Como: Control a MediaElement by Using a Storyboard
Este exemplo mostra como controlar um MediaElement usando uma MediaTimeline em um Storyboard.
Exemplo
Quando você usa uma MediaTimeline em um Storyboard para controlar a temporização de um MediaElement, a funcionalidade é idêntica à funcionalidade dos outros objetos Timeline, como animações. Por exemplo, uma MediaTimeline usa propriedades de Timeline como a propriedade BeginTime para especificar quando iniciar um MediaElement (início da reprodução de mídia). Ela também usa a propriedade Duration para especificar quanto tempo o MediaElement estará ativo (duração da reprodução de mídia). Para obter mais informações sobre como usar objetos Timeline com um Storyboard, consulte Visão geral sobre Storyboards.
Este exemplo mostra como criar um reprodutor de mídia simples que usa uma MediaTimeline para controlar a reprodução. O reprodutor de mídia inclui botões de reprodução, pausa, continuação e parada. O reprodutor também tem um controle Slider que atua como uma barra de progresso.
O exemplo a seguir cria a interface do usuário (UI) do reprodutor de mídia.
<Page xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
x:Class="SDKSample.MediaTimelineExample" >
<StackPanel Background="Black">
<MediaElement Name="myMediaElement" MediaOpened="Element_MediaOpened"
Width="260" Height="150" Stretch="Fill" />
<!-- Button controls for play, pause, resume, and stop. -->
<StackPanel HorizontalAlignment="Center" Width="260" Orientation="Horizontal">
<Image Name="PlayButton" Source="images\UI_play.gif" Margin="30,10,10,10" />
<Image Name="PauseButton" Source="images\UI_pause.gif" Margin="10" />
<Image Name="ResumeButton" Source="images\UI_resume.gif" Margin="10" />
<Image Name="StopButton" Source="images\UI_stop.gif" Margin="10" />
</StackPanel>
<!-- Ths slider shows the progress of the media. -->
<Slider Name="timelineSlider" Margin="5" Width="250" HorizontalAlignment="Center"/>
<StackPanel.Triggers>
<EventTrigger RoutedEvent="Image.MouseDown" SourceName="PlayButton">
<EventTrigger.Actions>
<BeginStoryboard Name= "myBegin">
<Storyboard SlipBehavior="Slip">
<!-- The MediaTimeline controls the timing of the video and acts like other Timeline objects.
For example, although the video clip (numbers.wmv) lasts longer, playback ends after six
seconds because that is the duration of the MediaTimeline (Duration="0:0:6"). -->
<MediaTimeline Source="media\numbers.wmv" Storyboard.TargetName="myMediaElement"
BeginTime="0:0:0" Duration="0:0:6" CurrentTimeInvalidated="MediaTimeChanged" />
</Storyboard>
</BeginStoryboard>
</EventTrigger.Actions>
</EventTrigger>
<!-- These triggers impliment the functionality of the Pause, Resume
and Stop buttons.-->
<EventTrigger RoutedEvent="Image.MouseDown" SourceName="PauseButton">
<EventTrigger.Actions>
<PauseStoryboard BeginStoryboardName="myBegin" />
</EventTrigger.Actions>
</EventTrigger>
<EventTrigger RoutedEvent="Image.MouseDown" SourceName="ResumeButton">
<EventTrigger.Actions>
<ResumeStoryboard BeginStoryboardName="myBegin" />
</EventTrigger.Actions>
</EventTrigger>
<EventTrigger RoutedEvent="Image.MouseDown" SourceName="StopButton">
<EventTrigger.Actions>
<StopStoryboard BeginStoryboardName="myBegin" />
</EventTrigger.Actions>
</EventTrigger>
</StackPanel.Triggers>
</StackPanel>
</Page>
<Page xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
x:Class="SDKSample.MediaTimelineExample" >
<StackPanel Background="Black">
<MediaElement Name="myMediaElement" MediaOpened="Element_MediaOpened"
Width="260" Height="150" Stretch="Fill" />
<!-- Button controls for play, pause, resume, and stop. -->
<StackPanel HorizontalAlignment="Center" Width="260" Orientation="Horizontal">
<Image Name="PlayButton" Source="images\UI_play.gif" Margin="30,10,10,10" />
<Image Name="PauseButton" Source="images\UI_pause.gif" Margin="10" />
<Image Name="ResumeButton" Source="images\UI_resume.gif" Margin="10" />
<Image Name="StopButton" Source="images\UI_stop.gif" Margin="10" />
</StackPanel>
<!-- Ths slider shows the progress of the media. -->
<Slider Name="timelineSlider" Margin="5" Width="250" HorizontalAlignment="Center"/>
<StackPanel.Triggers>
<EventTrigger RoutedEvent="Image.MouseDown" SourceName="PlayButton">
<EventTrigger.Actions>
<BeginStoryboard Name= "myBegin">
<Storyboard SlipBehavior="Slip">
<!-- The MediaTimeline controls the timing of the video and acts like other Timeline objects.
For example, although the video clip (numbers.wmv) lasts longer, playback ends after six
seconds because that is the duration of the MediaTimeline (Duration="0:0:6"). -->
<MediaTimeline Source="media\numbers.wmv" Storyboard.TargetName="myMediaElement"
BeginTime="0:0:0" Duration="0:0:6" CurrentTimeInvalidated="MediaTimeChanged" />
</Storyboard>
</BeginStoryboard>
</EventTrigger.Actions>
</EventTrigger>
<!-- These triggers impliment the functionality of the Pause, Resume
and Stop buttons.-->
<EventTrigger RoutedEvent="Image.MouseDown" SourceName="PauseButton">
<EventTrigger.Actions>
<PauseStoryboard BeginStoryboardName="myBegin" />
</EventTrigger.Actions>
</EventTrigger>
<EventTrigger RoutedEvent="Image.MouseDown" SourceName="ResumeButton">
<EventTrigger.Actions>
<ResumeStoryboard BeginStoryboardName="myBegin" />
</EventTrigger.Actions>
</EventTrigger>
<EventTrigger RoutedEvent="Image.MouseDown" SourceName="StopButton">
<EventTrigger.Actions>
<StopStoryboard BeginStoryboardName="myBegin" />
</EventTrigger.Actions>
</EventTrigger>
</StackPanel.Triggers>
</StackPanel>
</Page>
O exemplo a seguir cria a funcionalidade para a barra de progresso.
Imports System
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Media
Namespace SDKSample
Partial Class MediaTimelineExample
Inherits Page
' 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 e As RoutedEventArgs)
timelineSlider.Maximum = myMediaElement.NaturalDuration.TimeSpan.TotalMilliseconds
End Sub 'Element_MediaOpened
Private Sub MediaTimeChanged(ByVal sender As Object, ByVal e As EventArgs)
timelineSlider.Value = myMediaElement.Position.TotalMilliseconds
End Sub 'MediaTimeChanged
End Class 'MediaTimelineExample
End Namespace 'SDKSample
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
namespace SDKSample
{
public partial class MediaTimelineExample : Page
{
// 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;
}
private void MediaTimeChanged(object sender, EventArgs e)
{
timelineSlider.Value = myMediaElement.Position.TotalMilliseconds;
}
}
}
For the complete sample, see Mídia Gallery.
Consulte também
Tarefas
Como: Control a MediaElement (Play, Pause, Stop, Volume, and Speed)
Conceitos
Visão geral de animações de Quadro-Chave
Visão Geral de elementos gráficos, animação e media do WPF