X11-ben színek ill. colormap használata

Üdv! A következő proggyt szeretném úgy kibővíteni hogy változtató legyen a rajzolószín. Ehhez szeretnék segítséget kérni, előre is köszi!

#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;

// Variables for color

long fgcolor, bgcolor;
int screen, pointx, pointy;
XGCValues gcval;
Colormap cmap;
XColor color, ignore;
char *colorname="grey";

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

bgcolor = BlackPixel(display,screen_num);
fgcolor = WhitePixel(display,screen_num);
x = y = 0;
width = 640;
height = 480;

win = XCreateSimpleWindow(display, RootWindow(display, screen_num),
x, y, width, height, border_width,
fgcolor,
bgcolor);

cmap = DefaultColormap (display, screen_num);
// XAllocNamedColor(display, cmap, colorname, &color, &ignore);
// fgcolor = color.pixel;

// XStandardColormap *XAllocStandardColormap();
gcval.foreground = fgcolor;
gcval.background = bgcolor;
gc = XCreateGC(display,win,GCForeground|GCBackground,&gcval);

// 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 | PMaxSize;
size_hints->min_width = 640;
size_hints->min_height = 480;
size_hints->max_width = 640;
size_hints->max_height = 480;

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);

// XSetRGBColormaps(display, win, std_colormap, 0, prop1);

// 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, fgcolor);

// 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 */
XDrawPoint(display,win,gc, report.xbutton.x,report.xbutton.y);
break;
case KeyPress:
/* Clean up and exit */
XUnloadFont(display, font_info->fid);
XFreeGC(display, gc);
XCloseDisplay(display);
exit(EXIT_SUCCESS);
break;

default:;

}

}

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