Set SkColorSpace object for PNGs and parse ICC profiles

tests/ColorSpaceTest.cpp

Index: tests/ColorSpaceTest.cpp
diff --git a/tests/ColorSpaceTest.cpp b/tests/ColorSpaceTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..a8903656c99cc0b35c192b08b73d25b71831a006
--- /dev/null
+++ b/tests/ColorSpaceTest.cpp
@@ -0,0 +1,47 @@
+/*
+ * 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 "Resources.h"
+#include "SkCodec.h"
+#include "SkColorSpace.h"
+#include "Test.h"
+
+static SkStreamAsset* resource(const char path[]) {
+    SkString fullPath = GetResourcePath(path);
+    return SkStream::NewFromFile(fullPath.c_str());
+}
+
+static bool almost_equal(float a, float b) {
+    return SkTAbs(a - b) < 0.0001f;
+}
+
+DEF_TEST(ColorSpaceParseICCProfile, r) {
+    SkAutoTDelete<SkStream> stream(resource("color_wheel_with_profile.png"));
+    REPORTER_ASSERT(r, nullptr != stream);
+
+    SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(stream.detach()));
+    REPORTER_ASSERT(r, nullptr != codec);
+
+    SkColorSpace* colorSpace = codec->getColorSpace();
+    REPORTER_ASSERT(r, nullptr != colorSpace);
+
+    SkFloat3 gammas = colorSpace->gamma();
+    REPORTER_ASSERT(r, 2.2f == gammas.fVec[0]);

[reed1, 2016/03/02 01:29:54]

interesting that you don't need/use almost_equal here... 2.2 cannot be
represented exactly in a float.

[msarett, 2016/03/02 14:09:40]

I think we are lucky.  Maybe we should use almost equal?

This particular profile has a gamma table so we guess 2.2.  I'm sure our "guess"
is rounded to the closest float match for 2.2, which is likely the same as what
happens to the 2.2 used in this test.

+    REPORTER_ASSERT(r, 2.2f == gammas.fVec[1]);
+    REPORTER_ASSERT(r, 2.2f == gammas.fVec[2]);
+
+    SkFloat3x3 xyz = colorSpace->xyz();
+    REPORTER_ASSERT(r, almost_equal(0.436066f, xyz.fMat[0]));

[reed1, 2016/03/02 01:29:54]

// We got these 9 values from ... ?

[msarett, 2016/03/02 14:09:41]

I printed out the profile when extracting it from a different PNG.  These were
the values.

We couldn't actually check in the other PNG, so I stuffed the profile into
color_wheel.png.  I guess this tests that we are pulling out the "same values as
before", but I feel confident these are the right values.

If not, we can always change the test.

+    REPORTER_ASSERT(r, almost_equal(0.222488f, xyz.fMat[1]));
+    REPORTER_ASSERT(r, almost_equal(0.013916f, xyz.fMat[2]));
+    REPORTER_ASSERT(r, almost_equal(0.385147f, xyz.fMat[3]));
+    REPORTER_ASSERT(r, almost_equal(0.716873f, xyz.fMat[4]));
+    REPORTER_ASSERT(r, almost_equal(0.0970764f, xyz.fMat[5]));
+    REPORTER_ASSERT(r, almost_equal(0.143066f, xyz.fMat[6]));
+    REPORTER_ASSERT(r, almost_equal(0.0606079f, xyz.fMat[7]));
+    REPORTER_ASSERT(r, almost_equal(0.714096f, xyz.fMat[8]));
+}