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From: dempson@atlantis.actrix.gen.nz (David Empson)
Newsgroups: comp.sys.apple2.programmer
Subject: Re: Polygons in Quickdraw?
Date: 22 Apr 1996 00:12:39 +1200
Organization: Actrix - Internet Services
Lines: 74
Message-ID: <4ld8nn$ra9@atlantis.atlantis.actrix.gen.nz>
References: <4kj0jb$4pa@styx.uwa.edu.au> <4klv08$ok4@styx.uwa.edu.au> <DpsFw2.5n7@vaxxine.com> <4l84st$hml@styx.uwa.edu.au>
NNTP-Posting-Host: atlantis.actrix.gen.nz

In article <4l84st$hml@styx.uwa.edu.au>,
Joseph Turner <jturner@tartarus.uwa.edu.au> wrote:
>
[snip]

> I am wondering how you actually _get_ the handle that a function gives you 
> when you call a function such as OpenPoly();.

OpenPoly internally calls NewHandle, and returns the handle to you.
The contents of the handle are updated automatically as you draw the
lines that make up the polygon.

> Also how would I actually refer to this definition of the shape once
> it is defined? I assume you just put in the handle in the brackets.

Correct.

Something like this (ignoring details such as error handling).

Handle SetupMyPoly(void) {
    Handle thePoly;
    /* You might need to hide the pen here */
    thePoly = OpenPoly();
    MoveTo(100, 100);
    LineTo(200, 100);
    LineTo(200, 200);
    LineTo(100, 200);
    LineTo(100, 100);
    ClosePoly();
    /* You might need to show the pen here */
    return thePoly;
}

void DrawIt(void) {
    Handle myPoly;
    int i;
    myPoly = SetupMyPoly();
    for (i = 100; i < 200; i += 10) {
        MoveTo(i, i);
        FramePoly(myPoly);
    }
    KillPoly(myPoly);
}

> And that would mean that you have to define this handle as a Global
> variable at the beginning ...right?  

Assuming you wanted to keep it around for a while without to pass it
in and out of functions, yes.  You could also use a local (auto)
variable, as in my example above.

> Really want I would appreciate is a little code that could get me 
> started(Little).

#include <quickdraw.h>
#include <orca.h>
#include <stdio.h>

/* insert above functions here */

int main(void) {
    startgraph(640);
    SetPenSize(2, 1);
    DrawIt();
    getchar();
    endgraph();
    return 0;
}

Press RETURN to terminate the program.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand