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Posts Tagged ‘evdev

actkbd

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After my X61 tablet arrived, I needed a keyboard daemon that can take care of hotkey events both under console and in X (I’d like to have control of brightness and volume level, etc., in both). After some search, I settled with actkbd, which to me is a good balance of speed (pure C), functionality and complexity (take a look at, say, gizmo daemon). It monitors evdev keyboard (e.g., /dev/input/event1. so need kernel evdev support), and reponds according to a config file.

  1. Simple config example
    A typical snippet in actkbd’s configuration file looks like this:

    ## mute key
    # hard mute if pressed long, otherwise toggle
    
    #code   event   attrib          ext command
    113	:rep	:grab,noexec	:
    113	:rel	:grabbed,ungrab	:/home/bin/mute
    113	:rel	:ungrabbed	:/home/bin/toggle
    
    # hard unmute (all muters)if shift+
    42+113:key::/home/bin/unmute Master Headphone Speaker
          

    With the helper scripts mute and toggle, this snippet either mutes or toggles the mute status of my soundcard depending on whether the Mute key (113) is just pressed or hold for a while.

    Each config line has four fields,

    • code: keycode as shown in showkey. multiple keys concatenated by ‘+’
    • event: one of key, rep (repeat), and rel (release)
    • attrib: (un)grab to block/release device from/to other programs, (un)grabbed to ensure action taking place only when (un)grabbed. This is the major featureset of actkbd. For a complete list, see the official README
    • ext command: external command to call. It could be better if actkbd can export relevant info as some sort of variable that can be passed to external commands (so that e.g. a general purpose hook program can handle all events).
  2. Tablet screen rotation
    The X61 tablet has some buttons alongside the tablet panel. When in tablet mode, these are the only keys accessible as the whole keyboard is covered under the tablet, so we want to use these keys wisely. With an external helper script rotate, the following snippet will

    • reset screen to normal orientation if “rotate” button hold for long
    • rotate screen 90 degrees clock-wise if “rotate” button is merely pressed
    • rotate screen to a relative orientation (left, right, or invert) if the “rotate” button is hold while the orientation arrow keys are pressed
    ## grab as `clean' bit, detectable
    # 191: "rotate" button
    # rotate clockwise if only hold short
    191	:key	:grab,noexec	:
    191	:rel	:grabbed,ungrab	:/home/bin/rotate
    
    ## 192 as `hold' bit
    191:rep:grabbed,set(192),noexec:
    # reset orientation if hold long
    191+192	:rel	:grabbed,ungrab,unset(192)	:/home/bin/rotate monitor
    191+192	:rel	:ungrabbed,unset(192),noexec	:
    
    ## u/d/l/r/enter: 103/108/105/106/28
    # u/d: invert; l/r: rotate; enter: pin down
    # relative rotation
    191+103		:rel	:ungrab	:/home/bin/rotate i
    191+108		:rel	:ungrab	:/home/bin/rotate i
    191+105		:rel	:ungrab	:/home/bin/rotate l
    191+106		:rel	:ungrab	:/home/bin/rotate r
    191+28		:rel	:ungrab	:/home/bin/rotate c
    191+192+103	:rel	:ungrab	:/home/bin/rotate i
    191+192+108	:rel	:ungrab	:/home/bin/rotate i
    191+192+105	:rel	:ungrab	:/home/bin/rotate l
    191+192+106	:rel	:ungrab	:/home/bin/rotate r
    191+192+28	:rel	:ungrab	:/home/bin/rotate c
          

    Here, the trick is to use ‘grab’ to indicate whether the current 191 key event is being processed or not, and use the ficticious 192 key to indicate whether it’s a long hold or a short one.

  3. LCD brightness control
    Similar trick can be used to control screen brightness. The master button to use now is “application” button right next to the “rotate” button.

    • short and long hold: reserverd for future use (:D)
    • app + up/down: turn brightness up/down by 1.
      app + left/right: turn brightness to min/max
      app + enter: turn brightness midway (7)
    ## similar `grab' and `hold' trick, but for 152
    152	:key	:grab,noexec			:
    152	:rel	:grabbed,ungrab			:echo "short press"
    152	:rep	:grabbed,set(153),noexec	:
    152+153	:rel	:grabbed,ungrab,unset(153)	:echo "long press"
    152+153	:rel	:ungrabbed,unset(153),noexec	:
    ## adjust brightness
    152+103		:rel	:ungrab	:echo up > /proc/acpi/ibm/brightness
    152+108		:rel	:ungrab	:echo down > /proc/acpi/ibm/brightness
    152+105		:rel	:ungrab	:echo level 0 > /proc/acpi/ibm/brightness
    152+106		:rel	:ungrab	:echo level 15 > /proc/acpi/ibm/brightness
    152+28		:rel	:ungrab	:echo level 7 > /proc/acpi/ibm/brightness
    152+153+103	:rel	:ungrab	:echo up > /proc/acpi/ibm/brightness
    152+153+108	:rel	:ungrab	:echo down > /proc/acpi/ibm/brightness
    152+153+105	:rel	:ungrab	:echo level 0 > /proc/acpi/ibm/brightness
    152+153+106	:rel	:ungrab	:echo level 15 > /proc/acpi/ibm/brightness
    152+153+28	:rel	:ungrab	:echo level 7 > /proc/acpi/ibm/brightness
          
  4. Microsoft Natural Ergonomic Keyboard 4000 (NE4k)
    The problem with NE4k, which I use on my desktop, is that kernel exports it as two devices, one for the normal keys (a,o,e,u,… yes I use dvorak), say /dev/input/event3, and one for all the multimedia/net/hot keys, say /dev/input/event4. Since each process of actkbd can only monitor a single device, there will be no way to capture something like shift+mute, which involves both devices. Even if you run two actkbd daemons monitoring both, there’s no easy way for them to crosstalk. A possible workaround is to somehow combine the two devices into one, or even one further step back, to “redirect” all events from one device to the other. Maybe I was using the wrong keywords, but a google search doesn’t reveal any such things, so here comes the stitch works: a simple “event replicator” which basically is a stripped down version of actkbd. Just gcc evpipe.c -o evpipe, and use ./evpipe /dev/input/event{4,3} to redirect event4 to event3. NB: although I “grabbed” the incoming device, it’d be a good idea to redirect the hotkey device to the standard keyboard instead of the other way around, so that even if something goes wrong you’ll still have a usable device. (I made the mistake of not “grabbing” the incoming device AND redirected the normal keyboard to the hotkeys, making each keypress of “a” generating “aa” and ended up having to kill the process from my laptop).

    /*******************************************
    * evpipe.c: *
    * basically c-k c-y of linux.c in actkbd. *
    * NO ERROR HANDLING!! (almost) *
    *******************************************/

    #include #include
    #include
    #include

    static FILE *from;
    static FILE *to;
    struct input_event ev;
    int grabbed=0;

    int main(int argc, char* argv[]){
    pipe(argv[1],argv[2]);
    }
    /* Allow SIGTERM to cause graceful termination */
    void close_and_quit(int signum) {
    if (to)
    fclose(to);
    if (from)
    fclose(from);
    if (grabbed)
    ungrab_dev();
    return;
    }

    int pipe(char* ffrom, char* fto){
    signal(SIGTERM, close_and_quit);
    signal(SIGINT, close_and_quit);
    from = fopen(ffrom, “a+”);
    if (from == NULL)
    return 1;
    to = fopen(fto, “a+”);
    if (to == NULL)
    return 2;

    grab_dev();
    while (get_key() == 0) {
    snd_key();
    // printf(“.”);
    // fflush(stdout);
    }
    //fclose(to);
    //fclose(from);
    }

    int get_key(){
    int ret;

    do {
    ret = fread(&ev, sizeof(ev), 1, from);
    if (ret < 1) return -1; /* read error */ } while (ev.type != EV_KEY); return 0; } int snd_key() { int ret; ret = fwrite(&ev, sizeof(ev), 1, to); fflush(to); if (ret < 1) return -2; /* write error */ return 0; } int grab_dev() { int ret; if (grabbed) return 0; ret = ioctl(fileno(from), EVIOCGRAB, (void *)1); if (ret == 0) grabbed = 1; // else // lprintf("Error: could not grab %s: %s\n", device, strerror(errno)); return ret; } int ungrab_dev() { int ret; if (!grabbed) return 0; ret = ioctl(fileno(from), EVIOCGRAB, (void *)0); if (ret == 0) grabbed = 0; // else // lprintf("Error: could not ungrab %s: %s\n", device, strerror(errno)); return ret; } [/sourcecode] Before I forget, there's also a ruby evdev binding. I myself am not using the code above, nor the ruby evdev binding, since I don’t urgently need shift + VolUp, etc.

Written by zsh

March 26, 2009 at 11:28 pm