IPC::ParamTraits for ui::Event (towards ui::Events over mojo IPC)

ui/events/event.h

Index: ui/events/event.h
diff --git a/ui/events/event.h b/ui/events/event.h
index 90ea9d98e03f5657a946bd5a386b9aa69dc461ee..f3a5df9fba3f319dd7193a87db1e3a9e532d74f0 100644
--- a/ui/events/event.h
+++ b/ui/events/event.h
@@ -6,7 +6,6 @@
 #define UI_EVENTS_EVENT_H_
 
 #include <stdint.h>
-
 #include "base/compiler_specific.h"
 #include "base/event_types.h"
 #include "base/gtest_prod_util.h"
@@ -14,6 +13,7 @@
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
+#include "ipc/ipc_message_utils.h"
 #include "ui/events/event_constants.h"
 #include "ui/events/gesture_event_details.h"
 #include "ui/events/gestures/gesture_types.h"
@@ -30,6 +30,9 @@ class Transform;
 namespace ui {
 class EventTarget;
 enum class DomCode;
+class Event;
+
+typedef scoped_ptr<Event> ScopedEvent;
 

[Tom Sepez, 2016/02/18 18:46:10]

nit: using ScopedEvent = scoped_ptr<Event>;

[Mark Dittmer, 2016/02/18 19:12:56]

Done.

 class EVENTS_EXPORT Event {
  public:
@@ -240,6 +243,9 @@ class EVENTS_EXPORT Event {
  private:
   friend class EventTestApi;
 
+  // For (de)serialization.
+  friend struct IPC::ParamTraits<ui::ScopedEvent>;

[Tom Sepez, 2016/02/18 18:46:10]

jam@ and I have argued about this in the past -- it's a layering violation for
this code to know about IPC traits.  I'll add him to see if he still feels the
same way.

[Mark Dittmer, 2016/02/18 19:12:56]

What is the proposed implementation alternative? Require getters + setters for
all serializable data?

[jam, 2016/02/18 21:01:26]

I care less about this now. 

My main question is who will use these traits? If it's just mus, why aren't the
ipc related code in mus' directory?

+
   EventType type_;
   std::string name_;
   base::TimeDelta time_stamp_;
@@ -261,8 +267,19 @@ class EVENTS_EXPORT CancelModeEvent : public Event {
  public:
   CancelModeEvent();
   ~CancelModeEvent() override;
+
+ private:
+  // For (de)serialization.
+  explicit CancelModeEvent(EventType type,

[Tom Sepez, 2016/02/18 18:46:10]

Nit: no |explicit| as it's not a single-arg ctor.

[Mark Dittmer, 2016/02/18 19:12:56]

Done.

+                           base::TimeDelta time_stamp,
+                           int flags)
+      : Event(type, time_stamp, flags) {}
+  friend struct IPC::ParamTraits<ui::ScopedEvent>;
+  friend struct IPC::ParamTraits<ui::CancelModeEvent>;
 };
 
+class MouseWheelEvent;

[Tom Sepez, 2016/02/18 18:46:10]

nit: move to top

[Mark Dittmer, 2016/02/18 19:12:56]

Done.

+
 class EVENTS_EXPORT LocatedEvent : public Event {
  public:
   ~LocatedEvent() override;
@@ -304,6 +321,13 @@ class EVENTS_EXPORT LocatedEvent : public Event {
 
  protected:
   friend class LocatedEventTestApi;
+
+  // For (de)serialization.
+  explicit LocatedEvent(EventType type, base::TimeDelta time_stamp, int flags)
+      : Event(type, time_stamp, flags) {}
+  friend struct IPC::ParamTraits<ui::ScopedEvent>;
+  friend struct IPC::ParamTraits<ui::LocatedEvent>;
+
   explicit LocatedEvent(const base::NativeEvent& native_event);
 
   // Create a new LocatedEvent which is identical to the provided model.
@@ -364,6 +388,9 @@ struct EVENTS_EXPORT PointerDetails {
            tilt_y == other.tilt_y;
   }
 
+  // For serialization.
+  friend struct IPC::ParamTraits<ui::PointerDetails>;
+
   // The type of pointer device.
   EventPointerType pointer_type = EventPointerType::POINTER_TYPE_UNKNOWN;
 
@@ -483,6 +510,13 @@ class EVENTS_EXPORT MouseEvent : public LocatedEvent {
     pointer_details_ = details;
   }
 
+ protected:
+  // For (de)serialization.
+  explicit MouseEvent(EventType type, base::TimeDelta time_stamp, int flags)
+      : LocatedEvent(type, time_stamp, flags) {}
+  friend struct IPC::ParamTraits<ui::ScopedEvent>;
+  friend struct IPC::ParamTraits<ui::MouseEvent>;
+
  private:
   FRIEND_TEST_ALL_PREFIXES(EventTest, DoubleClickRequiresRelease);
   FRIEND_TEST_ALL_PREFIXES(EventTest, SingleClickRightLeft);
@@ -543,6 +577,14 @@ class EVENTS_EXPORT MouseWheelEvent : public MouseEvent {
   const gfx::Vector2d& offset() const { return offset_; }
 
  private:
+  // For (de)serialization.
+  explicit MouseWheelEvent(EventType type,
+                           base::TimeDelta time_stamp,
+                           int flags)
+      : MouseEvent(type, time_stamp, flags) {}
+  friend struct IPC::ParamTraits<ui::ScopedEvent>;
+  friend struct IPC::ParamTraits<ui::MouseWheelEvent>;
+
   gfx::Vector2d offset_;
 };
 
@@ -615,15 +657,22 @@ class EVENTS_EXPORT TouchEvent : public LocatedEvent {
   }
 
  private:
+  // For (de)serialization.
+  explicit TouchEvent(EventType type, base::TimeDelta time_stamp, int flags)
+      : LocatedEvent(type, time_stamp, flags),
+        should_remove_native_touch_id_mapping_(false) {}
+  friend struct IPC::ParamTraits<ui::ScopedEvent>;
+  friend struct IPC::ParamTraits<ui::TouchEvent>;
+
   // Adjusts rotation_angle_ to within the acceptable range.
   void FixRotationAngle();
 
   // The identity (typically finger) of the touch starting at 0 and incrementing
   // for each separable additional touch that the hardware can detect.
-  const int touch_id_;
+  int touch_id_;
 
   // A unique identifier for the touch event.
-  const uint32_t unique_event_id_;
+  uint32_t unique_event_id_;
 
   // Clockwise angle (in degrees) of the major axis from the X axis. Must be
   // less than 180 and non-negative.
@@ -824,6 +873,11 @@ class EVENTS_EXPORT KeyEvent : public Event {
   void set_is_char(bool is_char) { is_char_ = is_char; }
 
  private:
+  // For (de)serialization.
+  explicit KeyEvent(EventType type, base::TimeDelta time_stamp, int flags);
+  friend struct IPC::ParamTraits<ui::ScopedEvent>;
+  friend struct IPC::ParamTraits<ui::KeyEvent>;
+
   // Determine key_ on a keystroke event from code_ and flags().
   void ApplyLayout() const;
 
@@ -902,6 +956,12 @@ class EVENTS_EXPORT ScrollEvent : public MouseEvent {
   int finger_count() const { return finger_count_; }
 
  private:
+  // For (de)serialization.
+  explicit ScrollEvent(EventType type, base::TimeDelta time_stamp, int flags)
+      : MouseEvent(type, time_stamp, flags) {}
+  friend struct IPC::ParamTraits<ui::ScopedEvent>;
+  friend struct IPC::ParamTraits<ui::ScrollEvent>;
+
   // Potential accelerated offsets.
   float x_offset_;
   float y_offset_;
@@ -934,6 +994,12 @@ class EVENTS_EXPORT GestureEvent : public LocatedEvent {
   const GestureEventDetails& details() const { return details_; }
 
  private:
+  // For (de)serialization.
+  explicit GestureEvent(EventType type, base::TimeDelta time_stamp, int flags)
+      : LocatedEvent(type, time_stamp, flags) {}
+  friend struct IPC::ParamTraits<ui::ScopedEvent>;
+  friend struct IPC::ParamTraits<ui::GestureEvent>;
+
   GestureEventDetails details_;
 };