matrix: default.nix to build icons

matrix/build.rb

@@ -0,0 +1,75 @@
+#!/usr/bin/env ruby
+
+require "nokogiri"
+require "fileutils"
+
+$document = ARGV.first
+$out = ENV["out"]
+
+include FileUtils
+
+def save(doc, out)
+  File.open("icons.src.svg", "w") do |f|
+    doc.write_xml_to(f, :encoding => "UTF-8")
+  end
+
+  system(
+    "inkscape",
+    "icons.src.svg",
+    "--export-area-page",
+    "--export-filename=#{out}",
+  )
+
+  rm("icons.src.svg")
+end
+
+puts("Matrix Icons Builder...")
+puts("=======================\n")
+
+mkdir_p($out)
+$doc = Nokogiri::XML::Document.parse(File.read($document))
+
+$doc.element_children.each do |svg|
+  # Checks we indeed loaded an SVG document...
+  raise unless svg.name == "svg"
+
+  # First hide everything.
+  svg.element_children.select {|el| el.name == "g"}.each do |el|
+    el["style"] = "display:none"
+  end
+
+  # Then prepare exports for this category
+  svg.element_children.select {|el| el.name == "g"}.each do |el|
+    type = el["inkscape:label"]
+
+    # Skip an unneeded category
+    next if type == "DO NOT PRINT"
+
+    # Show the current layer
+    el["style"] = ""
+
+    # But first hide everything but the background
+    el.element_children.each do |child|
+      if child["inkscape:label"].match(/^\$BACKGROUND/)
+        child["style"] = ""
+      else
+        child["style"] = "display:none"
+      end
+    end
+
+    el.element_children.each do |child|
+      next if child["inkscape:label"].match(/^\$BACKGROUND/)
+      # Show the layer
+      child["style"] = ""
+
+      name = child["inkscape:label"]
+      save($doc, File.join($out, "#{type}-#{name}.png"))
+
+      # Hide the layer
+      child["style"] = "display:none"
+    end
+
+    # Hide the current layer again
+    el["style"] = "display:none"
+  end
+end

matrix/default.nix

@@ -0,0 +1,70 @@
+# This uses a pinned Nixpkgs so the software
+# used for the export (inkscape) and fonts used
+# for the export stay proper.
+{ pkgs ? import ./pkgs.nix {} }:
+
+let
+  FONTCONFIG_FILE = pkgs.callPackage (
+    { symlinkJoin
+    , writeText
+    , encode-sans
+  }:
+  let
+    mkFontsDir = fonts: symlinkJoin {
+      name = "fonts-dir";
+      paths = fonts;
+    };
+
+    fontsDir = mkFontsDir [
+      encode-sans
+    ];
+  in
+
+  writeText "fonts.conf" ''
+    <?xml version='1.0'?>
+    <!DOCTYPE fontconfig SYSTEM 'urn:fontconfig:fonts.dtd'>
+    <fontconfig>
+    <dir>${fontsDir}</dir>
+
+    <!-- Default rendering settings -->
+    <match target="pattern">
+    <edit mode="append" name="hinting">
+    <bool>true</bool>
+    </edit>
+    <edit mode="append" name="autohint">
+    <bool>true</bool>
+    </edit>
+    <edit mode="append" name="hintstyle">
+    <const>hintslight</const>
+    </edit>
+    <edit mode="append" name="antialias">
+    <bool>true</bool>
+    </edit>
+    </match>
+
+
+    </fontconfig>
+  ''
+  ) {};
+in
+
+# Yes, you can callPackage something else than a path!
+pkgs.callPackage (
+
+  { runCommandNoCC, inkscape, encode-sans, FONTCONFIG_FILE, ruby }:
+  runCommandNoCC "nixos-artwork-matrix-icons" {
+    nativeBuildInputs = [
+      inkscape
+      ruby
+    ];
+    inherit FONTCONFIG_FILE;
+  } ''
+    ruby ${./build.rb} ${./icons.src.svg}
+  ''
+
+) {
+  inherit FONTCONFIG_FILE;
+  ruby = pkgs.ruby.withPackages(p: [
+    p.nokogiri
+  ]);
+}

matrix/pkgs.nix

@@ -0,0 +1,9 @@
+let
+  rev = "d42cd445dde587e9a993cd9434cb43da07c4c5de";
+  sha256 = "0dzrn97srxyw5a3g7hf8chwccxns5z3aij23hc0fch7ygc8w0gq0";
+  tarball = builtins.fetchTarball {
+    url = "https://github.com/NixOS/nixpkgs/archive/${rev}.tar.gz";
+    inherit sha256;
+  };
+in
+builtins.trace "Using default Nixpkgs revision '${rev}'..." (import tarball)