[WPF问题] Command 对部分UI element 不起作用

[wxtp]

代码如下：

using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;


namespace WpfApplication1
{
	public class Window1: Window
	{
		[STAThread]
		public static void Main()
		{
			Application app = new Application();
			app.Run(new Window1());
		}

		public Window1()
		{
			Title = "Window1";
			Width = 300;
			Height = 300;

			DockPanel panel = new DockPanel();
			Content = panel;

			ToolBar toolbar = new ToolBar();
			toolbar.Height = 30;
			Button toolbutton = new Button();
			toolbutton.Content = "Cut";
			toolbutton.Command = ApplicationCommands.Cut;
			toolbar.Items.Add(toolbutton);
			toolbar.SetValue(DockPanel.DockProperty, Dock.Top);
			panel.Children.Add(toolbar);

			TextBox text = new TextBox();
			text.Width = 80;
			text.Height = 20;
			text.SetValue(DockPanel.DockProperty, Dock.Top);
			panel.Children.Add(text);

			

			Button button = new Button();
			button.Content = "Copy";
			button.Command = ApplicationCommands.Copy;
			button.VerticalAlignment = VerticalAlignment.Top;
			button.HorizontalAlignment = HorizontalAlignment.Center;
			button.SetValue(DockPanel.DockProperty, Dock.Top);
			panel.Children.Add(button);
		}
	}
}

现在的问题是对于toolbutton 和 button分别绑定了Cut和Copy命令，而在textbox中选中输入文字的时候，toolbutton由disable状态变成enable状态，但是button却始终是disable状态。
请问一下大家这是什么原因？如果要使button变成enable，应该怎么改呢？

[wxtp]

我对Copy命令添加了CommandBinding后正常。

CommandBindings.Add(new CommandBinding(ApplicationCommands.Copy,CopyOnExcecute, CopyCanExcecute));

void CopyCanExcecute(object sender, CanExecuteRoutedEventArgs args)
{
    args.CanExecute = !String.IsNullOrEmpty(text.Text);
}

void CopyOnExcecute(object sender, ExecutedRoutedEventArgs args)
{
    Clipboard.SetText(text.Text);
}

可问题是为什么toolbutton不用command binding就可以正常响应Command,而button需要添加command binding？

[cppfaq]

[Quote=引用 2 楼 wxtp 的回复:]
我对Copy命令添加了CommandBinding后正常。


C# code
CommandBindings.Add(new CommandBinding(ApplicationCommands.Copy,CopyOnExcecute, CopyCanExcecute));




C# code
void CopyCanExcecute(object sender, CanExecuteRoutedEventArgs args)
{
args.CanExecute = !String.IsNullOrEmpty(text.Text);
}

void CopyOnExcecute(object sender, ExecutedRoutedEventArgs args)
{
Clipboard.SetText(…
[/Quote]
因为VS悄悄地帮你做了

[luckapple2]

同意。toolbutton已经封装了。你当然不用再写了。

[wxtp]

[Quote=引用 3 楼 cppfaq 的回复:]
引用 2 楼 wxtp 的回复:
我对Copy命令添加了CommandBinding后正常。


C# code
CommandBindings.Add(new CommandBinding(ApplicationCommands.Copy,CopyOnExcecute, CopyCanExcecute));


C# code
void CopyCanExcecute(object sender, CanExecuteRoutedEventArgs args)
{
args.CanExecute = !String.IsNullOrEmpty(text.Text);
}

void CopyOnExcecute(object sender, ExecutedRoutedEventArgs args)…
[/Quote]
应该说是WPF类帮我们做了些事，但是，Command是怎么被传递的。同样是Button，为什么ToolBar上的Button收到Command，panel上的没有收到，有熟悉Command机制的朋友能解释一下吗？