Path: utzoo!utgpu!watserv1!watmath!att!att!rutgers!maverick.ksu.ksu.edu!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!m.cs.uiuc.edu!gillies
From: gillies@m.cs.uiuc.edu
Newsgroups: comp.sys.mac.apps
Subject: Re: Canvas is good enough (was:Sugg
Message-ID: <70100025@m.cs.uiuc.edu>
Date: 18 Nov 90 08:07:00 GMT
References: <164858@<1990Nov16>
Lines: 49
Nf-ID: #R:<1990Nov16:164858:m.cs.uiuc.edu:70100025:000:2520
Nf-From: m.cs.uiuc.edu!gillies    Nov 18 02:07:00 1990


> o Canvas 2.1 - My personal favorite.  Slow, but still acceptable, on
> 68000 Macs.  Much more useful on Mac II level machines.  Very full
> command set, follows the Macintosh interface well.  Well-written
> documentation.

I have used canvas 2.0 and find it to be screwed up.  No other draw
program I have ever seen would produce postscript that caused our
printer to crash, or caused it to loop for 20 minutes without a
result.

I have drawn pictures in canvas 2.0, pasted it on the clipboard, and
taken it to MacDraw II.  Well, the picture was seriously distorted by
this operation.  The circles became ovals.  The circles also printed
as ovals on the printer.  My conclusion is that the people who wrote
this program have little understanding of numerical analysis and
roundoff error.  This can be a very serious problem when you want to
draw two objects that overlap PRECISELY on a laserprinter.

Canvas 2.0 exports bad PICTs.  A frame with text gets converted into a
frame, with a white frame behind it.  In other draw programs you have
to delete this extra junk Canvas has included.

Canvas 2.0 does not compact files.  I had some 3-d plots which took
300K in canvas.  Finally, I decided to save them as pict and reload
them, and the size went down to 140K!  This was a big shock to me.
Perhaps it stripped away annotated postscript, but this postscript was
not printing anyway so I don't understand why the big decrease in file
size. 

MacDraw II generates some "custom" postscript for postscript printers.
I believe it partially bypasses the macintosh driver, since many
problems do not appear IF YOU PRINT with MacDraw II.  For example,
when I shade a box and use a .5-point box border, most macintosh
programs including Canvas will screw up slightly, letting the
fill-shading escape the box in the postscript printout, by about 1-2
dpi on the postscript printer (making the box border look somewhat
ragged).  If you print from MacDraw II, you get the correct WYSWYG
result.  Also, the mac print driver seems to put an infinitesimal
border around figures with .5-pt lines, so that if you (for example)
inscrible a circle within a box, there is an infinitesimal halo around
the circle.  If you print from MacDraw II, this problem does not
occur.

I suggest you use canvas quite extensively before you make a decision
to purchase it.  I have given up on canvas because of its quirks for
drawing precise technical figures, and now use MacDraw II.

If you just want to make party posters, by all means buy canvas.