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Re: Question: units of AppKit coordinates.
From: |
Chris Hanson |
Subject: |
Re: Question: units of AppKit coordinates. |
Date: |
Wed, 15 Oct 2003 19:00:13 -0500 |
On Wednesday, October 15, 2003, at 06:47 PM, Vaisburd, Haim wrote:
AppKit accepts coordinates as floating point numbers.
I have drawn a conclusion that they are probably meant
to be some device-independent units like millimeters
or inches or something alike.
Coordinates should probably be kept as floating point right up until
the point they're sent to the back-end.
User-space coordinates in AppKit are considered to be in PostScript
points, *unless you change the coordinate system*. In PostScript,
there are 72 points to the inch. This is close (but not exactly equal)
to the typographer's point; there are just over 72 typographer's points
to the inch.
It should be up to the back-end to translate device-independent
coordinates into device-dependent coordinates for the particular output
device in use. This is going to be particularly important in the near
future as users start getting 200dpi displays. (The cost of a 24-inch
200dpi widescreen LCD monitor is already down to US$4000 from ViewSonic
or IBM.)
-- Chris
--
Chris Hanson, bDistributed.com, Inc. | Email: cmh@bDistributed.com
Custom Mac OS X Development | Phone: +1-847-372-3955
http://bdistributed.com/ | Fax: +1-847-589-3738
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