Introduce PlatformBitmap, which is a minimal helper class that wraps an SkBitmap

skia/ext/bitmap_platform_device_win.cc

 // 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.
 
 #include <windows.h>
 #include <psapi.h>
 
 #include "skia/ext/bitmap_platform_device_win.h"
-
 #include "skia/ext/bitmap_platform_device_data.h"
+#include "skia/ext/platform_canvas.h"
 #include "third_party/skia/include/core/SkMatrix.h"
 #include "third_party/skia/include/core/SkRefCnt.h"
 #include "third_party/skia/include/core/SkRegion.h"
 #include "third_party/skia/include/core/SkUtils.h"
 
+static HBITMAP CreateHBitmap(int width, int height, bool is_opaque,
+                             HANDLE shared_section, SkBitmap* output) {
+  // CreateDIBSection appears to get unhappy if we create an empty bitmap, so
+  // just create a minimal bitmap
+  if ((width == 0) || (height == 0)) {
+    width = 1;
+    height = 1;
+  }
+    
+  BITMAPINFOHEADER hdr = {0};
+  hdr.biSize = sizeof(BITMAPINFOHEADER);
+  hdr.biWidth = width;
+  hdr.biHeight = -height;  // minus means top-down bitmap
+  hdr.biPlanes = 1;
+  hdr.biBitCount = 32;
+  hdr.biCompression = BI_RGB;  // no compression
+  hdr.biSizeImage = 0;
+  hdr.biXPelsPerMeter = 1;
+  hdr.biYPelsPerMeter = 1;
+  hdr.biClrUsed = 0;
+  hdr.biClrImportant = 0;
+
+  void* data = NULL;
+  HBITMAP hbitmap = CreateDIBSection(NULL, reinterpret_cast<BITMAPINFO*>(&hdr),
+                                     0, &data, shared_section, 0);
+  if (hbitmap) {
+    output->setConfig(SkBitmap::kARGB_8888_Config, width, height);
+    output->setPixels(data);
+    output->setIsOpaque(is_opaque);
+  }
+  return hbitmap;
+}
+
 namespace skia {
 
 BitmapPlatformDevice::BitmapPlatformDeviceData::BitmapPlatformDeviceData(
     HBITMAP hbitmap)
     : bitmap_context_(hbitmap),
       hdc_(NULL),
       config_dirty_(true),  // Want to load the config next time.
       transform_(SkMatrix::I()) {
   // Initialize the clip region to the entire bitmap.
   BITMAP bitmap_data;
@@ skipping 61 matching lines @@
 // that we can create the pixel data before calling the constructor. This is
 // required so that we can call the base class' constructor with the pixel
 // data.
 BitmapPlatformDevice* BitmapPlatformDevice::Create(
     int width,
     int height,
     bool is_opaque,
     HANDLE shared_section) {
   SkBitmap bitmap;
 
-  // CreateDIBSection appears to get unhappy if we create an empty bitmap, so
-  // just create a minimal bitmap
-  if ((width == 0) || (height == 0)) {
-    width = 1;
-    height = 1;
-  }
-
-  BITMAPINFOHEADER hdr = {0};
-  hdr.biSize = sizeof(BITMAPINFOHEADER);
-  hdr.biWidth = width;
-  hdr.biHeight = -height;  // minus means top-down bitmap
-  hdr.biPlanes = 1;
-  hdr.biBitCount = 32;
-  hdr.biCompression = BI_RGB;  // no compression
-  hdr.biSizeImage = 0;
-  hdr.biXPelsPerMeter = 1;
-  hdr.biYPelsPerMeter = 1;
-  hdr.biClrUsed = 0;
-  hdr.biClrImportant = 0;
-
-  void* data = NULL;
-  HBITMAP hbitmap = CreateDIBSection(NULL,
-                                     reinterpret_cast<BITMAPINFO*>(&hdr), 0,
-                                     &data,
-                                     shared_section, 0);
+  HBITMAP hbitmap = CreateHBitmap(width, height, is_opaque, shared_section,
+                                  &bitmap);
   if (!hbitmap)
     return NULL;
 
-  bitmap.setConfig(SkBitmap::kARGB_8888_Config, width, height);
-  bitmap.setPixels(data);
-  bitmap.setIsOpaque(is_opaque);
-
 #ifndef NDEBUG
   // If we were given data, then don't clobber it!
   if (!shared_section && is_opaque)
     // To aid in finding bugs, we set the background color to something
     // obviously wrong so it will be noticable when it is not cleared
     bitmap.eraseARGB(255, 0, 255, 128);  // bright bluish green
 #endif
 
   // The device object will take ownership of the HBITMAP. The initial refcount
   // of the data object will be 1, which is what the constructor expects.
@@ skipping 116 matching lines @@
 
 SkDevice* BitmapPlatformDevice::onCreateCompatibleDevice(
     SkBitmap::Config config, int width, int height, bool isOpaque,
     Usage /*usage*/) {
   SkASSERT(config == SkBitmap::kARGB_8888_Config);
   SkDevice* bitmap_device = BitmapPlatformDevice::CreateAndClear(width, height,
                                                                  isOpaque);
   return bitmap_device;
 }
 
+// Port of PlatformBitmap to win
+
+PlatformBitmap::~PlatformBitmap() {
+  if (surface_)
+    DeleteDC(surface_);
+}
+
+bool PlatformBitmap::Allocate(int width, int height, bool is_opaque) {
+  HBITMAP hbitmap = CreateHBitmap(width, height, is_opaque, 0, &bitmap_);
+  if (!hbitmap)
+    return false;
+
+  surface_ = CreateCompatibleDC(NULL);
+  InitializeDC(surface_);
+  HGDIOBJ old_bitmap = SelectObject(surface_, hbitmap);
+  // When the memory DC is created, its display surface is exactly one
+  // monochrome pixel wide and one monochrome pixel high. Since we select our
+  // own bitmap, we must delete the previous one.
+  DeleteObject(old_bitmap);
+  return true;
+}
+
 }  // namespace skia