Bug 961783. Remove unneeded DDB optimization. r=vlad

As far as I can tell we always draw images to dc's that are in system memory.
In this case there's no upside to having ddb and a potential downside because
we have to do a readback from gpu into system memory.

--HG--
extra : rebase_source : e536721adc1de2bcff3300ee29c2d1c4b8c15ac0

gfx/thebes/gfxWindowsSurface.cpp

@@ -199,31 +199,6 @@ gfxWindowsSurface::GetAsImageSurface()
     return result.forget();
 }
 
-already_AddRefed<gfxWindowsSurface>
-gfxWindowsSurface::OptimizeToDDB(HDC dc, const gfxIntSize& size, gfxImageFormat format)
-{
-    if (mForPrinting)
-        return nullptr;
-
-    if (format != gfxImageFormatRGB24)
-        return nullptr;
-
-    nsRefPtr<gfxWindowsSurface> wsurf = new gfxWindowsSurface(dc, size, format);
-    if (wsurf->CairoStatus() != 0)
-        return nullptr;
-
-    gfxContext tmpCtx(wsurf);
-    tmpCtx.SetOperator(gfxContext::OPERATOR_SOURCE);
-    tmpCtx.SetSource(this);
-    tmpCtx.Paint();
-
-    // we let the new DDB surfaces be converted back to dibsections if
-    // acquire_source_image is called on them
-    cairo_win32_surface_set_can_convert_to_dib(wsurf->CairoSurface(), TRUE);
-
-    return wsurf.forget().downcast<gfxWindowsSurface>();
-}
-
 nsresult
 gfxWindowsSurface::BeginPrinting(const nsAString& aTitle,
                                  const nsAString& aPrintToFileName)

gfx/thebes/gfxWindowsSurface.h

@@ -57,10 +57,6 @@ public:
 
     already_AddRefed<gfxImageSurface> GetAsImageSurface();
 
-    already_AddRefed<gfxWindowsSurface> OptimizeToDDB(HDC dc,
-                                                      const gfxIntSize& size,
-                                                      gfxImageFormat format);
-
     nsresult BeginPrinting(const nsAString& aTitle, const nsAString& aPrintToFileName);
     nsresult EndPrinting();
     nsresult AbortPrinting();

image/src/imgFrame.cpp

@@ -28,13 +28,6 @@ static bool gDisableOptimize = false;
 /* Whether to use the windows surface; only for desktop win32 */
 #define USE_WIN_SURFACE 1
 
-static uint32_t gTotalDDBs = 0;
-static uint32_t gTotalDDBSize = 0;
-// only use up a maximum of 64MB in DDBs
-#define kMaxDDBSize (64*1024*1024)
-// and don't let anything in that's bigger than 4MB
-#define kMaxSingleDDBSize (4*1024*1024)
-
 #endif
 
 using namespace mozilla;
@@ -113,9 +106,6 @@ imgFrame::imgFrame() :
   mFormatChanged(false),
   mCompositingFailed(false),
   mNonPremult(false),
-#ifdef USE_WIN_SURFACE
-  mIsDDBSurface(false),
-#endif
   mInformedDiscardTracker(false),
   mDirty(false)
 {
@@ -132,12 +122,6 @@ imgFrame::~imgFrame()
 {
   moz_free(mPalettedImageData);
   mPalettedImageData = nullptr;
-#ifdef USE_WIN_SURFACE
-  if (mIsDDBSurface) {
-      gTotalDDBs--;
-      gTotalDDBSize -= mSize.width * mSize.height * 4;
-  }
-#endif
 
   if (mInformedDiscardTracker) {
     DiscardTracker::InformAllocation(-4 * mSize.height * mSize.width);
@@ -296,40 +280,8 @@ nsresult imgFrame::Optimize()
   mOptSurface = nullptr;
 
 #ifdef USE_WIN_SURFACE
-  // we need to special-case windows here, because windows has
-  // a distinction between DIB and DDB and we want to use DDBs as much
-  // as we can.
   if (mWinSurface) {
-    // Don't do DDBs for large images; see bug 359147
-    // Note that we bother with DDBs at all because they are much faster
-    // on some systems; on others there isn't much of a speed difference
-    // between DIBs and DDBs.
-    //
-    // Originally this just limited to 1024x1024; but that still
-    // had us hitting overall total memory usage limits (which was
-    // around 220MB on my intel shared memory system with 2GB RAM
-    // and 16-128mb in use by the video card, so I can't make
-    // heads or tails out of this limit).
-    //
-    // So instead, we clamp the max size to 64MB (this limit shuld
-    // be made dynamic based on.. something.. as soon a we figure
-    // out that something) and also limit each individual image to
-    // be less than 4MB to keep very large images out of DDBs.
-
-    // assume (almost -- we don't quadword-align) worst-case size
-    uint32_t ddbSize = mSize.width * mSize.height * 4;
-    if (ddbSize <= kMaxSingleDDBSize &&
-        ddbSize + gTotalDDBSize <= kMaxDDBSize)
-    {
-      nsRefPtr<gfxWindowsSurface> wsurf = mWinSurface->OptimizeToDDB(nullptr, gfxIntSize(mSize.width, mSize.height), mFormat);
-      if (wsurf) {
-        gTotalDDBs++;
-        gTotalDDBSize += ddbSize;
-        mIsDDBSurface = true;
-        mOptSurface = wsurf;
-      }
-    }
-    if (!mOptSurface && !mFormatChanged) {
+    if (!mFormatChanged) {
       // just use the DIB if the format has not changed
       mOptSurface = mWinSurface;
     }

image/src/imgFrame.h

@@ -178,9 +178,6 @@ private: // data
   /** Have we called DiscardTracker::InformAllocation()? */
   bool mInformedDiscardTracker;
 
-#ifdef XP_WIN
-  bool mIsDDBSurface;
-#endif
   bool mDirty;
 };