Onscreen Keyboard

I needed a simple onscreen keyboard to interface with a touch / pen based computer that I bought through an online auction. Although Microsoft supplies one with its Pen Extensions 2.0 it only works win Win95 and I wanted to use NT.

All of the available onscreen keyboards I found were either too expensive, or they were only designed to operate with 3.1 and 9x so (of course) I decided to see if I could make one. Along the way I learned a little about how the keyboard is handled, and the thread keyboard maps.

Included with this article is a working, but simple, onscreen keyboard. I submitted it mostly as an example of the methods:

• AttachThreadInput
• keybd_event
• VkKeyScan
• GetKeyState

This program has one nasty limitation, and that is that it "flashes" since it does not prevent the changing of focus to itself when clicked, and then back to the target window when the keystroke is generated. If someone wants to tackle that one please feel free ;-)