WPF Mediaelement.Position无法正常工作 [英] WPF Mediaelement.Position is not working

问题描述

我需要在WPF的 MediaElement 控件上设置 Position 属性.但是，当我播放视频(通过 Play()或通过 Opacity 上的某种动画)播放时，它根本无法工作.它显示的是00:00:00时间，但我希望将其设置为00:00:05.

What I need is to set the Position property on WPF's MediaElement control. But when I play the video, (either via Play() or through some kind of animation on Opacity) it is is not working at all. It is showing 00:00:00 time, but I would expect it to be set to 00:00:05.

我有一个硬编码的Position值，它根本不起作用.

I have hard-coded Position value and it is not working at all.

以防万一我要把所有的代码都放进去，以便您可以看到整个动画逻辑.

Just In case I am going to put all my code I have so u can see the whole animation logic.

有任何线索吗?

  public partial class CrossFadeTransition : UserControl
    {
        DoubleAnimation _doubleAnimationFrontPlayer = new DoubleAnimation();
        DoubleAnimation _doubleAnimationBackPlayer = new DoubleAnimation();

        Storyboard _sb1 = new Storyboard();
        Storyboard _sb2 = new Storyboard();

        public TimeSpan Duration = TimeSpan.FromSeconds(2);
        public Dictionary<string, Position2D> PlayerPosition { set; get; }

        public CrossFadeTransition()
        {
            InitializeComponent();

            Player1.LoadedBehavior = MediaState.Manual;
            Player1.UnloadedBehavior = MediaState.Stop;

            Player2.LoadedBehavior = MediaState.Manual;
            Player2.UnloadedBehavior = MediaState.Stop;

            PlayerPosition = new Dictionary<string, Position2D>();

            PlayerPosition.Add("Player1", Position2D.Front);
            PlayerPosition.Add("Player2", Position2D.Back);

        }
        Position2D positionPlayer1;
        Position2D positionPlayer2;

        public void Stop()
        {
            if (Player1.IsEnabled)
                Player1.Stop();

            if (Player2.IsEnabled)
                Player2.Stop();

        }

        public void Start(Uri uri, int? position)
        {
            try
            {
                positionPlayer1 = PlayerPosition["Player1"];

                positionPlayer2 = PlayerPosition["Player2"];

                if (positionPlayer1 == Library.Position2D.Back)
                {
                    Player1.Source = uri;
                    if (Player1.IsEnabled)
                        Player1.Stop();

                    Player1.Position = TimeSpan.FromSeconds(5); // IT IS NOT WORKING !!!

                    Player1.Play();

                }

                if (positionPlayer2 == Library.Position2D.Back)
                {
                    Player2.Source = uri;
                    if (Player2.IsEnabled)
                        Player2.Stop();

                    Player2.Position = TimeSpan.FromSeconds(5); // IT IS NOT WORKING !!!

                    Player2.Play();

                }



                _sb1.Children.Clear();
                _sb2.Children.Clear();



                if (positionPlayer1 == Position2D.Front)
                {
                    _doubleAnimationFrontPlayer.From = 1;
                    _doubleAnimationFrontPlayer.To = 0;
                    _doubleAnimationFrontPlayer.Duration = new Duration(Duration);

                    PlayerPosition["Player1"] = Position2D.Back;
                }
                else if (positionPlayer1 == Position2D.Back)
                {
                    _doubleAnimationFrontPlayer.From = 0;
                    _doubleAnimationFrontPlayer.To = 1;
                    _doubleAnimationFrontPlayer.Duration = new Duration(Duration);

                    PlayerPosition["Player1"] = Position2D.Front;
                }

                if (positionPlayer2 == Position2D.Front)
                {
                    _doubleAnimationBackPlayer.From = 1;
                    _doubleAnimationBackPlayer.To = 0;
                    _doubleAnimationBackPlayer.Duration = new Duration(Duration);

                    PlayerPosition["Player2"] = Position2D.Back;
                }
                else if (positionPlayer2 == Position2D.Back)
                {
                    _doubleAnimationBackPlayer.From = 0;
                    _doubleAnimationBackPlayer.To = 1;
                    _doubleAnimationBackPlayer.Duration = new Duration(Duration);

                    PlayerPosition["Player2"] = Position2D.Front;
                }

                _sb1.Children.Add(_doubleAnimationFrontPlayer);
                Storyboard.SetTargetProperty(_doubleAnimationFrontPlayer, new PropertyPath("(Panel.Opacity)"));
                Storyboard.SetTarget(_doubleAnimationFrontPlayer, Player1);
                _sb1.Completed += _sb1_Completed;
                _sb1.Begin();

                //
                _sb2.Children.Add(_doubleAnimationBackPlayer);
                Storyboard.SetTargetProperty(_doubleAnimationBackPlayer, new PropertyPath("(Panel.Opacity)"));
                Storyboard.SetTarget(_doubleAnimationBackPlayer, Player2);
                _sb2.Completed += _sb2_Completed;
                _sb2.Begin();

            }
            catch (Exception)
            {

                throw;
            }
        }

        void _sb2_Completed(object sender, EventArgs e)
        {
            _sb2.Completed -= _sb2_Completed;

            Debug.WriteLine("Player2 COMPLETED " + DateTime.Now.TimeOfDay);

            if (positionPlayer2 == Position2D.Front)
            {
                Player2.Stop();
            }
        }

        void _sb1_Completed(object sender, EventArgs e)
        {
            _sb1.Completed -= _sb1_Completed;

            Debug.WriteLine("Player1 COMPLETED " + DateTime.Now.TimeOfDay);
            if (positionPlayer1 == Position2D.Front)
            {
                Player1.Stop();
            }
        }
    }

我试图做喜欢的人

Player2.Play();
Player2.Pause();
Player2.Position = TimeSpan.FromSeconds(5); // IT IS NOT WORKING !!!
Player2.Play();

但没有喜悦...

推荐答案

我找到了一些解决方案.这并不完全理想，因为有时会显示第一个视频帧，但至少可以正常工作.

I found some solution. It is not completely ideal because sometimes it shows the first video frame, but at least it is working.

1. 我们需要可以在其中应用新的 Position 的事件.

void Player2_MediaOpened(object sender, RoutedEventArgs e)
{
     Player2.Position = new TimeSpan(0, 0, 7);
}

void Player1_MediaOpened(object sender, RoutedEventArgs e)
{
    Player1.Position = new TimeSpan(0, 0, 7);
}

我们必须像这样关闭 Mediaelement .

Player1.Stop();
Player1.Close();
Player1.Source = uri;
Player1.Play();

玩得开心！(啤酒)

这篇关于WPF Mediaelement.Position无法正常工作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！