Path: utzoo!attcan!uunet!lll-winken!ames!mailrus!tut.cis.ohio-state.edu!bloom-beacon!ANDREW.CMU.EDU!yt07+
From: yt07+@ANDREW.CMU.EDU (Yin-Cheng Tsai)
Newsgroups: comp.windows.x
Subject: Question about colormap!!
Message-ID: <cXtXlKy00WB9E5oEtR@andrew.cmu.edu>
Date: 31 Jan 89 23:08:06 GMT
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 98


Hi, folks,

     Could someone help me to find the bug in my code?

     I tried to make some exercises on Colormap, nevertheless, I got an
unsolvable problem.  If I use the default colormap, everything is going
very fine.  However, if I create the colormap with the default visual,
the XStoreNamedColor seems not working.

     Thanks for any comment and suggestion.
                                    -- yin-cheng


##-----------------  tst.c start from here  -------------------##
#include <stdio.h>
#include <X11/Xlib.h>

#define NPLANES               1
#define NCOLORS               4

main ()
{
    unsigned long plane_mask[NPLANES], pixels[NCOLORS], pixel;
    Display *display;
    XColor color;
    Window simple;
    Colormap cmap;
    int flag = 0;
    GC gc;

    if (!(display = XOpenDisplay (NULL))) {
        fprintf (stderr, "cannot open display\n");
        exit (-1);
    }

    simple = XCreateSimpleWindow (display, DefaultRootWindow (display),
             100, 100, 300, 300, 2, 0);

==>    cmap = DefaultColormap (display, DefaultScreen (display));

==>/*    cmap = XCreateColormap (display, simple,
            DefaultVisual (display, DefaultScreen (display)), AllocNone);
         XSetWindowColormap (display, simple, cmap);*/

    color.red = 255 << 8;
    color.green = 0;
    color.blue = 0;
    if (!XAllocColor (display, cmap, &color))
        fprintf (stderr, "allocation error\n");

    color.red = 0;
    color.green = 255 << 8;
    color.blue = 0;
    if (!XAllocColor (display, cmap, &color))
        fprintf (stderr, "allocation error\n");

    color.red = 0;
    color.green = 0;
    color.blue = 255 << 8;
    if (!XAllocColor (display, cmap, &color))
        fprintf (stderr, "allocation error\n");

    if (!XAllocColorCells (display, cmap, False, plane_mask, NPLANES,
            pixels, NCOLORS)) {
        fprintf (stderr, "cannot allocate any color cell\n");
        exit (-1);
    }

    pixel = pixels[0];
    gc = XCreateGC (display, simple, 0, NULL);
    XSetForeground (display, gc, pixel);

    XMapWindow (display, simple);
    XFlush (display);
    sleep (5);         /*  window must come up before next drawing command
                          is executed */

    XFillRectangle (display, simple, gc, 50, 50, 200, 200);
    XFlush (display);

    fprintf (stderr, "press '^C' to exit! ");
    fflush (stderr);
    while (1) {
        if (flag) {
            flag = 0;
            XStoreNamedColor (display, cmap, "gold", pixel, ~0);
            XFlush (display);
            sleep (1);
        }
        else {
            flag = 1;
            XStoreNamedColor (display, cmap, "navy", pixel, ~0);
            XFlush (display);
            sleep (1);
        }
    }
}