Add EventForwarder for routing touch events

ui/android/view_android.h

Index: ui/android/view_android.h
diff --git a/ui/android/view_android.h b/ui/android/view_android.h
index 0abd77cdc40d55152a13aa423e46c79d90082f0c..9251c63dc80936bb830625604f9addb4001872f8 100644
--- a/ui/android/view_android.h
+++ b/ui/android/view_android.h
@@ -20,6 +20,10 @@ class Layer;
 
 namespace ui {
 
+class EventHandler;
+class EventSender;
+class MotionEventAndroid;
+class ViewClient;
 class WindowAndroid;
 
 // A simple container for a UI layer.
@@ -56,9 +60,16 @@ class UI_ANDROID_EXPORT ViewAndroid {
     // Default copy/assign disabled by move constructor.
   };
 
-  // A ViewAndroid may have its own delegate or otherwise will
-  // use the next available parent's delegate.
-  ViewAndroid(const base::android::JavaRef<jobject>& delegate);
+  // Abstracts out the dispatcher for various types of events. Used for hit
+  // testing logic.
+  struct EventSender {
+    virtual bool SendToView(ViewAndroid* view,
+                            const MotionEventAndroid& event) const = 0;
+    virtual bool SendToClient(ViewClient* client,
+                              const MotionEventAndroid& event) const = 0;
+  };
+
+  explicit ViewAndroid(ViewClient* view_client);
 
   ViewAndroid();
   virtual ~ViewAndroid();
@@ -83,12 +94,24 @@ class UI_ANDROID_EXPORT ViewAndroid {
 
   void SetDelegate(const base::android::JavaRef<jobject>& delegate);
 
-  // Adds this view as a child of another view.
+  // Gets (creates one if not present) Java object of the EventHandler
+  // for a view tree in the view hierarchy including this node.
+  // Only one instance per the view tree is allowed.
+  base::android::ScopedJavaLocalRef<jobject> GetEventHandler();
+
+  // Adds a child to this view.
   void AddChild(ViewAndroid* child);
 
+  // Moves the give child ViewAndroid to the top of the list so that it can be
+  // the first responder of events.
+  void MoveToTop(ViewAndroid* child);
+
   // Detaches this view from its parent.
   void RemoveFromParent();
 
+  // Sets the layout relative to parent. Used to do hit testing against events.
+  void SetLayout(int x, int y, int width, int height, bool match_parent);
+
   bool StartDragAndDrop(const base::android::JavaRef<jstring>& jtext,
                         const base::android::JavaRef<jobject>& jimage);
 
@@ -106,12 +129,29 @@ class UI_ANDROID_EXPORT ViewAndroid {
   // This may return null.
   base::android::ScopedJavaLocalRef<jobject> GetContainerView();
 
+  bool OnTouchEvent(const MotionEventAndroid& event, bool for_touch_handle);

[boliu, 2017/03/03 22:01:32]

these are still public..? I think the original comment was the other way around,
that these two methods should be private

[Jinsuk Kim, 2017/03/06 04:07:34]

Got the comments wrong. Done. Now ViewAndroid/EventHandler are friends to each
other - EventHandler ctor is private and VA is the only class that can
instantiate it.

+  bool OnMouseEvent(const MotionEventAndroid& event);
+
+  // Virtual for testing.
+  virtual float GetDipScale();
+
  protected:
   ViewAndroid* parent_;
 
  private:
   void RemoveChild(ViewAndroid* child);
 
+  bool HitTest(const EventSender& es, const MotionEventAndroid& event);
+
+  bool has_event_handler() const { return !!event_handler_; }
+
+  // Returns true if any node of the tree along the hierarchy (view's children
+  // and parents) already has |EventHandler| attached to it.
+  static bool ViewTreeHasEventHandler(ViewAndroid* view);
+
+  // Returns true if any children node (or self) has |EventHandler|.
+  static bool ChildrenHaveEventHandler(ViewAndroid* view);
+
   // Returns the Java delegate for this view. This is used to delegate work
   // up to the embedding view (or the embedder that can deal with the
   // implementation details).
@@ -121,7 +161,17 @@ class UI_ANDROID_EXPORT ViewAndroid {
   std::list<ViewAndroid*> children_;
   scoped_refptr<cc::Layer> layer_;
   JavaObjectWeakGlobalRef delegate_;
-  gfx::Vector2dF content_offset_;  // in CSS pixel
+
+  ViewClient* const client_;
+
+  // Basic view layout information. Used to do hit testing deciding whether
+  // the passed events should be processed by the view.
+  gfx::Point origin_;  // In parent's coordinate space.
+  gfx::Size size_;
+  bool match_parent_;  // Bounds matches that of the parent if true.
+
+  gfx::Vector2dF content_offset_;  // in CSS pixel.
+  std::unique_ptr<EventHandler> event_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(ViewAndroid);
 };