Refactor pdf_scripting_api.js to remove the PDFMessagingHost in OOP PDF

chrome/browser/resources/pdf/pdf.js

 // Copyright 2013 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.
 
 'use strict';
 
 <include src="../../../../ui/webui/resources/js/util.js">
+<include src="pdf_scripting_api.js">
 <include src="viewport.js">
-<include src="pdf_scripting_api.js">
 
 /**
  * @return {number} Width of a scrollbar in pixels
  */
 function getScrollbarWidth() {
   var div = document.createElement('div');
   div.style.visibility = 'hidden';
   div.style.overflow = 'scroll';
   div.style.width = '50px';
   div.style.height = '50px';
@@ skipping 27 matching lines @@
                                 this.viewportChangedCallback_.bind(this),
                                 getScrollbarWidth());
 
   // Create the plugin object dynamically so we can set its src. The plugin
   // element is sized to fill the entire window and is set to be fixed
   // positioning, acting as a viewport. The plugin renders into this viewport
   // according to the scroll position of the window.
   this.plugin_ = document.createElement('object');
   this.plugin_.id = 'plugin';
   this.plugin_.type = 'application/x-google-chrome-pdf';
-  this.plugin_.addEventListener('message', this.handleMessage_.bind(this),
+  this.plugin_.addEventListener('message', this.handlePluginMessage_.bind(this),
                                 false);
 
+  // Handle scripting messages from outside the extension that wish to interact
+  // with it. We also send a message indicating that extension has loaded and
+  // is ready to receive messages.
+  window.addEventListener('message', this.handleScriptingMessage_.bind(this),
+                          false);
+  this.sendScriptingMessage_({type: 'readyToReceive'});
+
   // If the viewer is started from a MIME type request, there will be a
   // background page and stream details object with the details of the request.
   // Otherwise, we take the query string of the URL to indicate the URL of the
   // PDF to load. This is used for print preview in particular.
   var streamDetails;
   if (chrome.extension.getBackgroundPage &&
       chrome.extension.getBackgroundPage()) {
     streamDetails = chrome.extension.getBackgroundPage().popStreamDetails();
   }
 
   if (!streamDetails) {
     // The URL of this page will be of the form
     // "chrome-extension://<extension id>?<pdf url>". We pull out the <pdf url>
     // part here.
     var url = window.location.search.substring(1);
     streamDetails = {
       streamUrl: url,
       originalUrl: url
     };
   }
 
   this.plugin_.setAttribute('src', streamDetails.streamUrl);
   document.body.appendChild(this.plugin_);
 
-  this.messagingHost_ = new PDFMessagingHost(window, this);
-
   this.setupEventListeners_(streamDetails);
 }
 
 PDFViewer.prototype = {
   /**
    * @private
    * Sets up event listeners for key shortcuts and also the UI buttons.
    * @param {Object} streamDetails the details of the original HTTP request for
    *     the PDF.
    */
@@ skipping 105 matching lines @@
       this.sizer_.style.display = 'none';
       this.toolbar_.style.visibility = 'hidden';
       if (this.passwordScreen_.active) {
         this.passwordScreen_.deny();
         this.passwordScreen_.active = false;
       }
     } else if (progress == 100) {
       // Document load complete.
       var loadEvent = new Event('pdfload');
       window.dispatchEvent(loadEvent);
-      // TODO(raymes): Replace this and other callbacks with events.
-      this.messagingHost_.documentLoaded();
+      this.sendScriptingMessage_({
+        type: 'documentLoaded'
+      });
       if (this.lastViewportPosition_)
         this.viewport_.position = this.lastViewportPosition_;
     }
   },
 
   /**
    * @private
    * An event handler for handling password-submitted events. These are fired
    * when an event is entered into the password screen.
    * @param {Object} event a password-submitted event.
    */
   onPasswordSubmitted_: function(event) {
     this.plugin_.postMessage({
       type: 'getPasswordComplete',
       password: event.detail.password
     });
   },
 
   /**
    * @private
    * An event handler for handling message events received from the plugin.
    * @param {MessageObject} message a message event.
    */
-  handleMessage_: function(message) {
+  handlePluginMessage_: function(message) {
     switch (message.data.type.toString()) {
       case 'documentDimensions':
         this.documentDimensions_ = message.data;
         this.viewport_.setDocumentDimensions(this.documentDimensions_);
         this.toolbar_.style.visibility = 'visible';
         // If we received the document dimensions, the password was good so we
         // can dismiss the password screen.
         if (this.passwordScreen_.active)
           this.passwordScreen_.accept();
 
@@ skipping 50 matching lines @@
 
     var hasScrollbars = this.viewport_.documentHasScrollbars();
     var scrollbarWidth = this.viewport_.scrollbarWidth;
     // Offset the toolbar position so that it doesn't move if scrollbars appear.
     var toolbarRight = hasScrollbars.vertical ? 0 : scrollbarWidth;
     var toolbarBottom = hasScrollbars.horizontal ? 0 : scrollbarWidth;
     this.toolbar_.style.right = toolbarRight + 'px';
     this.toolbar_.style.bottom = toolbarBottom + 'px';
 
     // Update the page indicator.
-    this.pageIndicator_.index = this.viewport_.getMostVisiblePage();
+    var visiblePage = this.viewport_.getMostVisiblePage();
+    this.pageIndicator_.index = visiblePage;
     if (this.documentDimensions_.pageDimensions.length > 1 &&
         hasScrollbars.vertical) {
       this.pageIndicator_.style.visibility = 'visible';
     } else {
       this.pageIndicator_.style.visibility = 'hidden';
     }
 
-    this.messagingHost_.viewportChanged();
-
     var position = this.viewport_.position;
     var zoom = this.viewport_.zoom;
     // Notify the plugin of the viewport change.
     this.plugin_.postMessage({
       type: 'viewport',
       zoom: zoom,
       xOffset: position.x,
       yOffset: position.y
     });
+
+    var visiblePageDimensions = this.viewport_.getPageScreenRect(visiblePage);
+    var size = this.viewport_.size;
+    this.sendScriptingMessage_({
+      type: 'viewport',
+      pageX: visiblePageDimensions.x,
+      pageY: visiblePageDimensions.y,
+      pageWidth: visiblePageDimensions.width,
+      viewportWidth: size.width,
+      viewportHeight: size.height,
+    });
   },
 
   /**
-   * Resets the viewer into print preview mode, which is used for Chrome print
-   * preview.
-   * @param {string} url the url of the pdf to load.
-   * @param {boolean} grayscale true if the pdf should be displayed in
-   *     grayscale, false otherwise.
-   * @param {Array.<number>} pageNumbers an array of the number to label each
-   *     page in the document.
-   * @param {boolean} modifiable whether the PDF is modifiable or not.
+   * @private
+   * Handle a scripting message from outside the extension (typically sent by
+   * PDFScriptingAPI in a page containing the extension) to interact with the
+   * plugin.
+   * @param {MessageObject} message the message to handle.
    */
-  resetPrintPreviewMode: function(url,
-                                  grayscale,
-                                  pageNumbers,
-                                  modifiable) {
-    if (!this.inPrintPreviewMode_) {
-      this.inPrintPreviewMode_ = true;
-      this.viewport_.fitToPage();
+  handleScriptingMessage_: function(message) {
+    switch (message.data.type.toString()) {
+      case 'resetPrintPreviewMode':
+        if (!this.inPrintPreviewMode_) {
+          this.inPrintPreviewMode_ = true;
+          this.viewport_.fitToPage();
+        }
+
+        // Stash the scroll location so that it can be restored when the new
+        // document is loaded.
+        this.lastViewportPosition_ = this.viewport_.position;
+
+        // TODO(raymes): Disable these properly in the plugin.
+        var printButton = $('print-button');
+        if (printButton)
+          printButton.parentNode.removeChild(printButton);
+        var saveButton = $('save-button');
+        if (saveButton)
+          saveButton.parentNode.removeChild(saveButton);
+
+        this.pageIndicator_.pageLabels = message.data.pageNumbers;
+
+        this.plugin_.postMessage({
+          type: 'resetPrintPreviewMode',
+          url: message.data.url,
+          grayscale: message.data.grayscale,
+          // If the PDF isn't modifiable we send 0 as the page count so that no
+          // blank placeholder pages get appended to the PDF.
+          pageCount: (message.data.modifiable ?
+                      message.data.pageNumbers.length : 0)
+        });
+        break;
+      case 'loadPreviewPage':
+        this.plugin_.postMessage(message.data);
+        break;
     }
 
-    // Stash the scroll location so that it can be restored when the new
-    // document is loaded.
-    this.lastViewportPosition_ = this.viewport_.position;
-
-    // TODO(raymes): Disable these properly in the plugin.
-    var printButton = $('print-button');
-    if (printButton)
-      printButton.parentNode.removeChild(printButton);
-    var saveButton = $('save-button');
-    if (saveButton)
-      saveButton.parentNode.removeChild(saveButton);
-
-    this.pageIndicator_.pageLabels = pageNumbers;
-
-    this.plugin_.postMessage({
-      type: 'resetPrintPreviewMode',
-      url: url,
-      grayscale: grayscale,
-      // If the PDF isn't modifiable we send 0 as the page count so that no
-      // blank placeholder pages get appended to the PDF.
-      pageCount: (modifiable ? pageNumbers.length : 0)
-    });
   },
 
   /**
-   * Load a page into the document while in print preview mode.
-   * @param {string} url the url of the pdf page to load.
-   * @param {number} index the index of the page to load.
+   * @private
+   * Send a scripting message outside the extension (typically to
+   * PDFScriptingAPI in a page containing the extension).
+   * @param {Object} message the message to send.
    */
-  loadPreviewPage: function(url, index) {
-    this.plugin_.postMessage({
-      type: 'loadPreviewPage',
-      url: url,
-      index: index
-    });
+  sendScriptingMessage_: function(message) {
+    window.parent.postMessage(message, '*');
   },
 
   /**
    * @type {Viewport} the viewport of the PDF viewer.
    */
   get viewport() {
     return this.viewport_;
   }
 };
 
 var viewer = new PDFViewer();