Windows 7 touch screen single touch problems

Question

I'm trying to receive touch events on a Windows 7 machine using a 3M touchscreen. I've hooked into the Windows message chain successfully and am able to receive touch inputs perfectly in all but one situation. If I place a single finger on the touch screen and don't move it, no touch message is sent. If I place a second finger on the screen I receive a message for 2 touch points. If I remove the second touch point I receive messages for the 1 touch point.

Also, if I place a single touch point and then move it the messages come through correct.

I need to be able to receive a touch message when a single touch has been added but not moved. Is there some setting in Windows that is causing this? Is it possibly translating this single touch as a mouse event?

Answer 1

I think that the driver is incapable of generating a touch message in this case because touching with a single finger can be the start of several scenarios.

The driver is obliged to wait for you to either :

• lift the finger for it to generate a right-mouse-click, or
• move the finger for it to generate left-mouse-down and left-mouse-move, or
• touch with another finger for it to generate one of several multi-finger messages.

You could try to update your touch device driver to the latest version, but I think that the driver has no choice in this case but to wait for a follow-up action before generating any sort of message.

My advice is to change your planned user interface so as not to use press-and-hold as a gesture.

I haven't been able to find any documentation to support my above ideas, so it is to be taken only as a conjuncture about the functioning of Windows touch drivers.