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

and a PlatformSurface. This is used to replace the PlatformCanvas that was being
passed to BackingStore to return pixels.

The problem to solve is that PlatformCanvas is an extension of SkCanvas, and
SkCanvas is losing the ability to have its backend specified after its
constructor (for performance reasons).

The BackingStore interface only needs to return a copy of its pixels, and offer
a platform-specific way to draw into it (i.e. BitBlt). The PlatformSurface is
sufficient for this, so the larger infrastructure of PlatformCanvas/PlatformDevice
is not required.
Review URL: https://codereview.chromium.org/11031055

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@161163 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 58 insertions, 30 deletions

diff --git a/skia/ext/bitmap_platform_device_win.cc b/skia/ext/bitmap_platform_device_win.cc
index a52dd4e..12b9266 100644
--- a/skia/ext/bitmap_platform_device_win.cc
+++ b/skia/ext/bitmap_platform_device_win.cc
@@ -6,13 +6,46 @@
 #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(
@@ -94,38 +127,11 @@ BitmapPlatformDevice* BitmapPlatformDevice::Create(
     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)
@@ -262,4 +268,26 @@ SkDevice* BitmapPlatformDevice::onCreateCompatibleDevice(
   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