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#include "font.h"
#include <assert.h>
#include <limits.h>
#include <stdlib.h>
/* Create a texture atlas containing all of the glyphs in a font. */
SDL_Texture *font_create_texture(SDL_Renderer *renderer, PSFFont *font)
{
SDL_Texture *result;
const int bytes_per_row = (font->bytes_per_glyph / font->height);
const int texture_width = font->num_glyphs * font->width;
SDL_Surface *surface = SDL_CreateRGBSurface(0, texture_width, font->height, 32, 0, 0, 0, 0);
for (int glyph_idx = 0; glyph_idx < font->num_glyphs; glyph_idx++) {
for (int y = 0; y < font->height; y++) {
for (int x = 0; x < font->width; x++) {
/*
* TODO: Make it possible for the texture atlas to have more
* than one row.
*/
int xp = x + glyph_idx * font->width;
int yp = y;
int bit_idx = 7 - (x % 8);
int row_byte_idx = (glyph_idx * font->bytes_per_glyph) + y * bytes_per_row + (x / 8);
char current_bit = font->glyph_data[row_byte_idx] & (1 << bit_idx);
((Uint32*)(surface->pixels))[xp + yp * surface->w] = current_bit ? 0xffffffff : 0;
}
}
}
result = SDL_CreateTextureFromSurface(renderer, surface);
if (result == NULL)
fatal_error("Failed to create texture: %s\n", SDL_GetError());
SDL_FreeSurface(surface);
printf("Created font texture atlas of size %dx%d\n", surface->w, surface->h);
return result;
}
PSFFont font_load(const char *filename)
{
PSFFont font;
FILE *fp = fopen(filename, "rb");
fseek(fp, 0, SEEK_END);
size_t filesize = ftell(fp);
fseek(fp, 0, SEEK_SET);
fread(&font.magic, 4, 1, fp);
if (font.magic != PSF_MAGIC_NUMBER)
fatal_error("Font header mismatch! '%s' has magic value %x.\n", filename, font.magic);
fread(&font.version, 4, 1, fp);
fread(&font.header_size, 4, 1, fp);
fread(&font.flags, 4, 1, fp);
fread(&font.num_glyphs, 4, 1, fp);
fread(&font.bytes_per_glyph, 4, 1, fp);
fread(&font.height, 4, 1, fp);
fread(&font.width, 4, 1, fp);
size_t glyph_buffer_size = font.num_glyphs * font.bytes_per_glyph;
font.glyph_data = malloc(glyph_buffer_size);
fseek(fp, font.header_size, SEEK_SET);
fread(font.glyph_data, font.bytes_per_glyph, font.num_glyphs, fp);
font.unicode_desc = NULL;
if (font.flags == PSF_FLAG_UNICODE) {
size_t current_pos = ftell(fp);
size_t bytes_left = filesize - current_pos;
/* Store the file's unicode information in a buffer. */
char *desc = malloc(bytes_left);
fread(desc, bytes_left, 1, fp);
/* Create a buffer in our object to map character codes to glyphs */
font.unicode_desc = calloc(USHRT_MAX, 2);
int glyph_index = 0;
unsigned char letter = 0;
for (int i = 0; i < bytes_left; i++) {
unsigned char uc = desc[i];
if (uc == 0xff) {
font.unicode_desc[letter] = glyph_index;
glyph_index++;
} else {
letter = uc;
}
}
}
fclose(fp);
printf("Loaded a font with %d glyphs of size %dx%d (%d bytes per glyph)\n",
font.num_glyphs, font.width, font.height, font.bytes_per_glyph);
return font;
}
void font_destroy(PSFFont *font)
{
free(font->glyph_data);
}
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