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-rw-r--r--core/fxcodec/codec/fx_codec_icc.cpp32
1 files changed, 25 insertions, 7 deletions
diff --git a/core/fxcodec/codec/fx_codec_icc.cpp b/core/fxcodec/codec/fx_codec_icc.cpp
index 29cfe0e9f4..8ffbffe985 100644
--- a/core/fxcodec/codec/fx_codec_icc.cpp
+++ b/core/fxcodec/codec/fx_codec_icc.cpp
@@ -1977,13 +1977,31 @@ void AdobeCMYK_to_sRGB(FX_FLOAT c,
FX_FLOAT& R,
FX_FLOAT& G,
FX_FLOAT& B) {
- uint8_t c1 = FXSYS_round(c * 255);
- uint8_t m1 = FXSYS_round(m * 255);
- uint8_t y1 = FXSYS_round(y * 255);
- uint8_t k1 = FXSYS_round(k * 255);
+ // Convert to uint8_t with round-to-nearest. Avoid using FXSYS_round because
+ // it is incredibly expensive with VC++ (tested on VC++ 2015) because round()
+ // is very expensive.
+ // Adding 0.5f and truncating can round the wrong direction in some edge
+ // cases but these do not matter in this context. For instance, the float that
+ // is one ULP (unit in the last place) before 0.5 should round to zero but
+ // this will round it to one. These edge cases are never hit in this function
+ // due to the very limited precision of the input integers.
+ // This method also doesn't handle negative or extremely large numbers, but
+ // those are not needed here.
+ uint8_t c1 = int(c * 255.f + 0.5f);
+ uint8_t m1 = int(m * 255.f + 0.5f);
+ uint8_t y1 = int(y * 255.f + 0.5f);
+ uint8_t k1 = int(k * 255.f + 0.5f);
+
+ ASSERT(c1 == FXSYS_round(c * 255));
+ ASSERT(m1 == FXSYS_round(m * 255));
+ ASSERT(y1 == FXSYS_round(y * 255));
+ ASSERT(k1 == FXSYS_round(k * 255));
+
uint8_t r, g, b;
AdobeCMYK_to_sRGB1(c1, m1, y1, k1, r, g, b);
- R = 1.0f * r / 255;
- G = 1.0f * g / 255;
- B = 1.0f * b / 255;
+ // Multiply by a constant rather than dividing because division is much
+ // more expensive.
+ R = r * (1.0f / 255);
+ G = g * (1.0f / 255);
+ B = b * (1.0f / 255);
}