Hi everyone i have managed to build a php-gtk point of sale system, and linked it to a cash drawer and receipt printer thanks to kksou for his assistance, but know i need to interface it with a touch screen, how do i go about this?

Not sure if you have an actual touch screen to play with.

If you have, you will find the touchscreen is just another pointer moving device - similar to a mouse or touch pad (on your laptop). The only difference is that you can move the pointer location by touching the screen instead of moving a mouse. You can also generate a button click by "applying some pressure" to the touchscreen.

To PHP-GTK, it doesn't care (actually it can't tell too) whether you have moved the pointer or clicked a button with the mouse, the trackpad or the touchscreen.

You must have seen many POS system used in restaurants in which the waiters or waitress select items by pressing different colored boxes on the touchscreen. Believe it or not, those are just standard buttons. You can use a standard mouse and left click on these buttons. That's what they do when the touch screens are not functioning.

So don't worry about coding anything extra to interface to the touchscreen. Those nitty gritties are taken care off by the hardware drivers. In your PHP-GTK app, the event comes in just like a standard mouse events (e.g. clicked, button-press-event, motion-notify-event, etc.) Just design your POS application such that they function well with a standard mouse. Also, design the buttons such that they're "big" enough for the big hands.

Hope this helps.

Regards,
/kksou