Hell Labs

Suppose that, for some reason, you’d like to have a program that sends a key combination such as <Control+Left Arrow> to your X server. You can do that trivially using the X Test extension and XTestFakeKeyEvent, but if you want something a bit more flexible you can add a configuration file like

fwd     64 102
back    64 100

where the command back would simulate simultaneous keypresses of ALT (keycode 64) and Left Arrow (keycode 100). Don’t ask why would someone want to do something like this — the only thing I can assure you is that we had a good reason. If that’s your case, the following C program is what you need. Released to the public domain, compile and link against libXtst.

Update: a better version is available.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <X11/extensions/XTest.h>

#define CONFFILE "conf"
#define LINE_MAX 256
#define KEY_MAX 10

int main(int argc, char **argv)
{
        FILE *f;
        char *token = NULL, line[LINE_MAX];
        int key[KEY_MAX];
        Display *dpy;
        int i, keynum;

        if (argc != 2)
                fprintf(stderr, “usage: %s <command>\\n”, argv[0]), exit(1);

        if ((f = fopen(CONFFILE, “r”)) == NULL)
                fprintf(stderr, “can’t find configuration file\\n”), exit(1);

        for (; !feof(f); token = NULL) {
                fgets(line, LINE_MAX, f);
                token = strtok(line, ” \\t”);
                if (!strcmp(argv[1], token))
                        break;
        }
        fclose(f);

        if (!token)
                fprintf(stderr, “command %s not defined\\n”, argv[1]), exit(1);

        for (i = 0; i < KEY_MAX; i++) {
                if ((token = strtok(NULL, " \\t")) == NULL)
                        break;
                key[i] = strtoul(token, NULL, 0);
        }
        keynum = i;

        if ((dpy = XOpenDisplay(NULL)) == NULL)
                fprintf(stderr, "can't open display\\n"), exit(1);

        for (i = 0; i < keynum; i++)
                XTestFakeKeyEvent(dpy, key[i], True, CurrentTime);
        while (i--)
                XTestFakeKeyEvent(dpy, key[i], False, CurrentTime);

        XCloseDisplay(dpy);

        return 0;
}

This entry was posted on Wednesday, August 29th, 2007 at 12:58 pm and is filed under code, dontask, en, quickhack. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.