[<<Previous Entry]
[^^Up^^]
[Next Entry>>]
[Menu]
[About The Guide]
DISPBEGIN()
Begin buffering screen output
------------------------------------------------------------------------------
Syntax
DISPBEGIN() --> NIL
Returns
DISPBEGIN() always returns NIL.
Description
DISPBEGIN() is a screen function that informs the CA-Clipper display
output system that the application is about to perform a series of
display operations.
Use DISPBEGIN() with DISPEND() to allow the display output system to
buffer display updates. Display output which occurs after DISPBEGIN()
but before DISPEND() is allowed to accumulate in internal buffers. When
DISPEND() executes, any pending updates appear on the physical display.
This is useful in applications where complex screen displays are slow
and the appearance of performance is desired.
DISPBEGIN() and DISPEND() calls are optional. They are not required for
normal output.
Notes
. Nested calls: DISPBEGIN() calls are nested internally. If
several DISPBEGIN() calls occur, buffering is allowed until a
corresponding number of DISPEND() calls occur.
. Guaranteed operations: Display updates performed between
DISPBEGIN() and DISPEND() are not guaranteed to be buffered--some
updates may become visible before DISPEND() is called. However, all
updates are guaranteed to be visible after the closing call to
DISPEND().
. Terminal operations: Terminal input operations such as INKEY()
or READ should not be performed between DISPBEGIN() and DISPEND().
Doing this may cause input or display output to be lost.
. Incompatible operations: Display output by other than the
CA-Clipper display functions (e.g., by add-on libraries or by DOS via
OUTSTD(), etc.) may not be compatible with DISPBEGIN() and DISPEND().
Output may be lost.
Examples
. This example buffers screen output, updates the screen, and
then displays the buffered screen output:
DISPBEGIN() // Start screen buffering
//
SETPOS(10, 10)
DISPOUT("A display update")
SETPOS(11, 10)
DISPOUT("Another display update")
//
DISPEND() // Display buffered screen data
Files Library is CLIPPER.LIB.
See Also:
DISPEND()
This page created by ng2html v1.05, the Norton guide to HTML conversion utility.
Written by Dave Pearson