Topic       : The GFA-Basic Compendium
Author      : GFA Systemtechnik GmbH
Version     : GFABasic.HYP v2.98 (12/31/2023)
Subject     : Documentation/Programming
Nodes       : 899
Index Size  : 28056
HCP-Version : 3
Compiled on : Atari
@charset    : atarist
@lang       : 
@default    : Document not found
@help       : Help
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@width      : 75
@hostname   : STRNGSRV
@hostname   : CAB     
@hostname   : HIGHWIRE
@hostname   : THING   
View Ref-FileRedirecting all VDI calls

handle&=V_OPNWK(...
V~H=handle&  !send all gfx commands to this handle
' many graphics/VDI calls...
' ...
V_CLSWK()  !gfa closes the workstation and internally does V~H=-1

This scheme might seem odd at first, but it's somewhat rare to open another
workstation. It does however have less overhead than the usual way. Why pass
the same handle to hundreds of VDI calls? Once you understand how GFA manages
VDI calls it's really rather simple.

V~H=x redirects all graphics commands like LINE, BOX, PLOT, and anything
called via VDISYS so long as you leave CONTRL(6) alone.

There's also no need to copy the contents of V~H before redirecting as GFA
itself keeps it's own backup copy. The command V~H=-1 reset it back to it's
original value, the default workstation opened at startup.