Ubuntuの gcc で Xlib を使って Hello world

[したいこと・しりたいこと]
Ubuntuの gcc で Xlib を使って Hello world

[環境]

Ubuntu Jaunty Jackalope 9.04 on VirtualBox 3.0.2

インストールするもの
build-essential



[したこと]

(1)インストール
$ sudo apt-get install build-essential

(2)ソースコードを書く

$ vi hellox.c

#include <X11/Xlib.h>

#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xos.h>
#include <X11/Xatom.h>

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


/* Global variables */
Display * display;
int screen_num;
static char * appname;


/* main() function */

int main( int argc, char * argv[] ) {

 /* Window variables */

 Window win;
 int x, y;
 unsigned int width, height;
 unsigned int border_width;
 char * window_name = "Hello, X Window System!";
 char * icon_name = "HelloX";


 /* Display variables */

 char * display_name = NULL;
 unsigned int display_width, display_height;


 /* Miscellaneous X variables */

 XSizeHints * size_hints;
 XWMHints * wm_hints;
 XClassHint * class_hints;
 XTextProperty windowName, iconName;
 XEvent report;
 XFontStruct * font_info;
 XGCValues values;
 GC gc;

 appname = argv[0];


 /* Allocate memory for our structures */

 if ( !( size_hints = XAllocSizeHints() ) ||
 !( wm_hints = XAllocWMHints() ) ||
 !( class_hints = XAllocClassHint() ) ) {
  fprintf(stderr, "%s: couldn't allocate memory.\n", appname);
  exit(EXIT_FAILURE);
 }


 /* Connect to X server */

 if ( (display = XOpenDisplay(display_name)) == NULL ) {
  fprintf(stderr, "%s: couldn't connect to X server %s\n",
  appname, display_name);
  exit(EXIT_FAILURE);
 }


 /* Get screen size from display structure macro */

 screen_num = DefaultScreen(display);
 display_width = DisplayWidth(display, screen_num);
 display_height = DisplayHeight(display, screen_num);


 /* Set initial window size and position, and create it */

 x = y = 0;
 width = display_width / 3;
 height = display_width / 3;

 win = XCreateSimpleWindow(display, RootWindow(display, screen_num),
 x, y, width, height, border_width,
 BlackPixel(display, screen_num),
 WhitePixel(display, screen_num));


 /* Set hints for window manager before mapping window */

 if ( XStringListToTextProperty(&window_name, 1, &windowName) == 0 ) {
  fprintf(stderr, "%s: structure allocation for windowName failed.\n",
  appname);
  exit(EXIT_FAILURE);
 }

 if ( XStringListToTextProperty(&icon_name, 1, &iconName) == 0 ) {
  fprintf(stderr, "%s: structure allocation for iconName failed.\n",
  appname);
  exit(EXIT_FAILURE);
 }

 size_hints->flags = PPosition | PSize | PMinSize;
 size_hints->min_width = 200;
 size_hints->min_height = 100;

 wm_hints->flags = StateHint | InputHint;
 wm_hints->initial_state = NormalState;
 wm_hints->input = True;

 class_hints->res_name = appname;
 class_hints->res_class = "hellox";

 XSetWMProperties(display, win, &windowName, &iconName, argv, argc,
 size_hints, wm_hints, class_hints);


 /* Choose which events we want to handle */

 XSelectInput(display, win, ExposureMask | KeyPressMask |
 ButtonPressMask | StructureNotifyMask);


 /* Load a font called "9x15" */

 if ( (font_info = XLoadQueryFont(display, "9x15")) == NULL ) {
  fprintf(stderr, "%s: cannot open 9x15 font.\n", appname);
  exit(EXIT_FAILURE);
 }


 /* Create graphics context */

 gc = XCreateGC(display, win, 0, &values);

 XSetFont(display, gc, font_info->fid);
 XSetForeground(display, gc, BlackPixel(display, screen_num));


 /* Display Window */

 XMapWindow(display, win);


 /* Enter event loop */

 while ( 1 ) {
  static char * message = "Hello, X Window System!";
  static int length;
  static int font_height;
  static int msg_x, msg_y;

  XNextEvent(display, &report);

  switch ( report.type ) {

   case Expose:

   if ( report.xexpose.count != 0 )
   break;

   /* Output message centrally in window */

   length = XTextWidth(font_info, message, strlen(message));
   msg_x = (width - length) / 2;

   font_height = font_info->ascent + font_info->descent;
   msg_y = (height + font_height) / 2;

   XDrawString(display, win, gc, msg_x, msg_y,
   message, strlen(message));

   break;


   case ConfigureNotify:

   /* Store new window width & height */

   width = report.xconfigure.width;
   height = report.xconfigure.height;

   break;


   case ButtonPress: /* Fall through */
   case KeyPress:

   /* Clean up and exit */

   XUnloadFont(display, font_info->fid);
   XFreeGC(display, gc);
   XCloseDisplay(display);
   exit(EXIT_SUCCESS);

  }
 }

 return EXIT_SUCCESS; /* We shouldn't get here */
}

(3)コンパイル
$ gcc -o hellox hellox.c -I/usr/X11R6/include -L/usr/X11R6/lib -lX11 -lm

(4)実行
$ ./hellox

[参考]
HTML output
http://www.paulgriffiths.net/program/c/srcs/helloxsrc.html