I've never found a good way to script this. The process I use is to open the postscript file with gimp, crop and save. It would be very pleasant to have a way to quickly generate high quality cropped images from groff. If anyone knows how to do that I'd like to know too.
On Wed, May 11, 2005 at 02:08:50PM +0100, David Griffiths wrote: > Hi, I'm new to pic/groff and I've been having some problems producing > either gif or jpeg images using them. The basic problem seems to be that > pic/groff/postscript all have the concept of a page that they are > drawing on whereas I want the resulting image to have all the whitespace > cropped from the margins. This is to go in a web page so the idea of a > page doesn't make sense. > > Anyway I started out following some instructions here: > http://www.spinellis.gr/sw/umlgraph/doc/faq.html#antialias but the > resulting command was very slow. Here are my findings as pasted from my > internal blog. I wondered if they made sense or if I'm missing some > simpler approach to the whole thing (btw I need the gs stage because > using -T gif in groff produces very poor text, no antialiasing). > > Thanks! > > Dave > > From my blog: > > I missed the hint in the FAQ and after a bit of messing around got the > following command to work: > > pic test | groff | ps2eps | gs -dDEVICEHEIGHTPOINTS=1000 -q -r360 > -dNOPAUSE -sDEVICE=pnm -sOutputFile=- - -c quit | pnmcrop | pnmscale 0.5 > | ppmtogif > test.gif > > I had to add the -dDEVICEHEIGHTPOINTS=1000 option because without that > it chopped off the top of the picture. > > Anyway, I think I prefer this approach if only because the pnmscale > command gives me the option to scale the size of the image. Plus > ppmtogif gives me control over transparency. > > Posted by D. H. Griffiths on May 04, 2005 at 07:02 AM EDT > I've been playing around with this some more because the command above > was just so slow (eg 17 seconds on my T40 for a trivial diagram). Turns > out that most of that time is spent in pnmcrop. The image is far larger > than it needs to be (as specified by the resolution argument -r360) and > is then shrunk back down again with pnmscale (for my tests I'm using > pnmscale 0.25). Why is that? Well if you use -r90 and get rid of the > pnmscale, the text looks ragged as though it's missing antialiasing. But > I found that you could overcome that by specifying -dTextAlphaBits=4 in > the gs command. So you end up with a command like this: > > pic test | groff | ps2eps -q | gs -dTextAlphaBits=4 > -dDEVICEHEIGHTPOINTS=1000 -q -r90 -dNOPAUSE -sDEVICE=pnm -sOutputFile=- > - -c quit | pnmcrop | ppmtogif > test.gif > > now that's about four times faster because the intermediate pnm image is > four times smaller. This command took about 4 seconds on my Thinkpad. > But I found a still faster way. > > Why bother to go to pnm format in the first place, why can't the image > be created directly by ghostscript? Well the answer is that can, but > ghostscript can only produce jpeg images, not gif. Which is fine for me. > The next issue relates to the pnmcrop command. What that does is chop > blank space from around your image. The problem is that a lot of what > groff and postscript do revolves round the concept of writing to a page > (typically letter size). Pic for instance has its coordinate origin at > the bottom left but positions your image at the top of the page. If you > play around you run into all sorts of issues with the image having white > space above or below or the image top gets chopped off because it's > above the top of the imaginary page and so on. After a lot of messing > around I came up with this version of the command: > > pic test | groff | ps2eps -q -g | fixbox | gs -dTextAlphaBits=4 -q > -r90 -dNOPAUSE -sDEVICE=jpeg -sOutputFile=- - -c quit > test.jpg > > the -g option to ps2eps is important because that tells it to use the > "internal bbox device of ghostscript" (whatever that means!), but anyway > it prevents ps2eps from setting the top of the bounding box to the top > of the default page. It's important because without it the diagram goes > above the bounding box set by ps2eps and the image gets cropped. > > fixbox is a small python script I wrote that is a much simplified > version of epstopdf. What this does is to move the image to the bottom > left corner and set the page size to just include the bounding box. > Using this means that there is no longer a need for cropping. The script > is here: > > #!/usr/bin/python > # This script converts the BoundingBox of a postscript file so that the > origin is at > # the bottom left corner (0, 0). It also sets the pagesize which avoids > the need for > # cropping blank space from the image. > > import sys > import os > import re > > inlines = sys.stdin.readlines() > > for line in inlines: > if line.find("%%BoundingBox: ") != -1: > tokens = line.split() > minx = int(tokens[1]) > miny = int(tokens[2]) > maxx = int(tokens[3]) > maxy = int(tokens[4]) > new_maxx = maxx - minx > new_maxy = maxy - miny > print "%%BoundingBox: 0 0 " + str(new_maxx) + " " + str(new_maxy) > print "<< /PageSize [" + str(new_maxx + 10) + " " + > str(new_maxy + 10) + "] >> setpagedevice" > print "gsave -" + str(minx) + " -" + str(miny - 1) + " translate" > else: > print line, > > print "grestore" > > And finally, the best news is that this takes just 1 second to run! > > > > _______________________________________________ > Groff mailing list > Groff@gnu.org > http://lists.gnu.org/mailman/listinfo/groff -- --- Larry McVoy lm at bitmover.com http://www.bitkeeper.com _______________________________________________ Groff mailing list Groff@gnu.org http://lists.gnu.org/mailman/listinfo/groff
