non-linear blending first steps

Code:
  - Add a non-linear blending bit and makeNonlinearBlending()
    to SkColorSpace
  - remove enough F16=linear checks to make it possible to
    create surfaces and encode pngs with nonlinear F16

Testing:
  - add "esrgb" software config to DM, run it
  - add "srgbnl" software config, run it
  - deemphasize importance of "srgb" config on bots
  - update unit tests to reflect relaxed F16 constraints
  - add a new unit test file with _really_ basic tests,
    and a new unit test that's not working yet

Bug: skia:7942

Change-Id: I8ac042bdf9f3d791765393b68fd9256375184d83
Reviewed-on: https://skia-review.googlesource.com/127325
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/core/SkColorSpace_XYZ.h b/src/core/SkColorSpace_XYZ.h
index 2ad2e38b1b..d0984ecd1e 100644
--- a/src/core/SkColorSpace_XYZ.h
+++ b/src/core/SkColorSpace_XYZ.h
@@ -23,12 +23,14 @@ public:
     bool onGammaCloseToSRGB() const override;
     bool onGammaIsLinear() const override;
     bool onIsNumericalTransferFn(SkColorSpaceTransferFn* coeffs) const override;
+    bool nonlinearBlending() const override { return fNonlinearBlending; }
 
     const SkData* onProfileData() const override { return fProfileData.get(); }
 
     sk_sp<SkColorSpace> makeLinearGamma() const override;
     sk_sp<SkColorSpace> makeSRGBGamma() const override;
     sk_sp<SkColorSpace> makeColorSpin() const override;
+    sk_sp<SkColorSpace> makeNonlinearBlending() const override;
 
     SkGammaNamed onGammaNamed() const override { return fGammaNamed; }
 
@@ -56,6 +58,8 @@ private:
     mutable const uint8_t* fToDstGammaTables[3];
     mutable SkOnce         fToDstGammaOnce;
 
+    bool fNonlinearBlending = false;
+
     friend class SkColorSpace;
     friend class ColorSpaceXformTest;
 };