Add SkColorSpace::Equals() API

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2196743002

Review-Url: https://codereview.chromium.org/2196743002

2 files changed, 47 insertions, 3 deletions

diff --git a/src/codec/SkJpegCodec.cpp b/src/codec/SkJpegCodec.cpp
index d158b4215a..2eea46bb2b 100644
--- a/src/codec/SkJpegCodec.cpp
+++ b/src/codec/SkJpegCodec.cpp
@@ -475,10 +475,9 @@ bool SkJpegCodec::onDimensionsSupported(const SkISize& size) {
 }
 
 static bool needs_color_xform(const SkImageInfo& dstInfo, const SkImageInfo& srcInfo) {
-    // FIXME (msarett):
-    // Do a better check for color space equality.
     return (kRGBA_F16_SkColorType == dstInfo.colorType()) ||
-           (dstInfo.colorSpace() && (dstInfo.colorSpace() != srcInfo.colorSpace()));
+           (dstInfo.colorSpace() && !SkColorSpace::Equals(srcInfo.colorSpace(),
+                                                          dstInfo.colorSpace()));
 }
 
 int SkJpegCodec::readRows(const SkImageInfo& dstInfo, void* dst, size_t rowBytes, int count) {
diff --git a/src/core/SkColorSpace.cpp b/src/core/SkColorSpace.cpp
index 3874f0e7d0..e7bd4e8111 100644
--- a/src/core/SkColorSpace.cpp
+++ b/src/core/SkColorSpace.cpp
@@ -316,6 +316,51 @@ sk_sp<SkColorSpace> SkColorSpace::Deserialize(const void* data, size_t length) {
     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);