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..fdc97abced66405690fa0f49fb39452357386f06 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. See https://crbug.com/671401
 class UI_ANDROID_EXPORT ViewAndroid {
  public:
   // Stores an anchored view to delete itself at the end of its lifetime
@@ -54,9 +57,7 @@ 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);
+  explicit ViewAndroid(ViewClient* client);
 
   ViewAndroid();
   virtual ~ViewAndroid();
@@ -75,18 +76,25 @@ 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();
+
   // 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 layout relative to parent. Used to do hit testing against events.
+  void SetLayout(const gfx::Rect& bounds, bool match_parent);
+
   bool StartDragAndDrop(const base::android::JavaRef<jstring>& jtext,
                         const base::android::JavaRef<jobject>& jimage);
 
@@ -98,9 +106,21 @@ 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);
+
+  // Virtual for testing.
+  virtual float GetDipScale();
+
+  // 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 +129,15 @@ class UI_ANDROID_EXPORT ViewAndroid {
   const base::android::ScopedJavaLocalRef<jobject>
       GetViewAndroidDelegate() const;
 
-  std::list<ViewAndroid*> children_;
   scoped_refptr<cc::Layer> layer_;
   JavaObjectWeakGlobalRef delegate_;
+  ViewClient* const client_;
+
+  // Basic view layout information. Used to hit testing deciding whether
+  // the passed events should be processed by the view.
+  gfx::Rect bounds_;

[boliu, 2017/02/05 19:20:23]

separate position from the size

size is something inherent to this view (unless it's match parent..)

but position is something in relationship to the parent, and is analogous to the
transform in cc::layer, it's just we only support translation transforms here

[Jinsuk Kim, 2017/02/06 02:23:44]

Done.

+  bool match_parent_;  // bounds matches that of the parent if true.
+
   gfx::Vector2dF content_offset_;  // in CSS pixel
 
   DISALLOW_COPY_AND_ASSIGN(ViewAndroid);