Allow CanvasSkia to bind to an existing SkCanvas.

skia/ext/canvas_paint_win.h

 // Copyright (c) 2009 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 SKIA_EXT_CANVAS_PAINT_WIN_H_
 #define SKIA_EXT_CANVAS_PAINT_WIN_H_
 #pragma once
 
+#include "skia/ext/canvas_paint_common.h"
 #include "skia/ext/platform_canvas.h"
 
 namespace skia {
 
 // A class designed to help with WM_PAINT operations on Windows. It will
 // do BeginPaint/EndPaint on init/destruction, and will create the bitmap and
 // canvas with the correct size and transform for the dirty rect. The bitmap
 // will be automatically painted to the screen on destruction.
 //
 // You MUST call isEmpty before painting to determine if anything needs
@@ skipping 34 matching lines @@
     memset(&ps_, 0, sizeof(ps_));
     ps_.rcPaint.left = x;
     ps_.rcPaint.right = x + w;
     ps_.rcPaint.top = y;
     ps_.rcPaint.bottom = y + h;
     init(opaque);
   }
 
   virtual ~CanvasPaintT() {
     if (!isEmpty()) {
-      restoreToCount(1);
+      PlatformCanvas* canvas = GetPlatformCanvas(this);
+      canvas->restoreToCount(1);
       // Commit the drawing to the screen
-      skia::DrawToNativeContext(this, paint_dc_, ps_.rcPaint.left,
+      skia::DrawToNativeContext(canvas, paint_dc_, ps_.rcPaint.left,
                                 ps_.rcPaint.top, NULL);
     }
     if (for_paint_)
       EndPaint(hwnd_, &ps_);
   }
 
   // Returns true if the invalid region is empty. The caller should call this
   // function to determine if anything needs painting.
   bool isEmpty() const {
     return ps_.rcPaint.right - ps_.rcPaint.left == 0 ||
@@ skipping 17 matching lines @@
   PAINTSTRUCT ps_;
 
  private:
   void initPaint(bool opaque) {
     paint_dc_ = BeginPaint(hwnd_, &ps_);
 
     init(opaque);
   }
 
   void init(bool opaque) {
+    PlatformCanvas* canvas = GetPlatformCanvas(this);
     // FIXME(brettw) for ClearType, we probably want to expand the bounds of
     // painting by one pixel so that the boundaries will be correct (ClearType
     // text can depend on the adjacent pixel). Then we would paint just the
     // inset pixels to the screen.
     const int width = ps_.rcPaint.right - ps_.rcPaint.left;
     const int height = ps_.rcPaint.bottom - ps_.rcPaint.top;
-    if (!initialize(width, height, opaque, NULL)) {
+    if (!canvas->initialize(width, height, opaque, NULL)) {
       // Cause a deliberate crash;
       *(char*) 0 = 0;
     }
 
     // This will bring the canvas into the screen coordinate system for the
     // dirty rect
-    translate(SkIntToScalar(-ps_.rcPaint.left),
-              SkIntToScalar(-ps_.rcPaint.top));
+    canvas->translate(SkIntToScalar(-ps_.rcPaint.left),
+                      SkIntToScalar(-ps_.rcPaint.top));
   }
 
   // If true, this canvas was created for a BeginPaint.
   const bool for_paint_;
 
   // Disallow copy and assign.
   CanvasPaintT(const CanvasPaintT&);
   CanvasPaintT& operator=(const CanvasPaintT&);
 };
 
 typedef CanvasPaintT<PlatformCanvas> PlatformCanvasPaint;
 
 }  // namespace skia
 
 #endif  // SKIA_EXT_CANVAS_PAINT_WIN_H_