peskin@caip.rutgers.edu (R. L. Peskin) (10/30/90)
To be fair about this issue, let me post the (e-mail) quote I got from
ParcPlace in response to my inquiry about the absence of Pen and whether they
planned to include it later, perhaps as a fileIn:
"Regarding the elimination of Pen class from R4, the developers reviewed
the data they had and concluded that Pen had been little used since
Smalltalk-72 (roughly 15 years ago). The other reason that Pen was
dropped is that Pen uses the old B&W BitBlt imaging model and R4 uses
the new color SPIM. Creating a Pen just like in 2.5, that draws
anywhere on the display and does its drawing by replicating a form along
a path, was considered very difficult. Creating a Pen that takes
reasonable advantage of SPIM is much more work than 2.5's Pen.
I regret that there are no plans to include Pen with the other
compatibility stuff for the above reasons. "
--dick peskin
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Richard L. Peskin CAIP Parallel Computing Lab
CAIP Center CN - 1390 Rutgers University
Piscataway, N. J. 08855-1390
net: peskin@caip.rutgers.edu
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hmm@exunido.uucp (Hans-Martin Mosner) (11/02/90)
When I was at ParcPlace some months ago, I implemented a rudimentary Pen substitute for release 4. The problem mainly was that the new SPIM sits on the host window system which means that window contents are not saved as they were in 2.5 and before. So you could just scribble on a window with a simple Pen implementation, but any pop-up menu or occluding window would destroy your drawing. What I did was implement a kind of polyline with width and color that would accumulate pen commands and be able to reconstruct the pen drawing when necessary. I did some quite nice fractal trees (and all of the old Pen examples, of course). Alas, due to very tight time constraints for my flight back I forgot to take this stuff with me. Anyway, it is rather simple to implement a mechanism like this. The hardest part is to make the graphics interactive in the sense that you see the evolving picture while the Pen code is running. In some days I will probably have this stuff and can post it to the newsgroup. Hans-Martin