60 lines
1.5 KiB
C++
60 lines
1.5 KiB
C++
#include <daguerre/ppm.hpp>
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namespace daguerre {
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//TODO: make this more robust
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static unsigned read_text_int(FILE *input) {
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unsigned n = 0;
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char ch;
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fread(&ch, 1, 1, input);
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if (ch == '#') {
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do
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fread(&ch, 1, 1, input);
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while (ch != '\n');
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fread(&ch, 1, 1, input);
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}
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do {
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n = n * 10 + ch - '0';
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fread(&ch, 1, 1, input);
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} while (ch >= '0' && ch <= '9');
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return n;
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}
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//TODO: this only supports p6 format, and assumes max < 256
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std::optional<image<rgb24>> try_load_ppm(FILE *input) {
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char header[3];
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if (fread(header, 1, 3, input) != 3)
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return {};
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if (header[0] != 'P' || header[1] != '6' || header[2] != '\n')
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return {};
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unsigned width = read_text_int(input);
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unsigned height = read_text_int(input);
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unsigned max = read_text_int(input);
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image<rgb24> im(width, height);
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for (unsigned y = 0; y < height; ++y)
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for (unsigned x = 0; x < width; ++x) {
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if (fread(&im.buffer[y * width + x].r, 1, 1, input) != 1)
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return {};
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if (fread(&im.buffer[y * width + x].g, 1, 1, input) != 1)
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return {};
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if (fread(&im.buffer[y * width + x].b, 1, 1, input) != 1)
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return {};
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}
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if (max != 255)
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for (unsigned v = 0; v < width * height; ++v) {
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im.buffer[v].r = ((uint16_t)im.buffer[v].r * 255) / max;
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im.buffer[v].g = ((uint16_t)im.buffer[v].g * 255) / max;
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im.buffer[v].b = ((uint16_t)im.buffer[v].b * 255) / max;
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}
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return im;
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}
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}
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