x11SimpleProg

/*
    Remember to compile try:
        1) gcc hi.c -o hi -lX11
        2) gcc hi.c -I /usr/include/X11 -L /usr/X11/lib -lX11
        3) gcc hi.c -I /where/ever -L /who/knows/where -l X11

    Brian Hammond 2/9/96.    Feel free to do with this as you will!
*/


/* include the X library headers */
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xos.h>

/* include some silly stuff */
#include <stdio.h>
#include <stdlib.h>

/* here are our X variables */
Display *dis;
int screen;
Window win;
GC gc;

/* here are our X routines declared! */
void init_x();
void close_x();
void redraw();

main () {
    XEvent event;       /* the XEvent declaration !!! */
    KeySym key;     /* a dealie-bob to handle KeyPress Events */
    char text[255];     /* a char buffer for KeyPress Events */

    init_x();

    /* look for events forever... */
    while(1) {
        /* get the next event and stuff it into our event variable.
           Note:  only events we set the mask for are detected!
        */
        XNextEvent(dis, &event);

        if (event.type==Expose && event.xexpose.count==0) {
        /* the window was exposed redraw it! */
            redraw();
        }
        if (event.type==KeyPress&&
            XLookupString(&event.xkey,text,255,&key,0)==1) {
        /* use the XLookupString routine to convert the invent
           KeyPress data into regular text.  Weird but necessary...
        */
            if (text[0]=='q') {
                close_x();
            }
            printf("You pressed the %c key!\n",text[0]);
        }
        if (event.type==ButtonPress) {
        /* tell where the mouse Button was Pressed */
            int x=event.xbutton.x,
                y=event.xbutton.y;

            strcpy(text,"X is FUN!");
            XSetForeground(dis,gc,rand()%event.xbutton.x%255);
            XDrawString(dis,win,gc,x,y, text, strlen(text));
        }
    }
}

void init_x() {
/* get the colors black and white (see section for details) */
    unsigned long black,white;

    dis=XOpenDisplay((char *)0);
    screen=DefaultScreen(dis);
    black=BlackPixel(dis,screen),
    white=WhitePixel(dis, screen);
    win=XCreateSimpleWindow(dis,DefaultRootWindow(dis),0,0,
        300, 300, 5,black, white);
    XSetStandardProperties(dis,win,"Howdy","Hi",None,NULL,0,NULL);
    XSelectInput(dis, win, ExposureMask|ButtonPressMask|KeyPressMask);
        gc=XCreateGC(dis, win, 0,0);
    XSetBackground(dis,gc,white);
    XSetForeground(dis,gc,black);
    XClearWindow(dis, win);
    XMapRaised(dis, win);
};

void close_x() {
    XFreeGC(dis, gc);
    XDestroyWindow(dis,win);
    XCloseDisplay(dis);
    exit(1);
};

void redraw() {
    XClearWindow(dis, win);
};