Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!icdoc!qmc-cs!george
From: george@cs.qmc.ac.uk (George Coulouris)
Newsgroups: comp.sys.mac.hypercard
Subject: Re: arrowheads at the end of lines.
Message-ID: <1514@sequent.cs.qmc.ac.uk>
Date: 7 Dec 89 00:10:58 GMT
References: <QZSVM7u00WB60VEUVB@andrew.cmu.edu>
Reply-To: george@cs.qmc.ac.uk (George Coulouris)
Organization: Computer Science Dept, Queen Mary and Westfield College, University of London, UK.
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Funny you should ask that!  I happen to have the answer.

Actually, I did a MacApp example a few months ago that drew
directed graphs, so I dug out the Pascal code, changed the :='s
to 'put' and it ran (well almost, of course the Quickdraw
procedures "MoveTo" and "Line" had to be defined in HyperTalk).

Put the following script into a button to demonstrate it.

After pressing the button, click anywhere on the card and an
arrow will be drawn from 100,100 to the point you clicked at.

on mouseUp
  set the hilite of me to true
  wait until the mouse is down
  arrow 100,100,the MouseH, the MouseV, 10, 1
  set the hilite of me to false
end mouseUp

on arrow x1, y1, x2, y2, k, d
  -- k is the length of the arms of the arrow
  -- d is the fractional distance along the line at which arrow is placed
  put the tool into saveTool
  choose line tool
  MoveTo x1,y1
  Line x2-x1,y2-y1
  if x1 < x2 then put -1 into sign
  else put 1 into sign
  put atan((y1-y2)/(x1-x2)) into alpha -- the angle of the line
  put alpha+3.14/4 into beta -- plus 45 degrees
  put alpha-3.14/4 into gamma -- minus 45 degrees
  MoveTo trunc(x1+(x2-x1)*d), trunc(y1+(y2-y1)*d)
  line sign*trunc(k*cos(beta)), sign*trunc(k*sin(beta))
  MoveTo trunc(x1+(x2-x1)*d), trunc(y1+(y2-y1)*d)
  line sign*trunc(k*cos(gamma)), sign*trunc(k*sin(gamma))
  choose saveTool
end  arrow

on MoveTo x, y
  global curpos
  put x&","&y into curpos
end MoveTo

on line x, y
  global curpos
  drag from curpos to (item 1 of curpos + x),(item 2 of curpos + y)
end line

-- 


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