How to make a "kiosk"-application

The computer could be any computer capable of running FreeBSD or Linux.

Since you have to place the windows yourself on to the screen, is is handy to have a grid to work with. This is dependent on the resolution of your screen.

Since your application is without a window manager you yourself have to resize and position your window. In Gtk you do that with:

// You must hold width and height and position
// within the application...

static gint window_x_width = 300;
static gint window_y_height = 300;
static gint window_x_pos = 100;
static gint window_y_pos = 200;
...
gtk_window_move( GTK_WINDOW( window ), window_x_pos, window_y_pos );
...
gtk_widget_set_size_request (da, window_x_width, window_y_height);
...

You have to install X-window on the system but without having the X-window start on boot.

This is how a startup script in FreeBSD could look like

/etc/rc.local
---
#!/usr/local/bin/bash

/usr/sbin/ntpdate -s 0.ubuntu.pool.ntp.org

DISPLAY=:0.0
export DISPLAY

/usr/local/bin/X -ac &

# Let the x-server have time to start
sleep 20

# Connect from any IP
/usr/local/bin/xhost + &

# Remove the cursor from the screen, turn off screensaver
/usr/local/bin/unclutter -root -idle 1 &
/usr/local/bin/xset -dpms &
/usr/local/bin/xset s off &

# set background
# https://en.wikipedia.org/wiki/X11_color_names
/usr/local/bin/xsetroot -solid Grey &

# show local time
TZ=CEST
export TZ
/usr/local/bin/xclock -geometry 384x307-0+0 &
...

#
# Infact... The application can be run on some other! computer.
# In the good old days we talked about X-terminals...
# https://en.wikipedia.org/wiki/X_terminal
#
# The arguments to the application should take care of the x,y positon and
# the size of the window.
#
DISPLAY=192.168.37.88:0.0 ./draw-text -x 0 -y 0 -X 896 -Y 307 -g logo -L "" -f 100 &

# And! some other applications...

---

You will have a kiosk that run applications without a window-manager.

It is also possible to update the kiosk from other system by using, for example, Spread.

Göran is a software developer working att Raditex Control AB