color: Add histograms for gamut

third_party/WebKit/Source/platform/graphics/BitmapImageMetrics.cpp

Index: third_party/WebKit/Source/platform/graphics/BitmapImageMetrics.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/BitmapImageMetrics.cpp b/third_party/WebKit/Source/platform/graphics/BitmapImageMetrics.cpp
index 6e2130c71e5bf807287025be497944ad1bab0625..568c41443b53d6196f5f1db2f8ce9c141cff4ddf 100644
--- a/third_party/WebKit/Source/platform/graphics/BitmapImageMetrics.cpp
+++ b/third_party/WebKit/Source/platform/graphics/BitmapImageMetrics.cpp
@@ -5,6 +5,7 @@
 #include "platform/graphics/BitmapImageMetrics.h"
 
 #include "platform/Histogram.h"
+#include "third_party/skia/include/core/SkColorSpaceXform.h"
 #include "wtf/Threading.h"
 #include "wtf/text/WTFString.h"
 
@@ -42,18 +43,28 @@ void BitmapImageMetrics::countImageOrientation(
   orientationHistogram.count(orientation);
 }
 
-void BitmapImageMetrics::countImageGamma(SkColorSpace* colorSpace) {
+void BitmapImageMetrics::countImageGammaAndGamut(SkColorSpace* colorSpace) {
   DEFINE_THREAD_SAFE_STATIC_LOCAL(
       EnumerationHistogram, gammaNamedHistogram,
       new EnumerationHistogram("Blink.ColorSpace.Source", GammaEnd));
   gammaNamedHistogram.count(getColorSpaceGamma(colorSpace));
+
+  DEFINE_THREAD_SAFE_STATIC_LOCAL(
+      EnumerationHistogram, gamutNamedHistogram,
+      new EnumerationHistogram("Blink.ColorGamut.Source", GamutEnd));
+  gamutNamedHistogram.count(getColorSpaceGamut(colorSpace));
 }
 
-void BitmapImageMetrics::countOutputGamma(SkColorSpace* colorSpace) {
+void BitmapImageMetrics::countOutputGammaAndGamut(SkColorSpace* colorSpace) {
   DEFINE_THREAD_SAFE_STATIC_LOCAL(
       EnumerationHistogram, gammaNamedHistogram,
       new EnumerationHistogram("Blink.ColorSpace.Destination", GammaEnd));
   gammaNamedHistogram.count(getColorSpaceGamma(colorSpace));
+
+  DEFINE_THREAD_SAFE_STATIC_LOCAL(
+      EnumerationHistogram, gamutNamedHistogram,
+      new EnumerationHistogram("Blink.ColorGamut.Destination", GamutEnd));
+  gamutNamedHistogram.count(getColorSpaceGamut(colorSpace));
 }
 
 BitmapImageMetrics::Gamma BitmapImageMetrics::getColorSpaceGamma(
@@ -71,4 +82,49 @@ BitmapImageMetrics::Gamma BitmapImageMetrics::getColorSpaceGamma(
   return gamma;
 }
 
+BitmapImageMetrics::Gamut BitmapImageMetrics::getColorSpaceGamut(
+    SkColorSpace* colorSpace) {
+  sk_sp<SkColorSpace> scRGB(
+      SkColorSpace::MakeNamed(SkColorSpace::kSRGBLinear_Named));
+  std::unique_ptr<SkColorSpaceXform> transform(
+      SkColorSpaceXform::New(colorSpace, scRGB.get()));
+
+  if (!transform)
+    return GamutUnknown;
+
+  unsigned char in[3][4];
+  float out[3][4];
+  memset(in, 0, sizeof(in));
+  in[0][0] = 255;
+  in[1][1] = 255;
+  in[2][2] = 255;
+  in[0][3] = 255;
+  in[1][3] = 255;
+  in[2][3] = 255;
+  transform->apply(SkColorSpaceXform::kRGBA_F32_ColorFormat, out,
+                   SkColorSpaceXform::kRGBA_8888_ColorFormat, in, 3,
+                   kOpaque_SkAlphaType);
+  float score = out[0][0] * out[1][1] * out[2][2];
+
+  if (score < 0.9)
+    return GamutLessThanNTSC;
+  if (score < 0.95)
+    return GamutNTSC;  // actual score 0.912839
+  if (score < 1.1)
+    return GamutSRGB;  // actual score 1.0
+  if (score < 1.3)
+    return GamutAlmostP3;
+  if (score < 1.425)
+    return GamutP3;  // actual score 1.401899
+  if (score < 1.5)
+    return GamutAdobeRGB;  // actual score 1.458385
+  if (score < 2.0)
+    return GamutWide;
+  if (score < 2.2)
+    return GamutBT2020;  // actual score 2.104520
+  if (score < 2.7)
+    return GamutProPhoto;  // actual score 2.913247
+  return GamutUltraWide;
+}
+
 }  // namespace blink