add subtitle

src/subtitle.js

@@ -3,6 +3,7 @@ import { errorHandle, getExt, setStyle } from './utils';
 export default class Subtitle {
   constructor(art) {
     this.art = art;
+    this.isShow = true;
 
     const { url } = this.art.option.subtitle;
     if (url) {
@@ -92,12 +93,14 @@ export default class Subtitle {
   show() {
     const { $subtitle } = this.art.refs;
     $subtitle.style.display = 'block';
+    this.isShow = true;
     this.art.emit('subtitle:show', $subtitle);
   }
 
   hide() {
     const { $subtitle } = this.art.refs;
     $subtitle.style.display = 'none';
+    this.isShow = false;
     this.art.emit('subtitle:hide', $subtitle);
   }