Kbase 16348: Statement on slow scrolling of DOWN frames in GUI V7 and V8
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
5/10/1998 |
|
Statement on slow scrolling of DOWN frames in GUI V7 and V8
An issue exists with the slow scrolling of DOWN frames on GUI
platforms running Version 7 and Version 8 PROGRESS.
When running procedures which make use of DOWN frames, it has been
noted that on GUI platforms it takes much longer for the client to
paint the screen when the DOWN frame scrolls and new information is
added. (DOWN frame behavior on V7/V8 character-mode (TTY) platforms
is comparable to Version 6 and does *not* appear to be slower.)
The problem on Version 7 and Version 8 GUI platforms is due to the
incompatibility between (a) the way the GUI environments manage screen
painting and (b) the lower-level algorithm used by Version 6 PROGRESS
to scroll a DOWN frame. The Version 6 algorithm was created and
optimized for a character-mode environment. Graphical environments
utilize an entirely different mode of screen refresh which, when
encountering the DOWN frame as ported over from Version 6, causes
the screen repaint to look slow. (One reason for this is the DOWN
frame's characteristic as an iterative structure. In graphical
environments, frames are expected to be used as non-iterative,
static displays. These frames do not exhibit scrolling behaviors on
their own the way a DOWN frame does, but rather are intended to
respond to user interaction via the mouse and keyboard.)
This issue is related to a more general one where Version 6 programs
cannot be guaranteed to run on GUI platforms in a manner identical
to that seen on earlier, TTY-only versions of PROGRESS. Screen
management in the GUI world is entirely different and could not have
been anticipated in Version 6 of PROGRESS and prior.
Programmers who wish their Version 6 style programs to exhibit
optimal performance on Version 7 or Version 8 GUI platforms should
anticipate that code changes *will* be necessary. While Progress does
assure that performance on Version 7 and Version 8 CHARACTER MODE
(ChUI) platforms will be comparable to Version 6, it is not possible
to achieve a comparable level of portability when moving a Version 6
character-mode program to a graphical user interface.
For more information, please see Kbase 11783, "4GL concerns when
moving from V6 PROGRESS to V7 or V8".
Progress Software Technical Support Note # 16348