Hi davep,
I personally use the EVENT_LEFT_CLICK instead of EVENT_COMMIT. The primary difference between the two is that EVENT_COMMIT occurs as you release your finger from the touch screen, and EVENT_LEFT_CLICK occurs as you contact the touch screen. This can make a big difference between usability if untrained users will be interacting with the screens. Most people think that if you touch the screen and slide you finger slightly off the control, that it should still accept the touch event. This is best done with EVENT_LEFT_CLICK.
This can bring up another scenario that may or may not apply to you as well. If you have the user touch a button on the screen, that must be held down for an action to continue to occur, then you will have to deal with what happens when their finger does slide off the control--from vibration, slippage, or laziness. If you have lots of this to do, you might consider panel event tracking instead of control event tracking. This is usually done less often these days, but occasionally it is useful.
Also, you have to be very careful on how you deal with the double-click situation. If your users have the opportunity to double enter a value, i.e. 5-5-1-3, you don't want your program to count the second 5 as a double-click and get 5-1-3. The way that I beat this usually is to turn the mouse double click time down to the lowest possible duration using the control panel. This way average users won't be fast enough to trigger the double-click--unless they have been drinking way too much coffee! 😆
Then, you also must be knowledgeable on how your touch screen deals with multiple touches. For example, the touch screen will sometimes average the two touches, sometimes it will stay on the first touch coordinate, and sometimes it will jump to the second. This again comes back into play when the user has to hold their finger over a control to make an action continue to occur. This is a situation where it is a human error, but if it results in someone getting their arm chopped off, you are not going to be a very happy camper--or will they!
Also there are different types of touch screens. Your environment will dictate which technology is appropriate, but the ones that most users find as natural are the resistive or the capacitive. The infrared screens are great too, but users need to remember to clear their finger from the beam before they can double enter a value. Just some of my experiences.... I've been using CVI with different types of touch screens for about 5 years now. Most scenarios are manageable, but they each require careful consideration on your part.
Good luck,
Orlan
