SkColorSpaceXformSteps
Lots TODO.
Change-Id: I95edb764b85a5140d432adb506c3b537869e6df4
Reviewed-on: https://skia-review.googlesource.com/129933
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: Mike Klein <mtklein@chromium.org>
diff --git a/tests/SkColorSpaceXformStepsTest.cpp b/tests/SkColorSpaceXformStepsTest.cpp
new file mode 100644
index 0000000..47e5e1b
--- /dev/null
+++ b/tests/SkColorSpaceXformStepsTest.cpp
@@ -0,0 +1,150 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkColorSpacePriv.h"
+#include "SkColorSpaceXformSteps.h"
+#include "Test.h"
+
+template <typename T>
+static void check_eq(skiatest::Reporter* r, SkColorSpaceXformSteps steps, T baseline) {
+ REPORTER_ASSERT(r, steps.early_unpremul == baseline.early_unpremul);
+ REPORTER_ASSERT(r, steps.linearize_src == baseline.linearize_src);
+ REPORTER_ASSERT(r, steps.late_unpremul == baseline.late_unpremul);
+ REPORTER_ASSERT(r, steps.gamut_transform == baseline.gamut_transform);
+ REPORTER_ASSERT(r, steps.early_encode == baseline.early_encode);
+ REPORTER_ASSERT(r, steps.premul == baseline.premul);
+ REPORTER_ASSERT(r, steps.linearize_dst == baseline.linearize_dst);
+ REPORTER_ASSERT(r, steps.late_encode == baseline.late_encode);
+
+ // A couple (redundant) sanity checks that cover impossible states.
+ // At most one of the early/late options should happen, possibly neither.
+ REPORTER_ASSERT(r, !(steps.early_unpremul && steps.late_unpremul));
+ REPORTER_ASSERT(r, !(steps.early_encode && steps.late_encode));
+}
+
+DEF_TEST(SkColorSpaceXformSteps, r) {
+ auto srgb_L = SkColorSpace::MakeSRGB(),
+ adobe_L = SkColorSpace::MakeRGB(g2Dot2_TransferFn, SkColorSpace::kAdobeRGB_Gamut),
+ srgb22_L = SkColorSpace::MakeRGB(g2Dot2_TransferFn, SkColorSpace:: kSRGB_Gamut),
+ srgb_N = srgb_L->makeNonlinearBlending(),
+ adobe_N = adobe_L->makeNonlinearBlending(),
+ srgb22_N = srgb22_L->makeNonlinearBlending();
+
+ struct {
+ sk_sp<SkColorSpace> src, dst;
+
+ bool early_unpremul;
+ bool linearize_src;
+ bool late_unpremul;
+
+ bool gamut_transform;
+ bool early_encode;
+ bool premul;
+
+ bool linearize_dst;
+ bool late_encode;
+ } tests[] = {
+ // The first eight cases we test are back and forth between two color spaces with
+ // different gamuts and transfer functions. There's not much optimization possible here.
+
+ { adobe_N, srgb_N,
+ true, // src is encoded as f(s)*a,a, so we unpremul to f(s),a before linearizing.
+ true, // Linearize to s,a.
+ false,
+
+ true, // Gamut transform.
+ true, // Non-linear blending, so we encode to sRGB g(s),a early.
+ true, // Premul to g(s)*a,a
+
+ false, // Non-linear blending, so no need to linearize dst.
+ false, // Non-linear blending, so the output of our blend function is what we want.
+ },
+ { srgb_N, adobe_N, true,true,false, true,true,true, false,false },
+
+ { adobe_L, srgb_L,
+ false, // src is encoded as f(s*a),a, so we linearize before unpremul.
+ true, // Linearize,
+ true, // then unpremul.
+
+ true, // Gamut transform.
+ false, // We're doing linear blending, so we don't encode to sRGB yet.
+ true, // Premul so we can blend.
+
+ true, // We're doing linear blending, so we need to linearize dst.
+ true, // Once blending is done, finally encode to sRGB.
+ },
+ { srgb_L, adobe_L, false,true,true, true,false,true, true,true },
+
+ { adobe_L, srgb_N,
+ false, // src is encoded as f(s*a),a, so we linearize before unpremul.
+ true, // Linearize,
+ true, // then unpremul.
+
+ true, // Gamut transform
+ true, // We're doing non-linear blending, so encode to sRGB now.
+ true, // (non-linear) premul
+
+ false, // We're doing non-linear blending, so dst is already ready to blend.
+ false, // The output of the blend is just what we want.
+ },
+ { srgb_L, adobe_N, false,true,true, true,true,true, false,false },
+
+ { adobe_N, srgb_L,
+ true, // src is encoded as f(s)*a,a, so we unpremul to f(s),a before linearizing.
+ true, // Linearize to s,a.
+ false,
+
+ true, // Gamut transform
+ false, // We're doing linear blending, so we don't encode to sRGB yet.
+ true, // (linear) premul
+
+ true, // We're doing linear blending, so we need to linearize dst.
+ true, // Once blending is done, finally encode to sRGB.
+ },
+ { srgb_N, adobe_L, true,true,false, true,false,true, true,true },
+
+ // These eight cases transform between color spaces with different
+ // transfer functions and the same gamut. Optimization here is limited
+ // to skipping the gamut_transform step: |
+ // v This column of true can all become false.
+ { srgb_N, srgb22_N, true,true,false, true,true,true, false,false },
+ { srgb22_N, srgb_N, true,true,false, true,true,true, false,false },
+
+ { srgb_L, srgb22_L, false,true,true, true,false,true, true,true },
+ { srgb22_L, srgb_L, false,true,true, true,false,true, true,true },
+
+ { srgb_N, srgb22_L, true,true,false, true,false,true, true,true },
+ { srgb22_N, srgb_L, true,true,false, true,false,true, true,true },
+
+ { srgb_L, srgb22_N, false,true,true, true,true,true, false,false },
+ { srgb22_L, srgb_N, false,true,true, true,true,true, false,false },
+
+ // These four test cases test drawing in the same color space.
+ // There is lots of room for optimization here, but none implemented yet.
+ { srgb_N, srgb_N, true,true,false, true,true,true, false,false }, // a.k.a legacy 8888
+ { srgb_L, srgb_L, false,true,true, true,false,true, true,true }, // <canvas> use case
+ { srgb_N, srgb_L, true,true,false, true,false,true, true,true },
+ { srgb_L, srgb_N, false,true,true, true,true,true, false,false },
+
+ // TODO: versions of above crossing in linear transfer functions
+ };
+
+ for (auto t : tests) {
+ // Our expectations are written for premul source alpha types.
+ check_eq(r, SkColorSpaceXformSteps(t.src.get(), kPremul_SkAlphaType, t.dst.get()), t);
+
+ // Opaque and unpremul sources should always go through the same steps,
+ // and they should be the same as premul's steps, with these fixed premul/unpremul steps.
+ auto upm = t;
+ upm.early_unpremul = false;
+ upm.late_unpremul = false;
+ upm.premul = true;
+
+ check_eq(r, SkColorSpaceXformSteps(t.src.get(), kUnpremul_SkAlphaType, t.dst.get()), upm);
+ check_eq(r, SkColorSpaceXformSteps(t.src.get(), kOpaque_SkAlphaType, t.dst.get()), upm);
+ }
+}