Create SkLayerRasterizer w/o destroying Builder.

src/effects/SkLayerRasterizer.cpp

Index: src/effects/SkLayerRasterizer.cpp
diff --git a/src/effects/SkLayerRasterizer.cpp b/src/effects/SkLayerRasterizer.cpp
index e35c5e828fb253d5447e36cf281f21172bf4a8ac..7143a3b40e915839406efb9fa401cd59d7a50ae2 100644
--- a/src/effects/SkLayerRasterizer.cpp
+++ b/src/effects/SkLayerRasterizer.cpp
@@ -34,15 +34,20 @@ SkLayerRasterizer::SkLayerRasterizer(SkDeque* layers) : fLayers(layers)
 {
 }
 
-SkLayerRasterizer::~SkLayerRasterizer() {
-    SkASSERT(fLayers);
-    SkDeque::F2BIter        iter(*fLayers);
+// Helper function to call destructors on SkPaints held by layers and delete layers.
+static void clean_up_layers(SkDeque* layers) {
+    SkDeque::F2BIter        iter(*layers);
     SkLayerRasterizer_Rec*  rec;
 
     while ((rec = (SkLayerRasterizer_Rec*)iter.next()) != NULL)
         rec->fPaint.~SkPaint();
 
-    SkDELETE(fLayers);
+    SkDELETE(layers);
+}
+
+SkLayerRasterizer::~SkLayerRasterizer() {
+    SkASSERT(fLayers);
+    clean_up_layers(const_cast<SkDeque*>(fLayers));
 }
 
 #ifdef SK_SUPPORT_LEGACY_LAYERRASTERIZER_API
@@ -194,7 +199,9 @@ SkLayerRasterizer::Builder::Builder()
 
 SkLayerRasterizer::Builder::~Builder()
 {
-    SkDELETE(fLayers);
+    if (fLayers != NULL) {
+        clean_up_layers(fLayers);
+    }
 }
 
 void SkLayerRasterizer::Builder::addLayer(const SkPaint& paint, SkScalar dx,
@@ -211,3 +218,20 @@ SkLayerRasterizer* SkLayerRasterizer::Builder::detachRasterizer() {
     fLayers = NULL;
     return rasterizer;
 }
+
+SkLayerRasterizer* SkLayerRasterizer::Builder::snapshotRasterizer() const {
+    SkDeque* layers = SkNEW_ARGS(SkDeque, (sizeof(SkLayerRasterizer_Rec), fLayers->count()));
+    SkDeque::F2BIter                iter(*fLayers);
+    const SkLayerRasterizer_Rec*    recOrig;
+    SkDEBUGCODE(int                 count = 0;)
+    while ((recOrig = static_cast<SkLayerRasterizer_Rec*>(iter.next())) != NULL) {
+        SkDEBUGCODE(count++);
+        SkLayerRasterizer_Rec* recCopy = static_cast<SkLayerRasterizer_Rec*>(layers->push_back());
+        SkNEW_PLACEMENT_ARGS(&recCopy->fPaint, SkPaint, (recOrig->fPaint));
+        recCopy->fOffset = recOrig->fOffset;
+    }
+    SkASSERT(fLayers->count() == count);
+    SkASSERT(layers->count() == count);
+    SkLayerRasterizer* rasterizer = SkNEW_ARGS(SkLayerRasterizer, (layers));
+    return rasterizer;
+}