Translates engine string attributes to embedder string attributes.
  EmbedderStringAttributes CreateStringAttributes(
      const StringAttributes& attribute);
 
  FML_DISALLOW_COPY_AND_ASSIGN(EmbedderSemanticsUpdate2);
};
 
}  // namespace flutter
 
#endif  // FLUTTER_SHELL_PLATFORM_EMBEDDER_EMBEDDER_SEMANTICS_UPDATE_H_