List pixel widths from front size 10 to 30 for given fonts

pixelsize.c

#include <libgen.h>
#include <ft2build.h>
#include FT_FREETYPE_H

#define DPI (96)       /* device resolution */

void die(void)
{
	printf("oops\n");
	exit(1);
}

int main(int argc, char *argv[])
{
	FT_Library lib;
	FT_Face face;
	int ret;

	if (argc < 2) die();

	ret = FT_Init_FreeType(&lib);
	if (ret) die();

	FT_ULong codepoints[] = {'a', 0x3042};

	int min_size = 10;
	int max_size = 30;
	printf("font size:");
	for (int i = min_size; i <= max_size; i++) {
		printf(" %d", i);
	}
	printf("\n");

	for (int j = 0; j < argc-1; j++) {
		printf("%s\n", basename(argv[j+1]));
		ret = FT_New_Face(lib, argv[j+1], 0, &face);
		if (ret) die();
		for (FT_ULong k = 0; k < 2; k++) {
			int index = FT_Get_Char_Index(face, codepoints[k]);
			//printf("%ld -> %d\n", codepoints[k], index);

			if (!index) {
				printf("   U+%04lx: (not found)\n", codepoints[k]);
			}
			else {
				printf("   U+%04lx:", codepoints[k]);
				for (int i = min_size; i <= max_size; i++) {
					FT_Set_Char_Size(face, 0, i*64, DPI, DPI);
					FT_Load_Glyph(face, index, FT_LOAD_DEFAULT);
					printf(" %2ld", face->glyph->metrics.horiAdvance/64);
				}
				printf("\n");
			}
		}
	}
	return 0;
}