Differentiate between sRGBGamma and 2Dot2Gamma

src/codec/SkPngCodec.cpp

Index: src/codec/SkPngCodec.cpp
diff --git a/src/codec/SkPngCodec.cpp b/src/codec/SkPngCodec.cpp
index 43d1580c176b0b0cfff9b3fda103fd6627f0b765..583a8ee8462416e9e67609d778d66d4c4fdb2680 100644
--- a/src/codec/SkPngCodec.cpp
+++ b/src/codec/SkPngCodec.cpp
@@ -8,7 +8,7 @@
 #include "SkBitmap.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
-#include "SkColorSpace.h"
+#include "SkColorSpace_Base.h"
 #include "SkColorTable.h"
 #include "SkMath.h"
 #include "SkOpts.h"
@@ -223,6 +223,8 @@ sk_sp<SkColorSpace> read_color_space(png_structp png_ptr, png_infop info_ptr) {
         for (int i = 0; i < 9; i++) {
             toXYZD50[i] = png_fixed_point_to_float(XYZ[i]);
         }
+        SkMatrix44 mat(SkMatrix44::kUninitialized_Constructor);
+        mat.set3x3ColMajorf(toXYZD50);
 
         if (PNG_INFO_gAMA == png_get_gAMA_fixed(png_ptr, info_ptr, &gamma)) {
             float value = png_inverted_fixed_point_to_float(gamma);
@@ -231,16 +233,12 @@ sk_sp<SkColorSpace> read_color_space(png_structp png_ptr, png_infop info_ptr) {
             gammas[2] = value;
 
         } else {
-            // Default to sRGB (gamma = 2.2f) if the image has color space information,
+            // Default to sRGB gamma if the image has color space information,
             // but does not specify gamma.
-            gammas[0] = 2.2f;
-            gammas[1] = 2.2f;
-            gammas[2] = 2.2f;
+            return SkColorSpace::NewRGB(SkColorSpace::kSRGB_GammaNamed, mat);
         }
 
-        SkMatrix44 mat(SkMatrix44::kUninitialized_Constructor);
-        mat.set3x3ColMajorf(toXYZD50);
-        return SkColorSpace::NewRGB(gammas, mat);
+        return SkColorSpace_Base::NewRGB(gammas, mat);

[Brian Osman, 2016/06/15 13:26:59]

Nit: Now that we're returning sRGB in the else case above, I'd move this line
into the previous 'if' block, to make the control flow symmetric/clearer.

[msarett, 2016/06/15 14:33:48]

Yup that makes a lot more sense.  Done.

     }
 
     // Last, check for gamma.
@@ -255,7 +253,7 @@ sk_sp<SkColorSpace> read_color_space(png_structp png_ptr, png_infop info_ptr) {
         gammas[1] = value;
         gammas[2] = value;
 
-        return SkColorSpace::NewRGB(gammas, SkMatrix44::I());
+        return SkColorSpace_Base::NewRGB(gammas, SkMatrix44::I());
     }
 
 #endif // LIBPNG >= 1.6