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

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

/* Test of X11 line drawing 12/17/2015 delaglio@nmrscience.com */

int main( int argc, char **argv )
{
    Display *dpy;
    Window  w;
    GC      gc;
    int     screen;

    XSizeHints    winInfo;
    unsigned int  borderWidth;
    unsigned long fg, bg, ultmp, white, black;
    int           i, ix, iy;

    dpy = XOpenDisplay( (char *)NULL );

    screen = DefaultScreen( dpy );
    white  = WhitePixel( dpy, screen );
    black  = BlackPixel( dpy, screen );

    winInfo.x      = 32;
    winInfo.y      = 32;
    winInfo.width  = 800;
    winInfo.height = 800;
    winInfo.flags  = PPosition | PSize;
    borderWidth    = 1;

    bg = black;
    fg = white;

    w = XCreateSimpleWindow( dpy, DefaultRootWindow( dpy ),
                             winInfo.x, winInfo.y,
                             winInfo.width, winInfo.height,
                             borderWidth, fg, bg );

    (void) XSetStandardProperties( dpy, w,
                                   argv[0], argv[0], None, 
                                   argv, argc, 
                                   &winInfo );

    gc = XCreateGC( dpy, w, (unsigned long)0, (XGCValues *)NULL );

    (void) XSetBackground( dpy, gc, bg );
    (void) XSetForeground( dpy, gc, fg );

    (void) XMapRaised( dpy, w );

    for( i = 0; i < 32; i++ ) 
       {
        for( iy = 1; iy < winInfo.height; iy++ )
           {
            for( ix = 1; ix < winInfo.width; ix++ )
               {
                (void) XDrawLine( dpy, w, gc, 1, 1, ix, iy );
               }
           }

        ultmp = fg; fg = bg; bg = ultmp;

        (void) XSetBackground( dpy, gc, bg );
        (void) XSetForeground( dpy, gc, fg );
       }

    (void) XFreeGC( dpy, gc );
    (void) XDestroyWindow( dpy, w );
    (void) XCloseDisplay( dpy );

    exit( 0 );
}