Por que usar INotifyPropertyChanged com ligações no WPF?
Eu percebi que praticamente todos os exemplos que eu encontro na internet sobre bindings tem uma classe (que se liga a outra propriedade) que herda a interface INotifyPropertyChanged e usa um método na parte set da propriedade da classe.
Eu tentei remover essa parte do exemplo de ligação e funcionou da mesma forma que com o método.
Aqui está o exemplo. Eu alterei isso para que fosse um modo de ligação TwoWay e mostre a propriedade alterada em um messagebox.
Eu fiz isso apenas para brincar um pouco com as ligações, mas agora eu realmente não sei porque essa interface é usada
XAML:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="30"/>
<RowDefinition Height="30"/>
<RowDefinition Height="30"/>
<RowDefinition Height="30"/>
<RowDefinition Height="30"/>
<RowDefinition Height="40"/>
<RowDefinition Height="30"/>
<RowDefinition Height="30"/>
<RowDefinition Height="30"/>
<RowDefinition Height="30"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="100"/>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="30"/>
<ColumnDefinition Width="30"/>
</Grid.ColumnDefinitions>
<Button Grid.Row="5" Grid.Column="5" Name="btnBinding" Click="btnBinding_Click" Width="100" Height="30">
<Grid HorizontalAlignment="Left" VerticalAlignment="Center">
<Grid.RowDefinitions>
<RowDefinition Height="25"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="50"/>
<ColumnDefinition Width="50"/>
</Grid.ColumnDefinitions>
<TextBox Name="txtBinding" Width="30" Height="25" HorizontalAlignment="Left"/>
<Label Grid.Column="1" Content="Bind"/>
</Grid>
</Button>
<Button Grid.Column="5" Grid.Row="6" Name="btnMessage" Click="btnMessage_Click" Content="MessageBox"/>
<Button Grid.Column="5" Grid.Row="4" Name="btnChangeproperty" Click="btnChangeproperty_Click" Content="Change Property"/>
</Grid>
</Window>
Main.cs:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
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 WpfApplication1
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
Binding bind;
MyData mydata;
public MainWindow()
{
InitializeComponent();
}
private void btnBinding_Click(object sender, RoutedEventArgs e)
{
mydata = new MyData("T");
bind = new Binding("MyDataProperty")
{
Source = mydata,
Mode = BindingMode.TwoWay
};
txtBinding.SetBinding(TextBox.TextProperty, bind);
}
private void btnMessage_Click(object sender, RoutedEventArgs e)
{
MessageBox.Show(mydata.MyDataProperty);
}
private void btnChangeproperty_Click(object sender, RoutedEventArgs e)
{
mydata.MyDataProperty = "New Binding";
}
}
}
Classe MyData:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;
namespace WpfApplication1
{
public class MyData
{
private string myDataProperty;
public MyData() { }
public MyData(DateTime dateTime)
{
myDataProperty = "Last bound time was " + dateTime.ToLongTimeString();
}
public MyData(string teste)
{
myDataProperty = teste;
}
public String MyDataProperty
{
get { return myDataProperty; }
set
{
myDataProperty = value;
OnPropertyChanged("MyDataProperty");
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string info)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(info));
}
}
}
}