Forms and their types are introduced in Form part.
The current page outlines how to present text forms.
The
converse statement is sufficient for giving
the user access to a single, fixed text form. The logical flow of your program
continues only after the user responds to the displayed form. You can also
construct output from multiple forms, as in the following case:
- At the top of the output, a fixed form identifies a purchasing company
and an order number
- In a subsequent floating area, a series of identically formatted floating
forms identify each item of the company's order
- At the bottom of the output, a fixed form indicates the number of screens
needed to scroll through the list of items
Two steps are necessary:
- First, you construct the order-and-item output by coding a series of display statements,
each of which adds a form to a runtime buffer but does not present data to
the screen. Each display statement operates on one
of the following forms:
- Top form
- Floating form, as presented by a display statement
that is invoked repeatedly in a loop
- Bottom form
- Next, the EGL runtime presents all the buffered text forms to the output
device in response to either of these situations:
- The program runs a converse statement; or
- The program ends.
In most cases, you present the last form of your screen output by coding
a converse statement rather than a display statement.
The fixed forms each have an on-screen position, so the order in which
you specify them, in relation to each other and in relation to the repeated
display of floating forms, does not matter. The contents of the buffer are
erased when output is sent to the screen.
If you overlay one text form with another, no error occurs, but the following
statements apply:
- If a partial form overlays any lines in another fixed form, EGL replaces
the existing form without clearing the rest of the output from the buffer.
If you want to erase the existing output before displaying the new form, invoke
the system function ConverseLib.clearScreen before issuing the display or converse statement
for the new form.
- If you use a display or converse statement
to place a floating map beyond the bottom of the floating area, all the floating
forms in that floating area are erased, and the added form is placed on the
first line of the same floating area.
- If a floating form overlays a fixed form, these statements apply- -
- Only the fixed-form lines that are in the floating area are overwritten
by the floating form
- The result is unpredictable if a fixed-form line is overwritten by a floating-form
line that includes a variable field
Whether you are presenting one form or many, the output destination is
the screen device at which the user began the run unit.