Gewusst wie: Steuern eines MediaElement (Wiedergeben, Anhalten, Stoppen, Lautstärke und Geschwindigkeit)

Im folgenden Beispiel wird gezeigt, wie Sie die Wiedergabe von Medien mithilfe eines MediaElement steuern. Im Beispiel wird ein einfacher Media Player erstellt, der es Ihnen ermöglicht, Medien wiederzugeben, zu beenden, anzuhalten und darin vor- und zurückzuspringen sowie die Lautstärke und Geschwindigkeit anzupassen.

Erstellen der Benutzeroberfläche

Der folgende Code erstellt die Benutzeroberfläche.

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  x:Class="SDKSample.MediaElementExample" >

  <StackPanel Background="Black">

    <!-- To interactively stop, pause, and play the media, the LoadedBehavior 
           property of the MediaElement must be set to "Manual". -->
    <MediaElement Source="media\numbers.wmv" Name="myMediaElement" 
     Width="450" Height="250" LoadedBehavior="Manual" UnloadedBehavior="Stop" Stretch="Fill" 
     MediaOpened="Element_MediaOpened" MediaEnded="Element_MediaEnded"/>
    
    <StackPanel HorizontalAlignment="Center" Width="450" Orientation="Horizontal">

      <!-- Play button. -->
      <Image Source="images\UI_play.gif" MouseDown="OnMouseDownPlayMedia" Margin="5" />

      <!-- Pause button. -->
      <Image Source="images\UI_pause.gif" MouseDown="OnMouseDownPauseMedia" Margin="5" />

      <!-- Stop button. -->
      <Image Source="images\UI_stop.gif" MouseDown="OnMouseDownStopMedia" Margin="5" />

      <!-- Volume slider. This slider allows a Volume range between 0 and 1. -->
      <TextBlock Foreground="White" VerticalAlignment="Center" Margin="5"  >Volume</TextBlock>
      <Slider Name="volumeSlider" VerticalAlignment="Center" ValueChanged="ChangeMediaVolume" 
       Minimum="0" Maximum="1" Value="0.5" Width="70"/>

      <!-- Volume slider. This slider allows you to change the speed of the media playback. -->
      <TextBlock Foreground="White" Margin="5"  VerticalAlignment="Center">Speed</TextBlock>
      <Slider Name="speedRatioSlider" VerticalAlignment="Center" ValueChanged="ChangeMediaSpeedRatio" 
       Value="1" Width="70" />
      
      <!-- Seek to slider. Ths slider allows you to jump to different parts of the media playback. -->
      <TextBlock Foreground="White" Margin="5"  VerticalAlignment="Center">Seek To</TextBlock>
      <Slider Name="timelineSlider" Margin="5" ValueChanged="SeekToMediaPosition" Width="70"/>

    </StackPanel>
  </StackPanel>
</Page>

Implementieren des Benutzeroberflächen-Steuerelements

Der folgende Code implementiert die Funktionalität der Steuerelement der Beispielbenutzeroberfläche. Die Methoden Play, Pause und Stop werden verwendet, um die Medien wiederzugeben, anzuhalten bzw. zu beenden. Das Ändern der Position-Eigenschaft des MediaElement ermöglicht Ihnen, in den Medien vor- und zurückzuspringen. Schließlich werden die Eigenschaften Volume und SpeedRatio verwendet, um die Lautstärke und Wiedergabegeschwindigkeit der Medien anzupassen.

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Windows.Data;
using System.Windows.Media;
using System.Windows.Input;

namespace SDKSample
{

   public partial class MediaElementExample : Page
   {

      // Play the media.
      void OnMouseDownPlayMedia(object sender, MouseButtonEventArgs args)
      {

         // The Play method will begin the media if it is not currently active or
         // resume media if it is paused. This has no effect if the media is
         // already running.
         myMediaElement.Play();

         // Initialize the MediaElement property values.
         InitializePropertyValues();
      }

      // Pause the media.
      void OnMouseDownPauseMedia(object sender, MouseButtonEventArgs args)
      {

         // The Pause method pauses the media if it is currently running.
         // The Play method can be used to resume.
         myMediaElement.Pause();
      }

      // Stop the media.
      void OnMouseDownStopMedia(object sender, MouseButtonEventArgs args)
      {

         // The Stop method stops and resets the media to be played from
         // the beginning.
         myMediaElement.Stop();
      }

      // Change the volume of the media.
      private void ChangeMediaVolume(object sender, RoutedPropertyChangedEventArgs<double> args)
      {
         myMediaElement.Volume = (double)volumeSlider.Value;
      }

      // Change the speed of the media.
      private void ChangeMediaSpeedRatio(object sender, RoutedPropertyChangedEventArgs<double> args)
      {
         myMediaElement.SpeedRatio = (double)speedRatioSlider.Value;
      }

      // When the media opens, initialize the "Seek To" slider maximum value
      // to the total number of miliseconds in the length of the media clip.
      private void Element_MediaOpened(object sender, EventArgs e)
      {
         timelineSlider.Maximum = myMediaElement.NaturalDuration.TimeSpan.TotalMilliseconds;
      }

      // When the media playback is finished. Stop() the media to seek to media start.
      private void Element_MediaEnded(object sender, EventArgs e)
      {
         myMediaElement.Stop();
      }

      // Jump to different parts of the media (seek to).
      private void SeekToMediaPosition(object sender, RoutedPropertyChangedEventArgs<double> args)
      {
         int SliderValue = (int)timelineSlider.Value;

         // Overloaded constructor takes the arguments days, hours, minutes, seconds, milliseconds.
         // Create a TimeSpan with miliseconds equal to the slider value.
         TimeSpan ts = new TimeSpan(0, 0, 0, 0, SliderValue);
         myMediaElement.Position = ts;
      }

      void InitializePropertyValues()
      {
         // Set the media's starting Volume and SpeedRatio to the current value of the
         // their respective slider controls.
         myMediaElement.Volume = (double)volumeSlider.Value;
         myMediaElement.SpeedRatio = (double)speedRatioSlider.Value;
      }
   }
}

Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Documents
Imports System.Windows.Navigation
Imports System.Windows.Shapes
Imports System.Windows.Data
Imports System.Windows.Media
Imports System.Windows.Input

Namespace SDKSample

    Partial Class MediaElementExample
        Inherits Page

        ' Play the media.
        Sub OnMouseDownPlayMedia(ByVal sender As Object, ByVal args As MouseButtonEventArgs)

            ' The Play method will begin the media if it is not currently active or 
            ' resume media if it is paused. This has no effect if the media is
            ' already running.
            myMediaElement.Play()

            ' Initialize the MediaElement property values.
            InitializePropertyValues()

        End Sub


        ' Pause the media.
        Sub OnMouseDownPauseMedia(ByVal sender As Object, ByVal args As MouseButtonEventArgs)

            ' The Pause method pauses the media if it is currently running.
            ' The Play method can be used to resume.
            myMediaElement.Pause()

        End Sub


        ' Stop the media.
        Sub OnMouseDownStopMedia(ByVal sender As Object, ByVal args As MouseButtonEventArgs)

            ' The Stop method stops and resets the media to be played from
            ' the beginning.
            myMediaElement.Stop()

        End Sub


        ' Change the volume of the media.
        Private Sub ChangeMediaVolume(ByVal sender As Object, ByVal args As RoutedPropertyChangedEventArgs(Of Double))
            myMediaElement.Volume = System.Convert.ToDouble(volumeSlider.Value)

        End Sub

        ' Change the speed of the media.
        Private Sub ChangeMediaSpeedRatio(ByVal sender As Object, ByVal args As RoutedPropertyChangedEventArgs(Of Double))
            myMediaElement.SpeedRatio = System.Convert.ToDouble(speedRatioSlider.Value)
            
        End Sub

        ' When the media opens, initialize the "Seek To" slider maximum value
        ' to the total number of miliseconds in the length of the media clip.
        Private Sub Element_MediaOpened(ByVal sender As Object, ByVal args As RoutedEventArgs)
            timelineSlider.Maximum = myMediaElement.NaturalDuration.TimeSpan.TotalMilliseconds
        End Sub

        ' When the media playback is finished. Stop() the media to seek to media start.
        Private Sub Element_MediaEnded(ByVal sender As Object, ByVal args As RoutedEventArgs)
            myMediaElement.Stop()
        End Sub

        ' Jump to different parts of the media (seek to). 
        Private Sub SeekToMediaPosition(ByVal sender As Object, ByVal args As RoutedPropertyChangedEventArgs(Of Double))
            Dim SliderValue As Integer = CType(timelineSlider.Value, Integer)

            ' Overloaded constructor takes the arguments days, hours, minutes, seconds, milliseconds.
            ' Create a TimeSpan with miliseconds equal to the slider value.
            Dim ts As New TimeSpan(0, 0, 0, 0, SliderValue)
            myMediaElement.Position = ts
        End Sub

        ' Set the media's starting Volume and SpeedRatio to the current value of the
        ' their respective slider controls.
        Private Sub InitializePropertyValues()
            myMediaElement.Volume = System.Convert.ToDouble(volumeSlider.Value)
            myMediaElement.SpeedRatio = System.Convert.ToDouble(speedRatioSlider.Value)
        End Sub
    End Class
End Namespace 'SDKSample

Weitere Informationen

• Steuern eines MediaElement-Objekts mit einem Storyboard