(WPF 교육추천)WPF 커맨드 실습, 데이터 바인딩을 이용한 계산기 실습(MVVM, ViewModel)

(WPF 교육추천)WPF 커맨드 실습, 데이터 바인딩을 이용한 계산기 실습(MVVM, ViewModel)

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n 지금까지 배운 데이터 바인딩 및 MVVM을 이용하여 간단한 계산기를 구현해 보자.

n MainWindow.xaml

<Window x:Class="Calculator.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:Calculator" mc:Ignorable="d" Title="MainWindow" Height="450" Width="800"> <Window.Resources> <local:Calc x:Key="calculator"/> </Window.Resources> <Grid HorizontalAlignment="Center" VerticalAlignment="Center"> <Grid.RowDefinitions> <RowDefinition Height="60" /> <RowDefinition Height="60" /> <RowDefinition Height="60" /> <RowDefinition Height="60" /> <RowDefinition Height="60" /> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition Width="60" /> <ColumnDefinition Width="60" /> <ColumnDefinition Width="60" /> <ColumnDefinition Width="60" /> </Grid.ColumnDefinitions> <Grid Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="4"> <Grid.ColumnDefinitions> <ColumnDefinition Width="120" /> <ColumnDefinition Width="50*" /> <ColumnDefinition Width="50*" /> </Grid.ColumnDefinitions> <Border BorderThickness="1" BorderBrush="Black"> <TextBlock FontSize="15" VerticalAlignment="Center" HorizontalAlignment="Center" Text="{Binding DisplayText,Source={StaticResource calculator}}" /> </Border> <Button Content="BACK" Grid.Column="1" Command="{Binding Backspace,Source={StaticResource calculator}}" /> <Button Content="Clear" Grid.Column="2" Command="{Binding Clear,Source={StaticResource calculator}}" /> </Grid> <Button Content="1" CommandParameter="1" Grid.Row="1" Grid.Column="0" Command="{Binding Append,Source={StaticResource calculator}}" /> <Button Content="2" CommandParameter="2" Grid.Row="1" Grid.Column="1" Command="{Binding Append,Source={StaticResource calculator}}" /> <Button Content="3" CommandParameter="3" Grid.Row="1" Grid.Column="2" Command="{Binding Append,Source={StaticResource calculator}}" /> <Button Content="+" CommandParameter="+" Grid.Row="1" Grid.Column="3" Command="{Binding Operator,Source={StaticResource calculator}}" /> <Button Content="4" CommandParameter="4" Grid.Row="2" Grid.Column="0" Command="{Binding Append,Source={StaticResource calculator}}" /> <Button Content="5" CommandParameter="5" Grid.Row="2" Grid.Column="1" Command="{Binding Append,Source={StaticResource calculator}}" /> <Button Content="6" CommandParameter="6" Grid.Row="2" Grid.Column="2" Command="{Binding Append,Source={StaticResource calculator}}" /> <Button Content="-" CommandParameter="-" Grid.Row="2" Grid.Column="3" Command="{Binding Operator,Source={StaticResource calculator}}" /> <Button Content="7" CommandParameter="7" Grid.Row="3" Grid.Column="0" Command="{Binding Append,Source={StaticResource calculator}}" /> <Button Content="8" CommandParameter="8" Grid.Row="3" Grid.Column="1" Command="{Binding Append,Source={StaticResource calculator}}" /> <Button Content="9" CommandParameter="9" Grid.Row="3" Grid.Column="2" Command="{Binding Append,Source={StaticResource calculator}}" /> <Button Content="x" CommandParameter="*" Grid.Row="3" Grid.Column="3" Command="{Binding Operator,Source={StaticResource calculator}}" /> <Button Content="0" CommandParameter="0" Grid.Row="4" Grid.Column="0" Command="{Binding Append,Source={StaticResource calculator}}" /> <Button Content="." CommandParameter="." Grid.Row="4" Grid.Column="1" Command="{Binding Append,Source={StaticResource calculator}}" /> <Button Content="=" CommandParameter="=" Grid.Row="4" Grid.Column="2" Command="{Binding Calculate,Source={StaticResource calculator}}" /> <Button Content="/" CommandParameter="/" Grid.Row="4" Grid.Column="3" Command="{Binding Operator,Source={StaticResource calculator}}" /> </Grid> </Window>

n Calc.cs

using System; using System.ComponentModel; using System.Windows.Input; namespace Calculator { public class Calc : INotifyPropertyChanged { //아래 두 필드는 속성으로 구현되어 있다. //출력될 문자들을 담아둘 변수 string inputString = ""; //계산기화면의 출력 텍스트박스에 대응되는 필드 string displayText = ""; //View와 바인딩된 속성값이 바뀔때 이를 WPF에게 알리기 위한 이벤트 public event PropertyChangedEventHandler PropertyChanged; public Calc() { //이벤트 핸들러 정의 //숫자 버튼을 클릭할 때 실행 this.Append = new Append(this); //백스페이스 버튼을 클릭할 때 실행, 한글자 삭제 this.Backspace = new Backspace(this); //출력화면 클리어 this.Clear = new Clear(this); //+, -등 연산자 클릭할 때 실행 this.Operator = new Operator(this); // ‘=’ 버튼을 클릭할 때 실행 this.Calculate = new Calculate(this); } public string InputString { internal set { if (inputString != value) { inputString = value; OnPropertyChanged("InputString"); if (value != "") { DisplayText = value; } } } get { return inputString; } } //계산기의 출력창과 바인딩된 속성 public string DisplayText { internal set { if (displayText != value) { displayText = value; OnPropertyChanged("DisplayText"); } } get { return displayText; } } public string Op { get; set; } // Opertaor public double? Op1 { get; set; } // Operand 1 public ICommand Append { protected set; get; } public ICommand Backspace { protected set; get; } public ICommand Clear { protected set; get; } public ICommand Operator { protected set; get; } public ICommand Calculate { protected set; get; } protected void OnPropertyChanged(string propertyName) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } } class Append : ICommand { private Calc c; public event EventHandler CanExecuteChanged; public Append(Calc c) { this.c = c; } public bool CanExecute(object parameter) { return true; } public void Execute(object parameter) { c.InputString += parameter; } } class Backspace : ICommand { private Calc c; public Backspace(Calc c) { this.c = c; } public event EventHandler CanExecuteChanged { add { CommandManager.RequerySuggested += value; } remove { CommandManager.RequerySuggested -= value; } } public bool CanExecute(object parameter) { return c.InputString.Length > 0; } public void Execute(object parameter) { int length = c.InputString.Length - 1; if (0 < length) { c.InputString = c.InputString.Substring(0, length); } else { c.InputString = c.DisplayText = ""; } } } class Clear : ICommand { private Calc c; public Clear(Calc c) { this.c = c; } public event EventHandler CanExecuteChanged { add { CommandManager.RequerySuggested += value; } remove { CommandManager.RequerySuggested -= value; } } public bool CanExecute(object parameter) { return c.InputString.Length > 0; } public void Execute(object parameter) { c.InputString = c.DisplayText = ""; c.Op1 = null; } } class Operator : ICommand { private Calc c; public Operator(Calc c) { this.c = c; } public event EventHandler CanExecuteChanged { add { CommandManager.RequerySuggested += value; } remove { CommandManager.RequerySuggested -= value; } } public bool CanExecute(object parameter) { return 0 < c.InputString.Length || parameter.ToString() == "-"; } public void Execute(object parameter) { string op = parameter.ToString(); double op1; if (double.TryParse(c.InputString, out op1)) { c.Op1 = op1; c.Op = op; c.InputString = ""; } else if (c.InputString == "" && op == "-") { c.InputString = "-"; } } } class Calculate : ICommand { private Calc c; public Calculate(Calc c) { this.c = c; } public event EventHandler CanExecuteChanged { add { CommandManager.RequerySuggested += value; } remove { CommandManager.RequerySuggested -= value; } } public bool CanExecute(object parameter) { double op2; return c.Op1 != null && double.TryParse(c.InputString, out op2) && (c.Op != "/" || op2 != 0); } public void Execute(object parameter) { double op2 = double.Parse(c.InputString); c.InputString = calculate(c.Op, (double)c.Op1, op2).ToString(); c.Op1 = null; } private static double calculate(string op, double op1, double op2) { switch (op) { case "+": return op1 + op2; case "-": return op1 - op2; case "*": return op1 * op2; case "/": return op1 / op2; } return 0; } } }

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