From 115f352ade7fbe133a42fd434dbcc1fca13287a7 Mon Sep 17 00:00:00 2001
From: Albin Larsson <mail@albinlarsson.com>
Date: Fri, 15 Jun 2018 23:56:47 +0200
Subject: Respect call order and prioritize public API calls for setting
 poster, in order to avoid race conditions

---
 src/js/ui.js | 63 +++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 37 insertions(+), 26 deletions(-)

(limited to 'src/js/ui.js')

diff --git a/src/js/ui.js b/src/js/ui.js
index 285739a7..5d7a6ae3 100644
--- a/src/js/ui.js
+++ b/src/js/ui.js
@@ -8,7 +8,7 @@ import i18n from './i18n';
 import support from './support';
 import browser from './utils/browser';
 import { getElement, toggleClass, toggleState } from './utils/elements';
-import { triggerEvent } from './utils/events';
+import { ready, triggerEvent } from './utils/events';
 import is from './utils/is';
 import loadImage from './utils/loadImage';
 
@@ -109,8 +109,8 @@ const ui = {
         ui.setTitle.call(this);
 
         // Assure the poster image is set, if the property was added before the element was created
-        if (this.poster && this.elements.poster && !this.elements.poster.style.backgroundImage) {
-            ui.setPoster.call(this, this.poster);
+        if (this.poster) {
+            ui.setPoster.call(this, this.poster, false).catch(() => {});
         }
 
         // Manually set the duration if user has overridden it.
@@ -163,32 +163,43 @@ const ui = {
     },
 
     // Set the poster image (async)
-    setPoster(poster) {
-        // Set property regardless of validity
-        this.media.setAttribute('poster', poster);
-
-        // Bail if element is missing
-        if (!is.element(this.elements.poster)) {
-            return Promise.reject();
+    // Used internally for the poster setter, with the passive option forced to false
+    setPoster(poster, passive = true) {
+        // Don't override if call is passive
+        if (passive && this.poster) {
+            return Promise.reject(new Error('Poster already set'));
         }
 
-        // Load the image, and set poster if successful
-        const loadPromise = loadImage(poster).then(() => {
-            this.elements.poster.style.backgroundImage = `url('${poster}')`;
-            Object.assign(this.elements.poster.style, {
-                backgroundImage: `url('${poster}')`,
-                // Reset backgroundSize as well (since it can be set to "cover" for padded thumbnails for youtube)
-                backgroundSize: '',
-            });
-            ui.togglePoster.call(this, true);
-            return poster;
-        });
-
-        // Hide the element if the poster can't be loaded (otherwise it will just be a black element covering the video)
-        loadPromise.catch(() => ui.togglePoster.call(this, false));
+        // Set property synchronously to respect the call order
+        this.media.setAttribute('poster', poster);
 
-        // Return the promise so the caller can use it as well
-        return loadPromise;
+        // Wait until ui is ready
+        return ready.call(this)
+            // Load image
+            .then(() => loadImage(poster))
+            .catch(err => {
+                // Hide poster on error unless it's been set by another call
+                if (poster === this.poster) {
+                    ui.togglePoster.call(this, false);
+                }
+                // Rethrow
+                throw err;
+            })
+            .then(() => {
+                // Prevent race conditions
+                if (poster !== this.poster) {
+                    throw new Error('setPoster cancelled by later call to setPoster');
+                }
+            })
+            .then(() => {
+                Object.assign(this.elements.poster.style, {
+                    backgroundImage: `url('${poster}')`,
+                    // Reset backgroundSize as well (since it can be set to "cover" for padded thumbnails for youtube)
+                    backgroundSize: '',
+                });
+                ui.togglePoster.call(this, true);
+                return poster;
+            });
     },
 
     // Check playing state
-- 
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