14.9 Beispiel – ein Button mit X
Zu Beginn des Abschnitts der Xlib hatte ich bereits erwähnt, dass Sie hiermit auch Buttons, Menüs usw. erstellen können. Allerdings ist dies ein nicht ganz unerheblicher Aufwand. Ein Beispiel gefällig? Das folgende Listing überlasse ich Ihnen ohne Kommentare zum Studieren. Es wird dabei ein Fenster erzeugt, und darin werden zwei Buttons gezeichnet. Anschließend wird über Maus-Events überprüft, ob der linke Mausbutton auf einen der Buttons gedrückt wurde.
/* xbutton.c */
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <unistd. h.>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
static Display *disp;
static Window win;
static GC gc;
static XFontStruct *font;
static int curbutton; /* Aktueller Button, der gedrückt wurde */
static int xs, ys; /* Aktuelle X-,Y-Größe des Fensters */
static unsigned long white, black, red, blue, green;
static void draw_buttons (void);
static int which_button (int, int);
static void draw_buttons (void) {
int wd = (xs) / 2 - 4; /* Weite von jedem Button */
int ht = (ys) / 3 - 4; /* Höhe von jedem Button */
int i1, i2, i3, xp, yp;
XCharStruct tsize;
XClearWindow (disp, win);
XSetForeground (disp, gc, red);
XFillRectangle (disp, win, gc, 2, 2, wd, ht);
XSetForeground (disp, gc, black);
XSetBackground (disp, gc, red);
XDrawRectangle (disp, win, gc, 2, 2, wd, ht);
XTextExtents (font, "Ende", strlen ("Ende"),
&i1, &i2, &i3, &tsize);
xp = (wd / 2) - (tsize.width / 2);
yp = (ht / 2) + (tsize.ascent) -
((tsize.ascent + tsize.descent) / 2);
XDrawImageString ( disp, win, gc, xp, yp,
"Ende", strlen ("Ende"));
XSetForeground (disp, gc, blue);
XSetBackground (disp, gc, white);
XDrawRectangle (disp, win, gc, xs / 2 + 2, 2, wd, ht);
XTextExtents (font, "Hallo", strlen ("Hallo"),
&i1, &i2, &i3, &tsize);
xp = (xs / 2 + wd / 2 + 2) - (tsize.width / 2);
yp = (ht / 2 + 2) + (tsize.ascent) -
((tsize.ascent + tsize.descent) / 2);
XDrawImageString (disp, win, gc, xp, yp,
"Hallo", strlen ("Hallo"));
}
static int which_button (int x, int y) {
int wd = (xs) / 2 - 4; /* Weite von jedem Button */
int ht = (ys) / 3 - 4; /* Höhe von jedem Button */
if (x >= 2 && y >= 2 && x <= wd + 2 && y <= ht + 2)
return 1;
if (x >= xs / 2 + 2 && y >= 2 &&
x <= wd + xs / 2 + 2 && y <= ht + 2)
return 2;
return 0;
}
int main (int argc, char **argv) {
int depth;
int screen;
XSetWindowAttributes wa;
XSizeHints sh;
XVisualInfo vinfo;
Visual *visual;
Colormap cmap;
Atom closeatom;
XColor col;
XEvent e;
int quit = 0;
XTextProperty name;
char *txt = "Buttons";
disp = XOpenDisplay ("");
if (disp == NULL) {
printf(" Kann keine Verbindung zum X-Server aufbauen\n");
exit (EXIT_FAILURE);
}
if (!XMatchVisualInfo (disp, 0, 32, TrueColor, &vinfo))
if (!XMatchVisualInfo (disp, 0, 24, TrueColor, &vinfo))
if (!XMatchVisualInfo (disp, 0, 16, TrueColor, &vinfo)) {
printf ("Cannot get TrueColor Visual!\n");
exit (EXIT_FAILURE);
}
visual = vinfo.visual;
depth = vinfo.depth;
screen = vinfo.screen;
cmap = XCreateColormap (
disp, RootWindow (disp, screen), visual, AllocNone );
col.red = 0xFFFF;
col.green = 0xFFFF;
col.blue = 0xFFFF;
col.flags = DoRed | DoGreen | DoBlue;
XAllocColor (disp, cmap, &col);
white = col.pixel;
col.red = 0x0000;
col.green = 0x0000;
col.blue = 0x0000;
col.flags = DoRed | DoGreen | DoBlue;
XAllocColor (disp, cmap, &col);
black = col.pixel;
col.red = 0xFFFF;
col.green = 0x0000;
col.blue = 0x0000;
col.flags = DoRed | DoGreen | DoBlue;
XAllocColor (disp, cmap, &col);
red = col.pixel;
col.red = 0x0000;
col.green = 0x0000;
col.blue = 0xAFFF;
col.flags = DoRed | DoGreen | DoBlue;
XAllocColor (disp, cmap, &col);
blue = col.pixel;
col.red = 0x0000;
col.green = 0xAFFF;
col.blue = 0x0000;
col.flags = DoRed | DoGreen | DoBlue;
XAllocColor (disp, cmap, &col);
green = col.pixel;
wa.background_pixel = white;
wa.border_pixel = black; /* Nicht verwendet, aber nötig */
wa.colormap = cmap; /* Nicht verwendet, aber nötig */
xs = 130, ys = 90;
win = XCreateWindow (disp, RootWindow (disp, screen),
200, 150, 130, 90, 2, depth,
InputOutput, visual,
CWBorderPixel | CWBackPixel | CWColormap, &wa);
sh.min_width = 130;
sh.min_height = 90;
sh.flags = PMinSize;
XSetWMNormalHints (disp, win, &sh);
XStringListToTextProperty (&txt, 1, &name);
XSetWMName (disp, win, &name);
gc = XCreateGC (disp, win, 0, NULL);
if (gc == 0) {
XDestroyWindow (disp, screen);
exit (EXIT_FAILURE);
}
XSelectInput (disp, win,
ButtonPressMask | ButtonReleaseMask |
ExposureMask | StructureNotifyMask );
closeatom = XInternAtom (disp, "WM_DELETE_WINDOW", 1);
if (closeatom)
XSetWMProtocols (disp, win, (Atom *) & closeatom, 1);
XMapWindow (disp, win);
font = XLoadQueryFont (disp, "9x15");
if (font == (XFontStruct *) NULL) {
printf ("Kann die Schrift nicht einrichten:9x15.\n");
exit (EXIT_FAILURE);
}
XSetFont (disp, gc, font->fid);
while (!quit) {
XNextEvent (disp, &e);
if (e.type == ClientMessage
&& (Atom) (e.xclient.data.l[0]) == closeatom) {
quit = 1;
}
else if (e.type == ButtonPress) {
curbutton = which_button (e.xbutton.x, e.xbutton.y);
}
else if (e.type == ButtonRelease) {
if (curbutton &&
which_button (e.xbutton.x, e.xbutton.y) == curbutton) {
if (curbutton == 1)
quit = 1;
else if (curbutton == 2)
printf ("'Hallo' gedrückt\n");
}
curbutton = 0;
}
else if (e.type == ConfigureNotify) {
if(e.xconfigure.width != xs || e.xconfigure.height != ys) {
xs = e.xconfigure.width;
ys = e.xconfigure.height;
}
}
else if (e.type == Expose) {
if (e.xexpose.count == 0) {
draw_buttons ();
}
}
}
XFreeFont (disp, font);
XDestroyWindow (disp, win);
XCloseDisplay (disp);
exit (EXIT_SUCCESS);
}
Das Beispiel bei der Ausführung:
$ gcc -o xbutton xbutton.c -L/usr/X11R6/lib -lX11
$ ./xbutton
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