From 4b64c371e1f6124f383eb4224a84d9f100b122c9 Mon Sep 17 00:00:00 2001
From: Jonathan Watt <jwatt@jwatt.org>
Date: Tue, 4 Mar 2014 16:56:44 +0000
Subject: [PATCH] Bug 950368 - Make nsWindowsShellService's WriteBitmap act on
 a Moz2D SourceSurface instead of a Thebes gfxASurface. r=mattwoodrow

---
 .../shell/src/nsWindowsShellService.cpp       | 43 ++++++++++++-------
 gfx/thebes/gfxImageSurface.h                  |  3 +-
 2 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/browser/components/shell/src/nsWindowsShellService.cpp b/browser/components/shell/src/nsWindowsShellService.cpp
index 680c126c9888..0d48251bef32 100644
--- a/browser/components/shell/src/nsWindowsShellService.cpp
+++ b/browser/components/shell/src/nsWindowsShellService.cpp
@@ -5,6 +5,8 @@
 
 #include "imgIContainer.h"
 #include "imgIRequest.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/RefPtr.h"
 #include "nsIDOMElement.h"
 #include "nsIDOMHTMLImageElement.h"
 #include "nsIImageLoadingContent.h"
@@ -55,6 +57,8 @@
 #define NS_TASKBAR_CONTRACTID "@mozilla.org/windows-taskbar;1"
 
 using mozilla::IsWin8OrLater;
+using namespace mozilla;
+using namespace mozilla::gfx;
 
 NS_IMPL_ISUPPORTS2(nsWindowsShellService, nsIWindowsShellService, nsIShellService)
 
@@ -749,21 +753,30 @@ WriteBitmap(nsIFile* aFile, imgIContainer* aImage)
 {
   nsresult rv;
 
-  nsRefPtr<gfxASurface> surface =
+  nsRefPtr<gfxASurface> thebesSurface =
     aImage->GetFrame(imgIContainer::FRAME_FIRST,
                      imgIContainer::FLAG_SYNC_DECODE);
-  NS_ENSURE_TRUE(surface, NS_ERROR_FAILURE);
+  NS_ENSURE_TRUE(thebesSurface, NS_ERROR_FAILURE);
 
-  nsRefPtr<gfxImageSurface> image(surface->GetAsReadableARGB32ImageSurface());
-  NS_ENSURE_TRUE(image, NS_ERROR_FAILURE);
+  nsRefPtr<gfxImageSurface> thebesImageSurface =
+    thebesSurface->GetAsReadableARGB32ImageSurface();
+  NS_ENSURE_TRUE(thebesImageSurface, NS_ERROR_FAILURE);
 
-  int32_t width = image->Width();
-  int32_t height = image->Height();
+  RefPtr<DataSourceSurface> dataSurface =
+    thebesImageSurface->CopyToB8G8R8A8DataSourceSurface();
+  NS_ENSURE_TRUE(dataSurface, NS_ERROR_FAILURE);
 
-  uint8_t* bits = image->Data();
-  uint32_t length = image->GetDataSize();
-  uint32_t bpr = uint32_t(image->Stride());
-  int32_t bitCount = bpr/width;
+  DataSourceSurface::MappedSurface map;
+  dataSurface->Map(DataSourceSurface::MapType::READ, &map);
+  if (!map.mData) {
+    return NS_ERROR_FAILURE;
+  }
+
+  int32_t width = dataSurface->GetSize().width;
+  int32_t height = dataSurface->GetSize().height;
+  int32_t bytesPerPixel = 4 * sizeof(uint8_t);
+  uint32_t bytesPerRow = bytesPerPixel * width;
+  uint32_t length = map.mStride * height;
 
   // initialize these bitmap structs which we will later
   // serialize directly to the head of the bitmap file
@@ -772,9 +785,9 @@ WriteBitmap(nsIFile* aFile, imgIContainer* aImage)
   bmi.biWidth = width;
   bmi.biHeight = height;
   bmi.biPlanes = 1;
-  bmi.biBitCount = (WORD)bitCount*8;
+  bmi.biBitCount = (WORD)bytesPerPixel*8;
   bmi.biCompression = BI_RGB;
-  bmi.biSizeImage = length;
+  bmi.biSizeImage = bytesPerRow * height;
   bmi.biXPelsPerMeter = 0;
   bmi.biYPelsPerMeter = 0;
   bmi.biClrUsed = 0;
@@ -804,9 +817,9 @@ WriteBitmap(nsIFile* aFile, imgIContainer* aImage)
         // show bitmaps with negative heights for top-to-bottom
         uint32_t i = length;
         do {
-          i -= bpr;
-          stream->Write(((const char*)bits) + i, bpr, &written);
-          if (written == bpr) {
+          i -= map.mStride;
+          stream->Write(((const char*)map.mData) + i, bytesPerRow, &written);
+          if (written == bytesPerRow) {
             rv = NS_OK;
           } else {
             rv = NS_ERROR_FAILURE;
diff --git a/gfx/thebes/gfxImageSurface.h b/gfx/thebes/gfxImageSurface.h
index 983cf6754327..2c86dd7f5646 100644
--- a/gfx/thebes/gfxImageSurface.h
+++ b/gfx/thebes/gfxImageSurface.h
@@ -112,8 +112,9 @@ public:
 
     /**
      * Copy to a Moz2D DataSourceSurface.
+     * Marked as virtual so that browsercomps can access this method.
      */
-    mozilla::TemporaryRef<mozilla::gfx::DataSourceSurface> CopyToB8G8R8A8DataSourceSurface();
+    virtual mozilla::TemporaryRef<mozilla::gfx::DataSourceSurface> CopyToB8G8R8A8DataSourceSurface();
 
     /* return new Subimage with pointing to original image starting from aRect.pos
      * and size of aRect.size. New subimage keeping current image reference