Consolidate Windows bitmap and DC code

skia/ext/skia_utils_win.h

 // Copyright (c) 2006-2008 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_SKIA_UTILS_WIN_H_
 #define SKIA_EXT_SKIA_UTILS_WIN_H_
 
+#include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkColor.h"
 
 #include "build/build_config.h"
 #include <windows.h>
 
 struct SkIRect;
 struct SkPoint;
 struct SkRect;
+class SkSurface;
 typedef unsigned long DWORD;
 typedef DWORD COLORREF;
 typedef struct tagPOINT POINT;
 typedef struct tagRECT RECT;
 
 namespace skia {
 
 // Converts a Skia point to a Windows POINT.
 POINT SkPointToPOINT(const SkPoint& point);
 
@@ skipping 16 matching lines @@
 
 // Converts COLORREFs (0BGR) to the ARGB layout Skia expects.
 SK_API SkColor COLORREFToSkColor(COLORREF color);
 
 // Converts ARGB to COLORREFs (0BGR).
 SK_API COLORREF SkColorToCOLORREF(SkColor color);
 
 // Initializes the default settings and colors in a device context.
 SK_API void InitializeDC(HDC context);
 
+// Creates a surface writing to the pixels backing the HDC's bitmap.
+// Returns NULL on error.

[Peter Kasting, 2016/02/16 21:12:10]

Nit: NULL -> null (since this actually returns nullptr)

[tomhudson, 2016/06/21 22:20:22]

"nullptr", or "null"?

[Peter Kasting, 2016/06/22 02:23:33]

"null" -- that reads better in comments than actually saying "nullptr" (think of
its meaning like "this returns the null pointer"  instead of "this returns the
value nullptr").

+SK_API SkSurface* MapPlatformSurface(HDC context);
+
+// Creates a bitmap backed by the same pixels backing the HDC's bitmap.
+// Returns an empty bitmap on error.
+SK_API SkBitmap MapPlatformBitmap(HDC context);
+
+// Creates an offscreen HDC suitable for writing to via MapPlatformSurface().
+// Caller is responsible for calling DeleteDC() when done.
+SK_API HDC CreateOffscreenSurface(int width, int height);
+
 }  // namespace skia
 
 #endif  // SKIA_EXT_SKIA_UTILS_WIN_H_