ui/file_manager/gallery/js/gallery_data_model.js

   1 // Copyright 2015 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  * Data model for gallery.
   7  *
   8  * @param {!MetadataModel} metadataModel
   9  * @param {!EntryListWatcher=} opt_watcher Entry list watcher.
  10  * @constructor
  11  * @extends {cr.ui.ArrayDataModel}
  12  */
  13 function GalleryDataModel(metadataModel, opt_watcher) {
  14   cr.ui.ArrayDataModel.call(this, []);
  15
  16   /**
  17    * File system metadata.
  18    * @private {!MetadataModel}
  19    * @const
  20    */
  21   this.metadataModel_ = metadataModel;
  22
  23   /**
  24    * Directory where the image is saved if the image is located in a read-only
  25    * volume.
  26    * @public {DirectoryEntry}
  27    */
  28   this.fallbackSaveDirectory = null;
  29
  30   // Start to watch file system entries.
  31   var watcher = opt_watcher ? opt_watcher : new EntryListWatcher(this);
  32   watcher.getEntry = function(item) { return item.getEntry(); };
  33 }
  34
  35 /**
  36  * Maximum number of full size image cache.
  37  * @type {number}
  38  * @const
  39  * @private
  40  */
  41 GalleryDataModel.MAX_FULL_IMAGE_CACHE_ = 3;
  42
  43 /**
  44  * Maximum number of screen size image cache.
  45  * @type {number}
  46  * @const
  47  * @private
  48  */
  49 GalleryDataModel.MAX_SCREEN_IMAGE_CACHE_ = 5;
  50
  51 GalleryDataModel.prototype = {
  52   __proto__: cr.ui.ArrayDataModel.prototype
  53 };
  54
  55 /**
  56  * Saves new image.
  57  *
  58  * @param {!VolumeManager} volumeManager Volume manager instance.
  59  * @param {!Gallery.Item} item Original gallery item.
  60  * @param {!HTMLCanvasElement} canvas Canvas containing new image.
  61  * @param {boolean} overwrite Whether to overwrite the image to the item or not.
  62  * @return {!Promise} Promise to be fulfilled with when the operation completes.
  63  */
  64 GalleryDataModel.prototype.saveItem = function(
  65     volumeManager, item, canvas, overwrite) {
  66   var oldEntry = item.getEntry();
  67   var oldMetadataItem = item.getMetadataItem();
  68   var oldThumbnailMetadataItem = item.getThumbnailMetadataItem();
  69   var oldLocationInfo = item.getLocationInfo();
  70   return new Promise(function(fulfill, reject) {
  71     item.saveToFile(
  72         volumeManager,
  73         this.metadataModel_,
  74         this.fallbackSaveDirectory,
  75         overwrite,
  76         canvas,
  77         function(success) {
  78           if (!success) {
  79             reject('Failed to save the image.');
  80             return;
  81           }
  82
  83           // Current entry is updated.
  84           // Dispatch an event.
  85           var event = new Event('content');
  86           event.item = item;
  87           event.oldEntry = oldEntry;
  88           event.thumbnailChanged = true;
  89           this.dispatchEvent(event);
  90
  91           if (!util.isSameEntry(oldEntry, item.getEntry())) {
  92             // New entry is added and the item now tracks it.
  93             // Add another item for the old entry.
  94             var anotherItem = new Gallery.Item(
  95                 oldEntry,
  96                 oldLocationInfo,
  97                 oldMetadataItem,
  98                 oldThumbnailMetadataItem,
  99                 item.isOriginal());
 100             // The item must be added behind the existing item so that it does
 101             // not change the index of the existing item.
 102             // TODO(hirono): Update the item index of the selection model
 103             // correctly.
 104             this.splice(this.indexOf(item) + 1, 0, anotherItem);
 105           }
 106
 107           fulfill();
 108         }.bind(this));
 109   }.bind(this));
 110 };
 111
 112 /**
 113  * Evicts image caches in the items.
 114  */
 115 GalleryDataModel.prototype.evictCache = function() {
 116   // Sort the item by the last accessed date.
 117   var sorted = this.slice().sort(function(a, b) {
 118     return b.getLastAccessedDate() - a.getLastAccessedDate();
 119   });
 120
 121   // Evict caches.
 122   var contentCacheCount = 0;
 123   var screenCacheCount = 0;
 124   for (var i = 0; i < sorted.length; i++) {
 125     if (sorted[i].contentImage) {
 126       if (++contentCacheCount > GalleryDataModel.MAX_FULL_IMAGE_CACHE_) {
 127         if (sorted[i].contentImage.parentNode) {
 128           console.error('The content image has a parent node.');
 129         } else {
 130           // Force to free the buffer of the canvas by assigning zero size.
 131           sorted[i].contentImage.width = 0;
 132           sorted[i].contentImage.height = 0;
 133           sorted[i].contentImage = null;
 134         }
 135       }
 136     }
 137     if (sorted[i].screenImage) {
 138       if (++screenCacheCount > GalleryDataModel.MAX_SCREEN_IMAGE_CACHE_) {
 139         if (sorted[i].screenImage.parentNode) {
 140           console.error('The screen image has a parent node.');
 141         } else {
 142           // Force to free the buffer of the canvas by assigning zero size.
 143           sorted[i].screenImage.width = 0;
 144           sorted[i].screenImage.height = 0;
 145           sorted[i].screenImage = null;
 146         }
 147       }
 148     }
 149   }
 150 };