Executing Command Logic in a View Model

<Window
  x:Class="RoutedCommandBindingSample.MainWindow"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  Title="Simple Media Player" Height="350" Width="525"
  Icon="pack://application:,,,/Resources/Sound.ico"
  xmlns:local="clr-namespace:RoutedCommandBindingSample"
  xmlns:cmd="clr-namespace:RoutedCommandBindingSample.Commands">

  <Window.Resources>
    <Style x:Key="MediaButtonStyle" TargetType="{x:Type Button}" BasedOn="{StaticResource {x:Type Button}}">
      <Setter Property="Margin" Value="2"/>
      <Setter Property="Width" Value="35"/>
      <Style.Triggers>
        <Trigger Property="IsEnabled" Value="False">
          <Setter Property="Opacity" Value=".5"/>
        </Trigger>
      </Style.Triggers>
    </Style>

    <Style x:Key="MediaToolbarButtonStyle" TargetType="{x:Type Button}" BasedOn="{StaticResource MediaButtonStyle}">
      <Setter Property="Margin" Value="0"/>
      <Setter Property="Width" Value="24"/>
    </Style>
  </Window.Resources>
  
  <Window.CommandBindings>
    <cmd:DataContextCommandBinding Command="MediaCommands.Play" Executed="Play" CanExecute="CanPlay" />
    <cmd:DataContextCommandBinding Command="MediaCommands.Stop" Executed="Stop" CanExecute="CanStop" />
    <cmd:DataContextCommandBinding Command="local:MyMediaCommands.Pause" Executed="Pause" CanExecute="CanPause" />
  </Window.CommandBindings>

  <DockPanel LastChildFill="True">

    <Menu DockPanel.Dock="Top">
      <MenuItem Header="Playback Menu">
        <MenuItem Header="Play" Command="MediaCommands.Play" />
        <MenuItem Header="Stop" Command="MediaCommands.Stop" />
        <MenuItem Header="Pause" Command="local:MyMediaCommands.Pause" />
      </MenuItem>
    </Menu>

    <ToolBar DockPanel.Dock="Top" Height="28">
      <Button Command="MediaCommands.Play" Style="{StaticResource MediaToolbarButtonStyle}">
        <Image Source="pack://application:,,,/Resources/Play.png"/>
      </Button>
      <Button Command="MediaCommands.Stop" Style="{StaticResource MediaToolbarButtonStyle}">
        <Image Source="pack://application:,,,/Resources/Stop.png"/>
      </Button>
      <Button Command="local:MyMediaCommands.Pause" Style="{StaticResource MediaToolbarButtonStyle}">
        <Image Source="pack://application:,,,/Resources/Pause.png"/>
      </Button>
    </ToolBar>

    <DockPanel DockPanel.Dock="Top" Margin="10" LastChildFill="True">
      <Label Content="Uri:" DockPanel.Dock="Left"/>
      <TextBox Text="{Binding SourceUri, UpdateSourceTrigger=PropertyChanged}" />
    </DockPanel>

    <DockPanel DockPanel.Dock="Top" Margin="10" LastChildFill="True">
      <Label Content="Volume:" DockPanel.Dock="Left"/>
      <Slider Value="{Binding Volume}" Minimum="0" Maximum="1" SmallChange=".01" LargeChange=".05" TickPlacement="BottomRight" TickFrequency=".05" />
    </DockPanel>

    <StackPanel Orientation="Horizontal" DockPanel.Dock="Top" Margin="10" Height="25">
      <Label Content="Via DataContextCommandBindings:" />
      <Button Command="MediaCommands.Play" Style="{StaticResource MediaButtonStyle}">
        <Image Source="pack://application:,,,/Resources/Play.png"/>
      </Button>
      <Button Command="MediaCommands.Stop" Style="{StaticResource MediaButtonStyle}">
        <Image Source="pack://application:,,,/Resources/Stop.png"/>
      </Button>
      <Button Command="local:MyMediaCommands.Pause" Style="{StaticResource MediaButtonStyle}">
        <Image Source="pack://application:,,,/Resources/Pause.png"/>
      </Button>
    </StackPanel>

    <StackPanel Orientation="Horizontal"  DockPanel.Dock="Top" Margin="10" Height="25">
      <Label Content="Via DataContextCommandAdapter:" />
      <Button Command="{cmd:DataContextCommandAdapter Play, CanPlay}" Style="{StaticResource MediaButtonStyle}">
        <Image Source="pack://application:,,,/Resources/Play.png"/>
      </Button>
      <Button Command="{cmd:DataContextCommandAdapter Stop, CanStop}" Style="{StaticResource MediaButtonStyle}">
        <Image Source="pack://application:,,,/Resources/Stop.png"/>
      </Button>
      <Button Command="{cmd:DataContextCommandAdapter Pause, CanPause}" Style="{StaticResource MediaButtonStyle}">
        <Image Source="pack://application:,,,/Resources/Pause.png"/>
      </Button>
    </StackPanel>

    <StackPanel Orientation="Horizontal"  DockPanel.Dock="Top" Margin="10" Height="25">
      <Label Content="Via DataContextCommandAdapter on InputBindings:" />
      <Button Style="{StaticResource MediaButtonStyle}">
        <Button.InputBindings>
          <MouseBinding Command="{cmd:DataContextCommandAdapter Play, CanPlay}" MouseAction="LeftClick"/>
        </Button.InputBindings>
        <Image Source="pack://application:,,,/Resources/Play.png"/>
      </Button>
      <Button Style="{StaticResource MediaButtonStyle}">
        <Button.InputBindings>
          <MouseBinding Command="{cmd:DataContextCommandAdapter Stop, CanStop}" MouseAction="LeftClick"/>
        </Button.InputBindings>
        <Image Source="pack://application:,,,/Resources/Stop.png"/>
      </Button>
      <Button Style="{StaticResource MediaButtonStyle}">
        <Button.InputBindings>
          <MouseBinding Command="{cmd:DataContextCommandAdapter Pause, CanPause}" MouseAction="LeftClick"/>
        </Button.InputBindings>
        <Image Source="pack://application:,,,/Resources/Pause.png"/>
      </Button>
    </StackPanel>

    <Label Content="Media Messages" DockPanel.Dock="Top" />
    <ListView ItemsSource="{Binding Messages}" />
  </DockPanel>
</Window>