LA Fox Presidents Column

On a recent project, a client wanted the application to be completely accessible by a touch screen. This request posed some interesting problems. How will the user enter an ID or password? How will the user enter numeric values? We were able to answer all of these questions with some clever user interfaces which allowed the user to enter values through “popup” keyboard and numpads. One of the most interesting user interfaces we developed was a “spinner” in the DOS environment. What we developed was a function which would use global variables to increment or decrement a specific variable’s value. These global variables are assigned values in a WHEN clause (Function SetScroll) attached to each variable being read. When the user depresses the arrow buttons drawn on the screen, the when clause on the invisible button (Function Spinner) is called and the value for the previously enabled field will be incremented or decremented by a specific amount (Variable mglnc). The spinners also have an upper and lower limit for validation purposes. In addition, the buttons can be held down to allow for faster scrolling. The procedure SpinShow demonstrates how to use the spinners.