[英]How do I handle events in a custom control?
我有一个像这样的自定义ItemsControl
public class MyControl : ItemsControl { }
我的模板会像
<Style TargetType="{x:Type local:MyControl}">
<Setter Property="ItemTemplate">
<Setter.Value>
<DataTemplate>
<TextBox Text="{Binding Text}" />
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
现在我想在按下ENTER或SPACE时采取行动,所以我会做这样的事情
<TextBox Text="{Binding Text}">
<TextBox.InputBindings>
<KeyBinding Key="Space"
Command="{Binding KeyPressedCommand}"
CommandParameter="{x:Static Key.Space}"/>
</TextBox.InputBindings>
</TextBox>
但是我如何将它绑定到我的控件?
解决它的方法之一是使用教程中的MVVM 模式和RelayCommand
类。
中继命令.cs
public class RelayCommand : ICommand
{
private readonly Action<object> _execute;
private readonly Func<object, bool> _canExecute;
public event EventHandler CanExecuteChanged
{
add { CommandManager.RequerySuggested += value; }
remove { CommandManager.RequerySuggested -= value; }
}
public RelayCommand(Action<object> execute, Func<object, bool> canExecute = null)
{
_execute = execute;
_canExecute = canExecute;
}
public bool CanExecute(object parameter) => _canExecute == null || _canExecute(parameter);
public void Execute(object parameter) => _execute(parameter);
}
然后你应该设置你的Window(或UserControl)的DataContext
,它需要解析xaml中的绑定。
这样做的方法之一:
主窗口.xaml
<Window.DataContext>
<local:MainViewModel/>
</Window.DataContext>
从MainViewModel
类中的“类似这样的”示例设置Text
属性和KeyPressedCommand
。
主视图模型.cs
public class MainViewModel : INotifyPropertyChanged
{
private bool _text;
public bool Text
{
get => _text;
set
{
_text = value;
OnPropertyChanged(nameof(Text));
// Text changed!
}
}
public ICommand KeyPressedCommand => new RelayCommand(obj =>
{
if (obj is Key key) {
// do something here with the 'key' provided by CommandParameter
}
});
public MainViewModel()
{
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
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