Introduced a Gulpfile for the generation of derived files.

SVG/PNG sprites, as well as Iconjar ijmaps can now be generated by
running `gulp`.

.babelrc

@@ -0,0 +1,3 @@
+{
+  "presets": ["es2015"]
+}

gulpfile.babel.js

@@ -0,0 +1,165 @@
+'use strict';
+
+import _ from 'lodash';
+import File from 'vinyl';
+import gulp from 'gulp';
+import merge from 'merge-stream';
+import sprity from 'sprity';
+import svgSprite from 'gulp-svg-sprite';
+import through2 from 'through2';
+import { humanize, titleize } from 'underscore.string';
+
+
+/** Names of directories containing icons. */
+const ICON_CATEGORIES = [
+  'action',
+  'alert',
+  'av',
+  'communication',
+  'content',
+  'editor',
+  'file',
+  'hardware',
+  'image',
+  'maps',
+  'navigation',
+  'notification',
+  'places',
+  'social',
+  'toggle',
+];
+
+
+/** Standard PNG colors. */
+const PNG_COLORS = [
+  'black',
+  'white',
+];
+
+
+/**
+ * Generates PNG sprites and their corresponding CSS files for each category of
+ * icon, and places them in `sprites/css-sprite`.
+ *
+ * TODO(shyndman): Add support for double density sprites.
+ */
+gulp.task('png-sprites', () =>
+  _(getCategoryColorPairs())
+    .map(([ category, color ]) =>
+      sprity.src({
+        src: `./${ category }/1x_web/*_${ color }_24dp.png`,
+        style: `sprite-${ category }-${ color }.css`,
+        name: `sprite-${ category }-${ color }`,
+        engine: 'sprity-gm',
+        orientation: 'left-right'
+      }))
+    .thru(merge)
+    .value()
+    .pipe(gulp.dest('./sprites/css-sprite/')));
+
+
+/**
+ * Generates CSS and Symbol-based SVG sprites for each category, and places
+ * them in `sprites/svg-sprite`.
+ */
+gulp.task('svg-sprites', () =>
+  _(ICON_CATEGORIES)
+    .map((category) =>
+      gulp.src(`./${ category }/svg/production/*_24px.svg`)
+        .pipe(svgSprite(getSvgSpriteConfig(category))))
+    .thru(merge)
+    .value()
+    .pipe(gulp.dest('./sprites/svg-sprite')));
+
+
+/**
+ * Generates a file to allow the consumption of the icon font by Iconjar
+ * (http://geticonjar.com/).
+ */
+gulp.task('iconjar', () =>
+  gulp.src('./iconfont/codepoints')
+    .pipe(generateIjmap('MaterialIcons-Regular.ijmap'))
+    .pipe(gulp.dest('./iconfont/')));
+
+
+/** Runs all tasks. */
+gulp.task('default', ['png-sprites', 'svg-sprites', 'iconjar']);
+
+
+/**
+ * Returns a stream that transforms between our icon font's codepoint file
+ * and an Iconjar ijmap.
+ */
+function generateIjmap(ijmapPath) {
+  return through2.obj((codepointsFile, encoding, callback) => {
+    const ijmap = {
+      icons: codepointsToIjmap(codepointsFile.contents.toString())
+    };
+
+    callback(null, new File({
+      path: ijmapPath,
+      contents: new Buffer(JSON.stringify(ijmap), 'utf8')
+    }));
+
+    function codepointsToIjmap(codepoints) {
+      return _(codepoints)
+        .split('\n')       // split into lines
+        .reject(_.isEmpty) // remove empty lines
+        .reduce((codepointMap, line) => {   // build up the codepoint map
+          let [ name, codepoint ] = line.split(' ');
+          codepointMap[codepoint] = { name: titleize(humanize(name)) };
+          return codepointMap;
+        }, {});
+    }
+  });
+}
+
+
+/**
+ * Returns the SVG sprite configuration for the specified category.
+ */
+function getSvgSpriteConfig(category) {
+  return {
+    shape: {
+      dimension: {
+        maxWidth: 24,
+        maxHeight: 24
+      },
+    },
+    mode: {
+      css : {
+        bust: false,
+        dest: './',
+        sprite: `./svg-sprite-${ category }.svg`,
+        example: {
+          dest: `./svg-sprite-${ category }.html`
+        },
+        render: {
+          css: {
+            dest: `./svg-sprite-${ category }.css`
+          }
+        }
+      },
+      symbol : {
+        bust: false,
+        dest: './',
+        sprite: `./svg-sprite-${ category }-symbol.svg`,
+        example: {
+          dest: `./svg-sprite-${ category }-symbol.html`
+        }
+      }
+    }
+  };
+}
+
+
+/**
+ * Returns the catesian product of categories and colors.
+ */
+function getCategoryColorPairs() {
+  return _(ICON_CATEGORIES)
+    .map((category) =>
+      _.zip(_.times(PNG_COLORS.length, () => category), PNG_COLORS))
+    .flatten() // flattens 1 level
+    .value();
+}

package.json

@@ -18,5 +18,18 @@
   "bugs": {
     "url": "https://github.com/google/material-design-icons/issues"
   },
-  "homepage": "https://github.com/google/material-design-icons"
+  "homepage": "https://github.com/google/material-design-icons",
+  "devDependencies": {
+    "babel-core": "^6.1.2",
+    "babel-preset-es2015": "^6.1.2",
+    "gulp": "^3.9.0",
+    "gulp-if": "^2.0.0",
+    "gulp-svg-sprite": "^1.2.13",
+    "lodash": "^3.10.1",
+    "sprity": "^1.0.7",
+    "sprity-gm": "^1.0.2",
+    "through2": "^2.0.0",
+    "underscore.string": "^3.2.2",
+    "vinyl": "^1.1.0"
+  }
 }