sample for stb truetype

ttfont.c

#include <stdio.h>
#define HEIGHT 24

#define STB_TRUETYPE_IMPLEMENTATION
#define STBTT_STATIC

// gcc -Wall -Wno-unused-function -g ttfont.c -o ttfont.exe
// https://github.com/nothings/stb/blob/master/stb_truetype.h
#include "stb_truetype.h"

unsigned char ttf_buffer[1<<25];

#define MAXUNICODE	0x10FFFF

static int
utf8_decode(const char *o) {
	static const unsigned int limits[] = {0xFF, 0x7F, 0x7FF, 0xFFFF};
	const unsigned char *s = (const unsigned char *)o;
	unsigned int c = s[0];
	unsigned int res = 0;  /* final result */
	if (c < 0x80)  /* ascii? */
		res = c;
	else {
		int count = 0;  /* to count number of continuation bytes */
		while (c & 0x40) {  /* still have continuation bytes? */
			int cc = s[++count];  /* read next byte */
			if ((cc & 0xC0) != 0x80)  /* not a continuation byte? */
				return -1;  /* invalid byte sequence */
			res = (res << 6) | (cc & 0x3F);  /* add lower 6 bits from cont. byte */
			c <<= 1;  /* to test next bit */
		}
		res |= ((c & 0x7F) << (count * 5));  /* add first byte */
		if (count > 3 || res > MAXUNICODE || res <= limits[count])
			return -1;  /* invalid byte sequence */
		s += count;  /* skip continuation bytes read */
	}
	return res;
}

int
main() {
	stbtt_fontinfo font;
	int i,j;
	int c = utf8_decode("中");
	fread(ttf_buffer, 1, 1<<25, fopen("c:/windows/fonts/msyh.ttc", "rb"));
	stbtt_InitFont(&font, ttf_buffer, stbtt_GetFontOffsetForIndex(ttf_buffer,0));
	float scale = stbtt_ScaleForPixelHeight(&font, HEIGHT);
	int x0,y0,x1,y1;
	int ascent,baseline, decent;
	stbtt_GetFontVMetrics(&font, &ascent,&decent,0);
	baseline = (int) (ascent*scale);
	int height = (int) ((ascent - decent)*scale);

	printf("ascent = %d, decent = %d, baseline = %d, height = %d\n", ascent, decent, baseline, height);

	stbtt_GetCodepointBitmapBox(&font, c, scale, scale, &x0, &y0, &x1, &y1);
	printf("x0=%d y0=%d x1=%d y1=%d\n", x0, y0, x1, y1);

	int w = x1-x0;
	int h = y1-y0;
	unsigned char bitmap[h][w];

	stbtt_MakeCodepointBitmap(&font, &bitmap[0][0], w,h, w, scale, scale, c);
	for (j=0; j < h; ++j) {
		for (i=0; i < w; ++i) {
			putchar(" .:ioVM@"[bitmap[j][i]>>5]);
		}
		putchar('\n');
	}
	return 0;
}