[英]adding commands to custom control for button binding wpf
我想在自定義控件中添加一個方法,可以在MainWindow.xaml中使用命令綁定從按鈕調用該方法。 我在網上遇到了一些解決方案,但是其中一個似乎沒有用,而另一個則可以。 有人可以向我解釋設置此方法的正確方法。 第一個解決方案產生並產生錯誤,如下所述。 第二種解決方案有效,但是我不確定任何利弊。
解決方案1-損壞
public partial class MyControl : Control
{
...
public static readonly RoutedCommand AlignLeftCommand = null;
static MyControl()
{
binding = new CommandBinding();
binding.Command = AlignLeftCommand;
binding.Executed += new ExecutedRoutedEventHandler(AlignLeft_Executed);
CommandManager.RegisterClassCommandBinding(typeof(MyControl), binding);
}
}
錯誤:
嚴重性代碼說明項目文件行錯誤CS0120非靜態字段,方法或屬性需要對象引用。
解決方案2
public partial class MyControl : Control
{
...
public static readonly RoutedCommand AlignLeftCommand = new RoutedCommand();
public MyControl()
{
this.CommandBindings.Add(new CommandBinding(MyControl.AlignLeftCommand, AlignLeft_Executed, null));
}
}
這是調用方法的按鈕。
<StackPanel Orientation="Horizontal">
<Button Content="Left Edges" FontSize="8"
Command="{x:Static JM:MyControl.AlignLeftCommand}"
CommandTarget="{Binding ElementName=mycontrol}"/>
</StackPanel>
首先,您應該像這樣在Window
上定義命令綁定 (為Executed
和CanExecute
事件創建處理程序):
<Window x:Class="CommandBindingWPF.MainWindow"
...The code omitted for the brevity...
Title="MainWindow" Height="350" Width="525">
<Window.CommandBindings>
<CommandBinding Command="ApplicationCommands.New" Executed="CommandBinding_Executed" CanExecute="CommandBinding_CanExecute" />
</Window.CommandBindings>
並聲明您的Button
ix xaml:
<StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
<Button Command="ApplicationCommands.New">New</Button>
</StackPanel>
命令綁定創建后,應在代碼隱藏中創建處理程序:
private void CommandBinding_Executed(object sender, ExecutedRoutedEventArgs e)
{
MessageBox.Show("Hello from Command");
}
private void CommandBinding_CanExecute(object sender, CanExecuteRoutedEventArgs e)
{ }
更新:
對於MVVM應用程序:
public class RelayCommand : ICommand
{
#region Fields
readonly Action<object> _execute;
readonly Predicate<object> _canExecute;
#endregion // Fields
#region Constructors
public RelayCommand(Action<object> execute)
: this(execute, null)
{
}
public RelayCommand(Action<object> execute, Predicate<object> canExecute)
{
if (execute == null)
throw new ArgumentNullException("execute");
_execute = execute;
_canExecute = canExecute;
}
#endregion // Constructors
#region ICommand Members
public bool CanExecute(object parameter)
{
return _canExecute == null ? true : _canExecute(parameter);
}
public event EventHandler CanExecuteChanged
{
add { CommandManager.RequerySuggested += value; }
remove { CommandManager.RequerySuggested -= value; }
}
public void Execute(object parameter)
{
_execute(parameter);
}
#endregion // ICommand Members
}
然后在您的viewModel中創建一個屬性。 例如:
public class YourViewModel
{
public RelayCommand YourCommand { get; set; }
public YourViewModel()
{
YourCommand = new RelayCommand(DoSmth, CanDoSmth);
}
private void DoSmth(object obj)
{
Message.Box("Hello from viewModel");
}
private bool CanDoSmth(object obj)
{
//you could implement your logic here. But by default it should be
//set to true
return true;
}
}
XAML應該看起來像:
<Button Content="Click me!" Command="{Binding YourCommand}"/>
要了解MVVM,建議您閱讀Rachel Lim的博客。 她有教人的才能,可以用簡單的術語來解釋。 閱讀Rachel Lim的博客。 要了解MVVM命令, 請參閱該文章
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