Refactor the Photo Editor to enable new feature work

chrome/browser/resources/file_manager/js/photo/slide_mode.js

Index: chrome/browser/resources/file_manager/js/photo/slide_mode.js
diff --git a/chrome/browser/resources/file_manager/js/photo/slide_mode.js b/chrome/browser/resources/file_manager/js/photo/slide_mode.js
new file mode 100644
index 0000000000000000000000000000000000000000..ceb026f463e640c4435db9dfde0e7c77c51ddf4b
--- /dev/null
+++ b/chrome/browser/resources/file_manager/js/photo/slide_mode.js
@@ -0,0 +1,871 @@
+// 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.
+
+/**
+ * Slide mode displays a single image and has a set of controls to navigate
+ * between the images and to edit an image.
+ *
+ * @param {Element} container Container element.
+ * @param {Element} toolbar Toolbar element.
+ * @param {ImageEditor.Prompt} prompt Prompt.
+ * @param {Object} context Context.
+ * @param {function(string):string} displayStringFunction String formatting
+ *     function.
+ * @constructor
+ */
+function SlideMode(container, toolbar, prompt, context, displayStringFunction) {
+  this.container_ = container;
+  this.toolbar_ = toolbar;
+  this.document_ = container.ownerDocument;
+  this.prompt_ = prompt;
+  this.context_ = context;
+  this.metadataCache_ = context.metadataCache;
+  this.displayStringFunction_ = displayStringFunction;
+
+  this.initListeners_();
+  this.initDom_();
+}
+
+/**
+ * SlideMode extends cr.EventTarget.
+ */
+SlideMode.prototype.__proto__ = cr.EventTarget.prototype;
+
+/**
+ * List of available editor modes.
+ * @type {Array.<ImageEditor.Mode>}
+ */
+SlideMode.editorModes = [
+  new ImageEditor.Mode.InstantAutofix(),
+  new ImageEditor.Mode.Crop(),
+  new ImageEditor.Mode.Exposure(),
+  new ImageEditor.Mode.OneClick('rotate_left', new Command.Rotate(-1)),
+  new ImageEditor.Mode.OneClick('rotate_right', new Command.Rotate(1))
+];
+
+/**
+ * Initialize the listeners.
+ * @private
+ */
+SlideMode.prototype.initListeners_ = function() {
+  var win = this.document_.defaultView;
+
+  this.onBeforeUnloadBound_ = this.onBeforeUnload_.bind(this);
+  win.top.addEventListener('beforeunload', this.onBeforeUnloadBound_);
+
+  win.addEventListener('unload', this.onUnload_.bind(this));
+
+  // We need to listen to the top window 'unload' and 'beforeunload' because
+  // the Gallery iframe does not get notified if the tab is closed.
+  this.onTopUnloadBound_ = this.onTopUnload_.bind(this);
+  win.top.addEventListener('unload', this.onTopUnloadBound_);
+
+  win.addEventListener('resize', this.onResize_.bind(this), false);
+};
+
+/**
+ * Initialize the UI.
+ * @private
+ */
+SlideMode.prototype.initDom_ = function() {
+  // Container for displayed image or video.
+  this.imageContainer_ = util.createChild(
+      this.document_.querySelector('.content'), 'image-container');
+  this.imageContainer_.addEventListener('click', this.onClick_.bind(this));
+
+  // Overwrite options and info bubble.
+  this.options_ = util.createChild(
+      this.toolbar_.querySelector('.filename-spacer'), 'options');
+
+  this.savedLabel_ = util.createChild(this.options_, 'saved');
+  this.savedLabel_.textContent = this.displayStringFunction_('saved');
+
+  var overwriteOriginalBox =
+      util.createChild(this.options_, 'overwrite-original');
+
+  this.overwriteOriginal_ = util.createChild(
+      overwriteOriginalBox, 'common white', 'input');
+  this.overwriteOriginal_.type = 'checkbox';
+  this.overwriteOriginal_.id = 'overwrite-checkbox';
+  this.overwriteOriginal_.checked = this.shouldOverwriteOriginal_();
+  this.overwriteOriginal_.addEventListener('click',
+      this.onOverwriteOriginalClick_.bind(this));
+
+  var overwriteLabel = util.createChild(overwriteOriginalBox, '', 'label');
+  overwriteLabel.textContent =
+      this.displayStringFunction_('overwrite_original');
+  overwriteLabel.setAttribute('for', 'overwrite-checkbox');
+
+  this.bubble_ = util.createChild(this.toolbar_, 'bubble');
+  this.bubble_.hidden = true;
+
+  var bubbleContent = util.createChild(this.bubble_);
+  bubbleContent.innerHTML = this.displayStringFunction_('overwrite_bubble');
+
+  util.createChild(this.bubble_, 'pointer bottom', 'span');
+
+  var bubbleClose = util.createChild(this.bubble_, 'close-x');
+  bubbleClose.addEventListener('click', this.onCloseBubble_.bind(this));
+
+  // Video player controls.
+  this.mediaSpacer_ =
+      util.createChild(this.container_, 'video-controls-spacer');
+  this.mediaToolbar_ = util.createChild(this.mediaSpacer_, 'tool');
+  this.mediaControls_ = new VideoControls(
+      this.mediaToolbar_,
+      this.showErrorBanner_.bind(this, 'VIDEO_ERROR'),
+      Gallery.toggleFullscreen,
+      this.container_);
+
+  // Ribbon and related controls.
+  this.arrowBox_ = util.createChild(this.container_, 'arrow-box');
+
+  this.arrowLeft_ =
+      util.createChild(this.arrowBox_, 'arrow left tool dimmable');
+  this.arrowLeft_.addEventListener('click',
+      this.selectNext.bind(this, -1, null));
+  util.createChild(this.arrowLeft_);
+
+  util.createChild(this.arrowBox_, 'arrow-spacer');
+
+  this.arrowRight_ =
+      util.createChild(this.arrowBox_, 'arrow right tool dimmable');
+  this.arrowRight_.addEventListener('click',
+      this.selectNext.bind(this, 1, null));
+  util.createChild(this.arrowRight_);
+
+  this.ribbonSpacer_ = util.createChild(this.toolbar_, 'ribbon-spacer');
+
+  // Error indicator.
+  var errorWrapper = util.createChild(this.container_, 'prompt-wrapper');
+  errorWrapper.setAttribute('pos', 'center');
+
+  this.errorBanner_ = util.createChild(errorWrapper, 'error-banner');
+
+  util.createChild(this.container_, 'spinner');
+
+
+  this.editButton_ = util.createChild(this.toolbar_, 'button edit');
+  this.editButton_.textContent = this.displayStringFunction_('edit');
+  this.editButton_.addEventListener('click', this.onEdit_.bind(this));
+
+  // Editor toolbar.
+
+  this.editBar_ = util.createChild(this.toolbar_, 'edit-bar');
+  this.editBarMain_ = util.createChild(this.editBar_, 'edit-main');
+
+  this.editBarMode_ = util.createChild(this.container_, 'edit-modal');
+  this.editBarModeWrapper_ = util.createChild(
+      this.editBarMode_, 'edit-modal-wrapper');
+  this.editBarModeWrapper_.hidden = true;
+
+  // Objects supporting image display and editing.
+  this.viewport_ = new Viewport();
+
+  this.imageView_ = new ImageView(
+      this.imageContainer_,
+      this.viewport_,
+      this.metadataCache_);
+
+  this.imageView_.addContentCallback(this.onImageContentChanged_.bind(this));
+
+  this.editor_ = new ImageEditor(
+      this.viewport_,
+      this.imageView_,
+      this.prompt_,
+      {
+        root: this.container_,
+        image: this.imageContainer_,
+        toolbar: this.editBarMain_,
+        mode: this.editBarModeWrapper_
+      },
+      SlideMode.editorModes,
+      this.displayStringFunction_);
+
+  this.editor_.getBuffer().addOverlay(
+      new SwipeOverlay(this.selectNext.bind(this)));
+};
+
+/**
+ * Load items, display the selected item.
+ *
+ * @param {Array.<Gallery.Item>} items Array of items.
+ * @param {number} selectedIndex Selected index.
+ * @param {function} callback Callback.
+ */
+SlideMode.prototype.load = function(items, selectedIndex, callback) {
+  var selectedItem = items[selectedIndex];
+  if (!selectedItem) {
+    this.showErrorBanner_('IMAGE_ERROR');
+    return;
+  }
+
+  var loadDone = function() {
+    this.items_ = items;
+    this.setSelectedIndex_(selectedIndex);
+    this.setupNavigation_();
+    setTimeout(this.requestPrefetch.bind(this, 1 /* Next item */), 1000);
+    callback();
+  }.bind(this);
+
+  var selectedUrl = selectedItem.getUrl();
+  // Show the selected item ASAP, then complete the initialization
+  // (loading the ribbon thumbnails can take some time).
+  this.metadataCache_.get(selectedUrl, Gallery.METADATA_TYPE,
+      function(metadata) {
+        this.loadItem_(selectedUrl, metadata, 0, loadDone);
+      }.bind(this));
+};
+
+/**
+ * Setup navigation controls.
+ * @private
+ */
+SlideMode.prototype.setupNavigation_ = function() {
+  this.sequenceDirection_ = 0;
+  this.sequenceLength_ = 0;
+
+  ImageUtil.setAttribute(this.arrowLeft_, 'active', this.items_.length > 1);
+  ImageUtil.setAttribute(this.arrowRight_, 'active', this.items_.length > 1);
+
+  this.ribbon_ = new Ribbon(
+      this.document_, this.metadataCache_, this.select.bind(this));
+  this.ribbonSpacer_.appendChild(this.ribbon_);
+  this.ribbon_.update(this.items_, this.selectedIndex_);
+};
+
+/**
+ * @return {Gallery.Item} Selected item
+ */
+SlideMode.prototype.getSelectedItem = function() {
+  return this.items_ && this.items_[this.selectedIndex_];
+};
+
+/**
+ * Change the selection.
+ *
+ * Commits the current image and changes the selection.
+ *
+ * @param {number} index New selected index.
+ * @param {number} opt_slideDir Slide animation direction (-1|0|1).
+ *   Derived from the new and the old selected indices if omitted.
+ * @param {function} opt_callback Callback.
+ */
+SlideMode.prototype.select = function(index, opt_slideDir, opt_callback) {
+  if (!this.items_)
+    return;  // Not fully initialized, still loading the first image.
+
+  if (index == this.selectedIndex_)
+    return;  // Do not reselect.
+
+  this.commitItem_(
+      this.doSelect_.bind(this, index, opt_slideDir, opt_callback));
+};
+
+/**
+ * Set the new selected index value.
+ * @param {number} index New selected index.
+ * @private
+ */
+SlideMode.prototype.setSelectedIndex_ = function(index) {
+  this.selectedIndex_ = index;
+  cr.dispatchSimpleEvent(this, 'selection');
+
+  // For once edited image, disallow the 'overwrite' setting change.
+  ImageUtil.setAttribute(this.options_, 'saved',
+      !this.getSelectedItem().isOriginal());
+};
+
+/**
+ * Perform the actual selection change.
+ *
+ * @param {number} index New selected index.
+ * @param {number} opt_slideDir Slide animation direction (-1|0|1).
+ *   Derived from the new and the old selected indices if omitted.
+ * @param {function} opt_callback Callback.
+ * @private
+ */
+SlideMode.prototype.doSelect_ = function(index, opt_slideDir, opt_callback) {
+  if (index == this.selectedIndex_)
+    return;  // Do not reselect
+
+  var step = opt_slideDir != undefined ?
+      opt_slideDir :
+      (index - this.selectedIndex_);
+
+  if (Math.abs(step) != 1) {
+    // Long leap, the sequence is broken, we have no good prefetch candidate.
+    this.sequenceDirection_ = 0;
+    this.sequenceLength_ = 0;
+  } else if (this.sequenceDirection_ == step) {
+    // Keeping going in sequence.
+    this.sequenceLength_++;
+  } else {
+    // Reversed the direction. Reset the counter.
+    this.sequenceDirection_ = step;
+    this.sequenceLength_ = 1;
+  }
+
+  if (this.sequenceLength_ <= 1) {
+    // We have just broke the sequence. Touch the current image so that it stays
+    // in the cache longer.
+    this.editor_.prefetchImage(this.getSelectedItem().getUrl());
+  }
+
+  this.setSelectedIndex_(index);
+
+  if (this.ribbon_)
+    this.ribbon_.update(this.items_, this.selectedIndex_);
+
+  function shouldPrefetch(loadType, step, sequenceLength) {
+    // Never prefetch when selecting out of sequence.
+    if (Math.abs(step) != 1)
+      return false;
+
+    // Never prefetch after a video load (decoding the next image can freeze
+    // the UI for a second or two).
+    if (loadType == ImageView.LOAD_TYPE_VIDEO_FILE)
+      return false;
+
+    // Always prefetch if the previous load was from cache.
+    if (loadType == ImageView.LOAD_TYPE_CACHED_FULL)
+      return true;
+
+    // Prefetch if we have been going in the same direction for long enough.
+    return sequenceLength >= 3;
+  }
+
+  var selectedItem = this.getSelectedItem();
+  var onMetadata = function(metadata) {
+    if (selectedItem != this.getSelectedItem()) return;
+    this.loadItem_(selectedItem.getUrl(), metadata, step,
+        function(loadType) {
+          if (selectedItem != this.getSelectedItem()) return;
+          if (shouldPrefetch(loadType, step, this.sequenceLength_)) {
+            this.requestPrefetch(step);
+          }
+          if (opt_callback) opt_callback();
+        }.bind(this));
+  }.bind(this);
+  this.metadataCache_.get(
+      selectedItem.getUrl(), Gallery.METADATA_TYPE, onMetadata);
+};
+
+/**
+ * @param {number} direction -1 for left, 1 for right.
+ * @return {number} Next index in the gived direction, with wrapping.
+ * @private
+ */
+SlideMode.prototype.getNextSelectedIndex_ = function(direction) {
+  var index = this.selectedIndex_ + (direction > 0 ? 1 : -1);
+  if (index == -1) return this.items_.length - 1;
+  if (index == this.items_.length) return 0;
+  return index;
+};
+
+/**
+ * Select the next item.
+ * @param {number} direction -1 for left, 1 for right.
+ * @param {function} opt_callback Callback.
+ */
+SlideMode.prototype.selectNext = function(direction, opt_callback) {
+  this.select(this.getNextSelectedIndex_(direction), direction, opt_callback);
+};
+
+/**
+ * Select the first item.
+ */
+SlideMode.prototype.selectFirst = function() {
+  this.select(0);
+};
+
+/**
+ * Select the last item.
+ */
+SlideMode.prototype.selectLast = function() {
+  this.select(this.items_.length - 1);
+};
+
+// Loading/unloading
+
+/**
+ * Load and display an item.
+ *
+ * @param {string} url Item url.
+ * @param {Object} metadata Item metadata.
+ * @param {number} slide Slide animation direction (-1|0|1).
+ * @param {function} callback Callback.
+ * @private
+ */
+SlideMode.prototype.loadItem_ = function(url, metadata, slide, callback) {
+  this.selectedImageMetadata_ = ImageUtil.deepCopy(metadata);
+
+  this.showSpinner_(true);
+
+  var loadDone = function(loadType) {
+    var video = this.isShowingVideo_();
+    ImageUtil.setAttribute(this.container_, 'video', video);
+
+    this.showSpinner_(false);
+    if (loadType == ImageView.LOAD_TYPE_ERROR) {
+      this.showErrorBanner_(video ? 'VIDEO_ERROR' : 'IMAGE_ERROR');
+    } else if (loadType == ImageView.LOAD_TYPE_OFFLINE) {
+      this.showErrorBanner_(video ? 'VIDEO_OFFLINE' : 'IMAGE_OFFLINE');
+    }
+
+    if (video) {
+      if (this.isEditing()) {
+        // The editor toolbar does not make sense for video, hide it.
+        this.onEdit_();
+      }
+      this.mediaControls_.attachMedia(this.imageView_.getVideo());
+      //TODO(kaznacheev): Add metrics for video playback.
+    } else {
+      ImageUtil.metrics.recordUserAction(ImageUtil.getMetricName('View'));
+
+      function toMillions(number) { return Math.round(number / (1000 * 1000)) }
+
+      ImageUtil.metrics.recordSmallCount(ImageUtil.getMetricName('Size.MB'),
+          toMillions(metadata.filesystem.size));
+
+      var canvas = this.imageView_.getCanvas();
+      ImageUtil.metrics.recordSmallCount(ImageUtil.getMetricName('Size.MPix'),
+          toMillions(canvas.width * canvas.height));
+
+      var extIndex = url.lastIndexOf('.');
+      var ext = extIndex < 0 ? '' : url.substr(extIndex + 1).toLowerCase();
+      if (ext == 'jpeg') ext = 'jpg';
+      ImageUtil.metrics.recordEnum(
+          ImageUtil.getMetricName('FileType'), ext, ImageUtil.FILE_TYPES);
+    }
+
+    callback(loadType);
+  }.bind(this);
+
+  this.editor_.openSession(
+      url, metadata, slide, this.saveCurrentImage_.bind(this), loadDone);
+};
+
+/**
+ * Commit changes to the current item and reset all messages/indicators.
+ *
+ * @param {function} callback Callback.
+ * @private
+ */
+SlideMode.prototype.commitItem_ = function(callback) {
+  this.showSpinner_(false);
+  this.showErrorBanner_(false);
+  this.editor_.getPrompt().hide();
+  if (this.isShowingVideo_()) {
+    this.mediaControls_.pause();
+    this.mediaControls_.detachMedia();
+  }
+  this.editor_.closeSession(callback);
+};
+
+/**
+ * Request a prefetch for the next image.
+ *
+ * @param {number} direction -1 or 1.
+ */
+SlideMode.prototype.requestPrefetch = function(direction) {
+  if (this.items_.length <= 1) return;
+
+  var index = this.getNextSelectedIndex_(direction);
+  var nextItemUrl = this.items_[index].getUrl();
+
+  var selectedItem = this.getSelectedItem();
+  this.metadataCache_.get(nextItemUrl, Gallery.METADATA_TYPE,
+      function(metadata) {
+        if (selectedItem != this.getSelectedItem()) return;
+        this.editor_.prefetchImage(nextItemUrl);
+      }.bind(this));
+};
+
+// Event handlers.
+
+/**
+ * Unload handler.
+ * @private
+ */
+SlideMode.prototype.onUnload_ = function() {
+  this.saveVideoPosition_();
+  window.top.removeEventListener('beforeunload', this.onBeforeUnloadBound_);
+  window.top.removeEventListener('unload', this.onTopUnloadBound_);
+};
+
+/**
+ * Top window unload handler.
+ * @private
+ */
+SlideMode.prototype.onTopUnload_ = function() {
+  this.saveVideoPosition_();
+};
+
+/**
+ * Top window beforeunload handler.
+ * @return {string} Message to show if there are unsaved changes.
+ * @private
+ */
+SlideMode.prototype.onBeforeUnload_ = function() {
+  if (this.editor_.isBusy())
+    return this.displayStringFunction_('unsaved_changes');
+  return null;
+};
+
+/**
+ * Click handler.
+ * @private
+ */
+SlideMode.prototype.onClick_ = function() {
+  if (this.isShowingVideo_())
+    this.mediaControls_.togglePlayStateWithFeedback();
+};
+
+/**
+ * Keydown handler.
+ *
+ * @param {Event} event Event.
+ * @return {boolean} True if handled.
+ */
+SlideMode.prototype.onKeyDown = function(event) {
+  if (this.isEditing() && this.editor_.onKeyDown(event))
+    return true;
+
+  switch (util.getKeyModifiers(event) + event.keyIdentifier) {
+    case 'U+0020':  // Space toggles the video playback.
+      if (this.isShowingVideo_()) {
+        this.mediaControls_.togglePlayStateWithFeedback();
+      }
+      break;
+
+    case 'U+0045':  // 'e' toggles the editor
+      this.onEdit_();
+      break;
+
+    case 'U+001B':  // Escape
+      if (!this.isEditing())
+        return false;  // Not handled.
+      this.onEdit_();
+      break;
+
+    case 'Ctrl-U+00DD':  // Ctrl+] (cryptic on purpose).
+      this.toggleSlideshow_();
+      break;
+
+    case 'Home':
+      this.selectFirst();
+      break;
+    case 'End':
+      this.selectLast();
+      break;
+    case 'Left':
+      this.selectNext(-1);
+      break;
+    case 'Right':
+      this.selectNext(1);
+      break;
+
+    default: return false;
+  }
+
+  return true;
+};
+
+/**
+ * Resize handler.
+ * @private
+ */
+SlideMode.prototype.onResize_ = function() {
+  this.viewport_.sizeByFrameAndFit(this.container_);
+  this.viewport_.repaint();
+};
+
+// Saving
+
+/**
+ * Save the current image to a file.
+ *
+ * @param {function} callback Callback.
+ * @private
+ */
+SlideMode.prototype.saveCurrentImage_ = function(callback) {
+  var item = this.getSelectedItem();
+  var oldUrl = item.getUrl();
+  var canvas = this.imageView_.getCanvas();
+
+  this.showSpinner_(true);
+  var metadataEncoder = ImageEncoder.encodeMetadata(
+      this.selectedImageMetadata_.media, canvas, 1 /* quality */);
+
+  this.selectedImageMetadata_ = ContentProvider.ConvertContentMetadata(
+      metadataEncoder.getMetadata(), this.selectedImageMetadata_);
+
+  item.saveToFile(
+      this.context_.saveDirEntry,
+      this.shouldOverwriteOriginal_(),
+      canvas,
+      metadataEncoder,
+      function(success) {
+        // TODO(kaznacheev): Implement write error handling.
+        // Until then pretend that the save succeeded.
+        this.showSpinner_(false);
+        this.flashSavedLabel_();
+        var newUrl = item.getUrl();
+        this.updateSelectedUrl_(oldUrl, newUrl);
+        this.ribbon_.updateThumbnail(
+            this.selectedIndex_, newUrl, this.selectedImageMetadata_);
+        callback();
+      }.bind(this));
+};
+
+/**
+ * Update caches when the selected item url has changed.
+ *
+ * @param {string} oldUrl Old url.
+ * @param {string} newUrl New url.
+ * @private
+ */
+SlideMode.prototype.updateSelectedUrl_ = function(oldUrl, newUrl) {
+  this.metadataCache_.clear(oldUrl, Gallery.METADATA_TYPE);
+
+  if (oldUrl == newUrl)
+    return;
+
+  this.imageView_.changeUrl(newUrl);
+  this.ribbon_.remapCache(oldUrl, newUrl);
+
+  // Let the gallery know that the selected item url has changed.
+  cr.dispatchSimpleEvent(this, 'selection');
+};
+
+/**
+ * Flash 'Saved' label briefly to indicate that the image has been saved.
+ * @private
+ */
+SlideMode.prototype.flashSavedLabel_ = function() {
+  var setLabelHighlighted =
+      ImageUtil.setAttribute.bind(null, this.savedLabel_, 'highlighted');
+  setTimeout(setLabelHighlighted.bind(null, true), 0);
+  setTimeout(setLabelHighlighted.bind(null, false), 300);
+};
+
+/**
+ * Local storage key for the 'Overwrite original' setting.
+ * @type {string}
+ */
+SlideMode.OVERWRITE_KEY = 'gallery-overwrite-original';
+
+/**
+ * Local storage key for the number of times that
+ * the overwrite info bubble has been displayed.
+ * @type {string}
+ */
+SlideMode.OVERWRITE_BUBBLE_KEY = 'gallery-overwrite-bubble';
+
+/**
+ * Max number that the overwrite info bubble is shown.
+ * @type {number}
+ */
+SlideMode.OVERWRITE_BUBBLE_MAX_TIMES = 5;
+
+/**
+ * @return {boolean} True if 'Overwrite original' is set.
+ * @private
+ */
+SlideMode.prototype.shouldOverwriteOriginal_ = function() {
+  return SlideMode.OVERWRITE_KEY in localStorage &&
+      (localStorage[SlideMode.OVERWRITE_KEY] == 'true');
+};
+
+/**
+ * 'Overwrite original' checkbox handler.
+ * @param {Event} event Event.
+ * @private
+ */
+SlideMode.prototype.onOverwriteOriginalClick_ = function(event) {
+  localStorage['gallery-overwrite-original'] = event.target.checked;
+};
+
+/**
+ * Overwrite info bubble close handler.
+ * @private
+ */
+SlideMode.prototype.onCloseBubble_ = function() {
+  this.bubble_.hidden = true;
+  localStorage[SlideMode.OVERWRITE_BUBBLE_KEY] =
+      SlideMode.OVERWRITE_BUBBLE_MAX_TIMES;
+};
+
+/**
+ * Callback called when the image is edited.
+ * @private
+ */
+SlideMode.prototype.onImageContentChanged_ = function() {
+  var revision = this.imageView_.getContentRevision();
+  if (revision == 0) {
+    // Just loaded.
+    var times = SlideMode.OVERWRITE_BUBBLE_KEY in localStorage ?
+        parseInt(localStorage[SlideMode.OVERWRITE_BUBBLE_KEY], 10) : 0;
+    if (times < SlideMode.OVERWRITE_BUBBLE_MAX_TIMES) {
+      this.bubble_.hidden = false;
+      if (this.isEditing()) {
+        localStorage[SlideMode.OVERWRITE_BUBBLE_KEY] = times + 1;
+      }
+    }
+  }
+
+  if (revision == 1) {
+    // First edit.
+    ImageUtil.setAttribute(this.options_, 'saved', true);
+    ImageUtil.metrics.recordUserAction(ImageUtil.getMetricName('Edit'));
+  }
+};
+
+// Misc
+
+/**
+ * Start/stop the slide show.
+ * @private
+ */
+SlideMode.prototype.toggleSlideshow_ = function() {
+  if (this.slideShowTimeout_) {
+    clearInterval(this.slideShowTimeout_);
+    this.slideShowTimeout_ = null;
+  } else {
+    var self = this;
+    function nextSlide() {
+      self.selectNext(1,
+          function() { self.slideShowTimeout_ = setTimeout(nextSlide, 5000) });
+    }
+    nextSlide();
+  }
+};
+
+/**
+ * @return {boolean} True if the editor is active.
+ */
+SlideMode.prototype.isEditing = function() {
+  return this.container_.hasAttribute('editing');
+};
+
+/**
+ * Activate/deactivate editor.
+ * @private
+ */
+SlideMode.prototype.onEdit_ = function() {
+  if (!this.isEditing() && this.isShowingVideo_())
+    return;  // No editing for videos.
+
+  ImageUtil.setAttribute(this.container_, 'editing', !this.isEditing());
+
+  if (this.isEditing()) { // isEditing_ has just been flipped to a new value.
+    if (this.context_.readonlyDirName) {
+      this.editor_.getPrompt().showAt(
+          'top', 'readonly_warning', 0, this.context_.readonlyDirName);
+    }
+  } else {
+    this.editor_.getPrompt().hide();
+  }
+
+  ImageUtil.setAttribute(this.editButton_, 'pressed', this.isEditing());
+
+  cr.dispatchSimpleEvent(this, 'edit');
+};
+
+/**
+ * Display the error banner.
+ * @param {string} message Message.
+ * @private
+ */
+SlideMode.prototype.showErrorBanner_ = function(message) {
+  if (message) {
+    this.errorBanner_.textContent = this.displayStringFunction_(message);
+  }
+  ImageUtil.setAttribute(this.container_, 'error', !!message);
+};
+
+/**
+ * Show/hide the busy spinner.
+ *
+ * @param {boolean} on True if show, false if hide.
+ * @private
+ */
+SlideMode.prototype.showSpinner_ = function(on) {
+  if (this.spinnerTimer_) {
+    clearTimeout(this.spinnerTimer_);
+    this.spinnerTimer_ = null;
+  }
+
+  if (on) {
+    this.spinnerTimer_ = setTimeout(function() {
+      this.spinnerTimer_ = null;
+      ImageUtil.setAttribute(this.container_, 'spinner', true);
+    }.bind(this), 1000);
+  } else {
+    ImageUtil.setAttribute(this.container_, 'spinner', false);
+  }
+};
+
+/**
+ * @return {boolean} True if the current item is a video.
+ * @private
+ */
+SlideMode.prototype.isShowingVideo_ = function() {
+  return !!this.imageView_.getVideo();
+};
+
+/**
+ * Save the current video position.
+ * @private
+ */
+SlideMode.prototype.saveVideoPosition_ = function() {
+  if (this.isShowingVideo_() && this.mediaControls_.isPlaying()) {
+    this.mediaControls_.savePosition();
+  }
+};
+
+/**
+ * Overlay that handles swipe gestures. Changes to the next or previous file.
+ * @param {function(number)} callback A callback accepting the swipe direction
+ *    (1 means left, -1 right).
+ * @constructor
+ * @implements {ImageBuffer.Overlay}
+ */
+function SwipeOverlay(callback) {
+  this.callback_ = callback;
+}
+
+/**
+ * Inherit ImageBuffer.Overlay.
+ */
+SwipeOverlay.prototype.__proto__ = ImageBuffer.Overlay.prototype;
+
+/**
+ * @param {number} x X pointer position.
+ * @param {number} y Y pointer position.
+ * @param {boolean} touch True if dragging caused by touch.
+ * @return {function} The closure to call on drag.
+ */
+SwipeOverlay.prototype.getDragHandler = function(x, y, touch) {
+  if (!touch)
+    return null;
+  var origin = x;
+  var done = false;
+  return function(x, y) {
+    if (!done && origin - x > SwipeOverlay.SWIPE_THRESHOLD) {
+      this.callback_(1);
+      done = true;
+    } else if (!done && x - origin > SwipeOverlay.SWIPE_THRESHOLD) {
+      this.callback_(-1);
+      done = true;
+    }
+  }.bind(this);
+};
+
+/**
+ * If the user touched the image and moved the finger more than SWIPE_THRESHOLD
+ * horizontally it's considered as a swipe gesture (change the current image).
+ */
+SwipeOverlay.SWIPE_THRESHOLD = 100;