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LibGfx: Simplify some excessive use of pow() in scanline unfiltering

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This commit is contained in:
Andreas Kling 2020-07-27 16:40:12 +02:00
parent d9f933df7b
commit 0b1a40a6fe
Notes: sideshowbarker 2024-07-19 04:34:00 +09:00 
Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/0b1a40a6fe8
1 changed files with 4 additions and 3 deletions
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7
Libraries/LibGfx/PNGLoader.cpp
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@ -364,6 +364,7 @@ NEVER_INLINE FLATTEN static void unfilter(PNGLoadingContext& context)
} else if (context.bit_depth == 16) {
unpack_grayscale_without_alpha<u16>(context);
} else if (context.bit_depth == 1 || context.bit_depth == 2 || context.bit_depth == 4) {
auto bit_depth_squared = context.bit_depth = context.bit_depth;
auto pixels_per_byte = 8 / context.bit_depth;
auto mask = (1 << context.bit_depth) - 1;
for (int y = 0; y < context.height; ++y) {
@ -372,9 +373,9 @@ NEVER_INLINE FLATTEN static void unfilter(PNGLoadingContext& context)
auto bit_offset = (8 - context.bit_depth) - (context.bit_depth * (x % pixels_per_byte));
auto value = (gray_values[x / pixels_per_byte] >> bit_offset) & mask;
auto& pixel = (Pixel&)context.bitmap->scanline(y)[x];
pixel.r = value * (0xff / pow(context.bit_depth, 2));
pixel.g = value * (0xff / pow(context.bit_depth, 2));
pixel.b = value * (0xff / pow(context.bit_depth, 2));
pixel.r = value * (0xff / bit_depth_squared);
pixel.g = value * (0xff / bit_depth_squared);
pixel.b = value * (0xff / bit_depth_squared);
pixel.a = 0xff;
}
}