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