Refactor print preview web ui

chrome/browser/resources/print_preview/component.js

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+cr.define('print_preview', function() {
+  'use strict';
+
+  /**
+   * Class that represents a UI component.
+   * @constructor
+   * @extends {cr.EventTarget}
+   */
+  function Component() {
+    cr.EventTarget.call(this);
+
+    /**
+     * Component's HTML element.
+     * @type {Element}
+     * @private
+     */
+    this.element_ = null;
+
+    this.isInDocument_ = false;
+
+    /**
+     * Component's event tracker.
+     * @type {EventTracker}
+     * @private
+     */
+     this.tracker_ = new EventTracker();
+
+    /**
+     * Child components of the component.
+     * @type {Array.<print_preview.Component>}
+     * @private
+     */
+    this.children_ = [];
+  };
+
+  Component.prototype = {
+    __proto__: cr.EventTarget.prototype,
+
+    /** Gets the component's element. */
+    getElement: function() {
+      return this.element_;
+    },
+
+    /** @return {EventTracker} Component's event tracker. */
+    get tracker() {
+      return this.tracker_;
+    },
+
+    /**
+     * @return {boolean} Whether the element of the component is already in the
+     *     HTML document.
+     */
+    get isInDocument() {
+      return this.isInDocument_;
+    },
+
+    /**
+     * Creates the root element of the component. Sub-classes should override
+     * this method.
+     */
+    createDom: function() {
+      this.element_ = cr.doc.createElement('div');
+    },
+
+    /**
+     * Called when the component's element is known to be in the document.
+     * Anything using document.getElementById etc. should be done at this stage.
+     * Sub-classes should extend this method and attach listeners.
+     */
+    enterDocument: function() {
+      this.isInDocument_ = true;
+      for (var child, i = 0; child = this.children_[i]; i++) {
+        if (!child.isInDocument && child.getElement()) {
+          child.enterDocument();
+        }
+      }
+    },
+
+    /** Removes all event listeners. */
+    exitDocument: function() {
+      for (var child, i = 0; child = this.children_[i]; i++) {
+        if (child.isInDocument) {
+          child.exitDocument();
+        }
+      }
+      this.tracker_.removeAll();
+      this.isInDocument_ = false;
+    },
+
+    /**
+     * Renders this UI component and appends the element to the given parent
+     * element.
+     * @param {!Element} parentElement Element to render the component's
+     *     element into.
+     */
+    render: function(parentElement) {
+      assert(!this.isInDocument, 'Component is already in the document');
+      if (!this.element_) {
+        this.createDom();
+      }
+      parentElement.appendChild(this.element_);
+      this.enterDocument();
+    },
+
+    /**
+     * Decorates an existing DOM element. Sub-classes should override the
+     * override the decorateInternal method.
+     * @param {Element} element Element to decorate.
+     */
+    decorate: function(element) {
+      assert(!this.isInDocument, 'Component is already in the document');
+      this.setElementInternal(element);
+      this.decorateInternal();
+      this.enterDocument();
+    },
+
+    /**
+     * @param {print_preview.Component} child Component to add as a child of
+     *     this component.
+     */
+    addChild: function(child) {
+      this.children_.push(child);
+    },
+
+    /**
+     * @param {!print_preview.Component} child Component to remove from this
+     *     component's children.
+     */
+    removeChild: function(child) {
+      var childIdx = this.children_.indexOf(child);
+      if (childIdx != -1) {
+        this.children_.splice(childIdx, 1);
+      }
+      if (child.isInDocument) {
+        child.exitDocument();
+        if (child.getElement()) {
+          child.getElement().parentNode.removeChild(child.getElement());
+        }
+      }
+    },
+
+    /** Removes all of the component's children. */
+    removeChildren: function() {
+      while (this.children_.length > 0) {
+        this.removeChild(this.children_[0]);
+      }
+    },
+
+    /**
+     * Sets the component's element.
+     * @param {Element} element HTML element to set as the component's element.
+     * @protected
+     */
+    setElementInternal: function(element) {
+      this.element_ = element;
+    },
+
+    /**
+     * Decorates the given element for use as the element of the component.
+     * @protected
+     */
+    decorateInternal: function() { /*abstract*/ },
+
+    /**
+     * Clones a template HTML DOM tree.
+     * @param {string} templateId Template element ID.
+     * @param {boolean=} opt_keepHidden Whether to leave the cloned template
+     *     hidden after cloning.
+     * @return {Element} Cloned element with its 'id' attribute stripped.
+     * @protected
+     */
+    cloneTemplateInternal: function(templateId, opt_keepHidden) {
+      var templateEl = $(templateId);
+      assert(templateEl != null,
+             'Could not find element with ID: ' + templateId);
+      var el = templateEl.cloneNode(true);
+      el.id = '';
+      if (!opt_keepHidden) {
+        setIsVisible(el, true);
+      }
+      return el;
+    }
+  };
+
+  return {
+    Component: Component
+  };
+});