WPF命令，如何声明应用程序级别的命令? [英] WPF Commands, How to declare Application level commands?

问题描述

我有兴趣创建可在WPF应用程序中任何位置使用的命令.

I'm interested in creating commands that are available from anywhere in my WPF application.

我希望它们以与Cut，Copy，Paste和其他应用程序级别命令相同的方式工作，即:

I'd like them to work in the same way as Cut, Copy, Paste and the other Application level commands, ie:

<Button Command="Paste" />

我假设我可以为Application实例设置CommandBindings，但是该属性不可用.

I assumed I could setup CommandBindings for the Application instance, but that property isn't available.

这是怎么做的?

到目前为止，我所能完成的最好的事情就是在顶层窗口上创建一组命令，然后像这样访问它们:

The best I have managed so far is to create a suite of commands on the top level window and then access them like this...:

<Button Command="{x:Static namespace::MainWindow.CommandName}" />

这是可行的，但是当然是紧密耦合的，所以非常脆弱.

Which works, but is of course tightly coupled, and so extremely brittle.

推荐答案

您可以为WPF应用程序的所有Windows"设置CommandBindings，并在Application类中实现命令处理程序.

You can setup CommandBindings for "All Windows" of your WPF application and implement command handlers in Application class.

首先，创建一个静态命令容器类.例如，

First of all, create a static command container class. For example,

namespace WpfApplication1 
{
    public static class MyCommands
    {
        private static readonly RoutedUICommand doSomethingCommand = new RoutedUICommand("description", "DoSomethingCommand", typeof(MyCommands));

        public static RoutedUICommand DoSomethingCommand
        {
            get
            {
                return doSomethingCommand;
            }
        }
    }
}

接下来，将自定义命令设置为Button.Command像这样.

Next, set your custom command to Button.Command like this.

<Window x:Class="WpfApplication1.MainWindow"
        ...
        xmlns:local="clr-namespace:WpfApplication1">
    <Grid>
        ...
        <Button Command="local:MyCommands.DoSomethingCommand">Execute</Button>
    </Grid>
</Window>

最后，在Application类中实现自定义命令的命令处理程序.

Finally, implement the command handler of your custom command in Application class.

namespace WpfApplication1 
{

    public partial class App : Application
    {
        public App()
        {
            var binding = new CommandBinding(MyCommands.DoSomethingCommand, DoSomething, CanDoSomething);

            // Register CommandBinding for all windows.
            CommandManager.RegisterClassCommandBinding(typeof(Window), binding);
        }

        private void DoSomething(object sender, ExecutedRoutedEventArgs e)
        {
            ...
        }

        private void CanDoSomething(object sender, CanExecuteRoutedEventArgs e)
        {
            ...
            e.CanExecute = true;
        }
    }
}

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