Hi Wade, yeah, that's exactly the sort of thing I'm doing. Seems like inventing a loopless way of doing it would be sorta fun, but maybe a bit difficult to handle all the situations in which one might do it. As you point out though, it does seem to arise frequently!
Cheers David From: [email protected] [mailto:[email protected]] On Behalf Of G. Wade Johnson Sent: Thursday, November 08, 2012 11:28 PM To: [email protected] Subject: Re: [svg-developers] an SVG /Javascript question Hi David, On Thu, 8 Nov 2012 20:10:06 -0500 "David Dailey" <[email protected] <mailto:ddailey%40zoominternet.net> > wrote: > In order to perform transform operations in script rather than doing > it declaratively (whence the stack of transforms can become gnarly), > I was thinking about ways to simplify the code (from the human rather > than the computational perspective). By such perspective, the minimum > number of statements is to be optimized rather than minimizing > run-time - I know it is a funny metric, but people have been looking > at things like this since the 1970's believe it or not. > > > > Anyhow, I wanted to develop a function which would take the d > attribute of paths or glyphs (of any sort): > > > > d="M 1550 710.5 Q 1650 840 1610.5 920.5 Q 1580 1010 1130.5 970 Q 690 > 930 840 810 Q 990 690 1010.5 450.5 Q 1040 220 1190 190.5 Q 1340 170 > 1480.5 210 Q 1630 250 1540 420 Q 1450 590 1550 710.5 M 940.5 860.5 Q > 610 1100 630.5 1170 Q 660 1240 770 1250.5 Q 880 1270 1110.5 1270 Q > 1350 1270 1610 1300 Q 1870 1330 1920 1250.5 Q 1970 1180 1810 1060 Q > 1650 940 1460.5 780.5 Q 1280 630 940.5 860.5 z" > > > > Or > > > > d="M50,100 > > A100,50 0 0 1 250,100 > > A80,40 0 0 1 90,100 > > A60,30 0 0 1 210,100 > > A40,20 0 0 1 130,100 > > A20,10 0 0 1 170,100" This description reminds me of a kind of functional programming approach I've used in the past. In pseudo-code, it would do something like new_d = join_command( transform_A( function(a) { /* do something to each A */ }, split_commands( d ) ) ); The split_commands function would return a list of commands. The transform_A function would identify A commands and apply the supplied function to each, returning a modified A. The transform_A function would then return the modified A commands along with the original of any non-A commands. Obviously, there would be a transform_M, etc. for each command type. As an alternative, you could use a generic transform() that expects the supplied function to recognize the command, parse it, modify the result and put it back together. I like the individual transform_* style because the identifying and parsing/recombining logic would be hidden inside that one function. The result would still require loop work, but it would be inside the split_command, transform_*, and join_command functions. This style takes a little getting used to, but it can be quite powerful for problems with this structure. HTH, G. Wade > and then separate the subcommands (A,M, Q, L, l, s, z, etc) from the > coordinates thusly > > > > A=d.match(/regexp/g) > > B=d.split(/regexp/g) > > > > And then perform arithmetic on all i in A and then join everything > back together in one swell foop: > > > > C=d.gaps(/regexp/g,/regexp2/g) (where the mythical "gaps" method of > the array object would return an array of the number of > regexp2-delimited items between A's boundaries) > > > > The properly defined "gaps" method would then allow something like > > > > D=superJoin(A,B,C) ==d > > And D=superjoin (A,arithmetic(B),C) == transform(d) > > > > As it is, I'm going to have to write loops to walk through the > structure, pushing operators, numbers and coordinates onto separate > stacks and then to loop through again to reconstitute the whole mess. > Not a terrible thing, but .. Such tedium! > > > > Any ideas if such a construct has been posited before? It would be > very handy for SVG path processing. > > > > Cheers > > David > > > > [Non-text portions of this message have been removed] > [Non-text portions of this message have been removed] ------------------------------------ ----- To unsubscribe send a message to: [email protected] -or- visit http://groups.yahoo.com/group/svg-developers and click "edit my membership" ----Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/svg-developers/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/svg-developers/join (Yahoo! ID required) <*> To change settings via email: [email protected] [email protected] <*> To unsubscribe from this group, send an email to: [email protected] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
