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..38b4e71cba1d4479eba42c7846ba833f533d0965 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;
@@ -215,13 +231,6 @@ bool SkPathRef::operator== (const SkPathRef& ref) const {
         SkASSERT(!genIDMatch);
         return false;
     }
-    // We've done the work to determine that these are equal. If either has a zero genID, copy
-    // the other's. If both are 0 then genID() will compute the next ID.
-    if (0 == fGenerationID) {
-        fGenerationID = ref.genID();
-    } else if (0 == ref.fGenerationID) {
-        ref.fGenerationID = this->genID();
-    }
     return true;
 }
 
@@ -269,9 +278,6 @@ void SkPathRef::copy(const SkPathRef& ref,
     memcpy(this->verbsMemWritable(), ref.verbsMemBegin(), ref.fVerbCnt * sizeof(uint8_t));
     memcpy(this->fPoints, ref.fPoints, ref.fPointCnt * sizeof(SkPoint));
     fConicWeights = ref.fConicWeights;
-    // We could call genID() here to force a real ID (instead of 0). However, if we're making
-    // a copy then presumably we intend to make a modification immediately afterwards.
-    fGenerationID = ref.fGenerationID;
     fBoundsIsDirty = ref.fBoundsIsDirty;
     if (!fBoundsIsDirty) {
         fBounds = ref.fBounds;
@@ -436,6 +442,24 @@ 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();