DevTools: introduce spritesheet assembler.

third_party/WebKit/Source/devtools/scripts/spritesheet_assembler/index.js

+var fs = require('fs');
+var path = require('path');
+var SVGSprite = require('./SVGSprite');
+var Packer = require('./Packer');
+var DevToolsDescriptors = require('./DevToolsDescriptors');
+
+var timestamp = 0;
+function markStart() {
+  timestamp = Date.now();
+}
+function markEnd(label) {
+  console.log('==> ' + label + ': ' + (Date.now() - timestamp) + 'ms');
+}
+
+/**
+ * @param {string} directoryPath
+ * @param {number} padding
+ * @param {string} outputSVGPath
+ * @param {string} outputJSPath
+ */
+module.exports = function(directoryPath, padding, outputSVGPath, outputJSPath) {
+  // 1. Read all the svg files from given directory.
+  markStart();
+  var svgFilePaths = fs.readdirSync(directoryPath)
+                         .filter(file => path.extname(file) === '.svg')
+                         .map(fileName => path.join(directoryPath, fileName));
+
+  var sprites = [];
+  var spritesArea = 0;
+  for (var filePath of svgFilePaths) {
+    var sprite = SVGSprite.loadFromFile(filePath);
+    spritesArea += sprite.width * sprite.height;
+    sprites.push(sprite);
+  }
+  markEnd('Loaded ' + svgFilePaths.length + ' files');
+
+  // 2. Iterate over different sprite compositions to find best.
+  markStart();
+  var bestStyleSheet = null;
+  var bestCoverage = 0;
+  for (var sortOrderName in Packer.SpriteSortOrder) {
+    var sortOrder = Packer.SpriteSortOrder[sortOrderName];
+    var spriteSheet = Packer.packSprites(sprites, sortOrder, padding, padding);
+    var coverage = spritesArea / (spriteSheet.width() * spriteSheet.height());
+    if (!bestStyleSheet || coverage > bestCoverage) {
+      bestStyleSheet = spriteSheet;
+      bestCoverage = coverage;
+    }
+  }
+  markEnd(
+      'Created spritesheet ' + bestStyleSheet.width() + 'x' + bestStyleSheet.height() + ' with ' +
+      ((bestCoverage * 10000 | 0) / 100) + '% coverage');
+
+  // 3. Write results to disk
+  fs.writeFileSync(outputSVGPath, bestStyleSheet.svgText());
+  fs.writeFileSync(outputJSPath, DevToolsDescriptors.generateJS(bestStyleSheet));
+}