src/embedder/embedder_state.h

// Copyright 2022 The Fuchsia 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 SRC_EMBEDDER_EMBEDDER_STATE_H_
#define SRC_EMBEDDER_EMBEDDER_STATE_H_

#include <fuchsia/sysmem/cpp/fidl.h>
#include <fuchsia/ui/composition/cpp/fidl.h>
#include <lib/sys/cpp/component_context.h>
#include <lib/zx/vmo.h>

#include <optional>

#include "src/embedder/accessibility_bridge.h"
#include "src/embedder/engine/embedder.h"
#include "src/embedder/flatland_connection.h"
#include "src/embedder/software_surface.h"

namespace embedder {

/// Mutable state for the embedder.
///
/// This is provided to all Engine callbacks through the
/// embedder's `user_data` argument. See `FlutterEngineRun` in
/// engine/embedder.h for more details on `user_data`.
struct EmbedderState {
  /// Capabilities are served from the embedder component
  /// parent components using this component context.
  //
  // WARNING: `component_context` MUST BE THE FIRST FIELD OF THIS DATA.
  // We shouldn't rely on the Dart SDK from our embedder, so instead we
  // do a terrible hack in https://github.com/flutter/engine/pull/33472 that
  // requires reading this field to work around http://fxbug.dev/75282 to set
  // the inspect node inside the embedder on the Fuchsia platform.
  //
  // TODO(fxb/75282): Properly fix this and remove the terrible hack.
  std::unique_ptr<sys::ComponentContext> component_context;

  // ===== FLUTTER ENGINE STATE =====

  /// The instance of the Flutter Engine that is running the
  /// Flutter app.
  FlutterEngine engine;

  // ===== RENDERING =====

  /// Maintains our Flatland server connection and associated state.
  ///
  /// Flatland is Fuchsia's 2D composition API, which lets us construct
  /// a scene graph and submit that graph to be rendered.
  ///
  /// See https://fuchsia.dev/fuchsia-src/concepts/ui/scenic/flatland?hl=en.
  std::unique_ptr<FlatlandConnection> flatland_connection;

  // ===== SOFTWARE RENDERING ====

  /// The allocator for memory in Flatland.
  ///
  /// Required to allocate a surface for Flatland. See
  /// notes in
  /// https://fuchsia.dev/fuchsia-src/concepts/ui/scenic/flatland?hl=en#design.
  fuchsia::ui::composition::AllocatorPtr flatland_allocator;

  /// Allocator for memory from sysmem.
  ///
  /// Memory for graphics surfaces on Fuchsia must come from sysmem.
  ///
  /// For more details on how sysmem works and how to interact with
  /// sysmem, see
  /// https://fuchsia.dev/fuchsia-src/development/graphics/sysmem/concepts/sysmem.
  fuchsia::sysmem::AllocatorSyncPtr sysmem_allocator;

  /// The last acquired surface for rendering.
  ///
  /// TODO(akbiggs): Replace with composition logic
  /// that supports multiple surfaces. See
  /// https://github.com/flutter/engine/blob/main/shell/platform/fuchsia/flutter/flatland_external_view_embedder.cc#L108.
  std::unique_ptr<SoftwareSurface> software_surface;

  /// The accessibility bridge responsible for intermediating
  /// accessibility-related calls between Fuchsia and Flutter
  std::unique_ptr<AccessibilityBridge> accessibility_bridge_;
};

}  // namespace embedder

#endif  // SRC_EMBEDDER_EMBEDDER_STATE_H_