Index: src/core/SkColorSpace_ICC.cpp |
diff --git a/src/core/SkColorSpace_ICC.cpp b/src/core/SkColorSpace_ICC.cpp |
index 9ab1da007d16e8dee5aa5dae7b0a358d65effcb9..92dcc0fcf5389985faf0f2d005eefdd7089b7d57 100755 |
--- a/src/core/SkColorSpace_ICC.cpp |
+++ b/src/core/SkColorSpace_ICC.cpp |
@@ -262,6 +262,14 @@ static float read_big_endian_16_dot_16(const uint8_t buf[4]) { |
return SkFixedToFloat(read_big_endian_i32(buf)); |
} |
+static inline float srgb_fn(float x) { |
+ if (x <= 0.04045f) { |
+ return x * (1.0f / 12.92f); |
+ } |
+ |
+ return powf(x * (1.0f / 1.055f) + (0.055f / 1.055f), 2.4f); |
+} |
+ |
/** |
* @param outData Set to the appropriate value on success. If we have table or |
* parametric gamma, it is the responsibility of the caller to set |
@@ -370,9 +378,35 @@ static SkGammas::Type parse_gamma(SkGammas::Data* outData, SkGammas::Params* out |
} |
} |
- // Otherwise, we will represent gamma with a table. |
- outData->fTable.fSize = count; |
- return SkGammas::Type::kTable_Type; |
+ // Perform a more robust check for sRGB. See if the table is a close |
+ // match to an sRGB table. This is in addition to the previous sRGB |
+ // checks for a couple reasons: |
+ // (1) It is much slower. |
+ // (2) The 26 entry "sRGB" curve is actually so inaccurate that it fails |
+ // this check. But it still wants to be sRGB. |
+ float x = 0.0f; |
+ float dx = 1.0f / ((float) (count - 1)); |
+ for (uint32_t i = 0; i < count; i++) { |
+ float y = srgb_fn(x); |
+ |
+ // Convert y to the same format as the table (0.16 fixed point), so we can |
+ // compare values. |
+ uint16_t srgbY = sk_float_round2int(y * (float) (1 << 16)); |
+ uint16_t actualY = read_big_endian_u16((const uint8_t*) &table[i]); |
+ |
+ // We allow "off by 1" curves to try to not be affected by rounding decisions. |
+ if (SkTAbs((int32_t) srgbY - (int32_t) actualY) > 1) { |
+ // Curve is not sRGB, will use table representation. |
+ outData->fTable.fSize = count; |
+ return SkGammas::Type::kTable_Type; |
+ } |
+ |
+ x += dx; |
+ } |
+ |
+ outData->fNamed = SkColorSpace::kSRGB_GammaNamed; |
+ return SkGammas::Type::kNamed_Type; |
+ |
} |
case kTAG_ParaCurveType: { |
enum ParaCurveType { |