Silverlight : Build a Download and Playback Progress Bar

10/9/2010 4:41:09 PM
One thing every media content downloader needs is a bar that shows both download progress and playback position. Thankfully, Silverlight fully supports the concept of custom controls. Listing 1 shows the XAML, and Listing 2 shows the code-behind for this control.
Listing 1. PlayDownloadProgressControl.xaml
<UserControl x:Class="VideoPlayer.PlayDownloadProgressControl"
Width="400" Height="300">
<Canvas x:Name="LayoutRoot" Background="White">
<Line x:Name="DownloadProgress" X1="0" Y1="0"
X2="0" Y2="0" Stroke="DarkGray"
Canvas.Left="0" Canvas.Top="2" StrokeThickness="3"/>
<Line x:Name="PlaybackProgress" X1="0" Y1="0"
X2="0" Y2="0" Stroke="DarkGreen"
Canvas.Left="0" Canvas.Top="2" StrokeThickness="3"/>

Listing 2. PlayDownloadProgressControl.xaml.cs
using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;

namespace VideoPlayer
public partial class PlayDownloadProgressControl : UserControl
public PlayDownloadProgressControl()
public void UpdatePlaybackProgress(double playbackPercent)

PlaybackProgress.X2 = PlaybackProgress.X1 +
(playbackPercent * LayoutRoot.ActualWidth / 100.0);

public void UpdateDownloadProgress(double downloadPercent)
DownloadProgress.X2 = DownloadProgress.X1 +
(downloadPercent * LayoutRoot.ActualWidth / 100.0);

To incorporate this into video player app, add the following bolded lines to the MainPage.xaml file from Listing 1:

<MediaElement Grid.Row="0"
<local:PlayDownloadProgressControl x:Name="progressBar"
Height="4" Grid.Row="0"
<StackPanel Grid.Row="1">

The DownloadProgressChanged event notifies you when a new chunk has been downloaded so you can update the progress:

private void videoPlayer_DownloadProgressChanged(object sender,
RoutedEventArgs e)
100.0 * videoPlayer.DownloadProgress);

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