From 5cec7f8f1e9e5cd18f9128a38c3f329da5c7bea3 Mon Sep 17 00:00:00 2001
From: Omar Roth <omarroth@protonmail.com>
Date: Mon, 27 May 2019 20:27:20 -0500
Subject: [PATCH] Cache sprites on request

---
 src/plugin.js | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/plugin.js b/src/plugin.js
index 64a9cd4..b742582 100644
--- a/src/plugin.js
+++ b/src/plugin.js
@@ -5,6 +5,9 @@ import { version as VERSION } from '../package.json'
 // Default options for the plugin.
 const defaults = {}
 
+// Cache for image elements
+var cache = {}
+
 // Cross-compatibility for Video.js 5 and 6.
 const registerPlugin = videojs.registerPlugin || videojs.plugin
 // const dom = videojs.dom || videojs;
@@ -207,6 +210,13 @@ class vttThumbnailsPlugin {
     for (let i = 0; i < this.vttData.length; ++i) {
       let item = this.vttData[i]
       if (time >= item.start && time < item.end) {
+        // Cache miss
+        if (item.css.url && !cache[item.css.url]) {
+          let image = new Image();
+          image.src = item.css.url;
+          cache[item.css.url] = image;
+        }
+
         return item.css
       }
     }
@@ -333,6 +343,7 @@ class vttThumbnailsPlugin {
     cssObj.background = 'url("' + imageProps.image + '") no-repeat -' + imageProps.x + 'px -' + imageProps.y + 'px'
     cssObj.width = imageProps.w + 'px'
     cssObj.height = imageProps.h + 'px'
+    cssObj.url = imageProps.image
 
     return cssObj
   }