[comp.sys.mac.programmer] Laserwriters vs. Transfer modes

wilson@csli.STANFORD.EDU (Nathan Wilson) (11/19/88)

Could someone in the know with regard to PostScript or LaserWriter drivers
please explain why it is that the LWII NTX doesn't support all the transfer
modes rather than just srcCopy and scrNotCopy?  And why it doesn't support
regions?  I personally really like to be able to use inverted objects and
transparent objects (ie the 'white' bits in patterns are clear), and it
would be nice to get them to come out on the LaserWriter as well as the
ImageWriter.  Is this just laziness on the part of Apple because no one
has asked for it or is there some underlying reason that makes it really
hard?  Are there graphics packages out there that support transparent,
invert or 'Bic' mode on the laserwriter?  SuperPaint 1.0 supports
transparent on the screen but it don't come out on the LW. :-(

	Please, somebody answer!
		Nathan Wilson
		Teleos Research
---
These aren't opinions, they're questions so I guess I don't need to say
anything.

oster@dewey.soe.berkeley.edu (David Phillip Oster) (11/19/88)

In article <6496@csli.STANFORD.EDU> wilson@csli.UUCP (Nathan Wilson) writes:
>Could someone in the know with regard to PostScript or LaserWriter drivers
>please explain why it is that the LWII NTX doesn't support all the transfer
>modes rather than just srcCopy and scrNotCopy?  And why it doesn't support
>regions?

Postscript was written by Adobe, not Apple. Adobe only provided the
transfer modes it provides. As for regions, they are one of Apple's big
trade secrets. There is a cute story about the invention of regions. Steve
Wozniak had been in a plane crash in the Santa Cruz mountains and lost his
memory. (Wow, imagine being a multi-millionare and not remembering it.
Imagine knowing the 6502 instruction set but not your own name.) Bill
Atkinson, after much struggle, awoke one morning with the secret of
regions suddenly clear in his head. Driving to work, he was in a car
crash. When Steve Jobs came to visit him in the hospital, he reassured
Jobs that he still remembered the secret of regions.

Yes, I know, it isn't that big a secret, nor that big a deal. But
technical realities and marketing realities are two different worlds.

kaufman@polya.Stanford.EDU (Marc T. Kaufman) (11/21/88)

In article <26879@ucbvax.BERKELEY.EDU> oster@dewey.soe.berkeley.edu.UUCP (David Phillip Oster) writes:

>                            As for regions, they are one of Apple's big
>trade secrets. 

Region format was documented in MacTutor earlier this year.  The thing that
makes them ugly from a postscript viewpoint is that they are BITmaps, not
outlines.  They don't scale well.

Marc Kaufman (kaufman@polya.stanford.edu)

jkjl@munnari.oz (John Lim) (11/21/88)

In article <6496@csli.STANFORD.EDU> wilson@csli.UUCP (Nathan Wilson) writes:
>Could someone in the know with regard to PostScript or LaserWriter drivers
>please explain why it is that the LWII NTX doesn't support all the transfer
>modes rather than just srcCopy and scrNotCopy?  And why it doesn't support
>regions?  I personally really like to be able to use inverted objects and
>transparent objects (ie the 'white' bits in patterns are clear), and it
>would be nice to get them to come out on the LaserWriter as well as the
>ImageWriter.  Is this just laziness on the part of Apple because no one
>has asked for it or is there some underlying reason that makes it really
>hard?  Are there graphics packages out there that support transparent,
>invert or 'Bic' mode on the laserwriter?  SuperPaint 1.0 supports
>transparent on the screen but it don't come out on the LW. :-(
>
>	Please, somebody answer!
>		Nathan Wilson
>		Teleos Research
>---
>These aren't opinions, they're questions so I guess I don't need to say
>anything.

I have never programed in postscript, but have studied the language. I
really can see no reason why regions couldnt be implemented in postscript
as a region can be easily interpreted and converted to a path. This looks
like laziness on apple's part.

The transfer modes problem looks a bit more difficult. Postscript is
more object orientated than QuickDraw. I have always thought that
postscript is a better tool for object orientated drawing, and quickdraw
better with bitmaps. There are no transfer modes per se in Postscript.
Furthermore bitmaps are transfered as hexadecimal characters in postscript.
With the conversion overheads, implementing transfer modes in ps is just
too slow i suspect (and too difficult ?).

Why dont you just save all your object orientated stuff as a macpaint file
and then use laserbits to get the high quality you're looking for.

Anyone out there know how Display Postscript is implemented. Is it 100%
interpreted ?

	john

Disclaimer : i bet i don't know what i'm talking about...