Xamarin Forms Video Player（Native）

Question

您好，我通过此链接开发了xamarin媒体播放器，它的运行非常完美https://docs.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/custom-renderer/video-player/但是我想知道当用户更改搜索栏的位置时如何捕获事件。请帮助

提前感谢

Answer 1

在Android中

由于MediaController中使用VideoPlayerRenderer.cs的链接的演示，MediaController不提供有关ScrollChangeListener的方法。https://developer.android.com/reference/android/widget/MediaController#public-methods

通常，我们应该为SeekBar创建一个自定义VideoView，然后添加ScrollChangeListener。

因为创建自定义SeekBar有点复杂，我们可以使用context.Resources.GetIdentifier("mediacontroller_progress", "id", "android");通过ID获取SeekBar的mediacontroller，然后也设置SetOnSeekBarChangeListener。

        int seekbarId = context.Resources.GetIdentifier("mediacontroller_progress", "id", "android");
        SeekBar seekBar = mediaController.FindViewById<SeekBar>(seekbarId);
        seekBar.SetOnSeekBarChangeListener(new MySeekBarChangeListener());

请注意：SeekBar的实例化必须在VideoView.onPrepared（..）回调方法中进行。

这里正在运行GIF。

这里是关于VideoPlayerRenderer的所有代码

[assembly: ExportRenderer(typeof(FormsVideoLibrary.VideoPlayer),
                          typeof(FormsVideoLibrary.Droid.VideoPlayerRenderer))]

namespace FormsVideoLibrary.Droid
{
    public class VideoPlayerRenderer : ViewRenderer<VideoPlayer, ARelativeLayout>
    {
        VideoView videoView;
        MediaController mediaController;    // Used to display transport controls
        bool isPrepared;
        Context context;
        public VideoPlayerRenderer(Context context) : base(context)
        {
           this.context = context;
        }

        protected override void OnElementChanged(ElementChangedEventArgs<VideoPlayer> args)
        {
            base.OnElementChanged(args);

            if (args.NewElement != null)
            {
                if (Control == null)
                {
                    // Save the VideoView for future reference
                    videoView = new VideoView(Context);

                    // Put the VideoView in a RelativeLayout
                    ARelativeLayout relativeLayout = new ARelativeLayout(Context);
                    relativeLayout.AddView(videoView);

                    // Center the VideoView in the RelativeLayout
                    ARelativeLayout.LayoutParams layoutParams =
                        new ARelativeLayout.LayoutParams(LayoutParams.MatchParent, LayoutParams.MatchParent);
                    layoutParams.AddRule(LayoutRules.CenterInParent);
                    videoView.LayoutParameters = layoutParams;

                    // Handle a VideoView event
                    videoView.Prepared += OnVideoViewPrepared;


                    SetNativeControl(relativeLayout);
                }

                SetAreTransportControlsEnabled();
                SetSource();

                args.NewElement.UpdateStatus += OnUpdateStatus;
                args.NewElement.PlayRequested += OnPlayRequested;
                args.NewElement.PauseRequested += OnPauseRequested;
                args.NewElement.StopRequested += OnStopRequested;
            }

            if (args.OldElement != null)
            {
                args.OldElement.UpdateStatus -= OnUpdateStatus;
                args.OldElement.PlayRequested -= OnPlayRequested;
                args.OldElement.PauseRequested -= OnPauseRequested;
                args.OldElement.StopRequested -= OnStopRequested;
            }
        }

        protected override void Dispose(bool disposing)
        {
            if (Control != null && videoView != null)
            {
                videoView.Prepared -= OnVideoViewPrepared;
            }
            if (Element != null)
            {
                Element.UpdateStatus -= OnUpdateStatus;
            }

            base.Dispose(disposing);
        }

        void OnVideoViewPrepared(object sender, EventArgs args)
        {
            isPrepared = true;

            int seekbarId = context.Resources.GetIdentifier("mediacontroller_progress", "id", "android");
            SeekBar seekBar = mediaController.FindViewById<SeekBar>(seekbarId);
            seekBar.SetOnSeekBarChangeListener(new MySeekBarChangeListener());
            ((IVideoPlayerController)Element).Duration = TimeSpan.FromMilliseconds(videoView.Duration);


        }

        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs args)
        {
            base.OnElementPropertyChanged(sender, args);

            if (args.PropertyName == VideoPlayer.AreTransportControlsEnabledProperty.PropertyName)
            {
                SetAreTransportControlsEnabled();
            }
            else if (args.PropertyName == VideoPlayer.SourceProperty.PropertyName)
            {
                SetSource();
            }
            else if (args.PropertyName == VideoPlayer.PositionProperty.PropertyName)
            {
                if (Math.Abs(videoView.CurrentPosition - Element.Position.TotalMilliseconds) > 1000)
                {
                    videoView.SeekTo((int)Element.Position.TotalMilliseconds);
                }
            }
        }

        void SetAreTransportControlsEnabled()
        {
            if (Element.AreTransportControlsEnabled)
            {
                mediaController = new MediaController(Context);


                mediaController.SetMediaPlayer(videoView);

                videoView.SetMediaController(mediaController);
            }
            else
            {
                videoView.SetMediaController(null);

                if (mediaController != null)
                {
                    mediaController.SetMediaPlayer(null);
                    mediaController = null;
                }
            }
        }



        void SetSource()
        {
            isPrepared = false;
            bool hasSetSource = false;

            if (Element.Source is UriVideoSource)
            {
                string uri = (Element.Source as UriVideoSource).Uri;

                if (!String.IsNullOrWhiteSpace(uri))
                {
                    videoView.SetVideoURI(Android.Net.Uri.Parse(uri));
                    hasSetSource = true;
                }
            }
            else if (Element.Source is FileVideoSource)
            {
                string filename = (Element.Source as FileVideoSource).File;

                if (!String.IsNullOrWhiteSpace(filename))
                {
                    videoView.SetVideoPath(filename);
                    hasSetSource = true;
                }
            }
            else if (Element.Source is ResourceVideoSource)
            {
                string package = Context.PackageName;
                string path = (Element.Source as ResourceVideoSource).Path;

                if (!String.IsNullOrWhiteSpace(path))
                {
                    string filename = Path.GetFileNameWithoutExtension(path).ToLowerInvariant();
                    string uri = "android.resource://" + package + "/raw/" + filename;
                    videoView.SetVideoURI(Android.Net.Uri.Parse(uri));
                    hasSetSource = true;
                }
            }

            if (hasSetSource && Element.AutoPlay)
            {
                videoView.Start();
            }
        }

        // Event handler to update status
        void OnUpdateStatus(object sender, EventArgs args)
        {
            VideoStatus status = VideoStatus.NotReady;

            if (isPrepared)
            {
                status = videoView.IsPlaying ? VideoStatus.Playing : VideoStatus.Paused;
            }

            ((IVideoPlayerController)Element).Status = status;

            // Set Position property
            TimeSpan timeSpan = TimeSpan.FromMilliseconds(videoView.CurrentPosition);
            ((IElementController)Element).SetValueFromRenderer(VideoPlayer.PositionProperty, timeSpan);
        }

        // Event handlers to implement methods
        void OnPlayRequested(object sender, EventArgs args)
        {
            videoView.Start();
        }

        void OnPauseRequested(object sender, EventArgs args)
        {
            videoView.Pause();
        }

        void OnStopRequested(object sender, EventArgs args)
        {
            videoView.StopPlayback();
        }
    }



    internal class MySeekBarChangeListener : Java.Lang.Object, SeekBar.IOnSeekBarChangeListener
    {
        public void OnProgressChanged(SeekBar seekBar, int progress, bool fromUser)
        {
            var on = "ss";

        }

        public void OnStartTrackingTouch(SeekBar seekBar)
        {
            var on = "ss";

        }

        public void OnStopTrackingTouch(SeekBar seekBar)
        {

        }
      }
    }