mix.c

/*
 * gcc -o mix mix.c `pkg-config --cflags --libs freetype2 x11 xrender`
 */
#include <stdio.h>
#include <stdlib.h>
#include <X11/Xlib.h>
#include <X11/extensions/Xrender.h>
#include <ft2build.h>
#include FT_FREETYPE_H

FT_Library library;

GlyphSet
load_glyphset(Display *dpy, char *filename, int size, char *s, int *x)
{
	FT_Face face;
	XRenderPictFormat *fmt = XRenderFindStandardFormat(dpy, PictStandardA8);
	GlyphSet gs = XRenderCreateGlyphSet(dpy, fmt);
	int i, idx;

	if (FT_New_Face(library, filename, 0, &face) != FT_Err_Ok) {
		printf("Unable to open %s\n", filename);
		return 0;
	}
	if (FT_Set_Char_Size(face, 0, size /* pt */ << 6 /* 1/64 */,
			     96 /* dpi */, 96) != FT_Err_Ok) {
		printf("Unable to set size for Noto Sans\n");
		gs = 0;
		goto bail;
	}

	for (i = 0; s[i] != 0; i++) {
		FT_Bitmap *bitmap;
		XGlyphInfo ginfo;
		Glyph gid;
		int stride;
		char *tmp;
		int y;

		idx = FT_Get_Char_Index(face, s[i]);
		if (FT_Load_Glyph(face, idx, FT_LOAD_RENDER) != FT_Err_Ok) {
			printf("Unable to load a glyph %02X\n", s[i]);
			continue;
		}

		bitmap = &face->glyph->bitmap;
		ginfo.x = -face->glyph->bitmap_left;
		ginfo.y = face->glyph->bitmap_left;
		ginfo.width = bitmap->width;
		ginfo.height = bitmap->rows;
		ginfo.xOff = face->glyph->advance.x >> 6;
		ginfo.yOff = face->glyph->advance.y >> 6;

		gid = s[i];

		stride = (ginfo.width + 3) & ~3;
		tmp = malloc(stride * ginfo.height);
		for (y = 0; y < ginfo.height; y++)
			memcpy(tmp+y*stride, bitmap->buffer+y*ginfo.width, ginfo.width);

		XRenderAddGlyphs(dpy, gs, &gid, &ginfo, 1, tmp, stride*ginfo.height);
		XSync(dpy, 0);

		*x += face->glyph->advance.x >> 6;
		free(tmp);
	}
  bail:
	FT_Done_Face(face);

	return gs;
}

int
main(void)
{
	FT_Error fterr;
	FT_Face facea, facen;
	char a[] = "ABCD";
	char n[] = "0123";
	Display *dpy;
	int screen, xa = 0, xn = 0;
	Window root, w;
	XRenderPictureAttributes pict_attr, pict_attr_pen;
	XRenderPictFormat *fmt, *fmt_pen;
	Picture pict, fg_pen;
	XRenderColor color = { .red = 0, .green = 0, .blue = 0, .alpha = 0xffff};
	XRenderColor bg_color = { .red = 0xffff, .green = 0xffff, .blue = 0xffff, .alpha = 0xffff};
	Pixmap pixmap;
	GlyphSet gsa, gsn;

	dpy = XOpenDisplay(NULL);
	screen = DefaultScreen(dpy);
	root = DefaultRootWindow(dpy);
	w = XCreateWindow(dpy, root, 0, 0, 640, 480, 0,
			  DefaultDepth(dpy, screen), InputOutput,
			  DefaultVisual(dpy, screen), 0, NULL);

	pict_attr.poly_edge = PolyEdgeSmooth;
	pict_attr.poly_mode = PolyModeImprecise;

	fmt = XRenderFindStandardFormat(dpy, PictStandardRGB24);
	pict = XRenderCreatePicture(dpy, w, fmt, CPPolyEdge|CPPolyMode, &pict_attr);

	XSelectInput(dpy, w, KeyPressMask|KeyReleaseMask|ExposureMask|ButtonPressMask|StructureNotifyMask);

	fmt_pen = XRenderFindStandardFormat(dpy, PictStandardARGB32);
	pixmap = XCreatePixmap(dpy, root, 1, 1, 32);
	pict_attr_pen.repeat = 1;
	fg_pen = XRenderCreatePicture(dpy, pixmap, fmt_pen, CPRepeat, &pict_attr_pen);
	XRenderFillRectangle(dpy, PictOpOver, fg_pen, &color, 0, 0, 1, 1);
	XFreePixmap(dpy, pixmap);

	fterr = FT_Init_FreeType(&library);
	if (fterr) {
		printf("Failed to initialize FreeType\n");
		return 1;
	}

	gsa = load_glyphset(dpy, "/usr/share/fonts/google-noto-vf/NotoSans[wght].ttf", 24, a, &xa);
	gsn = load_glyphset(dpy, "/usr/share/fonts/google-noto-vf/NotoSansArabic[wght].ttf", 24, n, &xn);

	XMapWindow(dpy, w);

	while (1) {
		XEvent event;

		XNextEvent(dpy, &event);
		switch (event.type) {
		    case Expose:
			    XRenderFillRectangle(dpy, PictOpOver, pict, &bg_color, 0, 0, 1640, 1640);
			    XRenderCompositeString8(dpy, PictOpOver,
						    fg_pen, pict, 0, gsa,
						    0, 0, 20, 50, a, 4);
			    XRenderCompositeString8(dpy, PictOpOver,
						    fg_pen, pict, 0, gsn,
						    0, 0, 20+xa, 50, n, 4);
			    break;
		    case DestroyNotify:
			    printf("Destroying\n");
			    return 0;
		}
	}

	return 0;
}