Alan,
A quick question, and hopefully quick positive answers
If I have a field of length 40 characters, within a DSPF, is there a way to
highlight/reverse image only a portion of that field, and that portion
could be different each and every time.
The original 5250 data stream used a paradigm where a single buffer
contained both the displayable characters and display attributes. That is,
for a 24x80 display, there were 1920 bytes in the WS controller buffer and
each of those bytes could contain a character OR a display attribute, but
not both. Any buffer position which contained a display attribute affected
all subsequent display positions until another attribute character was
found.
For output only fields, if what you wanted to do was change the display
attributes on complete "words", you could replace the blanks on either side
of a word with a display attribute and achieve the result you want.
However, you needed to have blanks available -- you could not for instance
reverse image part of a word. Also, if you wanted the first word different
and had no leading space, you had to change the display attribute of the
field (using DDS indicators or a program-to-system attribute field) for the
effect you wanted on the leading word, then change the blank after the word
for the next effect.
For input fields, you would most likely want to xlate those values back to
blanks.
In the early 90's or so, the 5250 data stream was enhanced and you had a
choice of the previously standard WS controller or an "Enhanced WS
controller". I think the enhanced WS controller became the default by V3R1
or so -- maybe late V2; its been too long for me to remember (or care).
The enhanced 5250 data stream *does* support having a different display
attribute for each position on the display, and you can achieve the affect
you want even for partial words. The problem is that DDS was never enhanced
to allow you to take advantage of it. I think the primary reason it got
added in the first place was to be able to add some features to Office
Vision, such as having a "shadow cursor" reverse image your current
horizontal position on a ruler near the top of the display.
Anyway, the bottom line is although the 5250 data stream supports it now,
DDS does not. That means to utilize it you
must output the appropriate 5250 data stream command yourself. But because
it is not supported by DDS, you may find some emulation software does not
implement the data stream. The vendor may not have ever added support for
it, or it may not work right. Few customers would have noticed the lack of
support.
In theory, before using the Workstation Enhanced Attributes (WEA) display
orders you should check the WS controller and device capabilties to make
sure it says WEA is supported. But I don't know if you can really trust the
answer from some emulators in the first place. You can use the Dynamic
Screen Manager (DSM) apis to discover a device's alledged capabilities even
when you use DDS for the display file.
But then assuming you want to continue using DDS for the display file
instead of DSM, you'd want to just embed the WEA display order as data in a
hidden field on the screen.
So technically, the answer is the 5250 data stream support it now and has
for well over a decade. But some emulators may not, and DDS does not. You
can find the WEA display orders documented in the 5494 Functions Reference
Manual. (Or at least last I knew, that is where the 5250 data stream was
documented.)
Doug
midrange.com
