font.h

#ifndef FONT_H
#define FONT_H

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#define FONT_CHAR_START ' '
#define FONT_CHAR_COUNT ('~' - ' ' + 1)

// Reads a font generated by figlet-to-font.py, outputting each character's width and height to
// `width` and `height`. `*out` will be malloc'd and filled with the font data - 0 for black pixel,
// 255 for white. You better free `*out` once you're done.
void load_font(const char *path, int *width, int *height, uint8_t **out) {
        FILE *fp = fopen(path, "r");
        if (fp == NULL) {
                fprintf(stderr, "Couldn't open font %s\n", path);
                exit(1);
        }

        char *lineptr = NULL;
        size_t line_len;

        // Read width
        if (getline(&lineptr, &line_len, fp) == -1) {
                fprintf(stderr, "Couldn't read font width\n");
                exit(1);
        }
        *width = strtol(lineptr, NULL, 10);

        // Read height
        if (getline(&lineptr, &line_len, fp) == -1) {
                fprintf(stderr, "Couldn't read font height\n");
                exit(1);
        }
        *height = strtol(lineptr, NULL, 10);
        free(lineptr);

        printf("Font dims %d x %d\n", *width, *height);

        // Alloc memory
        // Range is inclusive
        *out = malloc(FONT_CHAR_COUNT * *width * *height * sizeof(**out));

        // Read chars
        // + 1 for the newline
        char *line = malloc((*width + 1) * sizeof(*line));

        for (int i = 0; i < FONT_CHAR_COUNT; i++) {
                // For each char...
                for (int j = 0; j < *height; j++) {
                        // And for each line...
                        if (fread(line, 1, *width + 1, fp) != *width + 1) {
                                fprintf(stderr, "Couldn't read char %c\n", (char)i);
                                exit(1);
                        }

                        for (int k = 0; k < *width; k++) {
                                // And for each pixel...
				// Set pixel in output
                                (*out)[i * *width * *height + j * *width + k] =
                                        line[k] == '#' ? 255 : 0;
                        }
                }
        }
        free(line);
}

#endif // FONT_H