Offset scissor and viewport when using SetDrawRectangle on surface.

ui/gl/gl_surface.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_GL_GL_SURFACE_H_
 #define UI_GL_GL_SURFACE_H_
 
 #include <string>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "build/build_config.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/rect_f.h"
 #include "ui/gfx/geometry/size.h"
+#include "ui/gfx/geometry/vector2d.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/overlay_transform.h"
 #include "ui/gfx/swap_result.h"
 #include "ui/gl/gl_export.h"
 #include "ui/gl/gl_image.h"
 #include "ui/gl/gl_implementation.h"
 #include "ui/gl/gl_surface_format.h"
 
 namespace gfx {
 class VSyncProvider;
@@ skipping 176 matching lines @@
 
   // Returns true if SwapBuffers or PostSubBuffers causes a flip, such that
   // the next buffer may be 2 frames old.
   virtual bool BuffersFlipped() const;
 
   virtual bool SupportsSetDrawRectangle() const;
 
   // Set the rectangle that will be drawn into on the surface.
   virtual bool SetDrawRectangle(const gfx::Rect& rect);
 
+  // This is the amount by which the scissor and viewport rectangles should be
+  // offset.
+  virtual gfx::Vector2d GetDrawOffset() const;
+
   static GLSurface* GetCurrent();
 
   // Called when the swap interval for the associated context changes.
   virtual void OnSetSwapInterval(int interval);
 
  protected:
   virtual ~GLSurface();
 
   static void SetCurrent(GLSurface* surface);
 
@@ skipping 52 matching lines @@
   bool ScheduleOverlayPlane(int z_order,
                             gfx::OverlayTransform transform,
                             GLImage* image,
                             const gfx::Rect& bounds_rect,
                             const gfx::RectF& crop_rect) override;
   bool IsSurfaceless() const override;
   bool FlipsVertically() const override;
   bool BuffersFlipped() const override;
   bool SupportsSetDrawRectangle() const override;
   bool SetDrawRectangle(const gfx::Rect& rect) override;
+  gfx::Vector2d GetDrawOffset() const override;
   void OnSetSwapInterval(int interval) override;
 
   GLSurface* surface() const { return surface_.get(); }
 
  protected:
   ~GLSurfaceAdapter() override;
 
  private:
   scoped_refptr<GLSurface> surface_;
 
   DISALLOW_COPY_AND_ASSIGN(GLSurfaceAdapter);
 };
 
 // Wraps GLSurface in scoped_refptr and tries to initializes it. Returns a
 // scoped_refptr containing the initialized GLSurface or nullptr if
 // initialization fails.
 GL_EXPORT scoped_refptr<GLSurface> InitializeGLSurface(
     scoped_refptr<GLSurface> surface);
 
 GL_EXPORT scoped_refptr<GLSurface> InitializeGLSurfaceWithFormat(
     scoped_refptr<GLSurface> surface, GLSurfaceFormat format);
 
 }  // namespace gl
 
 #endif  // UI_GL_GL_SURFACE_H_