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From: mkt059@ipl.jpl.nasa.gov (Mike Tschudi (Cartographic Applic.))
Newsgroups: comp.sys.mac.programmer
Subject: Re: Printing Questions
Message-ID: <77756@ipl.jpl.nasa.gov>
Date: 26 Nov 90 14:26:06 GMT
Organization: Jet Propulsion Laboratory, Image Processing Lab
Lines: 39

Keywords: printing
Date: 26 Nov 90 22:10 GMT

> Group: comp.sys.mac.programmer, Item 13162,
> Subject: Printing Questions
> From: leue@galen.crd.ge.com (Bill Leue), General Electric Research &
Development
> 
> 1. I want to be able to print thin hairlines; down to as thin as the
> printing device can support, or at least to some width much thinner than
> 1 screen pixel.  QD only allows you to set the pen to a 1x1 with PenSize(),
> no thinner, unless I am missing something.  Is there a 'standard' way to
> draw thinner lines?  How does MacDraw II do it, for instance?  With
> PICT comments?  I suppose I could generate the PostScript directly for
> PS printers, but that seems to pretty much bypass all of the standard
> print driver structure.
> 
> 2. (Related to #1) I want to be able to locate the vertices of polygons to
> an accuracy better than plus or minus one screen pixel.  That is, I have
> a display list containing many sets of double-precision coordinates.  When
> I render to the screen, I round these coordinates to the nearest integer
> pixel coordinate, load them into an appropriate data structure, and call
> PaintPoly().  I want to do something similar for printing, but make use
> of the (usually finer) pixel grid on the printer so that the round-off
> errors are smaller.  Note that I'm not worrying here about reducing
> the "jaggies" caused by aliasing:  I'm aware that the print driver already
> handles this aspect of line drawing.  Rather, it's the location of the
> endpoints that I care about.  The same questions apply as for #1.


See Inside Mac, vol 5, page 416, to change the resolution of the printing
port. This is great stuff, and our maps look MUCH better using 300 dpi (our
LaserWriter's physical resolution) than they do using 72 dpi. (Your drawing
routine has to handle the varying resolution to maintain WYSIWYG, however.)


Michael Tschudi
Cartographic Applications Group
Jet Propulsion Lab, Pasadena, CA