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From: gelphman@adobe.COM (David Gelphman)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Meaning of visRgn in offscreen bitmaps + whinings about PrintManager.
Message-ID: <1136@adobe.UUCP>
Date: 31 Aug 89 11:59:19 GMT
References: <1358@speedy.mcnc.org> <3925@internal.Apple.COM>
Reply-To: gelphman@adobe.UUCP (David Gelphman)
Organization: Adobe Systems Incorporated, Mountain View
Lines: 29

In article <3925@internal.Apple.COM> parent@apple.com (Sean Parent) writes:
>In article <1358@speedy.mcnc.org> kk@mcnc.org (Krzysztof Kozminski) writes:
...
>> used to speed up bitmap printing. Probably the PostScript software in the
>> LW (hardware) should be smart enough to notice that the dimension of the
>> bitmap is exactly the same as it destination rectangle.
>
>Yes, the PostScript software should be smart enough to notice that the 
>dimension of the bitmap is exactly the same as its destination rectangle. 
>But it isn't (at least not today).
...
>Sean Parent
    
   The PostScript interpreter DOES recognize when the bit image would
exactly fit in the 'destination rectangle' and there is a performance
win in that case. Of course that assumes that you are really matched
with device resolution. Most Macintosh applications are working with
bit images at 72 dpi and when you try to maintain the same physical
image size on a 300 dpi device, there is not a one to one correspondence 
between a bit in the source data and a bit in the frame buffer. The 
performance win also occurs in a number of cases such as 90 degree rotations 
and some other simple transformations. As far as I know, all implementations
have the optimization for the most simple cases, more recent implementations
have a number of other cases optimized. Note that this only applies to
one bit per pixel images and I'm not certain if it applies to imagemask
which is used heavily by the Apple printshop.

David Gelphman
Adobe Systems Incorporated