From 4a1fab93965854e6150f0575f4a811a1be790a14 Mon Sep 17 00:00:00 2001
From: Ben Wiley <therealbenwiley@gmail.com>
Date: Mon, 25 Feb 2019 21:39:31 -0500
Subject: [PATCH] Fixes to help avoid progressbar jumping around during track
 load.

---
 packages/core/src/PlayerContextProvider.js    | 56 +++++++++++--------
 packages/core/src/utils/getInitialDuration.js | 15 +++++
 2 files changed, 48 insertions(+), 23 deletions(-)
 create mode 100644 packages/core/src/utils/getInitialDuration.js

diff --git a/packages/core/src/PlayerContextProvider.js b/packages/core/src/PlayerContextProvider.js
index 6b859c80..b236de3d 100644
--- a/packages/core/src/PlayerContextProvider.js
+++ b/packages/core/src/PlayerContextProvider.js
@@ -17,7 +17,7 @@ import getRepeatStrategy from './utils/getRepeatStrategy';
 import convertToNumberWithinIntervalBounds from './utils/convertToNumberWithinIntervalBounds';
 import { logError, logWarning } from './utils/console';
 import getDisplayText from './utils/getDisplayText';
-import parseTimeString from './utils/parseTimeString';
+import getInitialDuration from './utils/getInitialDuration';
 import { repeatStrategyOptions } from './constants';
 
 function playErrorHandler(err) {
@@ -90,16 +90,8 @@ function getGoToTrackState({
   const isNewTrack = prevState.activeTrackIndex !== index;
   const shouldLoadAsNew = Boolean(isNewTrack || shouldForceLoad);
   const currentTime = track.startingTime || 0;
-  let duration = 0;
-  if (track.duration) {
-    if (typeof track.duration === 'string') {
-      duration = parseTimeString(track.duration);
-    } else {
-      duration = track.duration;
-    }
-  }
   return {
-    duration,
+    duration: getInitialDuration(track),
     activeTrackIndex: index,
     trackLoading: shouldLoadAsNew,
     mediaCannotPlay: prevState.mediaCannotPlay && !shouldLoadAsNew,
@@ -123,7 +115,8 @@ export class PlayerContextProvider extends Component {
       props.startingTrackIndex,
       0
     );
-    if (isPlaylistValid(props.playlist) && props.playlist[activeTrackIndex]) {
+    const playlistIsValid = isPlaylistValid(props.playlist);
+    if (playlistIsValid && props.playlist[activeTrackIndex]) {
       currentTime = props.playlist[activeTrackIndex].startingTime || 0;
     }
     const { initialStateSnapshot } = props;
@@ -165,9 +158,12 @@ export class PlayerContextProvider extends Component {
       // true if user is currently dragging mouse to change the volume
       setVolumeInProgress: false,
       // initialize shouldRequestPlayOnNextUpdate from autoplay prop
-      shouldRequestPlayOnNextUpdate:
-        props.autoplay && isPlaylistValid(props.playlist),
+      shouldRequestPlayOnNextUpdate: props.autoplay && playlistIsValid,
       awaitingForceLoad: false,
+      // duration might be set on track object
+      duration: getInitialDuration(
+        playlistIsValid && props.playlist[activeTrackIndex]
+      ),
       // playlist prop copied to state (for getDerivedStateFromProps)
       __playlist__: props.playlist,
       // load overrides from previously-captured state snapshot
@@ -725,10 +721,12 @@ export class PlayerContextProvider extends Component {
   handleMediaTimeupdate() {
     const { currentTime, played } = this.media;
     const { onTimeUpdate, playlist } = this.props;
-    const { activeTrackIndex } = this.state;
-    if (this.state.trackLoading) {
-      // correct currentTime to preset, if applicable, during load
-      this.media.currentTime = this.state.currentTime;
+    const { activeTrackIndex, trackLoading } = this.state;
+    if (trackLoading) {
+      // we'll get another time update when the track loads
+      // but for now this helps us avoid unnecessarily
+      // jumping back to currentTime: 0 in the UI while
+      // the track is loading.
       return;
     }
     this.setState(state => ({
@@ -925,9 +923,12 @@ export class PlayerContextProvider extends Component {
           ...baseStateUpdate,
           awaitingResumeOnSeekComplete: paused
             ? awaitingResumeOnSeekComplete
-            : true
+            : true,
+          currentTime: targetTime
         }));
-        this.media.currentTime = targetTime;
+        if (!this.state.trackLoading) {
+          this.media.currentTime = targetTime;
+        }
         if (!this.state.paused) {
           this.togglePause(true);
         }
@@ -937,9 +938,12 @@ export class PlayerContextProvider extends Component {
           ...baseStateUpdate,
           awaitingResumeOnSeekComplete: paused
             ? awaitingResumeOnSeekComplete
-            : true
+            : true,
+          currentTime: targetTime
         }));
-        this.media.currentTime = targetTime;
+        if (!this.state.trackLoading) {
+          this.media.currentTime = targetTime;
+        }
         if (this.state.awaitingResumeOnSeekComplete && !this.media.ended) {
           // if we earlier encountered an 'ended' state,
           // un-pausing becomes necessary to resume playback
@@ -953,7 +957,11 @@ export class PlayerContextProvider extends Component {
   }
 
   seekComplete(targetTime) {
-    const { seekPreviewTime, awaitingResumeOnSeekComplete } = this.state;
+    const {
+      seekPreviewTime,
+      awaitingResumeOnSeekComplete,
+      trackLoading
+    } = this.state;
     const baseStateUpdate = {
       seekInProgress: false,
       awaitingResumeOnSeekComplete: false
@@ -974,7 +982,9 @@ export class PlayerContextProvider extends Component {
        */
       currentTime
     });
-    this.media.currentTime = currentTime;
+    if (!trackLoading) {
+      this.media.currentTime = currentTime;
+    }
     if (awaitingResumeOnSeekComplete) {
       if (this.media.ended) {
         this.forwardSkip();
diff --git a/packages/core/src/utils/getInitialDuration.js b/packages/core/src/utils/getInitialDuration.js
new file mode 100644
index 00000000..df308563
--- /dev/null
+++ b/packages/core/src/utils/getInitialDuration.js
@@ -0,0 +1,15 @@
+import parseTimeString from './parseTimeString';
+
+function getInitialDuration(track) {
+  let duration = 0;
+  if (track.duration) {
+    if (typeof track.duration === 'string') {
+      duration = parseTimeString(track.duration);
+    } else {
+      duration = track.duration;
+    }
+  }
+  return duration;
+}
+
+export default getInitialDuration;