dom/gamepad/GamepadHandle.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 // This file defines a strongly-typed opaque gamepad handle
   8 //
   9 // The handle is designed to be copied around and passed over IPC. It keeps
  10 // track of which "provider" created the handle so it can ensure that
  11 // providers are never mixed. It also allows each provider to have its own
  12 // algorithm for generating gamepad IDs, since the VR and Platform services
  13 // do it differently.
  14
  15 #ifndef mozilla_dom_gamepad_GamepadHandle_h
  16 #define mozilla_dom_gamepad_GamepadHandle_h
  17
  18 #include "PLDHashTable.h"
  19 #include <type_traits>
  20 #include <cinttypes>
  21
  22 namespace IPC {
  23
  24 template <class>
  25 struct ParamTraits;
  26
  27 }  // namespace IPC
  28
  29 namespace mozilla::gfx {
  30
  31 class VRDisplayClient;
  32 class VRManager;
  33
  34 }  // namespace mozilla::gfx
  35
  36 namespace mozilla::dom {
  37
  38 class GamepadPlatformService;
  39 class GamepadServiceTest;
  40 class XRInputSource;
  41
  42 // The "kind" of a gamepad handle is based on which provider created it
  43 enum class GamepadHandleKind : uint8_t {
  44   GamepadPlatformManager,
  45   VR,
  46 };
  47
  48 class GamepadHandle {
  49  public:
  50   // Allow handle to be passed around as a simple object
  51   GamepadHandle() = default;
  52   GamepadHandle(const GamepadHandle&) = default;
  53   GamepadHandle& operator=(const GamepadHandle&) = default;
  54
  55   // Helps code know which manager to send requests to
  56   GamepadHandleKind GetKind() const;
  57
  58   // Define operators so the handle can compared and stored in maps
  59   friend bool operator==(const GamepadHandle& a, const GamepadHandle& b);
  60   friend bool operator!=(const GamepadHandle& a, const GamepadHandle& b);
  61   friend bool operator<(const GamepadHandle& a, const GamepadHandle& b);
  62
  63   PLDHashNumber Hash() const;
  64
  65  private:
  66   explicit GamepadHandle(uint32_t aValue, GamepadHandleKind aKind);
  67   uint32_t GetValue() const { return mValue; }
  68
  69   uint32_t mValue{0};
  70   GamepadHandleKind mKind{GamepadHandleKind::GamepadPlatformManager};
  71
  72   // These are the classes that are "gamepad managers". They are allowed to
  73   // create new handles and inspect their actual value
  74   friend class mozilla::dom::GamepadPlatformService;
  75   friend class mozilla::dom::GamepadServiceTest;
  76   friend class mozilla::dom::XRInputSource;
  77   friend class mozilla::gfx::VRDisplayClient;
  78   friend class mozilla::gfx::VRManager;
  79
  80   // Allow IPDL to serialize us
  81   friend struct IPC::ParamTraits<mozilla::dom::GamepadHandle>;
  82 };
  83
  84 static_assert(std::is_trivially_copyable<GamepadHandle>::value,
  85               "GamepadHandle must be trivially copyable");
  86
  87 }  // namespace mozilla::dom
  88
  89 #endif  // mozilla_dom_gamepad_GamepadHandle_h