I have a Raspberry Pi set up as a web kiosk that displays a web app that I wrote for parents to check their children in and out of a preschool. The browser is chromium in kiosk mode. The web app is written in php and runs in apache on an OpenSuse server. A mariadb database is used to store the pins and list of children.

The users interact with it by pressing onscreen buttons to enter their 4-digit pin code. They are then presented with a button for each of their children that they can click to log in or out.

Frequently when a user presses a button on screen, instead of the click being registered, they get a little file icon where they pressed that disappears as soon as they lift their finger. This icons appearance means the button wasn't pressed and they have to press it again. This happens with such frequency that to enter the 4 digit pin frequently requires 6-12 taps.

I think this is happening because their presses aren't straight clicks. There is some small amount of "roll" in their finger as they press and the pi is judging it to be a drag event.

How can I prevent this from happening?

  • Have you considered buying a better touch screen? – Mohammad Ali Oct 11 '16 at 19:45
  • Also you could look into disabling drag on those particular buttons such as stackoverflow.com/questions/4211909/… – Mohammad Ali Oct 11 '16 at 19:46
  • @MohammadAli It also happens on the Pi Foundations 7in Touchscreen. I will investigate the article mentioned for disabling dragging and post back if it works. – Hudson Hallenbeck Oct 13 '16 at 13:29
  • also if you could look into running the Pi and the interface on two separate pis it may help as your problem may be lag induced, if you don't have two pis running the server on something like a PC would help you identify if the problem is lag related – Mohammad Ali Oct 13 '16 at 16:28
  • Also look into this as if it's registered as a right click it won't drag: raspberrypi.org/forums/viewtopic.php?f=108&t=121602 – Mohammad Ali Oct 21 '16 at 4:04

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