#include <X11/Xlib.h>
#include <X11/Xatom.h>
#include <X11/Xutil.h>
#include <cairo.h>
#include <cairo-xlib.h>
#include <ft2build.h>
#include <freetype.h>

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

/*! Simple Cairo/Xlib example.
 * @author Bernhard R. Fischer, 2048R/5C5FFD47 <bf@abenteuerland.at>.
 * @version 2014110801
 * Compile with
 * gcc -Wall $(pkg-config --libs --cflags cairo x11) -o cairo_xlib_simple cairo_xlib_simple.c
 */

/*! Check for Xlib Mouse/Keypress events. All other events are discarded.
 * @param sfc Pointer to Xlib surface.
 * @param block If block is set to 0, this function always returns immediately
 * and does not block. if set to a non-zero value, the function will block
 * until the next event is received.
 * @return The function returns 0 if no event occured (and block is set). A
 * positive value indicates that a key was pressed and the X11 key symbol as
 * defined in <X11/keysymdef.h> is returned. A negative value indicates a mouse
 * button event. -1 is button 1 (left button), -2 is the middle button, and -3
 * the right button.
 */
int cairo_check_event(cairo_surface_t *sfc, int block)
{
	char keybuf[8];
	KeySym key;
	XEvent e;

	for (;;)
	{
		if (block || XPending(cairo_xlib_surface_get_display(sfc)))
			XNextEvent(cairo_xlib_surface_get_display(sfc), &e);
		else
			return 0;

		switch (e.type)
		{
		case ButtonPress:
			return -e.xbutton.button;
		case KeyPress:
			XLookupString(&e.xkey, keybuf, sizeof(keybuf), &key, NULL);
			return key;
		default:
			fprintf(stderr, "Dropping unhandled XEevent.type = %d.\n", e.type);
		}
	}
}


/*! Open an X11 window and create a cairo surface base on that window.
 * @param x Width of window.
 * @param y Height of window.
 * @return Returns a pointer to a valid Xlib cairo surface. The function does
 * not return on error (exit(3)).
 */
cairo_surface_t *cairo_create_x11_surface0(int x, int y)
{
	Display *dsp;
	Drawable da;
	int screen;
	cairo_surface_t *sfc;

	if ((dsp = XOpenDisplay(NULL)) == NULL)
		exit(1);
	screen = DefaultScreen(dsp);
	da = XCreateSimpleWindow(dsp, DefaultRootWindow(dsp), 0, 0, x, y, 0, 0, 0);
	XSelectInput(dsp, da, ButtonPressMask | KeyPressMask);
	XMapWindow(dsp, da);

	sfc = cairo_xlib_surface_create(dsp, da, DefaultVisual(dsp, screen), x, y);
	cairo_xlib_surface_set_size(sfc, x, y);

	return sfc;
}


/*! Destroy cairo Xlib surface and close X connection.
 */
void cairo_close_x11_surface(cairo_surface_t *sfc)
{
	Display *dsp = cairo_xlib_surface_get_display(sfc);

	cairo_surface_destroy(sfc);
	XCloseDisplay(dsp);
}

static int sizes[]= {8,10,12,16,18,24,36,48,60,72,84,96};

int main(int argc, char **argv)
{
	cairo_surface_t *sfc;
	cairo_t *ctx;

	sfc = cairo_create_x11_surface0(700, 400);

	ctx = cairo_create(sfc);
	cairo_set_source_rgb(ctx, 1, 1, 1);
	cairo_paint(ctx);

	FT_Library lib;
	FT_Init_FreeType(&lib);
	FT_Face ft_face;
	FT_New_Face(lib,"cmex10.otf",0,&ft_face);

	cairo_font_face_t *font_face = cairo_ft_font_face_create_for_ft_face (ft_face, 0);

	cairo_set_source_rgb(ctx, 0, 0, 0);

	int i;
	for (i=0; i<12; i++)
	{

		cairo_move_to (ctx, 5+100*(i%6), 20+80*(i/6));

		cairo_select_font_face(ctx,"sans-serif",CAIRO_FONT_SLANT_NORMAL,CAIRO_FONT_WEIGHT_NORMAL);
		cairo_set_font_size (ctx, 8);
		char size[3];
		sprintf(size,"%d",sizes[i]);
		cairo_show_text(ctx,size);

		cairo_set_font_face (ctx, font_face);
		cairo_set_font_size (ctx, sizes[i]);
		cairo_show_text(ctx,"r");
	}

	cairo_destroy(ctx);

	cairo_check_event(sfc, 1);

	cairo_close_x11_surface(sfc);

	return 0;
}