Implements core logic for Pixel Canvas

ui/views/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_VIEW_H_
 #define UI_VIEWS_VIEW_H_
 
 #include <stddef.h>
 
 #include <algorithm>
@@ skipping 1028 matching lines @@
   // implementations of common cases.
   virtual int GetPageScrollIncrement(ScrollView* scroll_view,
                                      bool is_horizontal, bool is_positive);
   virtual int GetLineScrollIncrement(ScrollView* scroll_view,
                                      bool is_horizontal, bool is_positive);
 
   void AddObserver(ViewObserver* observer);
   void RemoveObserver(ViewObserver* observer);
   bool HasObserver(const ViewObserver* observer) const;
 
+  // Returns the type of scaling to be done for this View. Values should be from
+  // ui::PaintContext::ScaleType.
+  virtual int GetContextScaleType() const;

[oshima, 2017/06/17 16:05:53]

can you make this protected?

+
  protected:
   // Used to track a drag. RootView passes this into
   // ProcessMousePressed/Dragged.
   struct DragInfo {
     // Sets possible_drag to false and start_x/y to 0. This is invoked by
     // RootView prior to invoke ProcessMousePressed.
     void Reset();
 
     // Sets possible_drag to true and start_pt to the specified point.
     // This is invoked by the target view if it detects the press may generate
@@ skipping 250 matching lines @@
 
   // Schedules a paint on the parent View if it exists.
   void SchedulePaintOnParent();
 
   // Returns whether this view is eligible for painting, i.e. is visible and
   // nonempty.  Note that this does not behave like IsDrawn(), since it doesn't
   // check ancestors recursively; rather, it's used to prune subtrees of views
   // during painting.
   bool ShouldPaint() const;
 
-  // Returns the offset that should be used when constructing the paint context
+  // Returns the bounds that should be used when constructing the paint context
   // for this view.
-  gfx::Vector2d GetPaintContextOffset() const;
+  gfx::Rect GetPaintContextBounds() const;
 
   // Adjusts the transform of |recorder| in advance of painting.
-  void SetupTransformRecorderForPainting(ui::TransformRecorder* recorder) const;
+  void SetupTransformRecorderForPainting(ui::TransformRecorder* recorder,
+                                         const ui::PaintContext& context) const;
 
   // Recursively calls the painting method |func| on all non-layered children,
   // in Z order.
   void RecursivePaintHelper(void (View::*func)(const ui::PaintContext&),
                             const ui::PaintContext& context);
 
   // Invokes Paint() and, if necessary, PaintDebugRects().  Should be called
   // only on the root of a widget/layer.  PaintDebugRects() is invoked as a
   // separate pass, instead of being rolled into Paint(), so that siblings will
   // not obscure debug rects.
@@ skipping 374 matching lines @@
   // Observers -------------------------------------------------------------
 
   base::ObserverList<ViewObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(View);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_VIEW_H_