The LA Fox Developer Newsletter -

July 1994

Hot Tip.

Spinners in a DOS

Environment

by Joseph J. Rourke

(Ed. Note: This article originally appeared in the

May 1994, edition of “FoxSpeak,” the newsletter of

the Capital District FoxPro Users Group.)

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 environ-

ment. What we developed was a function which

would use global variables to increment or decre-

ment 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 demon-

strates how to use the spinners.

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