Added preview thumbnails setter & fixed cannot set property 'hover' of null (#2256)

* added iPad to isIos

* elements.controls can be null

* elements.controls can be null

* added previewThumbnails setter

* fixed readme formatting

* previewThumbnails setter to method

src/js/listeners.js

@@ -841,7 +841,9 @@ class Listeners {
         .filter((c) => !c.contains(elements.container))
         .forEach((child) => {
           this.bind(child, 'mouseenter mouseleave', (event) => {
-            elements.controls.hover = !player.touch && event.type === 'mouseenter';
+            if (elements.controls) {
+              elements.controls.hover = !player.touch && event.type === 'mouseenter';
+            }
           });
         });
     }

src/js/plyr.d.ts

@@ -211,6 +211,11 @@ declare class Plyr {
    */
   airplay(): void;
 
+  /**
+   * Sets the preview thubmnails for the current source.
+   */
+  setPreviewThumbnails(source: Plyr.PreviewThumbnailsOptions): void;
+
   /**
    * Toggle the controls (video only). Takes optional truthy value to force it on/off.
    */
@@ -619,6 +624,11 @@ declare namespace Plyr {
      * Booleans are converted to HTML5 value-less attributes.
      */
     tracks?: Track[];
+
+    /**
+     * Enable or disable preview thumbnails for current source
+     */
+    previewThumbnails?: Plyr.PreviewThumbnailsOptions;
   }
 
   interface Source {

src/js/plyr.js

@@ -1030,6 +1030,23 @@ class Plyr {
     return this.media === document.pictureInPictureElement;
   }
 
+  /**
+   * Sets the preview thubmnails for the current source
+   */
+  setPreviewThumbnails(thumbnailSource) {
+    if (this.previewThumbnails && this.previewThumbnails.loaded) {
+      this.previewThumbnails.destroy();
+      this.previewThumbnails = null;
+    }
+
+    Object.assign(this.config.previewThumbnails, thumbnailSource);
+
+    // Create new instance if it is still enabled
+    if (this.config.previewThumbnails.enabled) {
+      this.previewThumbnails = new PreviewThumbnails(this);
+    }
+  }
+
   /**
    * Trigger the airplay dialog
    * TODO: update player with state, support, enabled