В приложении, над которым я работаю, я программно создаю несколько FrameworkElements с разными источниками данных. К сожалению, привязка данных не работает.
Мне удалось перегнать проблему в следующую программу:
using System.Collections.Generic;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Data;
namespace TestBinding
{
public class BindingSource : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
protected bool SetField<T>(ref T field, T value, [CallerMemberName] string propertyName = null)
{
if (EqualityComparer<T>.Default.Equals(field, value)) return false;
field = value;
OnPropertyChanged(propertyName);
return true;
}
private string _text = "Initial Text";
public string Text
{
get { return _text; }
set { SetField(ref _text, value); }
}
}
public sealed partial class MainPage : Page
{
BindingSource bs = new BindingSource();
public MainPage()
{
this.InitializeComponent();
TextBlock tb = new TextBlock();
tb.HorizontalAlignment = HorizontalAlignment.Center;
tb.VerticalAlignment = VerticalAlignment.Center;
tb.FontSize = 36;
Binding bind = new Binding() { Source = bs.Text, Mode=BindingMode.OneWay, UpdateSourceTrigger=UpdateSourceTrigger.PropertyChanged };
tb.SetBinding(TextBlock.TextProperty, bind);
Patergrid.Children.Add(tb);
}
private void ClickText1(object sender, RoutedEventArgs e)
{
bs.Text = "First text button clicked!";
}
private void ClickText2(object sender, RoutedEventArgs e)
{
bs.Text = "Second text button stroked!";
}
}
}
И вот xaml:
<Page
x:Class="TestBinding.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:TestBinding"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Grid x:Name="Patergrid" Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<StackPanel Grid.Column="1" HorizontalAlignment="Center" VerticalAlignment="Center">
<Button Content="Text 1" Margin="25" HorizontalAlignment="Center" Click="ClickText1" />
<Button Content="Text 2" Margin="25" HorizontalAlignment="Center" Click="ClickText2" />
</StackPanel>
</Grid>
</Page>
Пошагово выполняя код при изменении свойств, я вижу, что нет подписчиков на событие PropertyChanged.
Почему SetBinding не регистрируется для события PropertyChanged?