对于Button的Command的绑定可以通过实现ICommand接口来进行，但是Slider并没有Command属性。
另外如果要实现MVVM模式的话，需要将一些Method和Slider的Event进行绑定，如何进行呢？
（对于UIElement的一些Event进行绑定一定有一些通用的方法，目前还没有深入研究。）
首先，Slider Value的绑定是很简单的, 绑定Slider的Value属性即可。
（1）ViewModel
public class SliderViewModel : ViewModelBase
{
private string selectedValue;
public SliderViewModel()
{
}
public string SelectedValue
{
get
{
return this.selectedValue;
}
set
{
if (this.selectedValue != value)
{
this.selectedValue = value;
base.OnPropertyChanged("SelectedValue");
}
}
}
}
(2) View, 设定 DataContext 为ViewModel， 绑定SelectValue到 Slider的Value 和TextBlock的Text属性上。
这样当拖动Slider时，Slider的值会传给SelectedValue, 然后SelectValue会传给TexBlock上。
x:Class="WpfApplication2.View.SliderView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:vm="clr-namespace:WpfApplication2.ViewModel"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<UserControl.DataContext>
<vm:SliderViewModel />
</UserControl.DataContext>
<Grid>
<Slider HorizontalAlignment="Left"
Margin="28,102,0,0"
VerticalAlignment="Top"
Width="158"
Minimum="0"
Maximum="100"
Value="{Binding SelectedValue}"/>
<TextBlock HorizontalAlignment="Left"
Margin="203,102,0,0"
TextWrapping="Wrap"
Text="{Binding SelectedValue}"
VerticalAlignment="Top" />
</Grid>
</UserControl>
效果如下：
如果不想显示double值，可以设定Slider的属性。
TickFrequency="1"
IsSnapToTickEnabled="True"
TickPlacement="None" />
其次， 当用鼠标或者键盘移动滑块结束的时候，需要进行一些处理。如果不用MVVM的方式的话，可以在Slider的Event里面增加处理。
用MVVM的话，就稍微麻烦一些。
（1）下载或者复制C:\Program Files (x86)\Microsoft SDKs\Expression\Blend\.NETFramework\v4.0\Libraries\System.Windows.Interactivity.dll
在工程中Reference 这个dll，命名空间里面增加：using System.Windows.Interactivity
（2）新写个SliderValueChangedBehavior 继承Behavior<Slider>
/// <summary>
/// Helps find the user-selected value of a slider only when the keyboard/mouse gesture has ended.
/// </summary>
public class SliderValueChangedBehavior : Behavior<Slider>
{
/// <summary>
/// Keys down.
/// </summary>
private int keysDown;
/// <summary>
/// Indicate whether to capture the value on latest key up.
/// </summary>
private bool applyKeyUpValue;
#region Dependency property Value
/// <summary>
/// DataBindable value.
/// </summary>
public double Value
{
get { return (double)GetValue(ValueProperty); }
set { SetValue(ValueProperty, value); }
}
public static readonly DependencyProperty ValueProperty = DependencyProperty.Register(
"Value",
typeof(double),
typeof(SliderValueChangedBehavior),
new PropertyMetadata(default(double), OnValuePropertyChanged));
#endregion
#region Dependency property Value
/// <summary>
/// DataBindable Command
/// </summary>
public ICommand Command
{
get { return (ICommand)GetValue(CommandProperty); }
set { SetValue(CommandProperty, value); }
}
public static readonly DependencyProperty CommandProperty = DependencyProperty.Register(
"Command",
typeof(ICommand),
typeof(SliderValueChangedBehavior),
new PropertyMetadata(null));
#endregion
/// <summary>
/// On behavior attached.
/// </summary>
protected override void OnAttached()
{
this.AssociatedObject.KeyUp += this.OnKeyUp;
this.AssociatedObject.KeyDown += this.OnKeyDown;
this.AssociatedObject.ValueChanged += this.OnValueChanged;
base.OnAttached();
}
/// <summary>
/// On behavior detaching.
/// </summary>
protected override void OnDetaching()
{
base.OnDetaching();
this.AssociatedObject.KeyUp -= this.OnKeyUp;
this.AssociatedObject.KeyDown -= this.OnKeyDown;
this.AssociatedObject.ValueChanged -= this.OnValueChanged;
}
/// <summary>
/// On Value dependency property change.
/// </summary>
private static void OnValuePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var me = (SliderValueChangedBehavior)d;
if (me.AssociatedObject != null)
me.Value = (double)e.NewValue;
}
/// <summary>
/// Occurs when the slider's value change.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void OnValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
{
if (Mouse.Captured != null)
{
this.AssociatedObject.LostMouseCapture += this.OnLostMouseCapture;
}
else if (this.keysDown != 0)
{
this.applyKeyUpValue = true;
}
else
{
this.ApplyValue();
}
}
private void OnLostMouseCapture(object sender, MouseEventArgs e)
{
this.AssociatedObject.LostMouseCapture -= this.OnLostMouseCapture;
this.ApplyValue();
}
private void OnKeyUp(object sender, KeyEventArgs e)
{
if (this.keysDown-- != 0)
{
this.ApplyValue();
}
}
private void OnKeyDown(object sender, KeyEventArgs e)
{
this.keysDown++;
}
/// <summary>
/// Applies the current value in the Value dependency property and raises the command.
/// </summary>
private void ApplyValue()
{
this.Value = this.AssociatedObject.Value;
if (this.Command != null)
this.Command.Execute(this.Value);
}
}
（3） 在View中为Slider的行为添加Command
<i:Interaction.Behaviors>
<helper:SliderValueChangedBehavior Command="{Binding ValueChangedCommand}"
/>
</i:Interaction.Behaviors>
（4）在ViewModel中实现当Slider值个改变的时候进行一些处理。
public ICommand ValueChangedCommand
{
get
{
if (this.valueChangedCommmand == null)
{
this.valueChangedCommmand = new RelayCommand(
param => this.PopValue(),
null);
}
return this.valueChangedCommmand;
}
}
private void PopValue()
{
MessageBox.Show(String.Format("Selected value is {0}", this.selectedValue));
}
最后，进行调试，发现ValueChangedCommand当每次Silder值变更的时候都会被执行。
那么如何实现最后一次值变更时，才执行Command呢？
对于Button的Command的绑定可以通过实现ICommand接口来进行，但是Slider并没有Command属性。
另外如果要实现MVVM模式的话，需要将一些Method和Slider的Event进行绑定，如何进行呢？
（对于UIElement的一些Event进行绑定一定有一些通用的方法，目前还没有深入研究。）
首先，Slider Value的绑定是很简单的, 绑定Slider的Value属性即可。
（1）ViewModel
public class SliderViewModel : ViewModelBase
{
private string selectedValue;
public SliderViewModel()
{
}
public string SelectedValue
{
get
{
return this.selectedValue;
}
set
{
if (this.selectedValue != value)
{
this.selectedValue = value;
base.OnPropertyChanged("SelectedValue");
}
}
}
}
(2) View, 设定 DataContext 为ViewModel， 绑定SelectValue到 Slider的Value 和TextBlock的Text属性上。
这样当拖动Slider时，Slider的值会传给SelectedValue, 然后SelectValue会传给TexBlock上。
x:Class="WpfApplication2.View.SliderView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:vm="clr-namespace:WpfApplication2.ViewModel"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<UserControl.DataContext>
<vm:SliderViewModel />
</UserControl.DataContext>
<Grid>
<Slider HorizontalAlignment="Left"
Margin="28,102,0,0"
VerticalAlignment="Top"
Width="158"
Minimum="0"
Maximum="100"
Value="{Binding SelectedValue}"/>
<TextBlock HorizontalAlignment="Left"
Margin="203,102,0,0"
TextWrapping="Wrap"
Text="{Binding SelectedValue}"
VerticalAlignment="Top" />
</Grid>
</UserControl>
效果如下：
如果不想显示double值，可以设定Slider的属性。
TickFrequency="1"
IsSnapToTickEnabled="True"
TickPlacement="None" />
其次， 当用鼠标或者键盘移动滑块结束的时候，需要进行一些处理。如果不用MVVM的方式的话，可以在Slider的Event里面增加处理。
用MVVM的话，就稍微麻烦一些。
（1）下载或者复制C:\Program Files (x86)\Microsoft SDKs\Expression\Blend\.NETFramework\v4.0\Libraries\System.Windows.Interactivity.dll
在工程中Reference 这个dll，命名空间里面增加：using System.Windows.Interactivity
（2）新写个SliderValueChangedBehavior 继承Behavior<Slider>
/// <summary>
/// Helps find the user-selected value of a slider only when the keyboard/mouse gesture has ended.
/// </summary>
public class SliderValueChangedBehavior : Behavior<Slider>
{
/// <summary>
/// Keys down.
/// </summary>
private int keysDown;
/// <summary>
/// Indicate whether to capture the value on latest key up.
/// </summary>
private bool applyKeyUpValue;
#region Dependency property Value
/// <summary>
/// DataBindable value.
/// </summary>
public double Value
{
get { return (double)GetValue(ValueProperty); }
set { SetValue(ValueProperty, value); }
}
public static readonly DependencyProperty ValueProperty = DependencyProperty.Register(
"Value",
typeof(double),
typeof(SliderValueChangedBehavior),
new PropertyMetadata(default(double), OnValuePropertyChanged));
#endregion
#region Dependency property Value
/// <summary>
/// DataBindable Command
/// </summary>
public ICommand Command
{
get { return (ICommand)GetValue(CommandProperty); }
set { SetValue(CommandProperty, value); }
}
public static readonly DependencyProperty CommandProperty = DependencyProperty.Register(
"Command",
typeof(ICommand),
typeof(SliderValueChangedBehavior),
new PropertyMetadata(null));
#endregion
/// <summary>
/// On behavior attached.
/// </summary>
protected override void OnAttached()
{
this.AssociatedObject.KeyUp += this.OnKeyUp;
this.AssociatedObject.KeyDown += this.OnKeyDown;
this.AssociatedObject.ValueChanged += this.OnValueChanged;
base.OnAttached();
}
/// <summary>
/// On behavior detaching.
/// </summary>
protected override void OnDetaching()
{
base.OnDetaching();
this.AssociatedObject.KeyUp -= this.OnKeyUp;
this.AssociatedObject.KeyDown -= this.OnKeyDown;
this.AssociatedObject.ValueChanged -= this.OnValueChanged;
}
/// <summary>
/// On Value dependency property change.
/// </summary>
private static void OnValuePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var me = (SliderValueChangedBehavior)d;
if (me.AssociatedObject != null)
me.Value = (double)e.NewValue;
}
/// <summary>
/// Occurs when the slider's value change.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void OnValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
{
if (Mouse.Captured != null)
{
this.AssociatedObject.LostMouseCapture += this.OnLostMouseCapture;
}
else if (this.keysDown != 0)
{
this.applyKeyUpValue = true;
}
else
{
this.ApplyValue();
}
}
private void OnLostMouseCapture(object sender, MouseEventArgs e)
{
this.AssociatedObject.LostMouseCapture -= this.OnLostMouseCapture;
this.ApplyValue();
}
private void OnKeyUp(object sender, KeyEventArgs e)
{
if (this.keysDown-- != 0)
{
this.ApplyValue();
}
}
private void OnKeyDown(object sender, KeyEventArgs e)
{
this.keysDown++;
}
/// <summary>
/// Applies the current value in the Value dependency property and raises the command.
/// </summary>
private void ApplyValue()
{
this.Value = this.AssociatedObject.Value;
if (this.Command != null)
this.Command.Execute(this.Value);
}
}
（3） 在View中为Slider的行为添加Command
<i:Interaction.Behaviors>
<helper:SliderValueChangedBehavior Command="{Binding ValueChangedCommand}"
/>
</i:Interaction.Behaviors>
（4）在ViewModel中实现当Slider值个改变的时候进行一些处理。
public ICommand ValueChangedCommand
{
get
{
if (this.valueChangedCommmand == null)
{
this.valueChangedCommmand = new RelayCommand(
param => this.PopValue(),
null);
}
return this.valueChangedCommmand;
}
}
private void PopValue()
{
MessageBox.Show(String.Format("Selected value is {0}", this.selectedValue));
}
最后，进行调试，发现ValueChangedCommand当每次Silder值变更的时候都会被执行。
那么如何实现最后一次值变更时，才执行Command呢？