chrome/browser/resources/print_preview/previewarea/preview_area.js

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /**
   6  * @typedef {{accessibility: Function,
   7  *            documentLoadComplete: Function,
   8  *            getHeight: Function,
   9  *            getHorizontalScrollbarThickness: Function,
  10  *            getPageLocationNormalized: Function,
  11  *            getVerticalScrollbarThickness: Function,
  12  *            getWidth: Function,
  13  *            getZoomLevel: Function,
  14  *            goToPage: Function,
  15  *            grayscale: Function,
  16  *            loadPreviewPage: Function,
  17  *            onload: Function,
  18  *            onPluginSizeChanged: Function,
  19  *            onScroll: Function,
  20  *            pageXOffset: Function,
  21  *            pageYOffset: Function,
  22  *            printPreviewPageCount: Function,
  23  *            reload: Function,
  24  *            removePrintButton: Function,
  25  *            resetPrintPreviewUrl: Function,
  26  *            sendKeyEvent: Function,
  27  *            setPageNumbers: Function,
  28  *            setPageXOffset: Function,
  29  *            setPageYOffset: Function,
  30  *            setZoomLevel: Function,
  31  *            fitToHeight: Function,
  32  *            fitToWidth: Function,
  33  *            zoomIn: Function,
  34  *            zoomOut: Function}}
  35  */
  36 print_preview.PDFPlugin;
  37
  38 cr.define('print_preview', function() {
  39   'use strict';
  40
  41   /**
  42    * Creates a PreviewArea object. It represents the area where the preview
  43    * document is displayed.
  44    * @param {!print_preview.DestinationStore} destinationStore Used to get the
  45    *     currently selected destination.
  46    * @param {!print_preview.PrintTicketStore} printTicketStore Used to get
  47    *     information about how the preview should be displayed.
  48    * @param {!print_preview.NativeLayer} nativeLayer Needed to communicate with
  49    *     Chromium's preview generation system.
  50    * @param {!print_preview.DocumentInfo} documentInfo Document data model.
  51    * @constructor
  52    * @extends {print_preview.Component}
  53    */
  54   function PreviewArea(
  55       destinationStore, printTicketStore, nativeLayer, documentInfo) {
  56     print_preview.Component.call(this);
  57     // TODO(rltoscano): Understand the dependencies of printTicketStore needed
  58     // here, and add only those here (not the entire print ticket store).
  59
  60     /**
  61      * Used to get the currently selected destination.
  62      * @type {!print_preview.DestinationStore}
  63      * @private
  64      */
  65     this.destinationStore_ = destinationStore;
  66
  67     /**
  68      * Used to get information about how the preview should be displayed.
  69      * @type {!print_preview.PrintTicketStore}
  70      * @private
  71      */
  72     this.printTicketStore_ = printTicketStore;
  73
  74     /**
  75      * Used to contruct the preview generator.
  76      * @type {!print_preview.NativeLayer}
  77      * @private
  78      */
  79     this.nativeLayer_ = nativeLayer;
  80
  81     /**
  82      * Document data model.
  83      * @type {!print_preview.DocumentInfo}
  84      * @private
  85      */
  86     this.documentInfo_ = documentInfo;
  87
  88     /**
  89      * Used to read generated page previews.
  90      * @type {print_preview.PreviewGenerator}
  91      * @private
  92      */
  93     this.previewGenerator_ = null;
  94
  95     /**
  96      * The embedded pdf plugin object. It's value is null if not yet loaded.
  97      * @type {HTMLEmbedElement|print_preview.PDFPlugin}
  98      * @private
  99      */
 100     this.plugin_ = null;
 101
 102     /**
 103      * Custom margins component superimposed on the preview plugin.
 104      * @type {!print_preview.MarginControlContainer}
 105      * @private
 106      */
 107     this.marginControlContainer_ = new print_preview.MarginControlContainer(
 108         this.documentInfo_,
 109         this.printTicketStore_.marginsType,
 110         this.printTicketStore_.customMargins,
 111         this.printTicketStore_.measurementSystem,
 112         this.onMarginDragChanged_.bind(this));
 113     this.addChild(this.marginControlContainer_);
 114
 115     /**
 116      * Current zoom level as a percentage.
 117      * @type {?number}
 118      * @private
 119      */
 120     this.zoomLevel_ = null;
 121
 122     /**
 123      * Current page offset which can be used to calculate scroll amount.
 124      * @type {print_preview.Coordinate2d}
 125      * @private
 126      */
 127     this.pageOffset_ = null;
 128
 129     /**
 130      * Whether the plugin has finished reloading.
 131      * @type {boolean}
 132      * @private
 133      */
 134     this.isPluginReloaded_ = false;
 135
 136     /**
 137      * Whether the document preview is ready.
 138      * @type {boolean}
 139      * @private
 140      */
 141     this.isDocumentReady_ = false;
 142
 143     /**
 144      * Timeout object used to display a loading message if the preview is taking
 145      * a long time to generate.
 146      * @type {?number}
 147      * @private
 148      */
 149     this.loadingTimeout_ = null;
 150
 151     /**
 152      * Overlay element.
 153      * @type {HTMLElement}
 154      * @private
 155      */
 156     this.overlayEl_ = null;
 157
 158     /**
 159      * The "Open system dialog" button.
 160      * @type {HTMLButtonElement}
 161      * @private
 162      */
 163     this.openSystemDialogButton_ = null;
 164   };
 165
 166   /**
 167    * Event types dispatched by the preview area.
 168    * @enum {string}
 169    */
 170   PreviewArea.EventType = {
 171     // Dispatched when the "Open system dialog" button is clicked.
 172     OPEN_SYSTEM_DIALOG_CLICK:
 173         'print_preview.PreviewArea.OPEN_SYSTEM_DIALOG_CLICK',
 174
 175     // Dispatched when the document preview is complete.
 176     PREVIEW_GENERATION_DONE:
 177         'print_preview.PreviewArea.PREVIEW_GENERATION_DONE',
 178
 179     // Dispatched when the document preview failed to be generated.
 180     PREVIEW_GENERATION_FAIL:
 181         'print_preview.PreviewArea.PREVIEW_GENERATION_FAIL',
 182
 183     // Dispatched when a new document preview is being generated.
 184     PREVIEW_GENERATION_IN_PROGRESS:
 185         'print_preview.PreviewArea.PREVIEW_GENERATION_IN_PROGRESS'
 186   };
 187
 188   /**
 189    * CSS classes used by the preview area.
 190    * @enum {string}
 191    * @private
 192    */
 193   PreviewArea.Classes_ = {
 194     OUT_OF_PROCESS_COMPATIBILITY_OBJECT:
 195         'preview-area-compatibility-object-out-of-process',
 196     CUSTOM_MESSAGE_TEXT: 'preview-area-custom-message-text',
 197     MESSAGE: 'preview-area-message',
 198     INVISIBLE: 'invisible',
 199     OPEN_SYSTEM_DIALOG_BUTTON: 'preview-area-open-system-dialog-button',
 200     OPEN_SYSTEM_DIALOG_BUTTON_THROBBER:
 201         'preview-area-open-system-dialog-button-throbber',
 202     OVERLAY: 'preview-area-overlay-layer',
 203     MARGIN_CONTROL: 'margin-control',
 204     PREVIEW_AREA: 'preview-area-plugin-wrapper'
 205   };
 206
 207   /**
 208    * Enumeration of IDs shown in the preview area.
 209    * @enum {string}
 210    * @private
 211    */
 212   PreviewArea.MessageId_ = {
 213     CUSTOM: 'custom',
 214     LOADING: 'loading',
 215     PREVIEW_FAILED: 'preview-failed'
 216   };
 217
 218   /**
 219    * Maps message IDs to the CSS class that contains them.
 220    * @type {Object<print_preview.PreviewArea.MessageId_, string>}
 221    * @private
 222    */
 223   PreviewArea.MessageIdClassMap_ = {};
 224   PreviewArea.MessageIdClassMap_[PreviewArea.MessageId_.CUSTOM] =
 225       'preview-area-custom-message';
 226   PreviewArea.MessageIdClassMap_[PreviewArea.MessageId_.LOADING] =
 227       'preview-area-loading-message';
 228   PreviewArea.MessageIdClassMap_[PreviewArea.MessageId_.PREVIEW_FAILED] =
 229       'preview-area-preview-failed-message';
 230
 231   /**
 232    * Amount of time in milliseconds to wait after issueing a new preview before
 233    * the loading message is shown.
 234    * @type {number}
 235    * @const
 236    * @private
 237    */
 238   PreviewArea.LOADING_TIMEOUT_ = 200;
 239
 240   PreviewArea.prototype = {
 241     __proto__: print_preview.Component.prototype,
 242
 243     /**
 244      * Should only be called after calling this.render().
 245      * @return {boolean} Whether the preview area has a compatible plugin to
 246      *     display the print preview in.
 247      */
 248     get hasCompatiblePlugin() {
 249       return this.previewGenerator_ != null;
 250     },
 251
 252     /**
 253      * Processes a keyboard event that could possibly be used to change state of
 254      * the preview plugin.
 255      * @param {KeyboardEvent} e Keyboard event to process.
 256      */
 257     handleDirectionalKeyEvent: function(e) {
 258       // Make sure the PDF plugin is there.
 259       // We only care about: PageUp, PageDown, Left, Up, Right, Down.
 260       // If the user is holding a modifier key, ignore.
 261       if (!this.plugin_ ||
 262           !arrayContains([33, 34, 37, 38, 39, 40], e.keyCode) ||
 263           e.metaKey || e.altKey || e.shiftKey || e.ctrlKey) {
 264         return;
 265       }
 266
 267       // Don't handle the key event for these elements.
 268       var tagName = document.activeElement.tagName;
 269       if (arrayContains(['INPUT', 'SELECT', 'EMBED'], tagName)) {
 270         return;
 271       }
 272
 273       // For the most part, if any div of header was the last clicked element,
 274       // then the active element is the body. Starting with the last clicked
 275       // element, and work up the DOM tree to see if any element has a
 276       // scrollbar. If there exists a scrollbar, do not handle the key event
 277       // here.
 278       var element = e.target;
 279       while (element) {
 280         if (element.scrollHeight > element.clientHeight ||
 281             element.scrollWidth > element.clientWidth) {
 282           return;
 283         }
 284         element = element.parentElement;
 285       }
 286
 287       // No scroll bar anywhere, or the active element is something else, like a
 288       // button. Note: buttons have a bigger scrollHeight than clientHeight.
 289       this.plugin_.sendKeyEvent(e);
 290       e.preventDefault();
 291     },
 292
 293     /**
 294      * Set a callback that gets called when a key event is received that
 295      * originates in the plugin.
 296      * @param {function(Event)} callback The callback to be called with a key
 297      *     event.
 298      */
 299     setPluginKeyEventCallback: function(callback) {
 300       this.keyEventCallback_ = callback;
 301     },
 302
 303     /**
 304      * Shows a custom message on the preview area's overlay.
 305      * @param {string} message Custom message to show.
 306      */
 307     showCustomMessage: function(message) {
 308       this.showMessage_(PreviewArea.MessageId_.CUSTOM, message);
 309     },
 310
 311     /** @override */
 312     enterDocument: function() {
 313       print_preview.Component.prototype.enterDocument.call(this);
 314       this.tracker.add(
 315           assert(this.openSystemDialogButton_),
 316           'click',
 317           this.onOpenSystemDialogButtonClick_.bind(this));
 318
 319       this.tracker.add(
 320           this.printTicketStore_,
 321           print_preview.PrintTicketStore.EventType.INITIALIZE,
 322           this.onTicketChange_.bind(this));
 323       this.tracker.add(
 324           this.printTicketStore_,
 325           print_preview.PrintTicketStore.EventType.TICKET_CHANGE,
 326           this.onTicketChange_.bind(this));
 327       this.tracker.add(
 328           this.printTicketStore_,
 329           print_preview.PrintTicketStore.EventType.CAPABILITIES_CHANGE,
 330           this.onTicketChange_.bind(this));
 331       this.tracker.add(
 332           this.printTicketStore_,
 333           print_preview.PrintTicketStore.EventType.DOCUMENT_CHANGE,
 334           this.onTicketChange_.bind(this));
 335
 336       this.tracker.add(
 337           this.printTicketStore_.color,
 338           print_preview.ticket_items.TicketItem.EventType.CHANGE,
 339           this.onTicketChange_.bind(this));
 340       this.tracker.add(
 341           this.printTicketStore_.cssBackground,
 342           print_preview.ticket_items.TicketItem.EventType.CHANGE,
 343           this.onTicketChange_.bind(this));
 344       this.tracker.add(
 345         this.printTicketStore_.customMargins,
 346           print_preview.ticket_items.TicketItem.EventType.CHANGE,
 347           this.onTicketChange_.bind(this));
 348       this.tracker.add(
 349           this.printTicketStore_.fitToPage,
 350           print_preview.ticket_items.TicketItem.EventType.CHANGE,
 351           this.onTicketChange_.bind(this));
 352       this.tracker.add(
 353           this.printTicketStore_.headerFooter,
 354           print_preview.ticket_items.TicketItem.EventType.CHANGE,
 355           this.onTicketChange_.bind(this));
 356       this.tracker.add(
 357           this.printTicketStore_.landscape,
 358           print_preview.ticket_items.TicketItem.EventType.CHANGE,
 359           this.onTicketChange_.bind(this));
 360       this.tracker.add(
 361           this.printTicketStore_.marginsType,
 362           print_preview.ticket_items.TicketItem.EventType.CHANGE,
 363           this.onTicketChange_.bind(this));
 364       this.tracker.add(
 365           this.printTicketStore_.pageRange,
 366           print_preview.ticket_items.TicketItem.EventType.CHANGE,
 367           this.onTicketChange_.bind(this));
 368       this.tracker.add(
 369           this.printTicketStore_.selectionOnly,
 370           print_preview.ticket_items.TicketItem.EventType.CHANGE,
 371           this.onTicketChange_.bind(this));
 372
 373       if (this.checkPluginCompatibility_()) {
 374         this.previewGenerator_ = new print_preview.PreviewGenerator(
 375             this.destinationStore_,
 376             this.printTicketStore_,
 377             this.nativeLayer_,
 378             this.documentInfo_);
 379         this.tracker.add(
 380             this.previewGenerator_,
 381             print_preview.PreviewGenerator.EventType.PREVIEW_START,
 382             this.onPreviewStart_.bind(this));
 383         this.tracker.add(
 384             this.previewGenerator_,
 385             print_preview.PreviewGenerator.EventType.PAGE_READY,
 386             this.onPagePreviewReady_.bind(this));
 387         this.tracker.add(
 388             this.previewGenerator_,
 389             print_preview.PreviewGenerator.EventType.FAIL,
 390             this.onPreviewGenerationFail_.bind(this));
 391         this.tracker.add(
 392             this.previewGenerator_,
 393             print_preview.PreviewGenerator.EventType.DOCUMENT_READY,
 394             this.onDocumentReady_.bind(this));
 395       } else {
 396         this.showCustomMessage(loadTimeData.getString('noPlugin'));
 397       }
 398     },
 399
 400     /** @override */
 401     exitDocument: function() {
 402       print_preview.Component.prototype.exitDocument.call(this);
 403       if (this.previewGenerator_) {
 404         this.previewGenerator_.removeEventListeners();
 405       }
 406       this.overlayEl_ = null;
 407       this.openSystemDialogButton_ = null;
 408     },
 409
 410     /** @override */
 411     decorateInternal: function() {
 412       this.marginControlContainer_.decorate(this.getElement());
 413       this.overlayEl_ = this.getElement().getElementsByClassName(
 414           PreviewArea.Classes_.OVERLAY)[0];
 415       this.openSystemDialogButton_ = this.getElement().getElementsByClassName(
 416           PreviewArea.Classes_.OPEN_SYSTEM_DIALOG_BUTTON)[0];
 417     },
 418
 419     /**
 420      * Checks to see if a suitable plugin for rendering the preview exists. If
 421      * one does not exist, then an error message will be displayed.
 422      * @return {boolean} true if Chromium has a plugin for rendering the
 423      *     the preview.
 424      * @private
 425      */
 426     checkPluginCompatibility_: function() {
 427       // TODO(raymes): It's harder to test compatibility of the out of process
 428       // plugin because it's asynchronous. We could do a better job at some
 429       // point.
 430       var oopCompatObj = this.getElement().getElementsByClassName(
 431           PreviewArea.Classes_.OUT_OF_PROCESS_COMPATIBILITY_OBJECT)[0];
 432       var isOOPCompatible = oopCompatObj.postMessage;
 433       oopCompatObj.parentElement.removeChild(oopCompatObj);
 434
 435       return isOOPCompatible;
 436     },
 437
 438     /**
 439      * Shows a given message on the overlay.
 440      * @param {!print_preview.PreviewArea.MessageId_} messageId ID of the
 441      *     message to show.
 442      * @param {string=} opt_message Optional message to show that can be used
 443      *     by some message IDs.
 444      * @private
 445      */
 446     showMessage_: function(messageId, opt_message) {
 447       // Hide all messages.
 448       var messageEls = this.getElement().getElementsByClassName(
 449           PreviewArea.Classes_.MESSAGE);
 450       for (var i = 0, messageEl; messageEl = messageEls[i]; i++) {
 451         setIsVisible(messageEl, false);
 452       }
 453       // Disable jumping animation to conserve cycles.
 454       var jumpingDotsEl = this.getElement().querySelector(
 455           '.preview-area-loading-message-jumping-dots');
 456       jumpingDotsEl.classList.remove('jumping-dots');
 457
 458       // Show specific message.
 459       if (messageId == PreviewArea.MessageId_.CUSTOM) {
 460         var customMessageTextEl = this.getElement().getElementsByClassName(
 461             PreviewArea.Classes_.CUSTOM_MESSAGE_TEXT)[0];
 462         customMessageTextEl.textContent = opt_message;
 463       } else if (messageId == PreviewArea.MessageId_.LOADING) {
 464         jumpingDotsEl.classList.add('jumping-dots');
 465       }
 466       var messageEl = this.getElement().getElementsByClassName(
 467             PreviewArea.MessageIdClassMap_[messageId])[0];
 468       setIsVisible(messageEl, true);
 469
 470       this.setOverlayVisible_(true);
 471     },
 472
 473     /**
 474      * Set the visibility of the message overlay.
 475      * @param {boolean} visible Whether to make the overlay visible or not
 476      * @private
 477      */
 478     setOverlayVisible_: function(visible) {
 479       this.overlayEl_.classList.toggle(
 480           PreviewArea.Classes_.INVISIBLE,
 481           !visible);
 482       this.overlayEl_.setAttribute('aria-hidden', !visible);
 483
 484       // Hide/show all controls that will overlap when the overlay is visible.
 485       var marginControls = this.getElement().getElementsByClassName(
 486           PreviewArea.Classes_.MARGIN_CONTROL);
 487       for (var i = 0; i < marginControls.length; ++i) {
 488         marginControls[i].setAttribute('aria-hidden', visible);
 489       }
 490       var previewAreaControls = this.getElement().getElementsByClassName(
 491           PreviewArea.Classes_.PREVIEW_AREA);
 492       for (var i = 0; i < previewAreaControls.length; ++i) {
 493         previewAreaControls[i].setAttribute('aria-hidden', visible);
 494       }
 495
 496       if (!visible) {
 497         // Disable jumping animation to conserve cycles.
 498         var jumpingDotsEl = this.getElement().querySelector(
 499             '.preview-area-loading-message-jumping-dots');
 500         jumpingDotsEl.classList.remove('jumping-dots');
 501       }
 502     },
 503
 504     /**
 505      * Creates a preview plugin and adds it to the DOM.
 506      * @param {string} srcUrl Initial URL of the plugin.
 507      * @private
 508      */
 509     createPlugin_: function(srcUrl) {
 510       if (this.plugin_) {
 511         console.warn('Pdf preview plugin already created');
 512         return;
 513       }
 514
 515       this.plugin_ = /** @type {print_preview.PDFPlugin} */(
 516           PDFCreateOutOfProcessPlugin(srcUrl));
 517       this.plugin_.setKeyEventCallback(this.keyEventCallback_);
 518
 519       this.plugin_.setAttribute('class', 'preview-area-plugin');
 520       this.plugin_.setAttribute('aria-live', 'polite');
 521       this.plugin_.setAttribute('aria-atomic', 'true');
 522       // NOTE: The plugin's 'id' field must be set to 'pdf-viewer' since
 523       // chrome/renderer/printing/print_web_view_helper.cc actually references
 524       // it.
 525       this.plugin_.setAttribute('id', 'pdf-viewer');
 526       this.getChildElement('.preview-area-plugin-wrapper').
 527           appendChild(/** @type {Node} */(this.plugin_));
 528
 529
 530       var pageNumbers =
 531           this.printTicketStore_.pageRange.getPageNumberSet().asArray();
 532       var grayscale = !this.printTicketStore_.color.getValue();
 533       this.plugin_.setLoadCallback(this.onPluginLoad_.bind(this));
 534       this.plugin_.setViewportChangedCallback(
 535           this.onPreviewVisualStateChange_.bind(this));
 536       this.plugin_.resetPrintPreviewMode(srcUrl, grayscale, pageNumbers,
 537                                          this.documentInfo_.isModifiable);
 538     },
 539
 540     /**
 541      * Dispatches a PREVIEW_GENERATION_DONE event if all conditions are met.
 542      * @private
 543      */
 544     dispatchPreviewGenerationDoneIfReady_: function() {
 545       if (this.isDocumentReady_ && this.isPluginReloaded_) {
 546         cr.dispatchSimpleEvent(
 547             this, PreviewArea.EventType.PREVIEW_GENERATION_DONE);
 548         this.marginControlContainer_.showMarginControlsIfNeeded();
 549       }
 550     },
 551
 552     /**
 553      * Called when the open-system-dialog button is clicked. Disables the
 554      * button, shows the throbber, and dispatches the OPEN_SYSTEM_DIALOG_CLICK
 555      * event.
 556      * @private
 557      */
 558     onOpenSystemDialogButtonClick_: function() {
 559       this.openSystemDialogButton_.disabled = true;
 560       var openSystemDialogThrobber = this.getElement().getElementsByClassName(
 561           PreviewArea.Classes_.OPEN_SYSTEM_DIALOG_BUTTON_THROBBER)[0];
 562       setIsVisible(openSystemDialogThrobber, true);
 563       cr.dispatchSimpleEvent(
 564           this, PreviewArea.EventType.OPEN_SYSTEM_DIALOG_CLICK);
 565     },
 566
 567     /**
 568      * Called when the print ticket changes. Updates the preview.
 569      * @private
 570      */
 571     onTicketChange_: function() {
 572       if (this.previewGenerator_ && this.previewGenerator_.requestPreview()) {
 573         cr.dispatchSimpleEvent(
 574             this, PreviewArea.EventType.PREVIEW_GENERATION_IN_PROGRESS);
 575         if (this.loadingTimeout_ == null) {
 576           this.loadingTimeout_ = setTimeout(
 577               this.showMessage_.bind(this, PreviewArea.MessageId_.LOADING),
 578               PreviewArea.LOADING_TIMEOUT_);
 579         }
 580       } else {
 581         this.marginControlContainer_.showMarginControlsIfNeeded();
 582       }
 583     },
 584
 585     /**
 586      * Called when the preview generator begins loading the preview.
 587      * @param {Event} event Contains the URL to initialize the plugin to.
 588      * @private
 589      */
 590     onPreviewStart_: function(event) {
 591       this.isDocumentReady_ = false;
 592       this.isPluginReloaded_ = false;
 593       if (!this.plugin_) {
 594         this.createPlugin_(event.previewUrl);
 595       } else {
 596         var grayscale = !this.printTicketStore_.color.getValue();
 597         var pageNumbers =
 598             this.printTicketStore_.pageRange.getPageNumberSet().asArray();
 599         var url = event.previewUrl;
 600         this.plugin_.resetPrintPreviewMode(url, grayscale, pageNumbers,
 601                                            this.documentInfo_.isModifiable);
 602       }
 603       cr.dispatchSimpleEvent(
 604           this, PreviewArea.EventType.PREVIEW_GENERATION_IN_PROGRESS);
 605     },
 606
 607     /**
 608      * Called when a page preview has been generated. Updates the plugin with
 609      * the new page.
 610      * @param {Event} event Contains information about the page preview.
 611      * @private
 612      */
 613     onPagePreviewReady_: function(event) {
 614       this.plugin_.loadPreviewPage(event.previewUrl, event.previewIndex);
 615     },
 616
 617     /**
 618      * Called when the preview generation is complete and the document is ready
 619      * to print.
 620      * @private
 621      */
 622     onDocumentReady_: function(event) {
 623       this.isDocumentReady_ = true;
 624       this.dispatchPreviewGenerationDoneIfReady_();
 625     },
 626
 627     /**
 628      * Called when the generation of a preview fails. Shows an error message.
 629      * @private
 630      */
 631     onPreviewGenerationFail_: function() {
 632       if (this.loadingTimeout_) {
 633         clearTimeout(this.loadingTimeout_);
 634         this.loadingTimeout_ = null;
 635       }
 636       this.showMessage_(PreviewArea.MessageId_.PREVIEW_FAILED);
 637       cr.dispatchSimpleEvent(
 638           this, PreviewArea.EventType.PREVIEW_GENERATION_FAIL);
 639     },
 640
 641     /**
 642      * Called when the plugin loads. This is a consequence of calling
 643      * plugin.reload(). Certain plugin state can only be set after the plugin
 644      * has loaded.
 645      * @private
 646      */
 647     onPluginLoad_: function() {
 648       if (this.loadingTimeout_) {
 649         clearTimeout(this.loadingTimeout_);
 650         this.loadingTimeout_ = null;
 651       }
 652
 653       this.setOverlayVisible_(false);
 654       this.isPluginReloaded_ = true;
 655       this.dispatchPreviewGenerationDoneIfReady_();
 656     },
 657
 658     /**
 659      * Called when the preview plugin's visual state has changed. This is a
 660      * consequence of scrolling or zooming the plugin. Updates the custom
 661      * margins component if shown.
 662      * @private
 663      */
 664     onPreviewVisualStateChange_: function(pageX,
 665                                           pageY,
 666                                           pageWidth,
 667                                           viewportWidth,
 668                                           viewportHeight) {
 669       this.marginControlContainer_.updateTranslationTransform(
 670           new print_preview.Coordinate2d(pageX, pageY));
 671       this.marginControlContainer_.updateScaleTransform(
 672           pageWidth / this.documentInfo_.pageSize.width);
 673       this.marginControlContainer_.updateClippingMask(
 674           new print_preview.Size(viewportWidth, viewportHeight));
 675     },
 676
 677     /**
 678      * Called when dragging margins starts or stops.
 679      * @param {boolean} isDragging True if the margin is currently being dragged
 680      *     and false otherwise.
 681      */
 682     onMarginDragChanged_: function(isDragging) {
 683       if (!this.plugin_)
 684         return;
 685
 686       // When hovering over the plugin (which may be in a separate iframe)
 687       // pointer events will be sent to the frame. When dragging the margins,
 688       // we don't want this to happen as it can cause the margin to stop
 689       // being draggable.
 690       this.plugin_.style.pointerEvents = isDragging ? 'none' : 'auto';
 691     }
 692   };
 693
 694   // Export
 695   return {
 696     PreviewArea: PreviewArea
 697   };
 698 });