Checking in patch for Denis Romanov (originally reviewed here: http://codereview.chromium.org/651027).

Make mouse wheel scroll contents of views::ScrollView control in Linux (GTK). 

BUG=26970
TEST=Make and run out/Debug/view_examples and scroll in ScrollView tab. 
TBR=denisromanov

Review URL: http://codereview.chromium.org/667008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@40555 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 64 insertions, 18 deletions

diff --git a/views/widget/widget_gtk.cc b/views/widget/widget_gtk.cc
index 7cce516..7cb0278 100644
--- a/views/widget/widget_gtk.cc
+++ b/views/widget/widget_gtk.cc
@@ -807,8 +807,7 @@ gboolean WidgetGtk::OnMotionNotify(GtkWidget* widget, GdkEventMotion* event) {
 }
 
 gboolean WidgetGtk::OnButtonPress(GtkWidget* widget, GdkEventButton* event) {
-  ProcessMousePressed(event);
-  return true;
+  return ProcessMousePressed(event);
 }
 
 gboolean WidgetGtk::OnButtonRelease(GtkWidget* widget, GdkEventButton* event) {
@@ -816,6 +815,10 @@ gboolean WidgetGtk::OnButtonRelease(GtkWidget* widget, GdkEventButton* event) {
   return true;
 }
 
+gboolean WidgetGtk::OnScroll(GtkWidget* widget, GdkEventScroll* event) {
+  return ProcessScroll(event);
+}
+
 gboolean WidgetGtk::OnFocusIn(GtkWidget* widget, GdkEventFocus* event) {
   if (has_focus_)
     return false;  // This is the second focus-in event in a row, ignore it.
@@ -936,18 +939,10 @@ bool WidgetGtk::ProcessMousePressed(GdkEventButton* event) {
     return true;
   }
 
-  // An event may come from a child widget which has its own gdk window.
-  // Translate it to the widget's cooridnate.
-  int x = event->x;
-  int y = event->y;
-  GdkWindow* dest = GTK_WIDGET(window_contents_)->window;
-  if (event->window != dest) {
-    int dest_x, dest_y;
-    gdk_window_get_root_origin(dest, &dest_x, &dest_y);
-    x = event->x_root - dest_x;
-    y = event->y_root - dest_y;
-  }
-
+  // An event may come from a contained widget which has its own gdk window.
+  // Translate it to the widget's coordinates.
+  int x, y;
+  GetContainedWidgetEventCoordinates(event, &x, &y);
   last_mouse_event_was_move_ = false;
   MouseEvent mouse_pressed(Event::ET_MOUSE_PRESSED, x, y,
                            GetFlagsForEventButton(*event));
@@ -968,7 +963,6 @@ void WidgetGtk::ProcessMouseReleased(GdkEventButton* event) {
                       GetFlagsForEventButton(*event));
   // Release the capture first, that way we don't get confused if
   // OnMouseReleased blocks.
-
   if (has_capture_ && ReleaseCaptureOnMouseReleased())
     ReleaseGrab();
   is_mouse_down_ = false;
@@ -977,6 +971,38 @@ void WidgetGtk::ProcessMouseReleased(GdkEventButton* event) {
     root_view_->OnMouseReleased(mouse_up, false);
 }
 
+bool WidgetGtk::ProcessScroll(GdkEventScroll* event) {
+  // An event may come from a contained widget which has its own gdk window.
+  // Translate it to the widget's coordinates.
+  int x, y;
+  GetContainedWidgetEventCoordinates(event, &x, &y);
+  int flags = Event::GetFlagsFromGdkState(event->state);
+  int increment = 0;
+  bool is_horizontal;
+  switch (event->direction) {
+    case GDK_SCROLL_UP:
+      increment = -1;
+      is_horizontal = false;
+      break;
+    case GDK_SCROLL_DOWN:
+      increment = 1;
+      is_horizontal = false;
+      break;
+    case GDK_SCROLL_LEFT:
+      increment = -1;
+      is_horizontal = true;
+      break;
+    case GDK_SCROLL_RIGHT:
+      increment = 1;
+      is_horizontal = false;
+      break;
+  }
+  increment *= is_horizontal ? root_view_->width() / 5 :
+      root_view_->height() / 5;
+  MouseWheelEvent wheel_event(increment, x, y, flags);
+  return root_view_->ProcessMouseWheelEvent(wheel_event);
+}
+
 // static
 void WidgetGtk::SetRootViewForWidget(GtkWidget* widget, RootView* root_view) {
   g_object_set_data(G_OBJECT(widget), "root-view", root_view);
diff --git a/views/widget/widget_gtk.h b/views/widget/widget_gtk.h
index 0c0096c..29d99be 100644
--- a/views/widget/widget_gtk.h
+++ b/views/widget/widget_gtk.h
@@ -186,6 +186,26 @@ class WidgetGtk
   virtual View* GetFocusTraversableParentView();
 
  protected:
+  // If widget containes another widget, translates event coordinates to the
+  // contained widget's coordinates, else returns original event coordinates.
+  template<class Event> bool GetContainedWidgetEventCoordinates(Event* event,
+                                                                int* x,
+                                                                int* y) {
+    if (event == NULL || x == NULL || y == NULL)
+      return false;
+    *x = event->x;
+    *y = event->y;
+    GdkWindow* dest = GTK_WIDGET(window_contents_)->window;
+    if (event->window != dest) {
+      int dest_x, dest_y;
+      gdk_window_get_root_origin(dest, &dest_x, &dest_y);
+      *x = event->x_root - dest_x;
+      *y = event->y_root - dest_y;
+      return true;
+    }
+    return false;
+  }
+
   // Returns the view::Event::flags for a GdkEventButton.
   static int GetFlagsForEventButton(const GdkEventButton& event);
 
@@ -228,9 +248,7 @@ class WidgetGtk
                                   gint y,
                                   gboolean keyboard_mode,
                                   GtkTooltip* tooltip);
-  virtual gboolean OnScroll(GtkWidget* widget, GdkEventScroll* event) {
-    return false;
-  }
+  virtual gboolean OnScroll(GtkWidget* widget, GdkEventScroll* event);
   virtual gboolean OnVisibilityNotify(GtkWidget* widget,
                                       GdkEventVisibility* event) {
     return false;
@@ -271,6 +289,8 @@ class WidgetGtk
   // Process a mouse click.
   bool ProcessMousePressed(GdkEventButton* event);
   void ProcessMouseReleased(GdkEventButton* event);
+  // Process scroll event.
+  bool ProcessScroll(GdkEventScroll* event);
 
   static void SetRootViewForWidget(GtkWidget* widget, RootView* root_view);