use SkRasterHandleAllocator to support GDI drawing in SkCanvas

skia/ext/bitmap_platform_device_win.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 SKIA_EXT_BITMAP_PLATFORM_DEVICE_WIN_H_
-#define SKIA_EXT_BITMAP_PLATFORM_DEVICE_WIN_H_
-
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-#include "skia/ext/platform_device.h"
-
-namespace skia {
-
-// A device is basically a wrapper around SkBitmap that provides a surface for
-// SkCanvas to draw into. Our device provides a surface Windows can also write
-// to. BitmapPlatformDevice creates a bitmap using CreateDIBSection() in a
-// format that Skia supports and can then use this to draw ClearType into, etc.
-// This pixel data is provided to the bitmap that the device contains so that it
-// can be shared.
-class SK_API BitmapPlatformDevice final : public SkBitmapDevice,
-                                          public PlatformDevice {
- public:
-  // Factory function. is_opaque should be set if the caller knows the bitmap
-  // will be completely opaque and allows some optimizations.
-  //
-  // The |shared_section| parameter is optional (pass NULL for default
-  // behavior). If |shared_section| is non-null, then it must be a handle to a
-  // file-mapping object returned by CreateFileMapping.  See CreateDIBSection
-  // for details. If |shared_section| is null, the bitmap backing store is not
-  // initialized.
-  static BitmapPlatformDevice* Create(int width, int height,
-                                      bool is_opaque, HANDLE shared_section,
-                                      bool do_clear = false);
-
-  // Create a BitmapPlatformDevice with no shared section. The bitmap is not
-  // initialized to 0.
-  static BitmapPlatformDevice* Create(int width, int height, bool is_opaque);
-
-  ~BitmapPlatformDevice() override;
-
- protected:
-  SkBaseDevice* onCreateDevice(const CreateInfo&, const SkPaint*) override;
-
- private:
-  // PlatformDevice override
-  // Retrieves the bitmap DC, which is the memory DC for our bitmap data. The
-  // bitmap DC may be lazily created.
-  NativeDrawingContext BeginPlatformPaint(const SkMatrix& transform,
-                                          const SkIRect& clip_bounds) override;
-
-  // Private constructor.
-  BitmapPlatformDevice(HBITMAP hbitmap, const SkBitmap& bitmap);
-
-  // Bitmap into which the drawing will be done. This bitmap not owned by this
-  // class, but by the BitmapPlatformPixelRef inside the device's SkBitmap.
-  // It's only stored here in order to lazy-create the DC (below).
-  HBITMAP hbitmap_;
-
-  // Previous bitmap held by the DC. This will be selected back before the
-  // DC is destroyed.
-  HBITMAP old_hbitmap_;
-
-  // Lazily-created DC used to draw into the bitmap; see GetBitmapDC().
-  HDC hdc_;
-
-  // Create/destroy hdc_, which is the memory DC for our bitmap data.
-  HDC GetBitmapDC(const SkMatrix& transform, const SkIRect& clip_bounds);
-  void ReleaseBitmapDC();
-  bool IsBitmapDCCreated() const;
-
-  // Loads the current transform and clip into the context. Can be called even
-  // when |hbitmap_| is NULL (will be a NOP).
-  void LoadConfig(const SkMatrix& transform, const SkIRect& clip_bounds);
-
-  DISALLOW_COPY_AND_ASSIGN(BitmapPlatformDevice);
-};
-
-}  // namespace skia
-
-#endif  // SKIA_EXT_BITMAP_PLATFORM_DEVICE_WIN_H_