Index: ui/gfx/skia_color_space_util.cc |
diff --git a/ui/gfx/skia_color_space_util.cc b/ui/gfx/skia_color_space_util.cc |
index 60617e764b96ae9d2b58a41780f77aa232add497..2dda075fe65c1b129c6488b6019aea778c29132d 100644 |
--- a/ui/gfx/skia_color_space_util.cc |
+++ b/ui/gfx/skia_color_space_util.cc |
@@ -10,11 +10,9 @@ |
namespace gfx { |
namespace { |
- |
-const float kEpsilon = 1.f / 256.f; |
} |
-float EvalSkTransferFn(const SkColorSpaceTransferFn& fn, float x) { |
+float SkTransferFnEval(const SkColorSpaceTransferFn& fn, float x) { |
if (x < 0.f) |
return 0.f; |
if (x < fn.fD) |
@@ -39,7 +37,32 @@ SkColorSpaceTransferFn SkTransferFnInverse(const SkColorSpaceTransferFn& fn) { |
return fn_inv; |
} |
+bool SkTransferFnsApproximatelyCancel(const SkColorSpaceTransferFn& a, |
+ const SkColorSpaceTransferFn& b) { |
+ const float kStep = 1.f / 8.f; |
+ const float kEpsilon = 2.5f / 256.f; |
+ for (float x = 0; x <= 1.f; x += kStep) { |
+ float a_of_x = SkTransferFnEval(a, x); |
+ float b_of_a_of_x = SkTransferFnEval(b, a_of_x); |
+ if (std::abs(b_of_a_of_x - x) > kEpsilon) |
+ return false; |
+ } |
+ return true; |
+} |
+ |
+bool SkTransferFnIsApproximatelyIdentity(const SkColorSpaceTransferFn& a) { |
+ const float kStep = 1.f / 8.f; |
+ const float kEpsilon = 2.5f / 256.f; |
+ for (float x = 0; x <= 1.f; x += kStep) { |
+ float a_of_x = SkTransferFnEval(a, x); |
+ if (std::abs(a_of_x - x) > kEpsilon) |
+ return false; |
+ } |
+ return true; |
+} |
+ |
bool SkMatrixIsApproximatelyIdentity(const SkMatrix44& m) { |
+ const float kEpsilon = 1.f / 256.f; |
for (int i = 0; i < 4; ++i) { |
for (int j = 0; j < 4; ++j) { |
float identity_value = i == j ? 1 : 0; |