uad1077@dircon.uucp (05/25/90)
>> <Discussion to the effect that you can't reverse engineer the Mac Toolbox >> without breaking the patent because the Toolbox uses regions internally. >> ....> Ahem. PostScript has regions. Cedar had regions. NeWS has regions. OpenWindows has regions. There were public domain implementations of regions in the last two years' SIGGRAPH course notes. The point about Atkinson's patent (from what I've seen go past in this discussion) is that he has the second most compact representation (after PostScript) for most cases. On the other hand, this may mean that his patent suffers from being the second slowest at the usual region operations. I think it's just that if you do write implement regions, there are more interesting (but possibly less lucrative!) things to do with it than reverse engineer a Mac. -- Ian D. Kemmish Tel. +44 767 601 361 18 Durham Close uad1077@dircon.UUCP Biggleswade ukc!dircon!uad1077 Beds SG18 8HZ United Kingdom
rjg@nosun.UUCP (Richard Greco) (05/25/90)
In article <30128@cup.portal.com> mmm@cup.portal.com (Mark Robert Thorson) writes: >A couple years ago, I wrote a short article for the BMUG newsletter about >the significance of the Atkinson patent on regions, and the small set of >efficient operations you can do on regions. At the time, I said the patent >would allow Apple to prevent a Mac clone from appearing, irrespective >of any silly copyright claims about look and feel. Actually it is even easier then this. While Atkinson's patent covers one way of dealing with regions, there are several other methods of representing regions that do not violate the patent, yet are still compact and efficient enough to implement on small microprocessors. The most notable of these is the one James Gosling developed for NeWS using a set of (x,y) sorted rectangles to represent the region. Although James never published this, Nola Donato and Robert Rocchetti of Sun presented a rework of James' algorithms at Usenix in 1988. The ideas in this paper were reworked and included as part of the course notes for "Introduction to Window Management" which was presented at Siggraph 89 and will be presented again this year at Siggraph 90. The Siggraph 88 course notes for "Introduction to Window Management" contain a reprint of the Donato and Rocchetti paper. The Siggraph 89 course notes are the source referenced by the forthcoming second edition of Foley and Van Dam which uses this algorithm for regions in the raster sections of the book.
amanda@mermaid.intercon.com (Amanda Walker) (05/29/90)
In article <1990May24.184352.29786@dircon.uucp>, uad1077@dircon.uucp writes: > The point about Atkinson's patent (from what I've seen go past in this > discussion) is that he has the second most compact representation (after > PostScript) for most cases. On the other hand, this may mean that his > patent suffers from being the second slowest at the usual region operations. Atkinson regions seem to be marginally better at handling extremely irregular regions, especially in low-memory environments. PostScript regions seem marginally better at handling regions with a fair amount of area coherence (such as font glyphs or "normal" clipping paths). For mainly rectangular regions (For doing "normal" window operations), they seem to be about neck-and-neck. -- Amanda Walker, InterCon Systems Corporation -- "Go not to the elves for counsel, for they will say both no and yes." --J.R.R. Tolkien, The Lord of the Rings
hunter@oakhill.UUCP (Hunter Scales) (05/30/90)
uad1077@dircon.uucp writes: >>> <Discussion to the effect that you can't reverse engineer the Mac Toolbox >>> without breaking the patent because the Toolbox uses regions internally. >>> ....> >I think it's just that if you do write implement regions, there are more >interesting (but possibly less lucrative!) things to do with it than >reverse engineer a Mac. >-- Question: how do the new graphics accelerators (from Supermac, among others) get around this? Dont they have to deal with Atkinson's implementation of regions to be compatible with Quickdraw calls? >Ian D. Kemmish Tel. +44 767 601 361 >18 Durham Close uad1077@dircon.UUCP >Biggleswade ukc!dircon!uad1077 >Beds SG18 8HZ United Kingdom -- Motorola Semiconductor Inc. Hunter Scales Austin, Texas {harvard,utah-cs,gatech}!cs.utexas.edu!oakhill!hunter #include <disclaimer.h>
amanda@mermaid.intercon.com (Amanda Walker) (05/30/90)
In article <3349@cerberus.oakhill.UUCP>, hunter@oakhill.UUCP (Hunter Scales) writes: > Question: how do the new graphics accelerators (from Supermac, > among others) get around this? Dont they have to deal with > Atkinson's implementation of regions to be compatible with > Quickdraw calls? Most of them don't replace QuickDraw lock, stock, and barrel, but only replace certain speed-critical common cases (bitblting rectangular regions around, scrolling a rectangle, filling a rectangle, etc.). Also, since these boards end up sitting in a Mac and require QuickDraw to already be there anyway, I imagine that Apple doesn't get too annoyed even if the accelerator code does peek into regions... -- Amanda Walker -- This posting is cursed. As you read it you will be confuset by ther printeb wertz. Yer intelijen will vabni ..... XRT! XRT!