Simplify flattening to just write enough to call the factory

src/core/SkXfermode.cpp

Index: src/core/SkXfermode.cpp
diff --git a/src/core/SkXfermode.cpp b/src/core/SkXfermode.cpp
index 0811808d46c3e72813b4c972337b4d662dcf0cee..501c19227626a07ce8f0e8df5ffb4e3502b987c8 100644
--- a/src/core/SkXfermode.cpp
+++ b/src/core/SkXfermode.cpp
@@ -1240,6 +1240,7 @@ GrEffect* XferEffect::TestCreate(SkRandom* rand,
 ///////////////////////////////////////////////////////////////////////////////
 ///////////////////////////////////////////////////////////////////////////////
 
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
 SkProcCoeffXfermode::SkProcCoeffXfermode(SkReadBuffer& buffer) : INHERITED(buffer) {
     uint32_t mode32 = buffer.read32() % SK_ARRAY_COUNT(gProcCoeffs);
     if (mode32 >= SK_ARRAY_COUNT(gProcCoeffs)) {
@@ -1254,6 +1255,19 @@ SkProcCoeffXfermode::SkProcCoeffXfermode(SkReadBuffer& buffer) : INHERITED(buffe
     fSrcCoeff = rec.fSC;
     fDstCoeff = rec.fDC;
 }
+#endif
+
+SkFlattenable* SkProcCoeffXfermode::CreateProc(SkReadBuffer& buffer) {
+    uint32_t mode32 = buffer.read32();
+    if (!buffer.validate(mode32 >= SK_ARRAY_COUNT(gProcCoeffs))) {
+        return NULL;
+    }
+    return SkXfermode::Create((SkXfermode::Mode)mode32);
+}
+
+void SkProcCoeffXfermode::flatten(SkWriteBuffer& buffer) const {
+    buffer.write32(fMode);
+}
 
 bool SkProcCoeffXfermode::asMode(Mode* mode) const {
     if (mode) {
@@ -1376,11 +1390,6 @@ bool SkProcCoeffXfermode::asNewEffect(GrEffect** effect, GrTexture* background)
 }
 #endif
 
-void SkProcCoeffXfermode::flatten(SkWriteBuffer& buffer) const {
-    this->INHERITED::flatten(buffer);
-    buffer.write32(fMode);
-}
-
 const char* SkXfermode::ModeName(Mode mode) {
     SkASSERT((unsigned) mode <= (unsigned)kLastMode);
     const char* gModeStrings[] = {
@@ -1437,12 +1446,18 @@ public:
 
 private:
     SkClearXfermode(const ProcCoeff& rec) : SkProcCoeffXfermode(rec, kClear_Mode) {}
-    SkClearXfermode(SkReadBuffer& buffer)
-        : SkProcCoeffXfermode(buffer) {}
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
+    SkClearXfermode(SkReadBuffer& buffer) : SkProcCoeffXfermode(buffer) {}
+#endif
+    virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE {}
 
     typedef SkProcCoeffXfermode INHERITED;
 };
 
+SkFlattenable* SkClearXfermode::CreateProc(SkReadBuffer& buffer) {
+    return SkXfermode::Create(kClear_Mode);
+}
+
 void SkClearXfermode::xfer32(SkPMColor* SK_RESTRICT dst,
                              const SkPMColor* SK_RESTRICT, int count,
                              const SkAlpha* SK_RESTRICT aa) const {
@@ -1502,12 +1517,18 @@ public:
 
 private:
     SkSrcXfermode(const ProcCoeff& rec) : SkProcCoeffXfermode(rec, kSrc_Mode) {}
-    SkSrcXfermode(SkReadBuffer& buffer)
-        : SkProcCoeffXfermode(buffer) {}
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
+    SkSrcXfermode(SkReadBuffer& buffer) : SkProcCoeffXfermode(buffer) {}
+#endif
+    virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE {}
 
     typedef SkProcCoeffXfermode INHERITED;
 };
 
+SkFlattenable* SkSrcXfermode::CreateProc(SkReadBuffer& buffer) {
+    return SkXfermode::Create(kSrc_Mode);
+}
+
 void SkSrcXfermode::xfer32(SkPMColor* SK_RESTRICT dst,
                            const SkPMColor* SK_RESTRICT src, int count,
                            const SkAlpha* SK_RESTRICT aa) const {
@@ -1571,11 +1592,18 @@ public:
 
 private:
     SkDstInXfermode(const ProcCoeff& rec) : SkProcCoeffXfermode(rec, kDstIn_Mode) {}
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
     SkDstInXfermode(SkReadBuffer& buffer) : INHERITED(buffer) {}
+#endif
+    virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE {}
 
     typedef SkProcCoeffXfermode INHERITED;
 };
 
+SkFlattenable* SkDstInXfermode::CreateProc(SkReadBuffer&) {
+    return SkXfermode::Create(kDstIn_Mode);
+}
+
 void SkDstInXfermode::xfer32(SkPMColor* SK_RESTRICT dst,
                              const SkPMColor* SK_RESTRICT src, int count,
                              const SkAlpha* SK_RESTRICT aa) const {
@@ -1617,12 +1645,18 @@ public:
 
 private:
     SkDstOutXfermode(const ProcCoeff& rec) : SkProcCoeffXfermode(rec, kDstOut_Mode) {}
-    SkDstOutXfermode(SkReadBuffer& buffer)
-        : INHERITED(buffer) {}
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
+    SkDstOutXfermode(SkReadBuffer& buffer) : INHERITED(buffer) {}
+#endif
+    virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE {}
 
     typedef SkProcCoeffXfermode INHERITED;
 };
 
+SkFlattenable* SkDstOutXfermode::CreateProc(SkReadBuffer&) {
+    return SkXfermode::Create(kDstOut_Mode);
+}
+
 void SkDstOutXfermode::xfer32(SkPMColor* SK_RESTRICT dst,
                               const SkPMColor* SK_RESTRICT src, int count,
                               const SkAlpha* SK_RESTRICT aa) const {
@@ -1692,7 +1726,7 @@ SkXfermode* create_mode(int iMode) {
                 break;
             default:
                 // no special-case, just rely in the rec and its function-ptrs
-                xfer = SkProcCoeffXfermode::Create(rec, mode);
+                xfer = SkNEW_ARGS(SkProcCoeffXfermode, (rec, mode));
                 break;
         }
     }