formalize named picture versions

include/core/SkReadBuffer.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 SkReadBuffer_DEFINED
 #define SkReadBuffer_DEFINED
 
@@ skipping 22 matching lines @@
     #define DEBUG_NON_DETERMINISTIC_ASSERT
 #endif
 
 class SkReadBuffer {
 public:
     SkReadBuffer();
     SkReadBuffer(const void* data, size_t size);
     SkReadBuffer(SkStream* stream);
     virtual ~SkReadBuffer();
 
-    /** Return the version of the serialized picture this buffer holds, or 0 if unset. */
-    int pictureVersion() const { return fPictureVersion; }
+    enum Version {
+        kFilterLevelIsEnum_Version         = 23,
+        kGradientFlippedFlag_Version       = 24,
+        kDashWritesPhaseIntervals_Version  = 25,
+        kColorShaderNoBool_Version         = 26,
+    };
+
+    /**
+     *  Returns true IFF the version is older than the specified version.
+     */
+    bool isVersionLT(Version targetVersion) const {
+        SkASSERT(targetVersion > 0);
+        return fVersion > 0 && fVersion < targetVersion;
+    }
 
     /** This may be called at most once; most clients of SkReadBuffer should not mess with it. */
-    void setPictureVersion(int version) {
-        SkASSERT(0 == fPictureVersion || version == fPictureVersion);
-        fPictureVersion = version;
+    void setVersion(int version) {
+        SkASSERT(0 == fVersion || version == fVersion);
+        fVersion = version;
     }
 
     enum Flags {
         kCrossProcess_Flag  = 1 << 0,
         kScalarIsFloat_Flag = 1 << 1,
         kPtrIs64Bit_Flag    = 1 << 2,
         kValidation_Flag    = 1 << 3,
     };
 
     void setFlags(uint32_t flags) { fFlags = flags; }
@@ skipping 120 matching lines @@
     virtual bool isValid() const { return true; }
     virtual bool validateAvailable(size_t size) { return true; }
 
 protected:
     SkReader32 fReader;
 
 private:
     bool readArray(void* value, size_t size, size_t elementSize);
 
     uint32_t fFlags;
-    int fPictureVersion;
+    int fVersion;
 
     void* fMemoryPtr;
 
     SkBitmapHeapReader* fBitmapStorage;
     SkTypeface** fTFArray;
     int        fTFCount;
 
     SkTDArray<SkFlattenable::Factory>* fFactoryTDArray;
     SkFlattenable::Factory* fFactoryArray;
     int                     fFactoryCount;
 
     SkPicture::InstallPixelRefProc fBitmapDecoder;
 
 #ifdef DEBUG_NON_DETERMINISTIC_ASSERT
     // Debugging counter to keep track of how many bitmaps we
     // have decoded.
     int fDecodedBitmapIndex;
 #endif // DEBUG_NON_DETERMINISTIC_ASSERT
 };
 
 #endif // SkReadBuffer_DEFINED