HP 3000 Manuals HP 3000 Manuals
CODING THE TOUCH FEATURE
In order to use the touch feature effectively, a method is needed to
provide feedback to the user when a field is touched. Changing the field
enhancement is one of the best methods to indicate that a field has been
touched. The enhancement of a field can be changed by using the
VCHANGEFIELD intrinsic, or family forms. If neither of these methods is
appropriate and the error count is not important, VSETERROR can be used
instead. VSETERROR toggles the error flag when called successively;
i.e., if VSETERROR is called the second time for a particular field, the
error flag is cleared. Therefore, the error enhancement can be used with
VSHOWFORM as feedback to the user to indicate that a field has been
touched. This feature is only activated if the showcontrol bit 0 is set
to 1.
When designing touch applications, the designer should keep the idea of
compatibility in mind. Applications should be able to run on HP
262X/239X terminals, or on a touch terminal/workstation using keyboard
input. For VPLUS/V applications, this objective can be achieved by
designing one single form interface for all HP 262X/239X terminals.
To design a touch application with compatibility in mind, the interface
should be built so that the user has the option of responding via the
keyboard or the touch screen. This consideration is important in two
respects. First, it provides an alternative path for the user when an
application is run on touch terminals. Second, an application can be run
on non-touch terminals as well as touch terminals.
For example, if an application is designed to display a form with many
items for the user to select from, the programmer may wish to include one
input field for the users to type in their choice. This will allow for
one interface for both touch and non-touch terminals.
Example
IF COM-LASTKEY < 0 THEN
CALL "VSHOWFORM" USING COMAREA
CALL "VREADFIELDS" USING COMAREA
IF COM-LASTKEY IS NOT EQUAL TO -999 THEN
NEXT-FIELD = -(COM-LASTKEY)
CALL "VSETERROR" USING COMAREA, NEXT-FIELD, MSG, MSGLEN
CALL "VSETERROR" USING COMAREA, PREVIOUS-FIELD, MSG, MSGLEN
PREVIOUS-FIELD = NEXTFIELD.
The first VSETERROR toggles the error flag of the new field touched,
and the second VSETERROR toggles the error flag of the previous
field touched. When VSHOWFORM is called, NEXT-FIELD will be
highlighted with the error enhancement, while PREVIOUS-FIELD reverts
to the normal enhancement. The VPLACECURSOR intrinsic can be used
to position the cursor if the default cursor position set by
VSETERROR needs to be overridden.