Modified platform bitmap to support GDI being unavailable

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 "base/debug/gdi_debug_util_win.h"
 #include "base/logging.h"
+#include "base/win/win_util.h"
 #include "skia/ext/bitmap_platform_device_win.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"
 
 namespace {
 
 HBITMAP CreateHBitmap(int width, int height, bool is_opaque,
@@ skipping 81 matching lines @@
   if (!config_dirty_ || !hdc_)
     return;  // Nothing to do.
   config_dirty_ = false;
 
   // Transform.
   LoadTransformToDC(hdc_, transform_);
   LoadClippingRegionToDC(hdc_, clip_region_, transform_);
 }
 
 static void DeleteHBitmapCallback(void* addr, void* context) {
-  DeleteObject(static_cast<HBITMAP>(context));
+  // If context is not NULL then it's a valid HBITMAP to delete.
+  // Otherwise we just unmap the pixel memory.
+  if (context)
+    DeleteObject(static_cast<HBITMAP>(context));
+  else
+    UnmapViewOfFile(addr);
 }
 
 static bool InstallHBitmapPixels(SkBitmap* bitmap, int width, int height,
                                  bool is_opaque, void* data, HBITMAP hbitmap) {
   const SkAlphaType at = is_opaque ? kOpaque_SkAlphaType : kPremul_SkAlphaType;
   const SkImageInfo info = SkImageInfo::MakeN32(width, height, at);
   const size_t rowBytes = info.minRowBytes();
   SkColorTable* color_table = NULL;
   return bitmap->installPixels(info, data, rowBytes, color_table,
                                DeleteHBitmapCallback, hbitmap);
 }
 
 // We use this static factory function instead of the regular constructor so
 // 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,
     bool do_clear) {
 
   void* data;
-  HBITMAP hbitmap = CreateHBitmap(width, height, is_opaque, shared_section,
-                                  &data);
-  if (!hbitmap)
-    return NULL;
+  HBITMAP hbitmap = NULL;
+
+  // This function contains an implementation of a Skia platform bitmap for
+  // drawing and compositing graphics. The original implementation uses Windows
+  // GDI to create the backing bitmap memory, however it's possible for a
+  // process to not have access to GDI which will cause this code to fail. It's
+  // possible to detect when GDI is unavailable and instead directly map the
+  // shared memory as the bitmap.
+  if (base::win::IsUser32AndGdi32Available()) {
+    hbitmap = CreateHBitmap(width, height, is_opaque, shared_section, &data);
+    if (!hbitmap)
+      return NULL;
+  } else {
+    DCHECK(shared_section != NULL);
+    data = MapViewOfFile(shared_section, FILE_MAP_WRITE, 0, 0,
+                         PlatformCanvasStrideForWidth(width) * height);
+    if (!data)
+      return NULL;
+  }
 
   SkBitmap bitmap;
   if (!InstallHBitmapPixels(&bitmap, width, height, is_opaque, data, hbitmap))
     return NULL;
 
   if (do_clear)
     bitmap.eraseColor(0);
 
 #ifndef NDEBUG
   // If we were given data, then don't clobber it!
@@ skipping 22 matching lines @@
     HBITMAP hbitmap,
     const SkBitmap& bitmap)
     : SkBitmapDevice(bitmap),
       hbitmap_(hbitmap),
       old_hbitmap_(NULL),
       hdc_(NULL),
       config_dirty_(true),  // Want to load the config next time.
       transform_(SkMatrix::I()) {
   // The data object is already ref'ed for us by create().
   SkDEBUGCODE(begin_paint_count_ = 0);
-  SetPlatformDevice(this, this);
-  // Initialize the clip region to the entire bitmap.
-  BITMAP bitmap_data;
-  if (GetObject(hbitmap_, sizeof(BITMAP), &bitmap_data)) {
-    SkIRect rect;
-    rect.set(0, 0, bitmap_data.bmWidth, bitmap_data.bmHeight);
-    clip_region_ = SkRegion(rect);
+  if (hbitmap) {
+    SetPlatformDevice(this, this);
+    // Initialize the clip region to the entire bitmap.
+    BITMAP bitmap_data;
+    if (GetObject(hbitmap_, sizeof(BITMAP), &bitmap_data)) {
+      SkIRect rect;
+      rect.set(0, 0, bitmap_data.bmWidth, bitmap_data.bmHeight);
+      clip_region_ = SkRegion(rect);
+    }
   }
 }
 
 BitmapPlatformDevice::~BitmapPlatformDevice() {
   SkASSERT(begin_paint_count_ == 0);
   if (hdc_)
     ReleaseBitmapDC();
 }
 
 HDC BitmapPlatformDevice::BeginPlatformPaint() {
@@ skipping 120 matching lines @@
   platform_extra_ = reinterpret_cast<intptr_t>(stock_bitmap);
 
   if (!InstallHBitmapPixels(&bitmap_, width, height, is_opaque, data, hbitmap))
     return false;
   bitmap_.lockPixels();
 
   return true;
 }
 
 }  // namespace skia