Refactor print preview web ui

chrome/browser/resources/print_preview/preview_generator.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';
+
+  /**
+   * Interface to the Chromium print preview generator.
+   * @param {!print_preview.DestinationStore} destinationStore Used to get the
+   *     currently selected destination.
+   * @param {!print_preview.PrintTicketStore} printTicketStore Used to read the
+   *     state of the ticket and write document information.
+   * @param {!print_preview.NativeLayer} nativeLayer Used to communicate to
+   *     Chromium's preview rendering system.
+   * @constructor
+   * @extends {cr.EventTarget}
+   */
+  function PreviewGenerator(destinationStore, printTicketStore, nativeLayer) {
+    cr.EventTarget.call(this);
+
+    /**
+     * Used to get the currently selected destination.
+     * @type {!print_preview.DestinationStore}
+     * @private
+     */
+    this.destinationStore_ = destinationStore;
+
+    /**
+     * Used to read the state of the ticket and write document information.
+     * @type {!print_preview.PrintTicketStore}
+     * @private
+     */
+    this.printTicketStore_ = printTicketStore;
+
+    /**
+     * Interface to the Chromium native layer.
+     * @type {!print_preview.NativeLayer}
+     * @private
+     */
+    this.nativeLayer_ = nativeLayer;
+
+    /**
+     * ID of current in-flight request. Requests that do not share this ID will
+     * be ignored.
+     * @type {number}
+     * @private
+     */
+    this.inFlightRequestId_ = -1;
+
+    /**
+     * Whether the previews are being generated in landscape mode.
+     * @type {boolean}
+     * @private
+     */
+    this.isLandscapeEnabled_ = false;
+
+    /**
+     * Whether the previews are being generated with a header and footer.
+     * @type {boolean}
+     * @private
+     */
+    this.isHeaderFooterEnabled_ = false;
+
+    /**
+     * Whether the previews are being generated in color.
+     * @type {boolean}
+     * @private
+     */
+    this.isColorEnabled_ = false;
+
+    /**
+     * Page number set used to generate the last preview.
+     * @type {print_preview.PageNumberSet}
+     * @private
+     */
+    this.pageNumberSet_ = null;
+
+    /**
+     * Margins type used to generate the last preview.
+     * @type {print_preview.ticket_items.MarginsType.Value}
+     * @private
+     */
+    this.marginsType_ = print_preview.ticket_items.MarginsType.Value.DEFAULT;
+
+    /**
+     * Custom margins used to generate the last preview.
+     * @type {print_preview.Margins}
+     * @private
+     */
+    this.customMargins_ = null;
+
+    /**
+     * Event tracker used to keep track of native layer events.
+     * @type {!EventTracker}
+     * @private
+     */
+    this.tracker_ = new EventTracker();
+
+    this.addEventListeners_();
+  };
+
+  /**
+   * Event types dispatched by the preview generator.
+   * @enum {string}
+   */
+  PreviewGenerator.EventType = {
+    // Dispatched when the document can be printed.
+    DOCUMENT_READY: 'print_preview.PreviewGenerator.DOCUMENT_READY',
+
+    // Dispatched when a page preview is ready. The previewIndex field of the
+    // event is the index of the page in the modified document, not the
+    // original. So page 4 of the original document might be previewIndex = 0 of
+    // the modified document.
+    PAGE_READY: 'print_preview.PreviewGenerator.PAGE_READY',
+
+    // Dispatched when the document preview starts to be generated.
+    PREVIEW_START: 'print_preview.PreviewGenerator.PREVIEW_START',
+
+    // Dispatched when the current print preview request fails.
+    FAIL: 'print_preview.PreviewGenerator.FAIL'
+  };
+
+  PreviewGenerator.prototype = {
+    __proto__: cr.EventTarget.prototype,
+
+    /**
+     * Request that new preview be generated. A preview request will not be
+     * generated if the print ticket has not changed sufficiently.
+     * @return {boolean} Whether a new preview was actually requested.
+     */
+    requestPreview: function() {
+      if (!this.printTicketStore_.isTicketValid()) {
+        throw Error('Requesting preview generation with invalid print ticket');
+      }
+      if (!this.hasPreviewChanged_()) {
+        // Changes to these ticket items might not trigger a new preview, but
+        // they still need to be recorded.
+        this.marginsType_ = this.printTicketStore_.getMarginsType();
+        this.customMargins_ = this.printTicketStore_.getCustomMargins();
+        return false;
+      }
+      this.isLandscapeEnabled_ = this.printTicketStore_.isLandscapeEnabled();
+      this.isHeaderFooterEnabled_ =
+          this.printTicketStore_.isHeaderFooterEnabled();
+      this.isColorEnabled_ = this.printTicketStore_.isColorEnabled();
+      this.pageNumberSet_ = this.printTicketStore_.getPageNumberSet();
+      this.marginsType_ = this.printTicketStore_.getMarginsType();
+      this.customMargins_ = this.printTicketStore_.getCustomMargins();
+
+      this.inFlightRequestId_++;
+      this.nativeLayer_.startGetPreview(
+          this.destinationStore_.selectedDestination,
+          this.printTicketStore_,
+          this.inFlightRequestId_);
+      return true;
+    },
+
+    /** Removes all event listeners that the preview generator has attached. */
+    removeEventListeners: function() {
+      this.tracker_.removeAll();
+    },
+
+    /**
+     * Adds event listeners to the relevant native layer events.
+     * @private
+     */
+    addEventListeners_: function() {
+      this.tracker_.add(
+          this.nativeLayer_,
+          print_preview.NativeLayer.EventType.PAGE_LAYOUT_READY,
+          this.onPageLayoutReady_.bind(this));
+      this.tracker_.add(
+          this.nativeLayer_,
+          print_preview.NativeLayer.EventType.PAGE_COUNT_READY,
+          this.onPageCountReady_.bind(this));
+      this.tracker_.add(
+          this.nativeLayer_,
+          print_preview.NativeLayer.EventType.PREVIEW_RELOAD,
+          this.onPreviewReload_.bind(this));
+      this.tracker_.add(
+          this.nativeLayer_,
+          print_preview.NativeLayer.EventType.PAGE_PREVIEW_READY,
+          this.onPagePreviewReady_.bind(this));
+      this.tracker_.add(
+          this.nativeLayer_,
+          print_preview.NativeLayer.EventType.PREVIEW_GENERATION_DONE,
+          this.onPreviewGenerationDone_.bind(this));
+      this.tracker_.add(
+          this.nativeLayer_,
+          print_preview.NativeLayer.EventType.PREVIEW_GENERATION_FAIL,
+          this.onPreviewGenerationFail_.bind(this));
+    },
+
+    /**
+     * Dispatches a PAGE_READY event to signal that a page preview is ready.
+     * @param {number} previewIndex Index of the page with respect to the pages
+     *     shown in the preview. E.g an index of 0 is the first displayed page,
+     *     but not necessarily the first original document page.
+     * @param {number} pageNumber Number of the page with respect to the
+     *     document. A value of 3 means it's the third page of the original
+     *     document.
+     * @param {string} previewUid Unique identifier of the preview.
+     * @private
+     */
+    dispatchPageReadyEvent_: function(previewIndex, pageNumber, previewUid) {
+      var pageGenEvent = new cr.Event(PreviewGenerator.EventType.PAGE_READY);
+      pageGenEvent.previewIndex = previewIndex;
+      pageGenEvent.previewUrl =
+          'chrome://print/' + previewUid + '/' + (pageNumber - 1) +
+          '/print.pdf';
+      this.dispatchEvent(pageGenEvent);
+    },
+
+    /**
+     * Dispatches a PREVIEW_START event. Signals that the preview should be
+     * reloaded.
+     * @param {string} previewUid Unique identifier of the preview.
+     * @private
+     */
+    dispatchPreviewStartEvent_: function(previewUid) {
+      var previewStartEvent = new cr.Event(
+          PreviewGenerator.EventType.PREVIEW_START);
+      var index = -1;
+      if (this.printTicketStore_.isDocumentModifiable) {
+        index = 0;
+      }
+      previewStartEvent.previewUrl =
+          'chrome://print/' + previewUid + '/' + index + '/print.pdf';
+      this.dispatchEvent(previewStartEvent);
+    },
+
+    /**
+     * @return {boolean} Whether the print ticket has changed sufficiently to
+     *     determine whether a new preview request should be issued.
+     * @private
+     */
+    hasPreviewChanged_: function() {
+      var ticketStore = this.printTicketStore_;
+      return this.inFlightRequestId_ == -1 ||
+          ticketStore.isLandscapeEnabled() != this.isLandscapeEnabled_ ||
+          ticketStore.isHeaderFooterEnabled() != this.isHeaderFooterEnabled_ ||
+          ticketStore.isColorEnabled() != this.isColorEnabled_ ||
+          !ticketStore.getPageNumberSet().equals(this.pageNumberSet_) ||
+          (ticketStore.getMarginsType() != this.marginsType_ &&
+              ticketStore.getMarginsType() !=
+                  print_preview.ticket_items.MarginsType.Value.CUSTOM) ||
+          (ticketStore.getMarginsType() ==
+              print_preview.ticket_items.MarginsType.Value.CUSTOM &&
+              !ticketStore.getCustomMargins().equals(this.customMargins_));
+    },
+
+    /**
+     * Called when the page layout of the document is ready. Always occurs
+     * as a result of a preview request.
+     * @param {cr.Event} event Contains layout info about the document.
+     * @private
+     */
+    onPageLayoutReady_: function(event) {
+      // NOTE: A request ID is not specified, so assuming its for the current
+      // in-flight request.
+
+      // TODO Do we need this?
+      //var hasCustomPageSizeStyle = event.hasCustomPageSizeStyle;
+
+      // Printable area info is unavailable on linux nor Google Chrome OS.
+      var origin = new print_preview.Coordinate2d(
+          event.pageLayout.printableAreaX,
+          event.pageLayout.printableAreaY);
+      var size = new print_preview.Size(
+          event.pageLayout.printableAreaWidth,
+          event.pageLayout.printableAreaHeight);
+      this.printTicketStore_.updatePrintableArea(
+          new print_preview.PrintableArea(origin, size));
+
+      var margins = new print_preview.Margins(
+          Math.round(event.pageLayout.marginTop),
+          Math.round(event.pageLayout.marginRight),
+          Math.round(event.pageLayout.marginBottom),
+          Math.round(event.pageLayout.marginLeft));
+
+      var orientationEnum =
+          print_preview.ticket_items.CustomMargins.Orientation;
+      var pageSize = new print_preview.Size(
+          event.pageLayout.contentWidth +
+              margins.get(orientationEnum.LEFT) +
+              margins.get(orientationEnum.RIGHT),
+          event.pageLayout.contentHeight +
+              margins.get(orientationEnum.TOP) +
+              margins.get(orientationEnum.BOTTOM));
+      this.printTicketStore_.updatePageSize(pageSize);
+
+      if (this.printTicketStore_.getMarginsType() !=
+          print_preview.ticket_items.MarginsType.Value.CUSTOM) {
+        this.printTicketStore_.updateDefaultCustomMargins(margins);
+      }
+    },
+
+    /**
+     * Called when the document page count is received from the native layer.
+     * Always occurs as a result of a preview request.
+     * @param {cr.Event} event Contains the document's page count.
+     * @private
+     */
+    onPageCountReady_: function(event) {
+      if (this.inFlightRequestId_ != event.previewResponseId) {
+        return; // Ignore old response.
+      }
+      this.printTicketStore_.updatePageCount(event.pageCount);
+      this.pageNumberSet_ = this.printTicketStore_.getPageNumberSet();
+    },
+
+    /**
+     * Called when the print preview should be reloaded.
+     * @param {cr.Event} event Contains the preview UID and request ID.
+     * @private
+     */
+    onPreviewReload_: function(event) {
+      if (this.inFlightRequestId_ != event.previewResponseId) {
+        return; // Ignore old response.
+      }
+      this.dispatchPreviewStartEvent_(event.previewUid);
+      var pageNumberSet = this.printTicketStore_.getPageNumberSet();
+      for (var i = 0; i < pageNumberSet.size; i++) {
+        var pageNumber = pageNumberSet.getPageNumberAt(i);
+        this.dispatchPageReadyEvent_(i, pageNumber, event.previewUid);
+      }
+      cr.dispatchSimpleEvent(this, PreviewGenerator.EventType.DOCUMENT_READY);
+    },
+
+    /**
+     * Called when a page's preview has been generated. Dispatches a
+     * PAGE_READY event.
+     * @param {cr.Event} event Contains the page index and preview UID.
+     * @private
+     */
+    onPagePreviewReady_: function(event) {
+      if (this.inFlightRequestId_ != event.previewResponseId) {
+        return; // Ignore old response.
+      }
+      var pageNumber = event.pageIndex + 1;
+      if (this.printTicketStore_.getPageNumberSet().hasPageNumber(pageNumber)) {
+        var previewIndex = this.printTicketStore_.getPageNumberSet()
+            .getPageNumberIndex(pageNumber);
+        if (previewIndex == 0) {
+          this.dispatchPreviewStartEvent_(event.previewUid);
+        }
+        this.dispatchPageReadyEvent_(
+            previewIndex, pageNumber, event.previewUid);
+      }
+    },
+
+    /**
+     * Called when the preview generation is complete. Dispatches a
+     * DOCUMENT_READY event.
+     * @param {cr.Event} event Contains the preview UID and response ID.
+     * @private
+     */
+    onPreviewGenerationDone_: function(event) {
+      if (this.inFlightRequestId_ != event.previewResponseId) {
+        return; // Ignore old response.
+      }
+      // Dispatch a PREVIEW_START event since non-modifiable documents don't
+      // trigger PAGE_READY events.
+      if (!this.printTicketStore_.isDocumentModifiable) {
+        this.dispatchPreviewStartEvent_(event.previewUid);
+      }
+      cr.dispatchSimpleEvent(this, PreviewGenerator.EventType.DOCUMENT_READY);
+    },
+
+    /**
+     * Called when the preview generation fails.
+     * @private
+     */
+    onPreviewGenerationFail_: function() {
+      // NOTE: No request ID is returned from Chromium so its assumed its the
+      // current one.
+      cr.dispatchSimpleEvent(this, PreviewGenerator.EventType.FAIL);
+    }
+  };
+
+  // Export
+  return {
+    PreviewGenerator: PreviewGenerator
+  };
+});