Implement vertex buffer caching in the tessellated path renderer.

src/core/SkPathRef.cpp

Index: src/core/SkPathRef.cpp
diff --git a/src/core/SkPathRef.cpp b/src/core/SkPathRef.cpp
index 44838f924637ff144a83aa86ac3aaf90f89d76fa..4017c531658304ed319da4e0895ab7c8c03eaad6 100644
--- a/src/core/SkPathRef.cpp
+++ b/src/core/SkPathRef.cpp
@@ -23,12 +23,27 @@ SkPathRef::Editor::Editor(SkAutoTUnref<SkPathRef>* pathRef,
         pathRef->reset(copy);
     }
     fPathRef = *pathRef;
+    fPathRef->callGenIDChangeListeners();
     fPathRef->fGenerationID = 0;
     SkDEBUGCODE(sk_atomic_inc(&fPathRef->fEditorsAttached);)
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
+SkPathRef::~SkPathRef() {
+    this->callGenIDChangeListeners();
+    SkDEBUGCODE(this->validate();)
+    sk_free(fPoints);
+
+    SkDEBUGCODE(fPoints = NULL;)
+    SkDEBUGCODE(fVerbs = NULL;)
+    SkDEBUGCODE(fVerbCnt = 0x9999999;)
+    SkDEBUGCODE(fPointCnt = 0xAAAAAAA;)
+    SkDEBUGCODE(fPointCnt = 0xBBBBBBB;)
+    SkDEBUGCODE(fGenerationID = 0xEEEEEEEE;)
+    SkDEBUGCODE(fEditorsAttached = 0x7777777;)
+}
+
 // As a template argument, this must have external linkage.
 SkPathRef* sk_create_empty_pathref() {
     SkPathRef* empty = SkNEW(SkPathRef);
@@ -154,6 +169,7 @@ SkPathRef* SkPathRef::CreateFromBuffer(SkRBuffer* buffer) {
 void SkPathRef::Rewind(SkAutoTUnref<SkPathRef>* pathRef) {
     if ((*pathRef)->unique()) {
         SkDEBUGCODE((*pathRef)->validate();)
+        (*pathRef)->callGenIDChangeListeners();
         (*pathRef)->fBoundsIsDirty = true;  // this also invalidates fIsFinite
         (*pathRef)->fVerbCnt = 0;
         (*pathRef)->fPointCnt = 0;
@@ -436,6 +452,24 @@ uint32_t SkPathRef::genID() const {
     return fGenerationID;
 }
 
+void SkPathRef::addGenIDChangeListener(GenIDChangeListener* listener) {
+    if (NULL == listener || this == empty.get()) {
+        SkDELETE(listener);
+        return;
+    }
+    *fGenIDChangeListeners.append() = listener;
+}
+
+// we need to be called *before* the genID gets changed or zerod
+void SkPathRef::callGenIDChangeListeners() {
+    for (int i = 0; i < fGenIDChangeListeners.count(); i++) {
+        fGenIDChangeListeners[i]->onChange();
+    }
+
+    // Listeners get at most one shot, so whether these triggered or not, blow them away.
+    fGenIDChangeListeners.deleteAll();
+}
+
 #ifdef SK_DEBUG
 void SkPathRef::validate() const {
     this->INHERITED::validate();