Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!agate!ucbvax!hplabs!hp-ses!hpcuhb!hpindda!tribby
From: tribby@hpindda.HP.COM (David Tribby)
Newsgroups: comp.sys.apple
Subject: Re: RE: 2 more //gs programming questions
Message-ID: <6230040@hpindda.HP.COM>
Date: 7 Jul 89 16:42:50 GMT
References: <8907011229.AA12157@decwrl.dec.com>
Organization: HP Information Networks Group/Cupertino CA
Lines: 39

The original poster, Jeff Hartkopf, asked me to be a little more explicit
in how I used the GetVisHandle call, so here are more details. The procedure
I'm writing plots a waveform from DOC memory to the screen; since those
waves can be 32K bytes long, it can take a long time to plot the entire
thing, even with plotting only every 8th byte! So I use the size of the
visible window to cut back on the amount of plotting that needs to be done.
Here's part of the code...


{ Redeclare GetVisHandle, since TML got it wrong in 1.5 QDIntf}
FUNCTION GetVisHandle1: RgnHandle;                        Tool 4,201;

{$LongGlobals+}   { Procedure may be called without data reg set properly }
PROCEDURE PlotWave(doc_index: INTEGER);
   VAR
      ...   { Several variables declared }
      min_h, max_h: INTEGER;          { Horiz limits, in local coordinates }
      vis_region_handle: RgnHandle;   { Visible region handle }
   BEGIN   { PlotWave }
   ...
   { Get waveform out of DOC memory, determine stepping size, & calculate }
   { limits of horizontal axis in local coordinates (min_h & max_h).      }
   ...
   
   { Determine how much of what we have to plot is visible }
   vis_region_handle := GetVisHandle1;
   WITH vis_region_handle^^.rgnBbox DO
      BEGIN
      IF left > min_h  THEN min_h := left;
      IF right < max_h THEN max_h := right;
      END;

   { Plot the wave in the window }
   ...
   END;    { PlotWave }
{$LongGlobals-}

--Dave Tribby
        ARPA: tribby%hpda@hplabs.HP.COM   UUCP: hplabs!hpda!tribby