Re: 5250 data stream displays secret APL symbols

On 13/03/2010, at 9:42 AM, Gene_Gaunt-GDFlLPZ4eRKEK/[email protected] wrote:

> After Googling this stuff, we found this table named 'Graphic Escape
> APL/TN, Code Page 310' and here is it's picture:
>
> http://www-03.ibm.com/systems/resources/systems_i_software_globalization_pdf_cp00310z.pdf

That helps explain something I'd noticed in the 5250 data stream for  
READ SCREEN (WITH EXTENDED ATTRIBUTES) and PRINT SCREEN (WITH EXTENDED  
ATTRIBUTES). When PC250 builds a data stream for these commands it  
uses GUI-like characters when windows, menu bars, scroll bars, etc.  
are active. These are what causes the "pretty" displays of these  
advanced DDS (extended 5250) features in PC5250 e.g., windows with  
solid borders and drop shadow on right and bottom borders.

For PRINT SCREEN (WITH EXTENDED ATTRIBUTES) the client is supposed to  
replace these GUI-like characters with their character equivalents. In  
some versions of PC5250 this is not done (e.g., V5.7) although I note  
the DBCS version (at the same release) does do it properly.

Given that the chart for CP 310 shows only those characters above  
x'40' and that the GUI-like characters used by PC5250 are all below  
x'40' I cannot be certain but my guess is that PC5250 uses CP 310 for  
drawing GUI-like constructs and therefore once it has switched into  
that mode any characters it encounters, such as those in the  
transparent data, are treated as CP 310 values until it switches out  
at the end of a given GUI construct.

As a test I modified your horizontal scroll bar program to generate a  
window and then put transparent data over the top and bottom borders  
and lo did I see the same APL characters.

I noted previously that the APL characters disappear and normal  
characters are displayed when another window overlays this screen. I'm  
not sure why the APL characters are not reinstated after the window is  
closed and the system redraws the underlying screen. Also printing the  
APL screen results in normal characters being printed and no evidence  
of scroll-bars. Compare this with printing the screen when it contains  
only the horizontal scroll-bars.

I've not found any documentation for the GUI-like characters so for  
anyone who cares the list (so far) is:

Horizontal scroll bar:
	03	left-arrow
	1B	scroll-bar shaft
	1D	scroll-bar slider
	(as many 1B and 1D characters as necessary are used to complete the  
scroll bar)
	05	right-arrow

Vertical scroll bar:
	01	up-arrow
	1A	scroll-bar shaft
	19	scroll-bar slider
	(as many 1A and 19 characters as necessary are used to complete the  
scroll bar)
	02	down-arrow

Window:
	0C	top-left corner
	13	top border
	0B	top-right corner
	12	left border
	10	right border
	0A	bottom-left corner
	11	bottom border
	0D	bottom-right corner

Drop-down Menu:
	08	top-left and top-right corners
	12	left border
	10	right-border
	11	bottom border

There are probably others I've not yet discovered such as the menu bar  
separator, check boxes, radio buttons, push buttons etc.


> Insane?


Perhaps not ... perhaps just slightly mad but then we all must be to  
some degree else we wouldn't bother trying to puzzle this stuff out.  
We'd be drinking beer and watching sports.

Regards,
Simon Coulter.
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