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 19 matching lines @@
 
   // Set the contents. Any previous contents will be deleted. The contents
   // is the view that needs to scroll.
   void SetContents(View* a_view);
   const View* contents() const { return contents_; }
   View* contents() { return contents_; }
 
   // Sets the header, deleting the previous header.
   void SetHeader(View* header);
 
+  // Sets the background color. The default is white when scrolling with layers,
+  // otherwise transparent. An opaque color when scrolling with layers ensures
+  // fonts can be drawn with subpixel antialiasing.
+  void SetBackgroundColor(SkColor color);
+
   // Returns the visible region of the content View.
   gfx::Rect GetVisibleRect() const;
 
   void set_hide_horizontal_scrollbar(bool visible) {
     hide_horizontal_scrollbar_ = visible;
   }
 
   // Turns this scroll view into a bounded scroll view, with a fixed height.
   // By default, a ScrollView will stretch to fill its outer container.
   void ClipHeightTo(int min_height, int max_height);
@@ skipping 54 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();
 
+  // 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);
+
+  // Whether the ScrollView scrolls using ui::Layer APIs.
+  bool ScrollsWithLayers() const;
+
+  // 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
   // |contents_viewport_|.
   View* contents_;
   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_;
 
   // Vertical scrollbar.
   ScrollBar* vert_sb_;
 
   // Corner view.
   View* corner_view_;
 
   // The min and max height for the bounded scroll view. These are negative
   // values if the view is not bounded.
   int min_height_;
   int max_height_;
 
+  // The background color given to the viewport (for overscroll), and to the
+  // contents when scrolling with layers.
+  SkColor background_color_;
+
   // If true, never show the horizontal scrollbar (even if the contents is wider
   // than the viewport).
   bool hide_horizontal_scrollbar_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollView);
 };
 
 // VariableRowHeightScrollHelper is intended for views that contain rows of
 // varying height. To use a VariableRowHeightScrollHelper create one supplying
 // a Controller and delegate GetPageScrollIncrement and GetLineScrollIncrement
@@ skipping 60 matching lines @@
  private:
   int top_margin_;
   int row_height_;
 
   DISALLOW_COPY_AND_ASSIGN(FixedRowHeightScrollHelper);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_SCROLL_VIEW_H_