Wire ScrollEvent to views and handle it in app list.

- Pass ScrollEvent to views system;
  - Add a OnScrollEvent to View;
  - Forward ScrollEvent to RootView in Widget;
  - RootView dispatches ScrollEvent to view under where event happens
    and if not processed, pass it to the parent;
- Handle ScrollEvent to switch pages in app list;

BUG=131075
TEST=Verify two-finger scroll on touch pad switches pages in app list;

Review URL: https://chromiumcodereview.appspot.com/10577045

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@143531 0039d316-1c4b-4281-b951-d872f2087c98

10 files changed, 53 insertions, 6 deletions

diff --git a/ui/app_list/apps_grid_view.cc b/ui/app_list/apps_grid_view.cc
index 38bbda4..50b2948 100644
--- a/ui/app_list/apps_grid_view.cc
+++ b/ui/app_list/apps_grid_view.cc
@@ -27,6 +27,7 @@ const int kPreferredTileHeight = 98;
 const int kMaxExtraColPaddingForInvalidTransition = 80;
 
 const int kMinMouseWheelToSwitchPage = 20;
+const int kMinScrollToSwitchPage = 20;
 const int kMinHorizVelocityToSwitchPage = 1100;
 
 }  // namespace
@@ -261,7 +262,20 @@ bool AppsGridView::OnKeyReleased(const views::KeyEvent& event) {
 
 bool AppsGridView::OnMouseWheel(const views::MouseWheelEvent& event) {
   if (abs(event.offset()) > kMinMouseWheelToSwitchPage) {
-    pagination_model_->SelectPageRelative(event.offset() > 0 ? -1 : 1, true);
+    if (!pagination_model_->has_transition())
+      pagination_model_->SelectPageRelative(event.offset() > 0 ? -1 : 1, true);
+    return true;
+  }
+
+  return false;
+}
+
+bool AppsGridView::OnScrollEvent(const views::ScrollEvent & event) {
+  if (abs(event.x_offset()) > kMinScrollToSwitchPage) {
+    if (!pagination_model_->has_transition()) {
+      pagination_model_->SelectPageRelative(event.x_offset() > 0 ? 1 : -1,
+                                            true);
+    }
     return true;
   }
 
diff --git a/ui/app_list/apps_grid_view.h b/ui/app_list/apps_grid_view.h
index 97ab5bb..4cff9ce 100644
--- a/ui/app_list/apps_grid_view.h
+++ b/ui/app_list/apps_grid_view.h
@@ -55,6 +55,7 @@ class APP_LIST_EXPORT AppsGridView : public views::View,
   virtual bool OnKeyPressed(const views::KeyEvent& event) OVERRIDE;
   virtual bool OnKeyReleased(const views::KeyEvent& event) OVERRIDE;
   virtual bool OnMouseWheel(const views::MouseWheelEvent& event) OVERRIDE;
+  virtual bool OnScrollEvent(const views::ScrollEvent & event) OVERRIDE;
   virtual void OnPaintFocusBorder(gfx::Canvas* canvas) OVERRIDE;
 
  private:
diff --git a/ui/app_list/pagination_model.h b/ui/app_list/pagination_model.h
index c61177f..ce013be 100644
--- a/ui/app_list/pagination_model.h
+++ b/ui/app_list/pagination_model.h
@@ -86,14 +86,14 @@ class APP_LIST_EXPORT PaginationModel : public ui::AnimationDelegate {
     return page >= 0 && page < total_pages_;
   }
 
- private:
-  void NotifySelectedPageChanged(int old_selected, int new_selected);
-  void NotifyTransitionChanged();
-
   bool has_transition() const {
     return transition_.target_page != -1 || transition_.progress != 0;
   }
 
+ private:
+  void NotifySelectedPageChanged(int old_selected, int new_selected);
+  void NotifyTransitionChanged();
+
   void clear_transition() {
     SetTransition(Transition(-1, 0));
   }
diff --git a/ui/app_list/search_box_view.cc b/ui/app_list/search_box_view.cc
index ab3dd11..1c5a6df 100644
--- a/ui/app_list/search_box_view.cc
+++ b/ui/app_list/search_box_view.cc
@@ -88,7 +88,7 @@ void SearchBoxView::Layout() {
 
 bool SearchBoxView::OnMouseWheel(const views::MouseWheelEvent& event) {
   if (contents_view_)
-    contents_view_->OnMouseWheel(event);
+    return contents_view_->OnMouseWheel(event);
 
   return false;
 }
diff --git a/ui/views/events/event.h b/ui/views/events/event.h
index d0fb969..44ef1b6 100644
--- a/ui/views/events/event.h
+++ b/ui/views/events/event.h
@@ -391,10 +391,19 @@ class VIEWS_EXPORT DropTargetEvent : public LocatedEvent {
 class VIEWS_EXPORT ScrollEvent : public MouseEvent {
  public:
   explicit ScrollEvent(const NativeEvent& native_event);
+
   float x_offset() const { return x_offset_; }
   float y_offset() const { return y_offset_; }
 
  private:
+  friend class internal::RootView;
+
+  ScrollEvent(const ScrollEvent& model, View* root)
+      : MouseEvent(model, root),
+        x_offset_(model.x_offset()),
+        y_offset_(model.y_offset()) {
+  }
+
   float x_offset_;
   float y_offset_;
 
diff --git a/ui/views/view.cc b/ui/views/view.cc
index 9541ab5..d200d03 100644
--- a/ui/views/view.cc
+++ b/ui/views/view.cc
@@ -846,6 +846,10 @@ bool View::OnMouseWheel(const MouseWheelEvent& event) {
   return false;
 }
 
+bool View::OnScrollEvent(const ScrollEvent& event) {
+  return false;
+}
+
 ui::TextInputClient* View::GetTextInputClient() {
   return NULL;
 }
diff --git a/ui/views/view.h b/ui/views/view.h
index f656747..10c2806 100644
--- a/ui/views/view.h
+++ b/ui/views/view.h
@@ -617,6 +617,12 @@ class VIEWS_EXPORT View : public ui::LayerDelegate,
   // will be given a chance.
   virtual bool OnMouseWheel(const MouseWheelEvent& event);
 
+  // Invoked when user scrolls (e.g. using two-finger scroll on touch pad).
+  // Returns true if the event has been processed and false otherwise. The event
+  // is sent to the view where the event happens first. If it has not been
+  // processed, the parent will be given a chance.
+  virtual bool OnScrollEvent(const ScrollEvent& event);
+
   // See field for description.
   void set_notify_enter_exit_on_child(bool notify) {
     notify_enter_exit_on_child_ = notify;
diff --git a/ui/views/widget/root_view.cc b/ui/views/widget/root_view.cc
index 515fa23..5d2aba3 100644
--- a/ui/views/widget/root_view.cc
+++ b/ui/views/widget/root_view.cc
@@ -381,6 +381,15 @@ bool RootView::OnMouseWheel(const MouseWheelEvent& event) {
   return consumed;
 }
 
+bool RootView::OnScrollEvent(const ScrollEvent& event) {
+  ScrollEvent e(event, this);
+  bool consumed = false;
+  for (View* v = GetEventHandlerForPoint(e.location());
+       v && v != this && !consumed; v = v->parent())
+    consumed = v->OnScrollEvent(e);
+  return consumed;
+}
+
 ui::TouchStatus RootView::OnTouchEvent(const TouchEvent& event) {
   // TODO: this looks all wrong. On a TOUCH_PRESSED we should figure out the
   // view and target that view with all touches with the same id until the
diff --git a/ui/views/widget/root_view.h b/ui/views/widget/root_view.h
index 9ffd601..2db8a91 100644
--- a/ui/views/widget/root_view.h
+++ b/ui/views/widget/root_view.h
@@ -105,6 +105,7 @@ class VIEWS_EXPORT RootView : public View, public FocusTraversable {
   virtual void OnMouseMoved(const MouseEvent& event) OVERRIDE;
   virtual void OnMouseExited(const MouseEvent& event) OVERRIDE;
   virtual bool OnMouseWheel(const MouseWheelEvent& event) OVERRIDE;
+  virtual bool OnScrollEvent(const ScrollEvent& event) OVERRIDE;
   virtual ui::TouchStatus OnTouchEvent(const TouchEvent& event) OVERRIDE;
   virtual ui::GestureStatus OnGestureEvent(const GestureEvent& event) OVERRIDE;
   virtual void SetMouseHandler(View* new_mouse_handler) OVERRIDE;
diff --git a/ui/views/widget/widget.cc b/ui/views/widget/widget.cc
index 31748ed..21c6735 100644
--- a/ui/views/widget/widget.cc
+++ b/ui/views/widget/widget.cc
@@ -1116,6 +1116,9 @@ bool Widget::OnMouseEvent(const MouseEvent& event) {
     case ui::ET_MOUSEWHEEL:
       return GetRootView()->OnMouseWheel(
           reinterpret_cast<const MouseWheelEvent&>(event));
+    case ui::ET_SCROLL:
+      return GetRootView()->OnScrollEvent(
+          reinterpret_cast<const ScrollEvent&>(event));
     default:
       return false;
   }