Initial error handling code

src/core/SkXfermode.cpp

Index: src/core/SkXfermode.cpp
diff --git a/src/core/SkXfermode.cpp b/src/core/SkXfermode.cpp
index ac5cee4e3592954ba4b8c34e558652fba054934d..922b0c087758eeb09abcb94f3de5d90995344072 100644
--- a/src/core/SkXfermode.cpp
+++ b/src/core/SkXfermode.cpp
@@ -12,6 +12,7 @@
 #include "SkFlattenableBuffers.h"
 #include "SkMathPriv.h"
 #include "SkString.h"
+#include "SkValidationUtils.h"
 
 SK_DEFINE_INST_COUNT(SkXfermode)
 
@@ -1375,6 +1376,8 @@ GrEffectRef* XferEffect::TestCreate(SkRandom* rand,
 ///////////////////////////////////////////////////////////////////////////////
 
 class SkProcCoeffXfermode : public SkProcXfermode {
+    typedef SkProcXfermode INHERITED;
+
 public:
     SkProcCoeffXfermode(const ProcCoeff& rec, Mode mode)
             : INHERITED(rec.fProc) {
@@ -1438,6 +1441,10 @@ protected:
         fDstCoeff = rec.fDC;
         // now update our function-ptr in the super class
         this->INHERITED::setProc(rec.fProc);
+
+        buffer.validate(SkIsValidMode(fMode) &&
+                        SkIsValidCoeff(fSrcCoeff) &&
+                        SkIsValidCoeff(fDstCoeff));
     }
 
     virtual void flatten(SkFlattenableWriteBuffer& buffer) const SK_OVERRIDE {
@@ -1448,8 +1455,6 @@ protected:
 private:
     Mode    fMode;
     Coeff   fSrcCoeff, fDstCoeff;
-
-    typedef SkProcXfermode INHERITED;
 };
 
 const char* SkXfermode::ModeName(Mode mode) {
@@ -1495,6 +1500,8 @@ void SkProcCoeffXfermode::toString(SkString* str) const {
 ///////////////////////////////////////////////////////////////////////////////
 
 class SkClearXfermode : public SkProcCoeffXfermode {
+    typedef SkProcCoeffXfermode INHERITED;
+
 public:
     SkClearXfermode(const ProcCoeff& rec) : SkProcCoeffXfermode(rec, kClear_Mode) {}
 
@@ -1507,8 +1514,6 @@ public:
 private:
     SkClearXfermode(SkFlattenableReadBuffer& buffer)
         : SkProcCoeffXfermode(buffer) {}
-
-    typedef SkProcCoeffXfermode INHERITED;
 };
 
 void SkClearXfermode::xfer32(SkPMColor* SK_RESTRICT dst,
@@ -1557,6 +1562,8 @@ void SkClearXfermode::toString(SkString* str) const {
 ///////////////////////////////////////////////////////////////////////////////
 
 class SkSrcXfermode : public SkProcCoeffXfermode {
+    typedef SkProcCoeffXfermode INHERITED;
+
 public:
     SkSrcXfermode(const ProcCoeff& rec) : SkProcCoeffXfermode(rec, kSrc_Mode) {}
 
@@ -1569,8 +1576,6 @@ public:
 private:
     SkSrcXfermode(SkFlattenableReadBuffer& buffer)
         : SkProcCoeffXfermode(buffer) {}
-
-    typedef SkProcCoeffXfermode INHERITED;
 };
 
 void SkSrcXfermode::xfer32(SkPMColor* SK_RESTRICT dst,
@@ -1624,6 +1629,8 @@ void SkSrcXfermode::toString(SkString* str) const {
 ///////////////////////////////////////////////////////////////////////////////
 
 class SkDstInXfermode : public SkProcCoeffXfermode {
+    typedef SkProcCoeffXfermode INHERITED;
+
 public:
     SkDstInXfermode(const ProcCoeff& rec) : SkProcCoeffXfermode(rec, kDstIn_Mode) {}
 
@@ -1634,8 +1641,6 @@ public:
 
 private:
     SkDstInXfermode(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {}
-
-    typedef SkProcCoeffXfermode INHERITED;
 };
 
 void SkDstInXfermode::xfer32(SkPMColor* SK_RESTRICT dst,
@@ -1667,6 +1672,8 @@ void SkDstInXfermode::toString(SkString* str) const {
 ///////////////////////////////////////////////////////////////////////////////
 
 class SkDstOutXfermode : public SkProcCoeffXfermode {
+    typedef SkProcCoeffXfermode INHERITED;
+
 public:
     SkDstOutXfermode(const ProcCoeff& rec) : SkProcCoeffXfermode(rec, kDstOut_Mode) {}
 
@@ -1678,8 +1685,6 @@ public:
 private:
     SkDstOutXfermode(SkFlattenableReadBuffer& buffer)
         : INHERITED(buffer) {}
-
-    typedef SkProcCoeffXfermode INHERITED;
 };
 
 void SkDstOutXfermode::xfer32(SkPMColor* SK_RESTRICT dst,
@@ -1710,6 +1715,44 @@ void SkDstOutXfermode::toString(SkString* str) const {
 
 ///////////////////////////////////////////////////////////////////////////////
 
+SkFlattenable::Factory SkProcXfermode::GetFactory(SkFlattenable::Type type) {
+    switch(type) {
+    case SkFlattenable::kSkClearXfermode:
+        return SkClearXfermode::CreateProc;
+    case SkFlattenable::kSkDstInXfermode:
+        return SkDstInXfermode::CreateProc;
+    case SkFlattenable::kSkDstOutXfermode:
+        return SkDstOutXfermode::CreateProc;
+    case SkFlattenable::kSkProcCoeffXfermode:
+        return SkProcCoeffXfermode::CreateProc;
+    case SkFlattenable::kSkSrcXfermode:
+        return SkSrcXfermode::CreateProc;
+    default:
+        break;
+    }
+    return NULL;
+}
+
+SkFlattenable::TypeCheck SkProcXfermode::GetTypeCheck(SkFlattenable::Type type) {
+    switch(type) {
+    case SkFlattenable::kSkClearXfermode:
+        return SkClearXfermode::IsA;
+    case SkFlattenable::kSkDstInXfermode:
+        return SkDstInXfermode::IsA;
+    case SkFlattenable::kSkDstOutXfermode:
+        return SkDstOutXfermode::IsA;
+    case SkFlattenable::kSkProcCoeffXfermode:
+        return SkProcCoeffXfermode::IsA;
+    case SkFlattenable::kSkSrcXfermode:
+        return SkSrcXfermode::IsA;
+    default:
+        break;
+    }
+    return NULL;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 SkXfermode* SkXfermode::Create(Mode mode) {
     SkASSERT(SK_ARRAY_COUNT(gProcCoeffs) == kModeCount);
     SkASSERT((unsigned)mode < kModeCount);