Customising the Status Line [Revelation On-Line Wiki]

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.
====== Customising the Status Line=====

^Published By^Date^Version^Knowledge Level^Keywords^
|Sprezzatura Ltd|01 AUG 1992|2.12+|EXPERT|STATUS, LINE, SYS.TEXT_PARMS|

When designing applications with an AREV "look and feel" it can be desirable
to create highlighted words on the bottom status line (as with the system
help level 2 function keys). In addition, when indicating cursor key
movement it makes sense to use the arrow characters to illustrate the keys
to press rather than spelling out "Cursor Left", "Cursor Right" etc.

Two minor points need to be made before the explanation proper begins.
Firstly, Status Line images are now stored in SYS.TEXT_PARMS, with a key of
Process*Status (or Process2*Status for help level 2 images). Secondly, there
are now only two supported help levels, 0 and 2. Whilst it is possible to
use a help level of 1 this can lead to problems.

When adding new status line images it behoves us to cater for both levels of
user, so two status line images should be created per process, one for level
0 and one for level 2. Statup will automatically select the correct image
when asked to load Process. This discussion will concentrate on level 2
status images but it can be amended for level 0.

The layout of the status line image is documented in various places (UTILITY
subdirectory on pre release 2.0, Programmer's Reference on 2.1, System
Subroutines book) but the field that is of interest when customising
highlighted words, is field 2. This field (in a level 2 status line)
contains four multivalues, three for the top three boxes of the status line
and the fourth for the bottom line. Highlighted words can only be put into
the fourth multivalue.

==== Very Simple Program to Test Amended Status Lines ====

So that the new status lines can be tested, a simple program such as the one
following can be used. Simply compile, catalog and attach to a macro key

<code>
      Subroutine TestStat
       /*
          Note that with help level 2 this will display record SPREZZ2
       */
       Call Statup(4,"SPREZZ",Save)
       Call Input.Char(x)
       Call Statup(5,"", Save)
      Return
</code>

==== Adding Highlighted Words ====

The key point here is the use of hyphens. In multivalue 4, everything up to
the first hyphen will be highlighted, then after the first hyphen, every
word before a hyphen will be highlighted. Thus if a record were created
called SPREZZ2*STATUS with a layout as follows

<code>
MENU
SprezzýRevM  ýField 3ýThis is Highlighted-This Isn't-ThisIs-This Isn't
1
</code>

it would appear on the status line as follows

<code>
³Sprezz³RevM  ³Field 3                           ³
ÃÄÄÄÄÄÄÁÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´
³This is Highlighted-This Isn't-ThisIs-This Isn't³
</code>

Note then that to give the illusion of multiple words being highlighted,
mixed capitalisation must be used (I.E. ThisIs, rather than This Is, where
only the Is would be highlighted). Note further that when the text in
the record is shorter than the width of the status line cell, a number of
spaces must be appended after the text to display to the width of the cell.
With the final cell this can be made easier by appending a value mark.

==== Adding Arrow Characters To the Status Line ====

Unfortunately the ASCII characters for the various arrow symbols cannot be
added directly into the status line as they cause the screen to become
corrupted. To get around this, a fix has been provided. It would not be
uncharitable to describe this fix as a kludge.

Essentially, five characters have been provided that are taken by the system
to mean that they should be replaced with arrow characters when they are
bracketed by *'s and a flag variable is set. The characters and their
meanings are as follows

|#|Þ (represents a double headed arrow)|
|~||
|%%|%%||
|%%^%%||
|`||

The flag variable is that somewhere in the preceding text, a ^ should have
been entered. For convenience it is recommended that this be the first
character on the line although this is not strictly necessary (see note 1).
Thus the the status record

<code>
  MENU
  ^SprezzýRev*^* M ýý*~*-Move Left *³*-Move Right
  1
</code>

would appear on the status line as follows

<code>
³Sprezz³RevM ³.......                           ³
ÃÄÄÄÄÄÄÁÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´
³-Move Left -Move Right                        ³
</code>

**Note 1**: Thus the example given could also have achieved the same results if rendered

<code>
     SprezzýRe^v*^*Mýý*~*-Move Left *|*-Move Right
</code>

(Volume 4, Issue 4, Pages 6-7)