Scroll with Layers in views::ScrollView

ui/views/controls/scroll_view.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_VIEWS_CONTROLS_SCROLL_VIEW_H_
 #define UI_VIEWS_CONTROLS_SCROLL_VIEW_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "ui/views/controls/scrollbar/scroll_bar.h"
 
+namespace gfx {
+class ScrollOffset;
+}
+
 namespace views {
 namespace test {
 class ScrollViewTestApi;
 }
 
 /////////////////////////////////////////////////////////////////////////////
 //
 // ScrollView class
 //
 // A ScrollView is used to make any View scrollable. The view is added to
@@ skipping 57 matching lines @@
   // View overrides:
   gfx::Size GetPreferredSize() const override;
   int GetHeightForWidth(int width) const override;
   void Layout() override;
   bool OnKeyPressed(const ui::KeyEvent& event) override;
   bool OnMouseWheel(const ui::MouseWheelEvent& e) override;
   void OnMouseEntered(const ui::MouseEvent& event) override;
   void OnMouseExited(const ui::MouseEvent& event) override;
   void OnGestureEvent(ui::GestureEvent* event) override;
   const char* GetClassName() const override;
+  ScrollView* EnclosingScrollView() override;
 
   // ScrollBarController overrides:
   void ScrollToPosition(ScrollBar* source, int position) override;
   int GetScrollIncrement(ScrollBar* source,
                          bool is_page,
                          bool is_positive) override;
 
  private:
   friend class test::ScrollViewTestApi;
 
@@ skipping 16 matching lines @@
                                    bool* horiz_is_shown,
                                    bool* vert_is_shown) const;
 
   // Shows or hides the scrollbar/corner_view based on the value of
   // |should_show|.
   void SetControlVisibility(View* control, bool should_show);
 
   // Update the scrollbars positions given viewport and content sizes.
   void UpdateScrollBarPositions();
 
-  // The current contents and its viewport. |contents_| is contained in
-  // |contents_viewport_|.
+  // Helpers to get and set the current scroll offset (either from the ui::Layer
+  // or from the |contents_| origin offset).
+  gfx::ScrollOffset CurrentOffset() const;
+  void ScrollToOffset(const gfx::ScrollOffset& offset);
+
+  // Callback entrypoint when hosted Layers are scrolled by the Compositor.
+  void OnLayerScrolled();
+
+  // Horizontally scrolls the header (if any) to match the contents.
+  void ScrollHeader();
+
+  // The current contents and its viewport. |contents_| is contained in the
+  // layer-backed |contents_container_| which guarantees it is at least as high
+  // and wide as the |contents_viewport_|, which does the clipping. If
+  // |contents_container_| is null, the origin of |contents_| is offset to
+  // perform scrolling.
   View* contents_;
+  View* contents_container_;
   View* contents_viewport_;
 
   // The current header and its viewport. |header_| is contained in
   // |header_viewport_|.
   View* header_;
   View* header_viewport_;
 
   // Horizontal scrollbar.
   ScrollBar* horiz_sb_;
 
@@ skipping 81 matching lines @@
  private:
   int top_margin_;
   int row_height_;
 
   DISALLOW_COPY_AND_ASSIGN(FixedRowHeightScrollHelper);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_SCROLL_VIEW_H_