ipe: optional support for qvoronoi

Ipe can optionally compiled with ipelets computing Voronoi diagrams. This
depends on qhull and is therefore needs to be enabled explicitly.

pkgs/applications/graphics/ipe/default.nix

@@ -15,9 +15,11 @@
 , qtbase
 , qtsvg
 , texliveSmall
+, qhull
 , wrapQtAppsHook
 , zlib
 , withTeXLive ? true
+, withQVoronoi ? false
 , buildPackages
 }:
 
@@ -48,6 +50,8 @@ stdenv.mkDerivation rec {
     zlib
   ] ++ (lib.optionals withTeXLive [
     texliveSmall
+  ]) ++ (lib.optionals withQVoronoi [
+    qhull
   ]);
 
   makeFlags = [
@@ -56,7 +60,10 @@ stdenv.mkDerivation rec {
     "LUA_PACKAGE=lua"
     "MOC=${buildPackages.qt6Packages.qtbase}/libexec/moc"
     "IPE_NO_SPELLCHECK=1" # qtSpell is not yet packaged
-  ];
+  ] ++ (lib.optionals withQVoronoi [
+    "IPEQVORONOI=1"
+    "QHULL_CFLAGS=-I${qhull}/include/libqhull_r"
+  ]);
 
   qtWrapperArgs = lib.optionals withTeXLive [ "--prefix PATH : ${lib.makeBinPath [ texliveSmall ]}" ];