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#include <mbgl/util/premultiply.hpp>
#include <cmath>
namespace mbgl {
namespace util {
PremultipliedImage premultiply(UnassociatedImage&& src) {
PremultipliedImage dst;
dst.width = src.width;
dst.height = src.height;
dst.data = std::move(src.data);
uint8_t* data = dst.data.get();
for (size_t i = 0; i < dst.size(); i += 4) {
uint8_t& r = data[i + 0];
uint8_t& g = data[i + 1];
uint8_t& b = data[i + 2];
uint8_t& a = data[i + 3];
r = (r * a + 127) / 255;
g = (g * a + 127) / 255;
b = (b * a + 127) / 255;
}
return dst;
}
UnassociatedImage unpremultiply(PremultipliedImage&& src) {
UnassociatedImage dst;
dst.width = src.width;
dst.height = src.height;
dst.data = std::move(src.data);
uint8_t* data = dst.data.get();
for (size_t i = 0; i < dst.size(); i += 4) {
uint8_t& r = data[i + 0];
uint8_t& g = data[i + 1];
uint8_t& b = data[i + 2];
uint8_t& a = data[i + 3];
if (a) {
r = (255 * r + (a / 2)) / a;
g = (255 * g + (a / 2)) / a;
b = (255 * b + (a / 2)) / a;
}
}
return dst;
}
} // namespace util
} // namespace mbgl
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