Add SkColorSpace::Equals() API

src/core/SkColorSpace.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkColorSpace.h"
 #include "SkColorSpace_Base.h"
 #include "SkColorSpacePriv.h"
@@ skipping 298 matching lines @@
     uint32_t profileSize = *((uint32_t*) data);
     data = SkTAddOffset<const void>(data, sizeof(uint32_t));
     length -= sizeof(uint32_t);
     if (length < profileSize) {
         return nullptr;
     }
 
     return NewICC(data, profileSize);
 }
 
+bool SkColorSpace::Equals(const SkColorSpace* src, const SkColorSpace* dst) {
+    if (src == dst) {
+        return true;
+    }
+
+    if (!src || !dst) {
+        return false;
+    }
+
+    switch (src->fNamed) {
+        case kSRGB_Named:
+        case kAdobeRGB_Named:
+            return src->fNamed == dst->fNamed;
+        case kUnknown_Named:
+            if (kUnknown_Named != dst->fNamed) {
+                return false;
+            }
+            break;
+    }
+
+    SkData* srcData = as_CSB(src)->fProfileData.get();
+    SkData* dstData = as_CSB(dst)->fProfileData.get();
+    if (srcData || dstData) {
+        if (srcData && dstData) {
+            return srcData->size() == dstData->size() &&
+                   0 == memcmp(srcData->data(), dstData->data(), srcData->size());
+        }
+
+        return false;
+    }
+
+    // It's important to check fProfileData before named gammas.  Some profiles may have named
+    // gammas, but also include other wacky features that cause us to save the data.
+    switch (src->fGammaNamed) {
+        case kSRGB_GammaNamed:
+        case k2Dot2Curve_GammaNamed:
+        case kLinear_GammaNamed:
+            return (src->fGammaNamed == dst->fGammaNamed) && (src->fToXYZD50 == dst->fToXYZD50);
+        default:
+            // If |src| does not have a named gamma, fProfileData should be non-null.
+            SkASSERT(false);
+            return false;
+    }
+}
+
 bool SkColorSpace::gammasAreMatching() const {
     const SkGammas* gammas = as_CSB(this)->gammas();
     SkASSERT(gammas);
     return gammas->fRedType == gammas->fGreenType && gammas->fGreenType == gammas->fBlueType &&
            gammas->fRedData == gammas->fGreenData && gammas->fGreenData == gammas->fBlueData;
 }
 
 bool SkColorSpace::gammasAreNamed() const {
     const SkGammas* gammas = as_CSB(this)->gammas();
     SkASSERT(gammas);
@@ skipping 18 matching lines @@
            gammas->fBlueType == SkGammas::Type::kTable_Type;
 }
 
 bool SkColorSpace::gammasAreParams() const {
     const SkGammas* gammas = as_CSB(this)->gammas();
     SkASSERT(gammas);
     return gammas->fRedType == SkGammas::Type::kParam_Type &&
            gammas->fGreenType == SkGammas::Type::kParam_Type &&
            gammas->fBlueType == SkGammas::Type::kParam_Type;
 }