ViewRoot class for event forwarding on Android

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 68adf34d70eb8e6496ff37e547b165eb5bcc4d98..390e1dae234b9dd00eac2a3c4c0d6dacc7afcf97 100644
--- a/ui/android/view_android.h
+++ b/ui/android/view_android.h
@@ -10,6 +10,7 @@
 #include "base/android/jni_weak_ref.h"
 #include "base/memory/ref_counted.h"
 #include "ui/android/ui_android_export.h"
+#include "ui/android/view_client.h"
 #include "ui/gfx/geometry/rect_f.h"
 
 namespace cc {
@@ -22,6 +23,8 @@ class WindowAndroid;
 
 // A simple container for a UI layer.
 // At the root of the hierarchy is a WindowAndroid, when attached.
+// TODO(jinsukkim): Replace WindowAndroid with ViewRoot for the root of the
+//     view hierarchy.
 class UI_ANDROID_EXPORT ViewAndroid {
  public:
   // Stores an anchored view to delete itself at the end of its lifetime
@@ -54,9 +57,23 @@ 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);
+  // Basic view layout information. Used to decide whether the passed events
+  // should be processed by the view.
+  class Bounds {
+   public:
+    // Used for |width_ | or |height_| to indicate that the bounds is matched
+    // with that of its parent.
+    static const int kMatchParent = 0x7FFFFFFF;

[boliu, 2017/01/24 23:47:12]

there is no need to use special values here, just use a boolean or an enum, and
only use rect_ if boolean/enum says it's not match parent


also, do we really need a new class here? why not just two member variables?

[Jinsuk Kim, 2017/01/25 02:34:34]

Done.

+
+    void SetBounds(const gfx::Point& origin, int width, int height);
+    bool IsInBounds(const MotionEventData& event);
+    gfx::Point origin() const { return rect_.origin(); }
+
+   private:
+    gfx::Rect rect_;
+  };
+
+  explicit ViewAndroid(ViewClient* client);
 
   ViewAndroid();
   virtual ~ViewAndroid();
@@ -75,18 +92,30 @@ class UI_ANDROID_EXPORT ViewAndroid {
   // if disconnected.
   virtual WindowAndroid* GetWindowAndroid() const;
 
+  // Returns |ViewRoot| of this hierarchy. |null| if the hierarchy isn't
+  // attached to a |ViewRoot|.
+  virtual ViewAndroid* GetViewRoot();
+
+  virtual float GetDipScale();

[boliu, 2017/01/24 23:47:12]

protected, and add a comment that says it's virtual for testing

[Jinsuk Kim, 2017/01/25 02:34:33]

Done.

+
   // Used to return and set the layer for this view. May be |null|.
   cc::Layer* GetLayer() const;
   void SetLayer(scoped_refptr<cc::Layer> layer);
 
   void SetDelegate(const base::android::JavaRef<jobject>& delegate);
 
-  // Adds this view as a child of another view.
+  // Adds a child to this view.
   void AddChild(ViewAndroid* child);
 
   // Detaches this view from its parent.
   void RemoveFromParent();
 
+  // Set the bounds used to do hit testing against motion events.

[boliu, 2017/01/24 23:47:12]

relative to parent?

[Jinsuk Kim, 2017/01/25 02:34:34]

Done.

+  void SetBounds(const gfx::Point& origin, int width, int height);

[boliu, 2017/01/24 23:47:13]

or just take a rect?

[Jinsuk Kim, 2017/01/25 02:34:33]

Changed to get a rect and a bool.

+
+  // Returns true if the event hits the area of this view defined by |bounds_|.
+  bool IsInBounds(const MotionEventData& event);

[boliu, 2017/01/24 23:47:12]

does this need to be public?

[Jinsuk Kim, 2017/01/25 02:34:33]

No... made it private ( and then removed)

+
   bool StartDragAndDrop(const base::android::JavaRef<jstring>& jtext,
                         const base::android::JavaRef<jobject>& jimage);
 
@@ -98,9 +127,18 @@ class UI_ANDROID_EXPORT ViewAndroid {
   base::android::ScopedJavaLocalRef<jobject> GetContainerView();
 
  protected:
+  // Internal implementation of ViewClient forwarding calls to the interface.
+  bool OnTouchEventInternal(const MotionEventData& event);
+
+  // The child view at the front of the list receives event first.
+  std::list<ViewAndroid*> children_;
+
   ViewAndroid* parent_;
 
  private:
+  // Returns true only if this is of type |ViewRoot|.
+  bool IsViewRoot();
+
   void RemoveChild(ViewAndroid* child);
 
   // Returns the Java delegate for this view. This is used to delegate work
@@ -109,9 +147,11 @@ class UI_ANDROID_EXPORT ViewAndroid {
   const base::android::ScopedJavaLocalRef<jobject>
       GetViewAndroidDelegate() const;
 
-  std::list<ViewAndroid*> children_;
   scoped_refptr<cc::Layer> layer_;

[boliu, 2017/01/24 23:47:12]

eventually constructing the layer tree probably should move into view_android as
well and use bounds from view_android to construct that tree? will that make
sense? should we do some research up front?

[Jinsuk Kim, 2017/01/25 02:34:33]

Layer tree makes use of physical backing size for its bounds, but it is not
always same as view bounds. OverlayPanel's view bounds keeps changing as user
interacts with it. 

   JavaObjectWeakGlobalRef delegate_;
+  ViewClient* const client_;
+  Bounds bounds_;
+
   gfx::Vector2dF content_offset_;  // in CSS pixel
 
   DISALLOW_COPY_AND_ASSIGN(ViewAndroid);