termage/src/pixels.cpp

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

// truecolor to palette color (216-color)
static inline int t2p(int val) {
    return .5 + 5 * val / 255.0;
}

static void write(std::ostream& os, FILE* in) {
    char* tc = getenv("COLORTERM");
    std::string colorterm {tc ? tc : ""};
    bool has_truecolor = colorterm.size() > 0;
    if (has_truecolor) {
        has_truecolor = colorterm == "truecolor" || colorterm == "24bit";
    }
    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) {
        pnm_readpamrow(&info, row1.get());
        pnm_readpamrow(&info, row2.get());
        for (int x = 0; x < info.width; ++x) {
            if (info.depth == 3) { // assume RGB, 1 byte per sample
                tuple* t1 {row1.get()};
                if (has_truecolor) {
                    os << sc::io::truecolorb(t1[x][0], t1[x][1], t1[x][2]);
                } else {
                    os << sc::io::rgbb(t2p(t1[x][0]), t2p(t1[x][1]), t2p(t1[x][2]));
                }
                tuple* t2 {row2.get()};
                if (has_truecolor) {
                    os << sc::io::truecolorf(t2[x][0], t2[x][1], t2[x][2]);
                } else {
                    os << sc::io::rgbf(t2p(t2[x][0]), t2p(t2[x][1]), t2p(t2[x][2]));
                }
                os << u8"\u2584"; // unicode lower half block
            }
        }
        os << sc::io::reset << '\n';
    }
}

void write_image(std::ostream& os) {
    write(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(os, infile.get());
}