Commands-Notes (-) and commands

Commands-Notes (-) and commands
Command-Note (-)

Basic Concepts

Basic elements of the command:

Command steps:

Second test

To achieve this requirement, define a command and use the Button to send this command. When the command reaches the Textbox, clear the Text (when the Textbox is empty, the Button is unavailable ).

XAML code:

<Window x:Class="CommandApplication.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:CommandApplication"
        mc:Ignorable="d"
        Title="MainWindow" Height="175" Width="200">
    <StackPanel x:Name="stackPanel">
        <Button x:Name="button1" Content="Send Command" Margin="5"/>
        <TextBox x:Name="textBoxA" Margin="5,0" Height="100"/>
    </StackPanel>
</Window>

CS code:

Using System;
Using System.Collections.Generic;
Using System.Linq;
Using System.Text;
Using System.Threading.Tasks;
Using System.Windows;
Using System.Windows.Controls;
Using System.Windows.Data;
Using System.Windows.Documents;
Using System.Windows.Input;
Using System.Windows.Media;
Using System.Windows.Media.Imaging;
Using System.Windows.Navigation;
Using System.Windows.Shapes;

Namespace CommandApplication
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    Public partial class MainWindow : Window
    {
        Public MainWindow()
        {
            InitializeComponent();
            InitializeCommand();
        }
        //RoutedCommand is a common command class that comes with the system.
        / / Declare the command instance
        Private RoutedCommand clearCmd = new RoutedCommand("Clear", typeof(MainWindow));
        Private void InitializeCommand()
        {
            / / specify the command source
            this.button1.Command = this.clearCmd;
            this.clearCmd.InputGestures.Add(new KeyGesture(Key.C, ModifierKeys.Alt));
            / / Specify the command target, specify the s in the command source properties
            this.button1.CommandTarget = this.textBoxA;

            / / Create a command association
            CommandBinding cb = new CommandBinding();
            cb.Command = this.clearCmd;
            cb.CanExecute += new CanExecuteRoutedEventHandler(cb_CanExecute);
            cb.Executed += new ExecutedRoutedEventHandler(cb_Execute);

            //this.stackPanel.CommandBindings.Add(cb);
            this.textBoxA.CommandBindings.Add(cb);
        }

        //This method is called when the command is delivered to the target.
        Private void cb_Execute(object sender, ExecutedRoutedEventArgs e)
        {
            this.textBoxA.Clear();
            e.Handled = true;

        }
        / / This method is called when the probe command is executable
        Private void cb_CanExecute(object sender, CanExecuteRoutedEventArgs e)
        {
            If (string.IsNullOrEmpty(this.textBoxA.Text))
                { e.CanExecute = false; }
            Else
            { e.CanExecute = true; }
            e.Handled = true;

        }
    }
} 

Running effect: