termage/src/pixels.cpp

#include <memory>
#include <libscterm.hpp>
#include <netpbm/pam.h>
#include "pixels.hpp"

void write_image(std::ostream& os, FILE* in) {
    struct pam info;
    pnm_readpaminit(in, &info, PAM_STRUCT_SIZE(tuple_type));
    std::unique_ptr<tuple, void(*)(void*)> row1 {pnm_allocpamrow(&info), pm_freerow};
    std::unique_ptr<tuple, void(*)(void*)> row2 {pnm_allocpamrow(&info), pm_freerow};
    for (int y = 0; y < info.height; y += 2) {
        tuple* t1 {row1.get()};
        tuple* t2 {row2.get()};
        pnm_readpamrow(&info, row1.get());
        if (y < info.height - 1) {
            pnm_readpamrow(&info, row2.get());
        } else {
            // fill second row with terminal background color
            for (int col = 0; col < info.width; ++col) {
                t2[col][0] = t2[col][1] = t2[col][2] = 0;
            }
        }
        for (int x = 0; x < info.width; ++x) {
            if (info.depth == 3) { // assume RGB, 1 byte per sample
                os << sc::io::truecolorb(t1[x][0], t1[x][1], t1[x][2]);
                os << sc::io::truecolorf(t2[x][0], t2[x][1], t2[x][2]);
                os << u8"\u2584"; // unicode lower half block
            }
        }
        os << sc::io::reset << '\n';
    }
}

void write_image(std::ostream& os) {
    write_image(os, stdin);
}

void write_image(std::ostream& os, const std::string& path) {
    std::unique_ptr<FILE, void(*)(FILE*)> infile {pm_openr(path.c_str()), pm_close};
    write_image(os, infile.get());
}