From 0f89a17b16a7a9f4e29a95e517c05080613e6588 Mon Sep 17 00:00:00 2001
From: Markus Stange <mstange@themasta.com>
Date: Wed, 8 Jan 2014 10:30:57 +0100
Subject: [PATCH] Bug 957366 - Skip the temporary surface during filter drawing
 for DrawTarget-backed gfxContexts. r=roc

---
 layout/svg/nsSVGFilterInstance.cpp | 42 ++++++++++++++++++------------
 layout/svg/nsSVGUtils.cpp          | 31 ----------------------
 layout/svg/nsSVGUtils.h            | 11 --------
 3 files changed, 25 insertions(+), 59 deletions(-)

diff --git a/layout/svg/nsSVGFilterInstance.cpp b/layout/svg/nsSVGFilterInstance.cpp
index acedc86177cb..c88cde07c9e5 100644
--- a/layout/svg/nsSVGFilterInstance.cpp
+++ b/layout/svg/nsSVGFilterInstance.cpp
@@ -459,13 +459,15 @@ nsSVGFilterInstance::Render(gfxContext* aContext)
   }
 
   nsIntRect filterRect = mPostFilterDirtyRect.Intersect(mFilterSpaceBounds);
+  gfxMatrix ctm = GetFilterSpaceToDeviceSpaceTransform();
 
-  if (filterRect.IsEmpty()) {
+  if (filterRect.IsEmpty() || ctm.IsSingular()) {
     return NS_OK;
   }
 
+  Matrix oldDTMatrix;
   nsRefPtr<gfxASurface> resultImage;
-  RefPtr<DrawTarget> resultImageDT;
+  RefPtr<DrawTarget> dt;
   if (aContext->IsCairo()) {
     resultImage =
       gfxPlatform::GetPlatform()->CreateOffscreenSurface(filterRect.Size(),
@@ -474,20 +476,24 @@ nsSVGFilterInstance::Render(gfxContext* aContext)
       return NS_ERROR_OUT_OF_MEMORY;
 
     // Create a Cairo DrawTarget around resultImage.
-    resultImageDT =
-      gfxPlatform::GetPlatform()->CreateDrawTargetForSurface(
-        resultImage, ToIntSize(filterRect.Size()));
+    dt = gfxPlatform::GetPlatform()->CreateDrawTargetForSurface(
+           resultImage, ToIntSize(filterRect.Size()));
   } else {
-    resultImageDT = gfxPlatform::GetPlatform()->CreateOffscreenContentDrawTarget(
-      ToIntSize(filterRect.Size()), FORMAT_B8G8R8A8);
+    // When we have a DrawTarget-backed context, we can call DrawFilter
+    // directly on the target DrawTarget and don't need a temporary DT.
+    dt = aContext->GetDrawTarget();
+    oldDTMatrix = dt->GetTransform();
+    Matrix matrix = ToMatrix(ctm);
+    matrix.Translate(filterRect.x, filterRect.y);
+    dt->SetTransform(matrix * oldDTMatrix);
   }
 
   ComputeNeededBoxes();
 
-  rv = BuildSourceImage(resultImage, resultImageDT);
+  rv = BuildSourceImage(resultImage, dt);
   if (NS_FAILED(rv))
     return rv;
-  rv = BuildSourcePaints(resultImage, resultImageDT);
+  rv = BuildSourcePaints(resultImage, dt);
   if (NS_FAILED(rv))
     return rv;
 
@@ -495,21 +501,23 @@ nsSVGFilterInstance::Render(gfxContext* aContext)
   FilterDescription filter(mPrimitiveDescriptions, filterSpaceBounds);
 
   FilterSupport::RenderFilterDescription(
-    resultImageDT, filter, ToRect(filterRect),
+    dt, filter, ToRect(filterRect),
     mSourceGraphic.mSourceSurface, mSourceGraphic.mSurfaceRect,
     mFillPaint.mSourceSurface, mFillPaint.mSurfaceRect,
     mStrokePaint.mSourceSurface, mStrokePaint.mSurfaceRect,
     mInputImages);
 
-  RefPtr<SourceSurface> resultImageSource;
-  if (!resultImage) {
-    resultImageSource = resultImageDT->Snapshot();
+  if (resultImage) {
+    aContext->Save();
+    aContext->Multiply(ctm);
+    aContext->Translate(filterRect.TopLeft());
+    aContext->SetSource(resultImage);
+    aContext->Paint();
+    aContext->Restore();
+  } else {
+    dt->SetTransform(oldDTMatrix);
   }
 
-  gfxMatrix ctm = GetFilterSpaceToDeviceSpaceTransform();
-  nsSVGUtils::CompositeSurfaceMatrix(aContext, resultImage, resultImageSource,
-                                     filterRect.TopLeft(), ctm);
-
   return NS_OK;
 }
 
diff --git a/layout/svg/nsSVGUtils.cpp b/layout/svg/nsSVGUtils.cpp
index 9c0a363a3b10..aa0a6fe59c5f 100644
--- a/layout/svg/nsSVGUtils.cpp
+++ b/layout/svg/nsSVGUtils.cpp
@@ -841,37 +841,6 @@ nsSVGUtils::GetClipRectForFrame(nsIFrame *aFrame,
   return gfxRect(aX, aY, aWidth, aHeight);
 }
 
-void
-nsSVGUtils::CompositeSurfaceMatrix(gfxContext *aContext,
-                                   gfxASurface *aSurface,
-                                   SourceSurface *aSourceSurface,
-                                   const gfxPoint &aSurfaceOffset,
-                                   const gfxMatrix &aCTM)
-{
-  if (aCTM.IsSingular())
-    return;
-
-  if (aSurface) {
-    aContext->Save();
-    aContext->Multiply(aCTM);
-    aContext->Translate(aSurfaceOffset);
-    aContext->SetSource(aSurface);
-    aContext->Paint();
-    aContext->Restore();
-  } else {
-    DrawTarget *destDT = aContext->GetDrawTarget();
-    Matrix oldMat = destDT->GetTransform();
-    destDT->SetTransform(ToMatrix(aCTM) * oldMat);
-
-    IntSize size = aSourceSurface->GetSize();
-    Rect sourceRect(Point(0, 0), Size(size.width, size.height));
-    Rect drawRect = sourceRect + ToPoint(aSurfaceOffset);
-    destDT->DrawSurface(aSourceSurface, drawRect, sourceRect);
-
-    destDT->SetTransform(oldMat);
-  }
-}
-
 void
 nsSVGUtils::SetClipRect(gfxContext *aContext,
                         const gfxMatrix &aCTM,
diff --git a/layout/svg/nsSVGUtils.h b/layout/svg/nsSVGUtils.h
index b660cf4395a5..8c298f39f5ea 100644
--- a/layout/svg/nsSVGUtils.h
+++ b/layout/svg/nsSVGUtils.h
@@ -413,17 +413,6 @@ public:
   GetClipRectForFrame(nsIFrame *aFrame,
                       float aX, float aY, float aWidth, float aHeight);
 
-  /**
-   * Composites a surface into a context with a given surface offset and an
-   * additional transform. Supports both Thebes and DrawTarget drawing.
-   * If aSurface is null, aSourceSurface will be used instead.
-   */
-  static void CompositeSurfaceMatrix(gfxContext *aContext,
-                                     gfxASurface *aSurface,
-                                     mozilla::gfx::SourceSurface *aSourceSurface,
-                                     const gfxPoint &aSurfaceOffset,
-                                     const gfxMatrix &aCTM);
-
   static void SetClipRect(gfxContext *aContext,
                           const gfxMatrix &aCTM,
                           const gfxRect &aRect);