Re: DDS Display attributes -- MIDRANGE-L

Doug
Thanks for taking the time for writing such a comprehensive response
I shall certainly investigate what I originally had planned on doing.

Alan Shore
Programmer/Analyst, Distribution
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"If you're going through Hell, keep going" - Winston Churchill

midrange-l-bounces@xxxxxxxxxxxx wrote on 02/23/2009 03:41:25 PM:

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

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

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

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
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