/*

 * simple-text.c - demonstrate drawing of text strings on a window. All

 *         drawings are done in black color over a white background.

 */



#include <X11/Xlib.h>



#include <stdio.h>

#include <stdlib.h>      /* getenv(), etc. */

#include <string.h>

#include <unistd.h>      /* sleep(), etc.  */



/*

 * function: create_simple_window. Creates a window with a white background

 *           in the given size.

 * input:    display, size of the window (in pixels), and location of the window

 *           (in pixels).

 * output:   the window's ID.

 * notes:    window is created with a black border, 2 pixels wide.

 *           the window is automatically mapped after its creation.

 */

Window create_simple_window(Display* display, int width, int height, int x, int y)

{

  int screen_num = DefaultScreen(display);

  int win_border_width = 2;

  Window win;



  /* create a simple window, as a direct child of the screen's */

  /* root window. Use the screen's black and white colors as   */

  /* the foreground and background colors of the window,       */

  /* respectively. Place the new window's top-left corner at   */

  /* the given 'x,y' coordinates.                              */

  win = XCreateSimpleWindow(display, RootWindow(display, screen_num),

                            x, y, width, height, win_border_width,

                            BlackPixel(display, screen_num),

                            WhitePixel(display, screen_num));



  /* make the window actually appear on the screen. */

  XMapWindow(display, win);



  /* flush all pending requests to the X server. */

  XFlush(display);



  return win;

}



GC create_gc(Display* display, Window win, int reverse_video)

{

  GC gc;            /* handle of newly created GC.  */

  unsigned long valuemask = 0;      /* which values in 'values' to  */

               /* check when creating the GC.  */

  XGCValues values;         /* initial values for the GC.   */

  unsigned int line_width = 2;      /* line width for the GC.       */

  int line_style = LineSolid;      /* style for lines drawing and  */

  int cap_style = CapButt;      /* style of the line's edje and */

  int join_style = JoinBevel;      /*  joined lines.      */

  int screen_num = DefaultScreen(display);



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

  if (gc < 0) {

   fprintf(stderr, "XCreateGC: \n");

  }



  /* allocate foreground and background colors for this GC. */

  if (reverse_video) {

    XSetForeground(display, gc, WhitePixel(display, screen_num));

    XSetBackground(display, gc, BlackPixel(display, screen_num));

  }

  else {

    XSetForeground(display, gc, BlackPixel(display, screen_num));

    XSetBackground(display, gc, WhitePixel(display, screen_num));

  }



  /* define the style of lines that will be drawn using this GC. */

  XSetLineAttributes(display, gc,

                     line_width, line_style, cap_style, join_style);



  /* define the fill style for the GC. to be 'solid filling'. */

  XSetFillStyle(display, gc, FillSolid);



  return gc;

}



void list_fonts(Display *display)

{

   int font_count, i;

   char **fonts;



   //列出所有GB2312

   printf("All fonts on this server:\n");

   fonts = XListFonts(display, "*-helvetica-*-12-*", 1000, &font_count);

   for(i=0; i<font_count; i++)

      printf("%s\n", fonts[i]);

   XFreeFontNames(fonts);

}



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

{

  Display* display;      /* pointer to X Display structure.           */

  int screen_num;      /* number of screen to place the window on.  */

  Window win;         /* pointer to the newly created window.      */

  unsigned int display_width,

               display_height;   /* height and width of the X display.        */

  unsigned int win_width,

          win_height;   /* height and width for the new window.      */

  char* display_name = getenv("DISPLAY");  /* address of the X display.      */

  GC gc;         /* GC (graphics context) used for drawing    */

            /*  in our window.              */

  XFontStruct* font_info;       /* Font structure, used for drawing text.    */

  char* font_name = "*-helvetica-*-12-*"; /* font to use for drawing text.   */

  //char* font_name = "-adobe-helvetica-medium-o-normal--12-120-75-75-p-67-iso10646-1";



  /* open connection with the X server. */

  display = XOpenDisplay(display_name);

  if (display == NULL) {

    fprintf(stderr, "%s: cannot connect to X server '%s'\n",

            argv[0], display_name);

    exit(1);

  }



  /* list all fonts */

  list_fonts(display);



  /* get the geometry of the default screen for our display. */

  screen_num = DefaultScreen(display);

  display_width = DisplayWidth(display, screen_num);

  display_height = DisplayHeight(display, screen_num);



  /* make the new window occupy 1/9 of the screen's size. */

  win_width = (display_width / 3);

  win_height = (display_height / 3);

  //printf("window width - '%d'; height - '%d'\n", win_width, win_height);



  /* create a simple window, as a direct child of the screen's   */

  /* root window. Use the screen's white color as the background */

  /* color of the window. Place the new window's top-left corner */

  /* at the given 'x,y' coordinates.                             */

  win = create_simple_window(display, win_width, win_height, 0, 0);



  /* allocate a new GC (graphics context) for drawing in the window. */

  gc = create_gc(display, win, 0);

  XSync(display, False);



  /* try to load the given font. */

  font_info = XLoadQueryFont(display, font_name);

  if (!font_info) {

      fprintf(stderr, "XLoadQueryFont: failed loading font '%s'\n", font_name);

      exit(-1);

  }



  /* assign the given font to our GC. */

  XSetFont(display, gc, font_info->fid);



  {

    /* variables used for drawing the text strings. */

    int x, y;

    char* text_string;

    int string_width;

    int font_height;



    /* find the height of the characters drawn using this font.        */

    font_height = font_info->ascent + font_info->descent;



   //setlocale("LANG", "");



    /* draw a "hello world" string on the top-left side of our window. */

    text_string = "hello world";

    x = 0;

    y = font_height;

    XDrawString(display, win, gc, x, y, text_string, strlen(text_string));



    /* draw a "middle of the road" string in the middle of our window. */

    //text_string = "middle of the road";

    text_string = "中间是中文";

    /* find the width, in pixels, of the text that will be drawn using */

    /* the given font.                                                 */

    string_width = XTextWidth(font_info, text_string, strlen(text_string));

    x = (win_width - string_width) / 2;

    y = (win_height + font_height) / 2;

    XDrawString(display, win, gc, x, y, text_string, strlen(text_string));

  }



  /* flush all pending requests to the X server. */

  XFlush(display);



  /* make a delay for a short period. */

  sleep(3);



  /* close the connection to the X server. */

  XCloseDisplay(display);



  return 0;

}