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 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. @
