DevTools: introduce spritesheet assembler.

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

+var postsvg = require('postsvg');
+var renameId = require('postsvg-rename-id');
+
+class SVGSpriteSheet {
+  /**
+   * @param {number} width
+   * @param {number} height
+   * @param {!Map<!SVGSprite, !{x: number, y: number}>} spritePositions
+   */
+  constructor(width, height, spritePositions) {
+    this._width = width;
+    this._height = height;
+    this._sprites = Array.from(spritePositions.keys());
+    this._positions = spritePositions;
+  }
+
+  /**
+   * @return {number}
+   */
+  width() {
+    return this._width;
+  }
+
+  /**
+   * @return {number}
+   */
+  height() {
+    return this._height;
+  }
+
+  /**
+   * @return {!Array<!SVGSprite>}
+   */
+  sprites() {
+    return this._sprites;
+  }
+
+  /**
+   * @param {!SVGSprite} sprite
+   * @return {!{x: number, y: number}}
+   */
+  spritePosition(sprite) {
+    console.assert(this._positions.has(sprite), 'sprite ' + sprite.filePath + ' has undefined position!');
+    return this._positions.get(sprite);
+  }
+
+  /**
+   * @return {string}
+   */
+  svgText() {
+    if (this._svgText)
+      return this._svgText;
+
+    var svgBody = '';
+    var spriteId = 0;
+    for (var sprite of this._sprites) {
+      var spriteSVG = sprite.content.trim();
+
+      // Strip of <?xml> header, if any.
+      if (spriteSVG.startsWith('<?xml')) {
+        var headerIndexEnd = spriteSVG.indexOf('?>');
+        spriteSVG = spriteSVG.substring(headerIndexEnd + 2);
+      }
+
+      // Rename sprite ids to avoid clashing.
+      spriteSVG = postsvg().use(renameId({pattern: 'sprite' + (++spriteId) + '_[id]'})).process(spriteSVG);
+
+      // Wrap sprite to SVG container with proper position.
+      var position = this._positions.get(sprite);
+      var prefix = `<svg x="${position.x}" y="${position.y}" width="${sprite.width}" height="${sprite.height}">`;
+      var suffix = '</svg>';
+      spriteSVG = prefix + spriteSVG + suffix;
+
+      svgBody += spriteSVG;
+    }
+
+    var xmlHeader = '<?xml version="1.0" encoding="utf-8"?>';
+    var spriteSheetHeader = `<svg width="${this._width}" height="${this._height}" xmlns="http://www.w3.org/2000/svg">`;
+    return xmlHeader + spriteSheetHeader + svgBody + '</svg>';
+  }
+};
+
+module.exports = SVGSpriteSheet;