Disable edit and print button when there is no selection.

ui/file_manager/gallery/js/slide_mode.js

 // Copyright 2014 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.
 
 'use strict';
 
 /**
  * Slide mode displays a single image and has a set of controls to navigate
  * between the images and to edit an image.
  *
@@ skipping 179 matching lines @@
       util.createChild(this.container_, 'tool slideshow-toolbar');
   util.createChild(slideShowToolbar, 'slideshow-play').
       addEventListener('click', this.toggleSlideshowPause_.bind(this));
   util.createChild(slideShowToolbar, 'slideshow-end').
       addEventListener('click', this.stopSlideshow_.bind(this));
 
   // Editor.
 
   this.editButton_ = this.toolbar_.querySelector('button.edit');
   this.editButton_.title = this.displayStringFunction_('GALLERY_EDIT');
-  this.editButton_.setAttribute('disabled', '');  // Disabled by default.
+  this.editButton_.disabled = true;  // Disabled by default.
   this.editButton_.addEventListener('click', this.toggleEditor.bind(this));
 
   this.printButton_ = this.toolbar_.querySelector('button.print');
   this.printButton_.title = this.displayStringFunction_('GALLERY_PRINT');
-  this.printButton_.setAttribute('disabled', '');  // Disabled by default.
+  this.printButton_.disabled = true;  // Disabled by default.
   this.printButton_.addEventListener('click', this.print_.bind(this));
 
   this.editBarSpacer_ = this.toolbar_.querySelector('.edit-bar-spacer');
   this.editBarMain_ = util.createChild(this.editBarSpacer_, 'edit-main');
 
   this.editBarMode_ = util.createChild(this.container_, 'edit-modal');
   this.editBarModeWrapper_ = util.createChild(
       this.editBarMode_, 'edit-modal-wrapper dimmable');
   this.editBarModeWrapper_.hidden = true;
 
@@ skipping 131 matching lines @@
 
   this.viewport_.resetView();
   if (this.getItemCount_() === 0) {
     this.errorBanner_.clear();
     commitDone();
   } else {
     this.commitItem_(commitDone);
   }
 
   // Disable the slide-mode only buttons when leaving.
-  this.editButton_.setAttribute('disabled', '');
-  this.printButton_.setAttribute('disabled', '');
+  this.editButton_.disabled = true;
+  this.printButton_.disabled = true;
 
   // Disable touch operation.
   this.touchHandlers_.enabled = false;
 };
 
 
 /**
  * Execute an action when the editor is not busy.
  *
  * @param {function()} action Function to execute.
@@ skipping 59 matching lines @@
 };
 
 /**
  * Selection change handler.
  *
  * Commits the current image and displays the newly selected image.
  * @private
  */
 SlideMode.prototype.onSelection_ = function() {
   if (this.selectionModel_.selectedIndexes.length === 0)
-    return;  // Temporary empty selection.
+    return;  // Ignore temporary empty selection.
 
   // Forget the saved selection if the user changed the selection manually.
   if (!this.isSlideshowOn_())
     this.savedSelection_ = null;
 
   if (this.getSelectedIndex() === this.displayedIndex_)
     return;  // Do not reselect.
 
   this.commitItem_(this.loadSelectedItem_.bind(this));
 };
@@ skipping 125 matching lines @@
       // The next item is now at the same index as the removed one, so we need
       // to correct displayIndex_ so that loadSelectedItem_ does not think
       // we are re-selecting the same item (and does right-to-left slide-in
       // animation).
       this.displayedIndex_ = event.index - 1;
       this.select(event.index);
     } else if (this.dataModel_.length) {
       // Removed item is the rightmost, but there are more items.
       this.select(event.index - 1);  // Select the new last index.
     } else {
-      // No items left. Unload the image and show the banner.
+      // No items left. Unload the image, disable edit and print button, and
+      // show the banner.
       this.commitItem_(function() {
         this.unloadImage_();
+        this.printButton_.disabled = true;
+        this.editButton_.disabled = true;
         this.errorBanner_.show('GALLERY_NO_IMAGES');
       }.bind(this));
     }
   }.bind(this), 0);
 };
 
 /**
  * @param {number} direction -1 for left, 1 for right.
  * @return {number} Next index in the given direction, with wrapping.
  * @private
@@ skipping 113 matching lines @@
 
     var extIndex = entry.name.lastIndexOf('.');
     var ext = extIndex < 0 ? '' :
         entry.name.substr(extIndex + 1).toLowerCase();
     if (ext === 'jpeg') ext = 'jpg';
     ImageUtil.metrics.recordEnum(
         ImageUtil.getMetricName('FileType'), ext, ImageUtil.FILE_TYPES);
 
     // Enable or disable buttons for editing and printing.
     if (error) {
-      this.editButton_.setAttribute('disabled', '');
-      this.printButton_.setAttribute('disabled', '');
+      this.editButton_.disabled = true;
+      this.printButton_.disabled = true;
     } else {
-      this.editButton_.removeAttribute('disabled');
-      this.printButton_.removeAttribute('disabled');
+      this.editButton_.disabled = false;
+      this.printButton_.disabled = false;
     }
 
     // For once edited image, disallow the 'overwrite' setting change.
     ImageUtil.setAttribute(this.options_, 'saved',
         !this.getSelectedItem().isOriginal());
 
     chrome.storage.local.get(SlideMode.OVERWRITE_BUBBLE_KEY,
         function(values) {
           var times = values[SlideMode.OVERWRITE_BUBBLE_KEY] || 0;
           if (times < SlideMode.OVERWRITE_BUBBLE_MAX_TIMES) {
@@ skipping 114 matching lines @@
         break;
     }
     return true;  // Consume all keystrokes in the slideshow mode.
   }
 
   if (this.isEditing() && this.editor_.onKeyDown(event))
     return true;
 
   switch (keyID) {
     case 'Ctrl-U+0050':  // Ctrl+'p' prints the current image.
-      if (!this.printButton_.hasAttribute('disabled'))
+      if (!this.printButton_.disabled)
         this.print_();
       break;
 
     case 'U+0045':  // 'e' toggles the editor.
-      if (!this.editButton_.hasAttribute('disabled'))
+      if (!this.editButton_.disabled)
         this.toggleEditor(event);
       break;
 
     case 'U+001B':  // Escape
       if (this.isEditing()) {
         this.toggleEditor(event);
       } else if (this.viewport_.isZoomed()) {
         this.viewport_.resetView();
         this.touchHandlers_.stopOperation();
         this.imageView_.applyViewportChange();
@@ skipping 684 matching lines @@
 TouchHandler.prototype.onMouseWheel_ = function(event) {
   var viewport = this.slideMode_.getViewport();
   if (!this.enabled_ || !viewport.isZoomed())
     return;
   this.stopOperation();
   viewport.setOffset(
       viewport.getOffsetX() + event.wheelDeltaX,
       viewport.getOffsetY() + event.wheelDeltaY);
   this.slideMode_.applyViewportChange();
 };