Print Preview Print Destination Search Widget

chrome/browser/resources/print_preview/data/destination_store.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';
 
   /**
    * A data store that stores destinations and dispatches events when the data
    * store changes.
+   * @param {!print_preview.NativeLayer} nativeLayer Used to fetch local print
+   *     destinations.
    * @constructor
    * @extends {cr.EventTarget}
    */
-  function DestinationStore() {
+  function DestinationStore(nativeLayer) {
     cr.EventTarget.call(this);
 
     /**
+     * Used to fetch local print destinations.
+     * @type {!print_preview.NativeLayer}
+     * @private
+     */
+    this.nativeLayer_ = nativeLayer;
+
+    /**
      * Internal backing store for the data store.
-     * @type {!Array.<print_preview.Destination>}
+     * @type {!Array.<!print_preview.Destination>}
      * @private
      */
     this.destinations_ = [];
 
     /**
+     * Cache used for constant lookup of printers.
+     * @type {object.<string, !print_preview.Destination>}
+     * @private
+     */
+    this.destinationMap_ = {};
+
+    /**
      * Currently selected destination.
      * @type {print_preview.Destination}
      * @private
      */
     this.selectedDestination_ = null;
 
     /**
      * Initial destination ID used to auto-select the first inserted destination
      * that matches. If {@code null}, the first destination inserted into the
      * store will be selected.
      * @type {?string}
      * @private
      */
     this.initialDestinationId_ = null;
 
     /**
      * Whether the destination store will auto select the destination that
      * matches the initial destination.
      * @type {boolean}
      * @private
      */
     this.isInAutoSelectMode_ = false;
+
+    /**
+     * Event tracker used to track event listeners of the destination store.
+     * @type {!EventTracker}
+     * @private
+     */
+    this.tracker_ = new EventTracker();
+
+    /**
+     * Used to fetch cloud-based print destinations.
+     * @type {!print_preview.CloudPrintInterface}

[dpapad, 2012/05/25 16:18:03]

cant use
@type {!Type}
this.blah_ = null;

! means non-nullable, but it is null here.

[Robert Toscano, 2012/05/25 19:47:01]

Whoops copy paste error. Done.

+     * @private
+     */
+    this.cloudPrintInterface_ = null;
+
+    /**
+     * Whether the destination store has already loaded or is loading all cloud
+     * destinations.
+     * @type {boolean}
+     * @private
+     */
+    this.hasLoadedAllCloudDestinations_ = false;
+
+    /**
+     * Timeout object that fires after the initial destination is set, but not
+     * matched with a destination within a timeout.
+     * @type {Object}
+     * @private
+     */
+    this.autoSelectTimeout_ = null;

[dpapad, 2012/05/25 16:18:03]

Isn't this just a timeout id, therefore a number?
https://developer.mozilla.org/en/DOM/window.setTimeout

[Robert Toscano, 2012/05/25 19:47:01]

I never looked up what exactly was returned by setTimeout. Thanks! Done.

+
+    this.addEventListeners_();
+    this.reset_();
   };
 
   /**
    * Event types dispatched by the data store.
    * @enum {string}
    */
   DestinationStore.EventType = {
     DESTINATIONS_INSERTED:
         'print_preview.DestinationStore.DESTINATIONS_INSERTED',
-    DESTINATION_SELECT: 'print_preview.DestinationStore.DESTINATION_SELECT'
+    DESTINATION_SELECT: 'print_preview.DestinationStore.DESTINATION_SELECT',
+    SELECTED_DESTINATION_CAPABILITIES_READY:
+        'print_preview.DestinationStore.SELECTED_DESTINATION_CAPABILITIES_READY'
+  };
+
+  /**
+   * Delay in milliseconds before the destination store ignores the initial
+   * destination ID and just selects any printer (since the initial destination
+   * was not found).
+   * @type {number}
+   * @const
+   * @private
+   */
+  DestinationStore.AUTO_SELECT_TIMEOUT_ = 2000;
+
+  /**
+   * Creates a local PDF print destination.
+   * @return {!print_preview.Destination} Created print destination.
+   * @private
+   */
+  DestinationStore.createLocalPdfPrintDestination_ = function() {
+    var dest = new print_preview.Destination(
+        print_preview.Destination.GooglePromotedId.SAVE_AS_PDF,
+        print_preview.Destination.Type.LOCAL,
+        localStrings.getString('printToPDF'),
+        false /*isRecent*/);
+    dest.capabilities = new print_preview.ChromiumCapabilities(
+        false /*hasCopiesCapability*/,
+        '1' /*defaultCopiesStr*/,
+        false /*hasCollateCapability*/,
+        false /*defaultIsCollateEnabled*/,
+        false /*hasDuplexCapability*/,
+        false /*defaultIsDuplexEnabled*/,
+        true /*hasOrientationCapability*/,
+        false /*defaultIsLandscapeEnabled*/,
+        true /*hasColorCapability*/,
+        true /*defaultIsColorEnabled*/);
+    return dest;
   };
 
   DestinationStore.prototype = {
     __proto__: cr.EventTarget.prototype,
 
     /**
      * @return {!Array.<!print_preview.Destination>} List of destinations in
      *     the store.
      */
     get destinations() {
       return this.destinations_.slice(0);
     },
 
     /**
      * @return {print_preview.Destination} The currently selected destination or
      *     {@code null} if none is selected.
      */
     get selectedDestination() {
       return this.selectedDestination_;
     },
 
     /**
      * Sets the initially selected destination. If any inserted destinations
      * match this ID, that destination will be automatically selected. This
      * occurs only once for every time this setter is called or if the store is
      * cleared.
-     * @param {string} ID of the destination that should be selected
-     *     automatically when added to the store.
+     * @param {?string} ID of the destination that should be selected
+     *     automatically when added to the store or {@code null} if the first
+     *     destination that is inserted should be selected.
      */
     setInitialDestinationId: function(initialDestinationId) {
       this.initialDestinationId_ = initialDestinationId;
       this.isInAutoSelectMode_ = true;
-      if (this.initialDestinationId_ == null && this.destinations_.length > 0) {
+      if (this.initialDestinationId_ == null) {
+        assert(this.destinations_.length > 0,
+               'No destinations available to select');
         this.selectDestination(this.destinations_[0]);
-      } else if (this.initialDestinationId_ != null) {
-        for (var dest, i = 0; dest = this.destinations_[i]; i++) {
-          if (dest.id == initialDestinationId) {
-            this.selectDestination(dest);
-            break;
-          }
+      } else {
+        var candidate = this.destinationMap_[this.initialDestinationId_];
+        if (candidate != null) {
+          this.selectDestination(candidate);
         }
       }
     },
 
+    /**
+     * Sets the destination store's Google Cloud Print interface.
+     * @param {!print_preview.CloudPrintInterface} cloudPrintInterface Interface
+     *     to set.
+     */
+    setCloudPrintInterface: function(cloudPrintInterface) {
+      this.cloudPrintInterface_ = cloudPrintInterface;
+      this.tracker_.add(
+          this.cloudPrintInterface_,
+          cloudprint.CloudPrintInterface.EventType.SEARCH_DONE,
+          this.onCloudPrintSearchDone_.bind(this));
+      this.tracker_.add(
+          this.cloudPrintInterface_,
+          cloudprint.CloudPrintInterface.EventType.PRINTER_DONE,
+          this.onCloudPrintPrinterDone_.bind(this));
+    },
+
     /** @param {!print_preview.Destination} Destination to select. */
     selectDestination: function(destination) {
       this.selectedDestination_ = destination;
       this.selectedDestination_.isRecent = true;
       this.isInAutoSelectMode_ = false;
+      if (this.autoSelectTimeout_ != null) {
+        clearTimeout(this.autoSelectTimeout_);
+        this.autoSelectTimeout_ = null;
+      }
       cr.dispatchSimpleEvent(
           this, DestinationStore.EventType.DESTINATION_SELECT);
+      if (destination.capabilities == null) {
+         if (destination.type == print_preview.Destination.Type.LOCAL) {
+          this.nativeLayer_.startGetLocalDestinationCapabilities(
+              destination.id);
+        } else {
+          assert(this.cloudPrintInterface_ != null,
+                 'Selected destination is a cloud destination, but Google ' +
+                     'Cloud Print is not enabled');
+          this.cloudPrintInterface_.printer(destination.id);
+        }
+      } else {
+        cr.dispatchSimpleEvent(
+            this,
+            DestinationStore.EventType.SELECTED_DESTINATION_CAPABILITIES_READY);
+      }
     },
 
     /**
      * Inserts a print destination to the data store and dispatches a
      * DESTINATIONS_INSERTED event. If the destination matches the initial
      * destination ID, then the destination will be automatically selected.
      * @param {!print_preview.Destination} destination Print destination to
      *     insert.
      */
     insertDestination: function(destination) {
-      this.destinations_.push(destination);
-      cr.dispatchSimpleEvent(
-          this, DestinationStore.EventType.DESTINATIONS_INSERTED);
-      if (this.isInAutoSelectMode_) {
-        if (this.initialDestinationId_ == null) {
+      if (this.insertDestination_(destination)) {
+        cr.dispatchSimpleEvent(
+            this, DestinationStore.EventType.DESTINATIONS_INSERTED);
+        if (this.isInAutoSelectMode_ &&
+            (this.initialDestinationId_ == null ||
+                destination.id == this.initialDestinationId_)) {
           this.selectDestination(destination);
-        } else {
-          if (destination.id == this.initialDestinationId_) {
-            this.selectDestination(destination);
-          }
         }
       }
     },
 
     /**
      * Inserts multiple print destinations to the data store and dispatches one
      * DESTINATIONS_INSERTED event. If any of the destinations match the initial
      * destination ID, then that destination will be automatically selected.
      * @param {!Array.<print_preview.Destination>} destinations Print
      *     destinations to insert.
      */
     insertDestinations: function(destinations) {
-      this.destinations_ = this.destinations_.concat(destinations);
-      cr.dispatchSimpleEvent(
-          this, DestinationStore.EventType.DESTINATIONS_INSERTED);
-      if (this.isInAutoSelectMode_) {
-        if (this.initialDestinationId_ == null && destinations.length > 0) {
-          this.selectDestination(destinations[0]);
-        } else if (this.initialDestinationId_ != null) {
-          for (var dest, i = 0; dest = destinations[i]; i++) {
-            if (dest.id == this.initialDestinationId_) {
-              this.selectDestination(dest);
-              break;
-            }
+      var insertedDestination = false;
+      var destinationToAutoSelect = null;
+      for (var dest, i = 0; dest = destinations[i]; i++) {

[dpapad, 2012/05/25 16:18:03]

This can probably be simplified if you use forEach
destinations.forEach(function(dest) {
  // do stuff here.
}, this);

[Robert Toscano, 2012/05/25 19:47:01]

Thanks! Didn't know about this one. Done.

+        if (this.insertDestination_(dest)) {

[dpapad, 2012/05/25 16:18:03]

You can merge these 2 nested if statements as follows.

if (insertedDestination = this.insertDestination_(dest) &&
    this.isInAutoSelectMode_ &&
    etc etc....) {
  destinationToAutoSelect = dest;
}

[Robert Toscano, 2012/05/25 19:47:01]

Kausalya recommended not using assignments in "if" conditions since they are
hard to tell whether it was a typo or actually an assignment. What do you think?

+          insertedDestination = true;
+          if (this.isInAutoSelectMode_ &&
+              destinationToAutoSelect == null &&
+              (this.initialDestinationId_ == null ||
+                  dest.id == this.initialDestinationId_)) {
+            destinationToAutoSelect = dest;
           }
         }
       }
+      if (insertedDestination) {
+        cr.dispatchSimpleEvent(
+            this, DestinationStore.EventType.DESTINATIONS_INSERTED);
+      }
+      if (destinationToAutoSelect != null) {
+        this.selectDestination(destinationToAutoSelect);
+      }
     },
 
     /**
      * Updates an existing print destination with capabilities information. If
      * the destination doesn't already exist, it will be added.
      * @param {!print_preview.Destination} destination Destination to update.
      * @return {!print_preview.Destination} The existing destination that was
      *     updated.
      */
     updateDestination: function(destination) {
-      var existingDestination = null;
-      for (var d, i = 0; d = this.destinations_[i]; i++) {
-        if (destination.id == d.id) {
-          existingDestination = d;
-          break;
-        }
-      }
-      if (existingDestination) {
+      var existingDestination = this.destinationMap_[destination.id];
+      if (existingDestination != null) {
         existingDestination.capabilities = destination.capabilities;
         return existingDestination;
       } else {
         this.insertDestination(destination);
       }
     },
 
-    /** Clears all print destinations. */
-    clear: function() {
+    /** Initiates loading of local print destinations. */
+    startLoadLocalDestinations: function() {
+      this.nativeLayer_.startGetLocalDestinations();
+    },
+
+    /** Initiates loading of recent cloud destinations. */
+    startLoadRecentCloudDestinations: function() {
+      if (this.cloudPrintInterface_ != null) {
+        this.cloudPrintInterface_.search(true /*isRecent*/);
+      }
+    },
+
+    /** Initiates loading of all cloud destinations. */
+    startLoadAllCloudDestinations: function() {
+      if (this.cloudPrintInterface_ != null &&
+          !this.hasLoadedAllCloudDestinations_) {
+        this.cloudPrintInterface_.search(false /*isRecent*/);
+        this.hasLoadedAllCloudDestinations_ = true;
+      }
+    },
+
+    /**
+     * Inserts a destination into the store without dispatching any events.
+     * @return {boolean} Whether the inserted destination was not already in the
+     *     store.
+     * @private
+     */
+    insertDestination_: function(destination) {
+      if (this.destinationMap_[destination.id] == null) {
+        this.destinations_.push(destination);
+        this.destinationMap_[destination.id] = destination;
+        return true;
+      } else {
+        return false;
+      }
+    },
+
+    /**
+     * Binds handlers to events.
+     * @private
+     */
+    addEventListeners_: function() {
+      this.tracker_.add(
+          this.nativeLayer_,
+          print_preview.NativeLayer.EventType.LOCAL_DESTINATIONS_SET,
+          this.onLocalDestinationsSet_.bind(this));
+      this.tracker_.add(
+          this.nativeLayer_,
+          print_preview.NativeLayer.EventType.CAPABILITIES_SET,
+          this.onLocalDestinationCapabilitiesSet_.bind(this));
+      this.tracker_.add(
+          this.nativeLayer_,
+          print_preview.NativeLayer.EventType.DESTINATIONS_RELOAD,
+          this.onDestinationsReload_.bind(this));
+    },
+
+    /**
+     * Resets the state of the destination store to its initial state.
+     * @private
+     */
+    reset_: function() {
       this.destinations_ = [];
+      this.destinationMap_ = {};
       this.selectedDestination_ = null;
       this.isInAutoSelectMode_ = true;
+      this.hasLoadedAllCloudDestinations_ = false;
+      this.insertDestination(
+          DestinationStore.createLocalPdfPrintDestination_());
+      this.autoSelectTimeout_ = setTimeout(
+          this.onAutoSelectTimeoutExpired_.bind(this),
+          DestinationStore.AUTO_SELECT_TIMEOUT_);
+    },
+
+    /**
+     * Called when the local destinations have been got from the native layer.
+     * @param {cr.Event} Contains the local destinations.
+     * @private
+     */
+    onLocalDestinationsSet_: function(event) {
+      var localDestinations = [];
+      for (var destInfo, i = 0; destInfo = event.destinationInfos[i]; i++) {

[dpapad, 2012/05/25 16:18:03]

use forEach.

[Robert Toscano, 2012/05/25 19:47:01]

Done.

+        localDestinations.push(
+            print_preview.LocalDestinationParser.parse(destInfo));
+      }
+      this.insertDestinations(localDestinations);
+    },
+
+    /**
+     * Called when the native layer retrieves the capabilities for the selected
+     * local destination.
+     * @param {cr.Event} event Contains the capabilities of the local print
+     *     destination.
+     * @private
+     */
+    onLocalDestinationCapabilitiesSet_: function(event) {
+      // TODO There may be a race condition here. This method is assumed to
+      // return capabilities for the currently selected printer. But between the
+      // time the local printer was selected and the capabilities were
+      // retrieved, the selected printer can change. One way to address this is
+      // to include the destination ID in the event.settingsInfo parameter.
+      if (this.selectedDestination_ && this.selectedDestination_.isLocal) {
+        var capabilities = print_preview.LocalCapabilitiesParser.parse(
+            event.settingsInfo);
+        this.selectedDestination_.capabilities = capabilities;
+        cr.dispatchSimpleEvent(
+            this,
+            DestinationStore.EventType.SELECTED_DESTINATION_CAPABILITIES_READY);
+      }
+    },
+
+    /**
+     * Called when the /search call completes. Adds the fetched printers to the
+     * destination store.
+     * @param {cr.Event} event Contains the fetched printers.
+     * @private
+     */
+    onCloudPrintSearchDone_: function(event) {
+      this.insertDestinations(event.printers);
+    },
+
+    /**
+     * Called when /printer call completes. Updates the specified destination's
+     * print capabilities.
+     * @param {cr.Event} event Contains detailed information about the
+     *     destination.
+     * @private
+     */
+    onCloudPrintPrinterDone_: function(event) {
+      var dest = this.updateDestination(event.printer);
+      if (this.selectedDestination_ == dest) {
+        cr.dispatchSimpleEvent(
+            this,
+            DestinationStore.EventType.SELECTED_DESTINATION_CAPABILITIES_READY);
+      }
+    },
+
+    /**
+     * Called from native layer after the user was requested to sign in, and did
+     * so successfully.
+     * @private
+     */
+    onDestinationsReload_: function() {
+      this.reset_();
+      this.startLoadLocalDestinations();
+      this.startLoadRecentCloudDestinations();
+      this.startLoadAllCloudDestinations();
+    },
+
+    /**
+     * Called when no destination was auto-selected after some timeout. Selects
+     * the first destination in store.
+     * @private
+     */
+    onAutoSelectTimeoutExpired_: function() {
+      this.autoSelectTimeout_ = null;
+      assert(this.destinations_.length > 0,
+             'No destinations were loaded before auto-select timeout expired');
+      this.selectDestination(this.destinations_[0]);
     }
   };
 
   // Export
   return {
     DestinationStore: DestinationStore
   };
 });