Convert the rendering queue to ES6 syntax

web/pdf_rendering_queue.js

@@ -13,60 +13,55 @@
  * limitations under the License.
  */
 
-var CLEANUP_TIMEOUT = 30000;
+const CLEANUP_TIMEOUT = 30000;
 
-var RenderingStates = {
+const RenderingStates = {
   INITIAL: 0,
   RUNNING: 1,
   PAUSED: 2,
-  FINISHED: 3
+  FINISHED: 3,
 };
 
 /**
  * Controls rendering of the views for pages and thumbnails.
- * @class
  */
-var PDFRenderingQueue = (function PDFRenderingQueueClosure() {
-  /**
-   * @constructs
-   */
-  function PDFRenderingQueue() {
+class PDFRenderingQueue {
+  constructor() {
     this.pdfViewer = null;
     this.pdfThumbnailViewer = null;
     this.onIdle = null;
-
     this.highestPriorityPage = null;
     this.idleTimeout = null;
     this.printing = false;
     this.isThumbnailViewEnabled = false;
   }
 
-  PDFRenderingQueue.prototype = /** @lends PDFRenderingQueue.prototype */ {
   /**
    * @param {PDFViewer} pdfViewer
    */
-    setViewer: function PDFRenderingQueue_setViewer(pdfViewer) {
+  setViewer(pdfViewer) {
     this.pdfViewer = pdfViewer;
-    },
+  }
 
   /**
    * @param {PDFThumbnailViewer} pdfThumbnailViewer
    */
-    setThumbnailViewer:
-        function PDFRenderingQueue_setThumbnailViewer(pdfThumbnailViewer) {
+  setThumbnailViewer(pdfThumbnailViewer) {
     this.pdfThumbnailViewer = pdfThumbnailViewer;
-    },
+  }
 
   /**
    * @param {IRenderableView} view
    * @returns {boolean}
    */
-    isHighestPriority: function PDFRenderingQueue_isHighestPriority(view) {
+  isHighestPriority(view) {
     return this.highestPriorityPage === view.renderingId;
-    },
+  }
 
-    renderHighestPriority: function
-        PDFRenderingQueue_renderHighestPriority(currentlyVisiblePages) {
+  /**
+   * @param {Object} currentlyVisiblePages
+   */
+  renderHighestPriority(currentlyVisiblePages) {
     if (this.idleTimeout) {
       clearTimeout(this.idleTimeout);
       this.idleTimeout = null;
@@ -76,7 +71,7 @@ var PDFRenderingQueue = (function PDFRenderingQueueClosure() {
     if (this.pdfViewer.forceRendering(currentlyVisiblePages)) {
       return;
     }
-      // No pages needed rendering so check thumbnails.
+    // No pages needed rendering, so check thumbnails.
     if (this.pdfThumbnailViewer && this.isThumbnailViewEnabled) {
       if (this.pdfThumbnailViewer.forceRendering()) {
         return;
@@ -91,16 +86,23 @@ var PDFRenderingQueue = (function PDFRenderingQueueClosure() {
     if (this.onIdle) {
       this.idleTimeout = setTimeout(this.onIdle.bind(this), CLEANUP_TIMEOUT);
     }
-    },
+  }
 
-    getHighestPriority: function
-        PDFRenderingQueue_getHighestPriority(visible, views, scrolledDown) {
-      // The state has changed figure out which page has the highest priority to
-      // render next (if any).
-      // Priority:
-      // 1 visible pages
-      // 2 if last scrolled down page after the visible pages
-      // 2 if last scrolled up page before the visible pages
+  /**
+   * @param {Object} visible
+   * @param {Array} views
+   * @param {boolean} scrolledDown
+   */
+  getHighestPriority(visible, views, scrolledDown) {
+    /**
+     * The state has changed. Figure out which page has the highest priority to
+     * render next (if any).
+     *
+     * Priority:
+     * 1. visible pages
+     * 2. if last scrolled down, the page after the visible pages, or
+     *    if last scrolled up, the page before the visible pages
+     */
     var visibleViews = visible.views;
 
     var numVisible = visibleViews.length;
@@ -114,12 +116,11 @@ var PDFRenderingQueue = (function PDFRenderingQueueClosure() {
       }
     }
 
-      // All the visible views have rendered, try to render next/previous pages.
+    // All the visible views have rendered; try to render next/previous pages.
     if (scrolledDown) {
       var nextPageIndex = visible.last.id;
-        // ID's start at 1 so no need to add 1.
-        if (views[nextPageIndex] &&
-            !this.isViewFinished(views[nextPageIndex])) {
+      // IDs start at 1, so no need to add 1.
+      if (views[nextPageIndex] && !this.isViewFinished(views[nextPageIndex])) {
         return views[nextPageIndex];
       }
     } else {
@@ -131,25 +132,25 @@ var PDFRenderingQueue = (function PDFRenderingQueueClosure() {
     }
     // Everything that needs to be rendered has been.
     return null;
-    },
+  }
 
   /**
    * @param {IRenderableView} view
    * @returns {boolean}
    */
-    isViewFinished: function PDFRenderingQueue_isViewFinished(view) {
+  isViewFinished(view) {
     return view.renderingState === RenderingStates.FINISHED;
-    },
+  }
 
   /**
    * Render a page or thumbnail view. This calls the appropriate function
    * based on the views state. If the view is already rendered it will return
-     * false.
+   * `false`.
+   *
    * @param {IRenderableView} view
    */
-    renderView: function PDFRenderingQueue_renderView(view) {
-      var state = view.renderingState;
-      switch (state) {
+  renderView(view) {
+    switch (view.renderingState) {
       case RenderingStates.FINISHED:
         return false;
       case RenderingStates.PAUSED:
@@ -161,18 +162,15 @@ var PDFRenderingQueue = (function PDFRenderingQueueClosure() {
         break;
       case RenderingStates.INITIAL:
         this.highestPriorityPage = view.renderingId;
-          var continueRendering = function () {
+        var continueRendering = () => {
           this.renderHighestPriority();
-          }.bind(this);
+        };
         view.draw().then(continueRendering, continueRendering);
         break;
     }
     return true;
-    },
-  };
-
-  return PDFRenderingQueue;
-})();
+  }
+}
 
 export {
   RenderingStates,