Show notification that no preview is available if no previewer is found for a public link to a file

apps/files_sharing/css/public.css

 body { background:#ddd; }
 #header { position:fixed; top:0; left:0; right:0; z-index:100; height:2.5em; line-height:2.5em; padding:.5em; background:#1d2d44; -moz-box-shadow:0 0 10px rgba(0, 0, 0, .5), inset 0 -2px 10px #222; -webkit-box-shadow:0 0 10px rgba(0, 0, 0, .5), inset 0 -2px 10px #222; box-shadow:0 0 10px rgba(0, 0, 0, .5), inset 0 -2px 10px #222; }
 #details { color:#fff; }
-#download { margin-left:2em; font-weight:bold; color:#fff; }
-#preview { min-height:30em; margin:50px auto; border-bottom:1px solid #f8f8f8; background:#eee; text-align:center; }
+#header #download { margin-left:2em; font-weight:bold; color:#fff; }
+#preview { min-height:30em; margin:50px auto; padding-top:2em; border-bottom:1px solid #f8f8f8; background:#eee; text-align:center; }
+#noPreview { display:none; padding-top:5em; }
 p.info { width:22em; text-align: center; margin:2em auto; color:#777; text-shadow:#fff 0 1px 0; }
 p.info a { font-weight:bold; color:#777; }
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apps/files_sharing/js/public.js

@@ -11,7 +11,11 @@ $(document).ready(function() {
 		if (mimetype.substr(0, mimetype.indexOf('/')) != 'image') {
 			// Trigger default action if not download TODO
 			var action = FileActions.getDefault(mimetype, 'file', FileActions.PERMISSION_READ);
-			action($('#filename').val());
+			if (typeof action === 'undefined') {
+				$('#noPreview').show();
+			} else {
+				action($('#filename').val());
+			}
 		}
 	}
 

apps/files_sharing/templates/public.php

@@ -13,5 +13,11 @@
 	<?php if (substr($_['mimetype'], 0 , strpos($_['mimetype'], '/')) == 'image'): ?>
 		<img src="<?php echo $_['downloadURL']; ?>" />
 	<?php endif; ?>
+	<ul id="noPreview">
+		<li class="error">
+			<?php echo $l->t('No preview available for').' '.$_['filename']; ?><br />
+			<a href="<?php echo $_['downloadURL']; ?>" id="download"><img class="svg" alt="Download" src="<?php echo OCP\image_path("core", "actions/download.svg"); ?>" /><?php echo $l->t('Download')?></a>
+		</li>
+	</ul>
 </div>
 <footer><p class="info"><a href="http://owncloud.org/">ownCloud</a> &ndash; <?php echo $l->t('web services under your control'); ?></p></footer>
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