Fix media player stuttering

Only call setPosition() on the QMediaPlayer object when the user has manually
dragged the slider position slider.

Otherwise the slider and player will call each other, probably causing a
feedback loop which causes stuttering.

src/widgets/mediaplayer.cpp

@@ -18,7 +18,8 @@ MediaPlayer::MediaPlayer(QWidget *parent) :
     QWidget(parent),
     ui(new Ui::MediaPlayer),
     media_stream(),
-    player()
+    player(),
+    manual_seek(false)
 {
     ui->setupUi(this);
 
@@ -51,7 +52,9 @@ MediaPlayer::MediaPlayer(QWidget *parent) :
 
     connect(&this->player, &QMediaPlayer::positionChanged, this, &MediaPlayer::on_media_positionChanged);
 
-    connect(this->ui->media_progress, &QSlider::valueChanged, &this->player, &QMediaPlayer::setPosition);
+    connect(this->ui->media_progress, &QSlider::valueChanged, this, &MediaPlayer::on_seekChanged);
+    connect(this->ui->media_progress, &QSlider::sliderPressed, this, &MediaPlayer::on_seekPressed);
+    connect(this->ui->media_progress, &QSlider::sliderReleased, this, &MediaPlayer::on_seekReleased);
 }
 
 MediaPlayer::~MediaPlayer()
@@ -132,3 +135,20 @@ void MediaPlayer::on_media_playbackChanged(QMediaPlayer::PlaybackState status)
     );
 }
 #endif
+
+void MediaPlayer::on_seekChanged(qint64 pos)
+{
+    if (this->manual_seek) {
+        player.setPosition(pos);
+    }
+}
+
+void MediaPlayer::on_seekPressed()
+{
+    this->manual_seek = true;
+}
+
+void MediaPlayer::on_seekReleased()
+{
+    this->manual_seek = false;
+}

src/widgets/mediaplayer.hpp

@@ -28,6 +28,10 @@ private slots:
 
     void on_mute_button_clicked(bool checked);
 
+    void on_seekChanged(qint64 pos);
+    void on_seekPressed();
+    void on_seekReleased();
+
 private: // slots
     void on_media_positionChanged(qint64 pos);
 
@@ -42,6 +46,7 @@ private:
     QBuffer media_stream;
     QString mime;
     QMediaPlayer player;
+    bool manual_seek;
 };
 
 #endif // MEDIAPLAYER_HPP