Bug 688368 - Make SourceSurfaceSkia data surfaces copy-on-write. r=joe

gfx/2d/DrawTargetSkia.cpp

@@ -201,16 +201,17 @@ DrawTargetSkia::DrawTargetSkia()
 
 DrawTargetSkia::~DrawTargetSkia()
 {
+  MarkChanged();
 }
 
 TemporaryRef<SourceSurface>
 DrawTargetSkia::Snapshot()
 {
-  //TODO: Wrong! Copy the pixels, preferably lazily
   RefPtr<SourceSurfaceSkia> source = new SourceSurfaceSkia();
-  if (!source->InitWithBitmap(mCanvas.get(), mFormat)) {
+  if (!source->InitWithBitmap(mBitmap, mFormat, this)) {
     return NULL;
   }
+  AppendSnapshot(source);
   return source;
 }
 
@@ -383,6 +384,8 @@ DrawTargetSkia::DrawSurface(SourceSurface *aSurface,
     return;
   }
 
+  MarkChanged();
+
   NS_ASSERTION(aSurfOptions.mFilter == FILTER_LINEAR, "Only linear filtering supported currently!");
   SkRect destRect = RectToSkRect(aDest);
   SkRect sourceRect = RectToSkRect(aSource);
@@ -407,6 +410,7 @@ DrawTargetSkia::DrawSurfaceWithShadow(SourceSurface *aSurface,
                                       Float aSigma,
                                       CompositionOp aOperator)
 {
+  MarkChanged();
   mCanvas->save(SkCanvas::kMatrix_SaveFlag);
   mCanvas->resetMatrix();
 
@@ -466,6 +470,7 @@ DrawTargetSkia::FillRect(const Rect &aRect,
                          const Pattern &aPattern,
                          const DrawOptions &aOptions)
 {
+  MarkChanged();
   SkRect rect = RectToSkRect(aRect);
   AutoPaintSetup paint(mCanvas.get(), aOptions, aPattern);
 
@@ -478,6 +483,7 @@ DrawTargetSkia::Stroke(const Path *aPath,
                        const StrokeOptions &aStrokeOptions,
                        const DrawOptions &aOptions)
 {
+  MarkChanged();
   if (aPath->GetBackendType() != BACKEND_SKIA) {
     return;
   }
@@ -497,6 +503,7 @@ DrawTargetSkia::StrokeRect(const Rect &aRect,
                            const StrokeOptions &aStrokeOptions,
                            const DrawOptions &aOptions)
 {
+  MarkChanged();
   AutoPaintSetup paint(mCanvas.get(), aOptions, aPattern);
   paint.SetStroke(aStrokeOptions);
 
@@ -510,6 +517,7 @@ DrawTargetSkia::StrokeLine(const Point &aStart,
                            const StrokeOptions &aStrokeOptions,
                            const DrawOptions &aOptions)
 {
+  MarkChanged();
   AutoPaintSetup paint(mCanvas.get(), aOptions, aPattern);
   paint.SetStroke(aStrokeOptions);
 
@@ -523,6 +531,7 @@ DrawTargetSkia::Fill(const Path *aPath,
                     const Pattern &aPattern,
                     const DrawOptions &aOptions)
 {
+  MarkChanged();
   if (aPath->GetBackendType() != BACKEND_SKIA) {
     return;
   }
@@ -544,6 +553,8 @@ DrawTargetSkia::FillGlyphs(ScaledFont *aFont,
     return;
   }
 
+  MarkChanged();
+
   ScaledFontSkia* skiaFont = static_cast<ScaledFontSkia*>(aFont);
 
   AutoPaintSetup paint(mCanvas.get(), aOptions, aPattern);
@@ -614,6 +625,8 @@ DrawTargetSkia::CopySurface(SourceSurface *aSurface,
     return;
   }
 
+  MarkChanged();
+  
   const SkBitmap& bitmap = static_cast<SourceSurfaceSkia*>(aSurface)->GetBitmap();
 
   mCanvas->save();
@@ -664,6 +677,7 @@ DrawTargetSkia::CreatePathBuilder(FillRule aFillRule) const
 void
 DrawTargetSkia::ClearRect(const Rect &aRect)
 {
+  MarkChanged();
   SkPaint paint;
   mCanvas->save();
   mCanvas->clipRect(RectToSkRect(aRect), SkRegion::kIntersect_Op);
@@ -704,5 +718,33 @@ DrawTargetSkia::CreateGradientStops(GradientStop *aStops, uint32_t aNumStops) co
   return new GradientStopsSkia(stops, aNumStops);
 }
 
+void
+DrawTargetSkia::AppendSnapshot(SourceSurfaceSkia* aSnapshot)
+{
+  mSnapshots.push_back(aSnapshot);
+}
+
+void
+DrawTargetSkia::RemoveSnapshot(SourceSurfaceSkia* aSnapshot)
+{
+  std::vector<SourceSurfaceSkia*>::iterator iter = std::find(mSnapshots.begin(), mSnapshots.end(), aSnapshot);
+  if (iter != mSnapshots.end()) {
+    mSnapshots.erase(iter);
+  }
+}
+
+void
+DrawTargetSkia::MarkChanged()
+{
+  if (mSnapshots.size()) {
+    for (std::vector<SourceSurfaceSkia*>::iterator iter = mSnapshots.begin();
+         iter != mSnapshots.end(); iter++) {
+      (*iter)->DrawTargetWillChange();
+    }
+    // All snapshots will now have copied data.
+    mSnapshots.clear();
+  }
+}
+
 }
 }

gfx/2d/DrawTargetSkia.h

@@ -42,12 +42,15 @@
 #include "Rect.h"
 #include "PathSkia.h"
 #include <sstream>
+#include <vector>
 using namespace std;
 #include "gfxImageSurface.h"
 
 namespace mozilla {
 namespace gfx {
 
+class SourceSurfaceSkia;
+
 class DrawTargetSkia : public DrawTarget
 {
 public:
@@ -119,6 +122,11 @@ public:
     return stream.str();
   }
 private:
+  friend class SourceSurfaceSkia;
+  void AppendSnapshot(SourceSurfaceSkia* aSnapshot);
+  void RemoveSnapshot(SourceSurfaceSkia* aSnapshot);
+
+  void MarkChanged();
 
   IntSize mSize;
   SkBitmap mBitmap;
@@ -126,6 +134,7 @@ private:
   SkRefPtr<SkDevice> mDevice;
   nsRefPtr<gfxImageSurface> mImageSurface;
   SurfaceFormat mFormat;
+  vector<SourceSurfaceSkia*> mSnapshots;
 };
 
 }

gfx/2d/SourceSurfaceSkia.cpp

@@ -41,16 +41,19 @@
 #include "skia/SkBitmap.h"
 #include "skia/SkDevice.h"
 #include "HelpersSkia.h"
+#include "DrawTargetSkia.h"
 
 namespace mozilla {
 namespace gfx {
 
 SourceSurfaceSkia::SourceSurfaceSkia()
+  : mDrawTarget(NULL)
 {
 }
 
 SourceSurfaceSkia::~SourceSurfaceSkia()
 {
+  MarkIndependent();
 }
 
 IntSize
@@ -86,13 +89,20 @@ SourceSurfaceSkia::InitFromData(unsigned char* aData,
 }
 
 bool
-SourceSurfaceSkia::InitWithBitmap(SkCanvas* aBitmap,
-                                  SurfaceFormat aFormat)
+SourceSurfaceSkia::InitWithBitmap(const SkBitmap& aBitmap,
+                                  SurfaceFormat aFormat,
+                                  DrawTargetSkia* aOwner)
 {
-  if (aBitmap->readPixels(&mBitmap)) {
-    mStride = mBitmap.rowBytes();
-    mSize = IntSize(mBitmap.width(), mBitmap.height());
   mFormat = aFormat;
+  mSize = IntSize(aBitmap.width(), aBitmap.height());
+
+  if (aOwner) {
+    mBitmap = aBitmap;
+    mStride = aBitmap.rowBytes();
+    mDrawTarget = aOwner;
+    return true;
+  } else if (aBitmap.copyTo(&mBitmap, aBitmap.getConfig())) {
+    mStride = mBitmap.rowBytes();
     return true;
   }
   return false;
@@ -108,6 +118,26 @@ SourceSurfaceSkia::GetData()
 
 }
 
+void
+SourceSurfaceSkia::DrawTargetWillChange()
+{
+  if (mDrawTarget) {
+    mDrawTarget = NULL;
+    SkBitmap temp = mBitmap;
+    mBitmap.reset();
+    temp.copyTo(&mBitmap, temp.getConfig());
+  }
+}
+
+void
+SourceSurfaceSkia::MarkIndependent()
+{
+  if (mDrawTarget) {
+    mDrawTarget->RemoveSnapshot(this);
+    mDrawTarget = NULL;
+  }
+}
+
 
 }
 }

gfx/2d/SourceSurfaceSkia.h

@@ -46,6 +46,8 @@
 namespace mozilla {
 namespace gfx {
 
+class DrawTargetSkia;
+
 class SourceSurfaceSkia : public DataSourceSurface
 {
 public:
@@ -63,8 +65,13 @@ public:
                     int32_t aStride,
                     SurfaceFormat aFormat);
 
-  bool InitWithBitmap(SkCanvas* aBitmap,
-                      SurfaceFormat aFormat);
+  /**
+   * If aOwner is NULL, we make a copy of the pixel data in the bitmap, 
+   * otherwise we just reference this data until DrawTargetWillChange is called.
+   */
+  bool InitWithBitmap(const SkBitmap& aBitmap,
+                      SurfaceFormat aFormat,
+                      DrawTargetSkia* aOwner);
 
 
   virtual unsigned char *GetData();
@@ -74,10 +81,14 @@ public:
 private:
   friend class DrawTargetSkia;
 
+  void DrawTargetWillChange();
+  void MarkIndependent();
+
   SkBitmap mBitmap;
   SurfaceFormat mFormat;
   IntSize mSize;
   int32_t mStride;
+  DrawTargetSkia* mDrawTarget;
 };
 
 }