On 28/04/2021 2:33 am, Seymour J Metz wrote:
GDDM and PGF are the primary programs for 3270 graphics. I don't know whether SAS Graph requires GDDM.
Well, I've coded programmed symbols and I've coded some native vector graphics, but I don't know the protocols to code PC-LINK graphics. I gather the latter is where the host offloads more of the work to the workstation.
The spec for programmed symbols is documented in the 3270 Data Stream Programmer's Reference, but for the other two you'd probably need to do a VTAM trace of GDDM terminal I/O to figure out.
Native vector graphics used to be documented in the 3179G book, but that disappeared after the 3179G was discontinued. (If anyone has one they'd like to sell then please let me know.) I'd say it is very close to the codes that GDDM uses itself internally.
If you have a 3270 graphics application that could be made to work with GDDM then I'd recommend you do so because then you can let GDDM figure out which graphics protocol to use for any given terminal and how to convert your requests to the appropriate data stream orders. I would guess that SAS Graph would call GDDM, but that's just a guess.
I've "assisted" (badgered?) two TN3270 client authors in adding programmed symbol graphics support to their products (really just clarified the spec and provided testing feedback). One decided the potential for support cases wasn't worth the effort/risk, and the other (Nexus Terminal) has retained it in the product.
As someone said, Nexus is very fast, and the support is very responsive to customers.
(Disclaimer: Both TN3270 client authors generously waived the fee to allow me to use their products, both of which are of excellent quality.)
The REVIEW command (available from CBT and elsewhere - release 50 should be coming out soon) has some code to render bitmaps (.BMP, .PCX, .GIF) on 3270 graphics screens (LPS and native vector graphics only) without using GDDM. (GDDM will be called for PC-LINK.) Don't expect true-color rendering. Haven't tested large pictures lately, but small ones work pretty well AFAICT.
Cheers, Greg ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
