add custom nerdfont package

modules/profiles/desktop.nix

@@ -8,13 +8,7 @@ with lib;
       security-tools = true;
     };
 
-    fonts.fonts = [
+    fonts.fonts = [ pkgs.bck-nerdfont ];
-      # vscode: "DejaVuSansMono Nerd Font" (size 16)
-      # gnome-terminal: "DejaVu Sans Mono, Inconsolata for Powerline Medium 12"
-      # gnome-terminal setting (dconf): /org/gnome/terminal/legacy/profiles/.../font
-      pkgs.powerline-fonts
-      (pkgs.nerdfonts.override { fonts = [ "DejaVuSansMono" ]; })
-    ];
 
     environment.systemPackages = with pkgs; [
       brave

pkgs/bck-nerdfont.nix

@@ -0,0 +1,57 @@
+{ stdenv
+, lib
+, dejavu_fonts
+, fetchFromGitHub
+, python3
+, writeScript
+}:
+
+let
+  py = python3.withPackages (p: [ p.fontforge ]);
+
+  # Stick a rectangle on the left edge of the
+  # powerline symbol to avoid anti-aliasing artifacts
+  postprocess = writeScript "postprocess.py" ''
+    #!${py}/bin/python
+    import fontforge, psMat, sys, os
+    f = fontforge.open(sys.argv[1])
+    glyph = f[0xE0B0]
+    bb = glyph.boundingBox()
+    pen = glyph.glyphPen(replace=False)
+    pen.moveTo(bb[0],bb[1])
+    pen.lineTo(bb[0],bb[3])
+    pen.lineTo(bb[0]-150,bb[3])
+    pen.lineTo(bb[0]-150,bb[1])
+    pen.closePath()
+    os.unlink(sys.argv[1])
+    f.generate(sys.argv[1])
+  '';
+
+in
+stdenv.mkDerivation {
+  name = "bck-nerdfont";
+
+  dontUnpack = true;
+
+  src = fetchFromGitHub {
+    owner = "ryanoasis";
+    repo = "nerd-fonts";
+    rev = "v2.1.0";
+    sha256 = "j0cLZHOLyoItdvLOQVQVurY3ARtndv0FZTynaYJPR9E=";
+  };
+
+  buildPhase = ''
+    # Either Octicons or FontAwesome are required. Take your pick.
+    # They cause the fontlinux characters to move to the correct slots.
+    # (see fontlinuxExactEncodingPosition)
+    find ${dejavu_fonts}/share/fonts/truetype -name 'DejaVuSansMono*' -print0 |
+      xargs -0n1 ${py}/bin/python $src/font-patcher \
+        --fontlinux --octicons --powerline \
+        --postprocess ${postprocess}
+  '';
+
+  installPhase = ''
+    mkdir -p $out/share/fonts/truetype
+    cp -v *.ttf $out/share/fonts/truetype/
+  '';
+}

pkgs/default.nix

@@ -9,6 +9,7 @@ let
 in
 rec
 {
+  bck-nerdfont = pkg ./bck-nerdfont.nix { };
   binaryninja = pkg ./binary-ninja-personal { };
   commander-x16 = pkg ./commander-x16 { };
   gef = pkg ./gef { };