Avoid updating glPathStencilFunc unless it changes

src/gpu/GrStencil.h

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef GrStencil_DEFINED
@@ skipping 259 matching lines @@
         bool writes = GR_STENCIL_SETTINGS_DOES_WRITE(
                             fPassOps[kFront_Face], fPassOps[kBack_Face],
                             fFailOps[kFront_Face], fFailOps[kBack_Face],
                             fFuncs[kFront_Face],   fFuncs[kBack_Face]);
         fFlags |= writes ? kDoesWrite_StencilFlag : kDoesNotWrite_StencilFlag;
         return writes;
     }
 
     void invalidate()  {
         // write an illegal value to the first member
-        fPassOps[0] = (GrStencilOp)(uint8_t)-1;
+        fPassOps[0] = kStencilOpCount;
         fFlags = 0;
     }
 
+    bool isValid() const {
+        return fPassOps[0] < kStencilOpCount;
+    }
+
     bool operator == (const GrStencilSettings& s) const {
         static const size_t gCompareSize = sizeof(GrStencilSettings) -
                                            sizeof(fFlags);
         SkASSERT((const char*)&fFlags + sizeof(fFlags) ==
                  (const char*)this + sizeof(GrStencilSettings));
         if (this->isDisabled() & s.isDisabled()) { // using & not &&
             return true;
         }
         return 0 == memcmp(this, &s, gCompareSize);
     }
@@ skipping 92 matching lines @@
         *GR_CONST_STENCIL_SETTINGS_PTR_FROM_STRUCT_PTR(&(NAME ## _STRUCT));
 
 
 #define GR_STATIC_CONST_SAME_STENCIL(NAME,                                   \
     PASS_OP, FAIL_OP, FUNC, MASK, REF, WRITE_MASK)                           \
     GR_STATIC_CONST_STENCIL(NAME, (PASS_OP), (PASS_OP), (FAIL_OP),           \
     (FAIL_OP), (FUNC), (FUNC), (MASK), (MASK), (REF), (REF), (WRITE_MASK),   \
     (WRITE_MASK))
 
 #endif