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-rw-r--r--src/core/SkColorSpaceXform_A2B.cpp48
1 files changed, 1 insertions, 47 deletions
diff --git a/src/core/SkColorSpaceXform_A2B.cpp b/src/core/SkColorSpaceXform_A2B.cpp
index 39c352cd8c..cde07f57cf 100644
--- a/src/core/SkColorSpaceXform_A2B.cpp
+++ b/src/core/SkColorSpaceXform_A2B.cpp
@@ -88,52 +88,6 @@ static inline bool gamma_to_parametric(SkColorSpaceTransferFn* coeffs, const SkG
return false;
}
}
-static inline SkColorSpaceTransferFn invert_parametric(const SkColorSpaceTransferFn& fn) {
- // Original equation is: y = (ax + b)^g + e for x >= d
- // y = cx + f otherwise
- //
- // so 1st inverse is: (y - e)^(1/g) = ax + b
- // x = ((y - e)^(1/g) - b) / a
- //
- // which can be re-written as: x = (1/a)(y - e)^(1/g) - b/a
- // x = ((1/a)^g)^(1/g) * (y - e)^(1/g) - b/a
- // x = ([(1/a)^g]y + [-((1/a)^g)e]) ^ [1/g] + [-b/a]
- //
- // and 2nd inverse is: x = (y - f) / c
- // which can be re-written as: x = [1/c]y + [-f/c]
- //
- // and now both can be expressed in terms of the same parametric form as the
- // original - parameters are enclosed in square brackets.
-
- // find inverse for linear segment (if possible)
- float c, f;
- if (0.f == fn.fC) {
- // otherwise assume it should be 0 as it is the lower segment
- // as y = f is a constant function
- c = 0.f;
- f = 0.f;
- } else {
- c = 1.f / fn.fC;
- f = -fn.fF / fn.fC;
- }
- // find inverse for the other segment (if possible)
- float g, a, b, e;
- if (0.f == fn.fA || 0.f == fn.fG) {
- // otherwise assume it should be 1 as it is the top segment
- // as you can't invert the constant functions y = b^g + c, or y = 1 + c
- g = 1.f;
- a = 0.f;
- b = 0.f;
- e = 1.f;
- } else {
- g = 1.f / fn.fG;
- a = powf(1.f / fn.fA, fn.fG);
- b = -a * fn.fE;
- e = -fn.fB / fn.fA;
- }
- const float d = fn.fC * fn.fD + fn.fF;
- return {g, a, b, c, d, e, f};
-}
SkColorSpaceXform_A2B::SkColorSpaceXform_A2B(SkColorSpace_A2B* srcSpace,
SkColorSpace_XYZ* dstSpace)
@@ -279,7 +233,7 @@ SkColorSpaceXform_A2B::SkColorSpaceXform_A2B(SkColorSpace_A2B* srcSpace,
} else {
SkColorSpaceTransferFn fn;
SkAssertResult(gamma_to_parametric(&fn, gammas, channel));
- this->addTransferFn(invert_parametric(fn), channel);
+ this->addTransferFn(fn.invert(), channel);
}
}
}