orr@cs.glasgow.ac.uk (Fraser Orr) (09/23/88)
Given an arbitrary path, I would like to be able to get a path
that discribes the outside shape of this. Has anybody done this
or have you any suggestions as to how to do this?
Any help would be most appreciated,
Regards,
==Fraser Orr ( Dept C.S., Univ. Glasgow, Glasgow, G12 8QQ, UK)
UseNet: {uk}!cs.glasgow.ac.uk!orr JANET: orr@uk.ac.glasgow.cs
ARPANet(preferred xAtlantic): orr%cs.glasgow.ac.uk@nss.cs.ucl.ac.ukkjk@pbhyf.PacBell.COM (Ken Keirnan) (09/25/88)
In article <1658@crete.cs.glasgow.ac.uk> orr%cs.glasgow.ac.uk@nss.ucl.ac.uk (Fraser Orr) writes: >Given an arbitrary path, I would like to be able to get a path >that discribes the outside shape of this. Has anybody done this >or have you any suggestions as to how to do this? > >Any help would be most appreciated, > >Regards, > >==Fraser Orr ( Dept C.S., Univ. Glasgow, Glasgow, G12 8QQ, UK) >UseNet: {uk}!cs.glasgow.ac.uk!orr JANET: orr@uk.ac.glasgow.cs >ARPANet(preferred xAtlantic): orr%cs.glasgow.ac.uk@nss.cs.ucl.ac.uk I know this isn't exactly what you had in mind (outline path of an arbitrary PostScript figure), but perhaps it will be a start. Even if you can't use it, others may find it useful. The following PostScript routines, prepended to a PostScript figure, will print the figure surrounded by the bounding box and coordinates. This handy little piece of PostScript was included in the "psfig" ditroff figure preprocessor software by Trevor Darrell and Ned Batchelder. -- Ken Keirnan %-------- CUT HERE -------- CUT HERE -------- CUT HERE -------- %! % bb.ps -- % % Prints a file, but keeps track of bounding box info, and prints the box at % the end (around the figure). Does not handle images and clipping well. % --Trevor % trevor@linc.cis.upenn.edu % uucp: seismo!linc.cis.upenn.edu!trevor (or any arpa/uucp gateway) % 50 dict dup /$BoundingBox exch def begin /xdef { exch def } def /xstore { exch store } def /bb-pt+ { exch 4 -1 roll add 3 1 roll add } def % % Stubs of old functions. % /-stroke /stroke load def /-fill /fill load def /-eofill /eofill load def /-image /image load def /-show /show load def /-awidthshow /awidthshow load def /-showpage /showpage load def % % New Functions. % /stroke { gsave { flattenpath strokepath % Make sure to take line width into account. } stopped { % strokepath often hits a limitcheck. grestore % Restore the original path gsave } if bb-path % Accumulate it into our box. grestore -stroke } def /fill { gsave bb-path grestore -fill } def /eofill { gsave bb-path grestore -eofill } def % % Text is implemented by reducing everything to an `awidthshow'. % /show { 0 0 0 0 0 % Extra parameters for awidthshow 6 -1 roll % Bring the string back up awidthshow } def /widthshow { 0 0 % Extra parameters for awidthshow 3 -1 roll % Bring the string back up. awidthshow } def /ashow { 0 0 0 6 3 roll awidthshow } def /awidthshow { 5 dict begin gsave currentpoint 2 copy /@starty xdef /@startx xdef 2 index stringwidth % Get the natural length of the string bb-pt+ % Add to the start to get the end. 2 index length % How many characters? dup % Add the offsets to each character 6 index mul exch 5 index mul bb-pt+ 5 index 3 index bb-chcount % How many padding characters? dup % Add the offsets for each pad. 9 index mul exch 8 index mul bb-pt+ /@endy xdef /@endx xdef bb-fontheight % Get the height and depth of the current font. 4 copy @startx @starty bb-pt+ bb-point @startx @starty bb-pt+ bb-point @endx @endy bb-pt+ bb-point @endx @endy bb-pt+ bb-point newpath % $Debug @startx @starty moveto % $Debug @endx @endy lineto % $Debug bb-bwstroke % $Debug grestore end -awidthshow } def % % `image': % % Assume here that the image lands in the unit square. % /image { -image } def % % `showpage': % % Just draw the box around the figure and print the page, and then initialize % the bounding box variables again. % /bb-string 10 string def /showpage { initgraphics bb-llx bb-lly itransform % Convert them into default coords. bb-urx bb-ury itransform /bb-lly xstore /bb-urx xstore /bb-ury xstore /bb-llx xstore bb-llx bb-lly moveto % Make the box bb-llx bb-ury lineto bb-urx bb-ury lineto bb-urx bb-lly lineto closepath bb-bwstroke % Draw the box. 0 setgray /Courier findfont 10 scalefont setfont bb-llx bb-lly 12 sub moveto bb-llx bb-string cvs -show ( ) -show bb-lly bb-string cvs -show ( ) -show bb-urx bb-string cvs -show ( ) -show bb-ury bb-string cvs -show bb-init -showpage } def % % BoundingBox functions: % % We accumulate the information about the bounding box into four variables. % The data is stored in device coordinates. % /bb-init { /bb-llx 99999 store /bb-lly 99999 store /bb-urx -99999 store /bb-ury -99999 store } def /bb-llx 0 def /bb-lly 0 def /bb-urx 0 def /bb-ury 0 def % % x y `bb-point' - % % Takes a point in user coordinates and adds it into the bounding box info. % /bb-point { transform % Convert to device coords. dup dup bb-lly lt { /bb-lly xstore } { pop } ifelse dup bb-ury gt { /bb-ury xstore } { pop } ifelse dup dup bb-llx lt { /bb-llx xstore } { pop } ifelse dup bb-urx gt { /bb-urx xstore } { pop } ifelse } def % % - `bb-path' - % % Incorporates the bounding box of the path into the bounding box info. % /bb-path { gsave { 0 setlinejoin flattenpath } stopped { grestore gsave } if pathbbox bb-point bb-point grestore } def % % A nice black-and white line drawing function. % /bb-bwstroke { 0 setlinewidth % Thinnest possible lines 1 setgray % White first [5] 0 setdash % Only half the line gsave -stroke grestore 0 setgray % Then black [5] 5 setdash % On the other half -stroke } def % % Stuff for text. % % % char-code string `bb-chcount' occurs % % Counts the number of times a character appears in a string. % /bb-chcount { 0 exch { 2 index eq { 1 add } if } forall exch pop } def % % - `bb-fontheight' heightx heighty depthx depthy % % Returns the offsets to the lowest point and highest point in the current % font. % /bb-fontheight { currentfont begin % following line commented out by PHW; replaced by next 2 lines % FontBBox currentfont /FontBBox get dup 0 get exch dup 1 get exch dup 2 get exch 3 get exch pop 0 exch FontMatrix transform 4 2 roll exch pop 0 exch FontMatrix transform end } def % Start it up. bb-init % end of bb.ps %-------- CUT HERE -------- CUT HERE -------- CUT HERE -------- -- Ken Keirnan - Pacific Bell - {att,bellcore,sun,ames,pyramid}!pacbell!pbhyf!kjk San Ramon, California kjk@pbhyf.PacBell.COM
mh@wlbr.EATON.COM (Mike Hoegeman) (09/26/88)
In article <1658@crete.cs.glasgow.ac.uk> orr%cs.glasgow.ac.uk@nss.ucl.ac.uk (Fraser Orr) writes: >Given an arbitrary path, I would like to be able to get a path >that discribes the outside shape of this. Has anybody done this >or have you any suggestions as to how to do this? > >Any help would be most appreciated, > depending on what you want to do 'strokepath' may be your ticket. check it out in the Red Book. -mike