Receiving Onboard (off screen keyboard) data

[gilad (Gilad Yarnitzky)]

I’m trying to receive the keys pressed in the Onboard application. I created a small test application in gtkmm (first application I wrote) based on the a gtk3 sample posted here:

Onscreen Keyboard integration with GTK+3 application

In the OS I use, onboard it is already packaged (pacman -S onboard on Archlinux or apt install onboard on Debian). I suspect many other distro have it ready to install. I connect it to my application by passing the XID via program arguments, e.g. by adding something like the following to the X11 startup script: # Always respawn a new virtual keyboard instance killall onboard onboard -e -l Phone -t ModelM -s 800x600 > kbdpid & sleep 4 myapp --keyboard-plug=$(cat kbdpid) There is definitely roo…

here is my code that manage to open the Onboard application but does not receive the events (I did not post the main function that is minor):

#include "onboard.h"
#include <iostream>

static gboolean watch_out_channel(GIOChannel *channel, GIOCondition cond, gpointer *data)
{
  if(cond==G_IO_HUP)
  {
    g_print("Unreference Channel\n");
    g_io_channel_unref(channel);
    return FALSE;
  } 
  else
  {
    g_print("Channel reached\n");
    if (g_io_channel_get_buffer_size(channel) > 0)
    {
      g_print("somethig to read\n");
    }
    gchar *string;
    gchar buf[100];
    gsize bytes_read;

  }

  return TRUE;
}

OnBoard::OnBoard() : m_button("Open Keyboard")
{
   m_button.set_margin(10);

    m_button.signal_clicked().connect(sigc::mem_fun(*this, &OnBoard::add_plug), nullptr);

    set_child(m_button);
}

OnBoard::~OnBoard()
{
}

void OnBoard::add_plug()
{  
  g_print("Add Plug\n");
  gboolean retval;
  const gchar      *argv[] = {"onboard", nullptr};
  gint std_out=0;
  GError *error=NULL;
  GIOChannel *std_out_ch;

  retval=g_spawn_async_with_pipes(NULL, argv, NULL, G_SPAWN_DO_NOT_REAP_CHILD|G_SPAWN_SEARCH_PATH, NULL, NULL, &child_pid, NULL, &std_out, NULL, &error);

  if(retval)
    {
      //gtk_widget_set_sensitive(widget, FALSE);
      std_out_ch=g_io_channel_unix_new(std_out);
      g_io_add_watch(std_out_ch, G_IO_IN | G_IO_HUP, (GIOFunc)watch_out_channel, nullptr);
      g_print("Channel Added\n");
    }
  else 
    {
      g_print("Couldn't start plug. %s\n", error->message);
      g_error_free(error);
    }
}

The button appears, I click on it, the keyboard opens and then the watch_out_channel function is reached with cond==G_IO_HUP and from that point nothing happens. What an I missing in creating the io channel?

Thank you for your help