【WPF】WPF开发用户控件、用户控件属性依赖DependencyProperty实现双向绑定、以及自定义实现Command双向绑定功能演示

<Grid>
<Viewbox Stretch="Fill">
<Canvas Width="200" Height="200">
<Ellipse Name="rect3" Width="200" Height="200" Stroke="Orange" StrokeThickness="100" >
</Ellipse>
</Canvas>
</Viewbox>
<TextBlock x:Name="TextName" Text="123" VerticalAlignment="Center" HorizontalAlignment="Center"></TextBlock>
</Grid>

public partial class TestUserControl : UserControl
{
public TestUserControl()
{
InitializeComponent();
} public static readonly DependencyProperty MyTextProperty =
DependencyProperty.Register("MyText", typeof(String), typeof(TestUserControl),
new PropertyMetadata((String)null, new PropertyChangedCallback(TextChanged))); private static void TextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
TestUserControl control = d as TestUserControl;
if (control != null)
{
String oldText = e.OldValue as String; // 旧的值
String newText = e.NewValue as String; // 更新的新的值
control.UpdateMyText(newText);
}
} private void UpdateMyText(string newValue)
{
this.TextName.Text = newValue;
} [Bindable(true)]
[Category("Appearance")] // using System.ComponentModel;
public string MyText
{
get
{
return (String)GetValue(MyTextProperty);
}
set
{
SetValue(MyTextProperty, value);
}
} public static readonly DependencyProperty CommandProperty =
DependencyProperty.Register("Command", typeof(ICommand), typeof(TestUserControl),
new PropertyMetadata((ICommand)null, new PropertyChangedCallback(CommandChanged))); public static readonly DependencyProperty CommandParameterProperty =
DependencyProperty.Register("CommandParameter", typeof(object), typeof(TestUserControl)); public static readonly DependencyProperty CommandTargetProperty =
DependencyProperty.Register("CommandTarget", typeof(IInputElement), typeof(TestUserControl)); private static void CommandChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
TestUserControl control = d as TestUserControl;
if (control != null)
{
ICommand oldCommand = e.OldValue as ICommand;
ICommand newCommand = e.NewValue as ICommand;
control.UpdateCommand(oldCommand, newCommand);
}
} private void UpdateCommand(ICommand oldCommand, ICommand newCommand)
{
if (oldCommand != null)
{
oldCommand.CanExecuteChanged -= CanExecuteChanged;
}
if (newCommand != null)
{
newCommand.CanExecuteChanged += CanExecuteChanged;
}
} private void CanExecuteChanged(object sender, EventArgs e)
{
RoutedCommand command = this.Command as RoutedCommand;
if (command != null)
{
this.IsEnabled = command.CanExecute(CommandParameter, CommandTarget);
}
else if (this.Command != null)
{
this.IsEnabled = this.Command.CanExecute(CommandParameter);
}
} public ICommand Command
{
get { return (ICommand)GetValue(CommandProperty); }
set { SetValue(CommandProperty, value); }
} public object CommandParameter
{
get { return GetValue(CommandParameterProperty); }
set { SetValue(CommandParameterProperty, value); }
} public IInputElement CommandTarget
{
get { return (IInputElement)GetValue(CommandTargetProperty); }
set { SetValue(CommandTargetProperty, value); }
} protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
{
base.OnMouseLeftButtonDown(e);
RoutedCommand command = Command as RoutedCommand;
if (command != null)
command.Execute(CommandParameter, CommandTarget);
else if (Command != null)
this.Command.Execute(CommandParameter);
} }
}

public class LoginViewModel: BindableBase
{
public LoginViewModel()
{ } public string _testText = "999";
public string TextText
{
get { return _testText; }
set { SetProperty(ref _testText, value); }
} private DelegateCommand<string> _testCommand;
public DelegateCommand<string> TestCommand
{
get
{
if (_testCommand == null)
{
_testCommand = new DelegateCommand<string>(ExecuteTestCommand);
}
return _testCommand;
}
} private void ExecuteTestCommand(string value)
{
MessageBox.Show(value);
} }