RSVG Package: Missing librsvg-2-2.dll

Questions & Answers
1

Hi, Racket Discourse.

I am trying to import .svg files to use in concert with the metapict library. I want to make use of the rsvg package to import the pertinent files, but I receive the following error:

..\..\..\..\..\..\Program Files\Racket\collects\ffi\unsafe.rkt:131:0: ffi-lib: could not load foreign library
path: librsvg-2-2.dll
system error: The specified procedure could not be found.; win_err=127

I installed the mingw64/mingw-w64-x86_64-librsvg variant of the library, which at least delayed the aforementioned error but when I again try to import the file, I get following error from DrRacket:

The procedure entry point g_string_free_and_steal could not be located in the dynamic link library C:\msys64\mingw64\bin\libgdk_pixbuf-2.0-0.dll.

I can confirm that the .dll above is present in the same directory.

Could this be due to the fact that I am using the mingw64 variant? I haven't used the FFI much, apart from some idle tinkering, so I'm not sure whether this assumption is even vaguely correct.

I make this assumption because I see that there has been a similar question in the past, on the old Google Racket Users group, here.

Any help would be greatly appreciated.

2

It seems librsvg dependson Pango. So does the graphic system (Cairo) used by Racket. I think, yourlibrsvgneeds to be built with the same (maybe just the same version) shared library as used byracket/draw`. It might be worth trying the DLL that Doug used - and
the same version of Racket as he used. Just to test that it is possible to get it
working on Windows.

FWIW on my machine with macOS librsvg works with Racket v.7.5 but not on the latest v8.8.
I can't remember how I got it working, but I see that I have a copy of the Github repo of
librsvg so maybe I compiled it myself?

Do you need full support for SVGs or is support for SVG paths enough?

There is a parser for svg paths included with MetaPict.
Here is an example where it is used to draw a bishop in the same style as on Lichess.

(define (draw-bishop dc brush pen-butt pen-round/miter decoration-pen)
  (define p1 (parse-svg-path (~a "M9 36c3.39-.97 10.11.43 13.5-2 3.39 2.43 10.11 1.03 13.5 2 "
                                 "0 0 1.65.54 3 2-.68.97-1.65.99-3 .5-3.39-.97-10.11.46-13.5-1-3.39 "
                                 "1.46-10.11.03-13.5 1-1.354.49-2.323.47-3-.5 1.354-1.94 3-2 3-2z")))
  (define p2 (parse-svg-path (~a "M15 32c2.5 2.5 12.5 2.5 15 0 .5-1.5 0-2 0-2 0-2.5-2.5-4-2.5-4 "
                                 "5.5-1.5 6-11.5-5-15.5-11 4-10.5 14-5 15.5 0 0-2.5 1.5-2.5 4 0 0-.5.5 0 2z")))
  (define p3 (parse-svg-path     "M25 8a2.5 2.5 0 1 1-5 0 2.5 2.5 0 1 1 5 0z"))
  (define p4 (parse-svg-path     "M17.5 26h10M15 30h15m-7.5-14.5v5M20 18h5"))

  (send dc set-brush brush)
  (send dc set-pen   pen-butt)
  (draw-paths dc (svg-path->paths p1) 0 0 'odd-even)
  (draw-paths dc (svg-path->paths p2) 0 0 'odd-even)
  (draw-paths dc (svg-path->paths p3) 0 0 'odd-even)
  ; decorations
  (send dc set-brush transparent-brush)
  (send dc set-pen   decoration-pen)
  (draw-paths dc (svg-path->paths p4)))

The example is from:
https://github.com/soegaard/metapict/blob/master/metapict/svg/chess.rkt

3

Hi, @soegaard.

Thank you for the helpful link/advice :+1:.

I probably don't need full support for SVGs, since I can likely retrieve the paths easily enough by inspecting the files; but then again, I could probably just convert them to more standard formats for my uses.

I will continue to have a look at the path route (I see lots of unfamiliar things, given that I've never paid much attention to SVG files), as well as trying out the particular DLL/version combination you mention from Doug's replies.

I'll update if I make any progress.