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icommand interface in wpf

admin 11月 12, 2020 0

MainWindow.xaml 전체 소스
MainWindow.cs
MainViewModel.cs
CommandHandler.cs
Reference

MVVM(Model View ViewMode) 패턴에서 XAML View가 WPF Command를 어떻게 바인딩하는지 살펴보자. ICommand Interface로 이벤트 핸들러를 구현하여 직접 xaml에서 사용하는 예제이다. 아래의 코드처럼 화면을 구현한다고 가정한다.

<TextBox x:Name="TextBoxSimple" Text="Default"/>
<Button x:Name="ButtonSimple" Content="Simple Command"/>

MainWindow.xaml 전체 소스

<Window x:Class="WPFDemo.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:WPFDemo"
        mc:Ignorable="d"
        xmlns:vm="clr-namespace:WPFDemo.ViewModels"
        Title="MainWindow" Height="600" Width="900" FontFamily="Malgun Gothic" FontSize="12">

    <Window.Resources>
        <vm:MainViewModel x:Key="viewModel" />
    </Window.Resources>

    <Grid>
        <StackPanel VerticalAlignment="Center" HorizontalAlignment="Center">
            <TextBox x:Name="TextBoxSimple" Text="Default" Margin="4" Height="30" Width="200"
                     VerticalContentAlignment="Center" />
            <Button x:Name="ButtonSimple" Content="Simple Command" Margin="4" Height="30" Width="200">
                <Button.InputBindings>
                    <MouseBinding Gesture="LeftClick"
                                  Command="{Binding HelloLeft, Source={StaticResource viewModel}}"
                                  CommandParameter= "{Binding ElementName=TextBoxSimple, Path=Text}" />
                    <MouseBinding Gesture="RightClick"
                                  Command="{Binding HelloRight, Source={StaticResource viewModel}}"
                                  CommandParameter= "{Binding ElementName=TextBoxSimple, Path=Text}" />
                </Button.InputBindings>
            </Button>
        </StackPanel>
    </Grid>
</Window>

MainWindow.cs

using System.Windows;

namespace WPFDemo
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }
}

MainViewModel.cs

using System.Windows;
using System.Windows.Input;
using WPFDemo.ViewModels.Commands;

namespace WPFDemo.ViewModels
{
    public class MainViewModel
    {
        public ICommand HelloLeft
        {
            get
            {
                return new CommandHandler(param => HelloWorldLeft(param), HelloWorld());
            }
        }

        public ICommand HelloRight
        {
            get
            {
                return new CommandHandler(param => HelloWorldRight(param), true);
            }
        }

        public void HelloWorldLeft(object param)
        {
            MessageBox.Show("LeftClick : " + param);
        }

        public bool HelloWorld()
        {
            return true;
        }

        public void HelloWorldRight(object param)
        {
            MessageBox.Show("RightClick : " + param);
        }
    }
}

CommandHandler.cs

using System;
using System.Windows.Input;

namespace WPFDemo.ViewModels.Commands
{
    public class CommandHandler : ICommand
    {
        private readonly Action<object> mAction;
        private readonly bool mCanExecute;

        public CommandHandler(Action<object> action, bool canExecute)
        {
            mAction = action;
            mCanExecute = canExecute;
        }

        public bool CanExecute(object parameter)
        {
            return mCanExecute;
        }

        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }

        public void Execute(object parameter)
        {
            mAction(parameter);
        }
    }
}

Reference