lab4

Привязка (Binding). Интерфейс INotifyPropertyChanged. Форматирование значений привязки и конвертеры значений.

Введение в привязку данных

<Window 
    x:Class="BindingApp.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:BindingApp"
    mc:Ignorable="d"
    Title="MainWindow" 
    Height="250" 
    Width="300"
>
    <StackPanel>
        <TextBox 
            x:Name="myTextBox" 
            Height="30" />
        <TextBlock 
            x:Name="myTextBlock" 
            Text="{Binding 
                ElementName=myTextBox,
                Path=Text}"
            Height="30" />
    </StackPanel>
</Window>

Работа с привязкой в C

public MainWindow()
{
    InitializeComponent();
  
    Binding binding = new Binding();
 
    // элемент-источник
    binding.ElementName = "myTextBox"; 

    // свойство элемента-источника
    binding.Path = new PropertyPath("Text"); 

    // установка привязки для элемента-приемника
    myTextBlock.SetBinding(TextBlock.TextProperty, binding); 
}

Режимы привязки

<StackPanel>
    <TextBox 
        x:Name="textBox1" 
        Height="30" />
    <TextBox 
        x:Name="textBox2" 
        Height="30" 
        Text="{Binding 
            ElementName=textBox1, 
            Path=Text, 
            Mode=TwoWay}" />
</StackPanel>

Свойство Source

class Phone
{
    public string Title { get; set; }
    public string Company { get; set; }
    public int Price { get; set; }
}

<Window 
    x:Class="BindingApp.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:BindingApp"
    mc:Ignorable="d"
    Title="MainWindow" 
    Height="150" 
    Width="300"
>
    <Window.Resources>
        <local:Phone 
            x:Key="nexusPhone" 
            Title="Nexus X5" 
            Company="Google" 
            Price="25000" />
    </Window.Resources>
    <Grid Background="Black">
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition />
            <ColumnDefinition />
        </Grid.ColumnDefinitions>
        <TextBlock 
            Text="Модель:" 
            Foreground="White"/>
        <TextBlock 
            x:Name="titleTextBlock" 
            Text="{Binding 
                Source={StaticResource nexusPhone}, 
                Path=Title}"
            Foreground="White" 
            Grid.Column="1"/>
        <TextBlock 
            Text="Цена:" 
            Foreground="White" 
            Grid.Row="1"/>
        <TextBlock 
            x:Name="priceTextBlock" 
            Text="{Binding 
                Source={StaticResource nexusPhone}, 
                Path=Price}"
            Foreground="White" 
            Grid.Column="1" 
            Grid.Row="1"/>
    </Grid>
</Window>

Свойство TargetNullValue

<Window.Resources>
    <local:Phone 
        x:Key="nexusPhone" 
        Company="Google" 
        Price="25000" />
</Window.Resources>
<StackPanel>
    <TextBlock 
        x:Name="titleTextBlock"
        Text="{Binding 
            Source={StaticResource nexusPhone}, 
            Path=Title, 
            TargetNullValue=Текст по умолчанию}" />
</StackPanel>

Свойство RelativeSource

<TextBox Text="{Binding 
    RelativeSource={RelativeSource Mode=Self}, 
    Path=Background, 
    Mode=TwoWay, 
    UpdateSourceTrigger=PropertyChanged}" />

<Grid Background="Black">
    <TextBlock 
        Foreground="White"
        Text="{Binding 
            RelativeSource={RelativeSource 
                Mode=FindAncestor,
                AncestorType={x:Type Grid}}, 
            Path=Background}" />
</Grid>

Свойство DataContext

<Window 
    x:Class="BindingApp.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:BindingApp"
    mc:Ignorable="d"
    Title="MainWindow" 
    Height="150" 
    Width="300">
    <Window.Resources>
        <local:Phone 
            x:Key="nexusPhone" 
            Title="Nexus X5" 
            Company="Google" 
            Price="25000" />
    </Window.Resources>
    <Grid 
        Background="Black" 
        DataContext="{StaticResource nexusPhone}" 
        TextBlock.Foreground="White">
        <Grid.ColumnDefinitions>
            <ColumnDefinition />
            <ColumnDefinition />
            <ColumnDefinition />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>
        <TextBlock 
            Text="Модель" />
        <TextBlock 
            Text="{Binding Title}" 
            Grid.Row="1" />
        <TextBlock 
            Text="Производитель" 
            Grid.Column="1"/>
        <TextBlock 
            Text="{Binding Company}" 
            Grid.Column="1" 
            Grid.Row="1" />
        <TextBlock 
            Text="Цена" 
            Grid.Column="2" />
        <TextBlock 
            Text="{Binding Price}" 
            Grid.Column="2" 
            Grid.Row="1" />
    </Grid>
</Window>

Интерфейс INotifyPropertyChanged.

<Window 
    x:Class="BindingApp.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:BindingApp"
    mc:Ignorable="d"
    Title="MainWindow" 
    Height="150" 
    Width="300"
>
    <Window.Resources>
        <local:Phone 
            x:Key="nexusPhone" 
            Title="Nexus X5" 
            Company="Google" 
            Price="25000" />
    </Window.Resources>
    <Grid 
        Background="Black" 
        DataContext="{StaticResource nexusPhone}" 
        TextBlock.Foreground="White">
        <Grid.ColumnDefinitions>
            <ColumnDefinition />
            <ColumnDefinition />
            <ColumnDefinition />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>
        <TextBlock 
            Text="Модель" />
        <TextBlock 
            Text="{Binding Title}" 
            Grid.Row="1" />
        <TextBlock 
            Text="Производитель" 
            Grid.Column="1"/>
        <TextBlock 
            Text="{Binding Company}" 
            Grid.Column="1" 
            Grid.Row="1" />
        <TextBlock 
            Text="Цена" 
            Grid.Column="2" />
        <TextBlock 
            Text="{Binding Price}" 
            Grid.Column="2" 
            Grid.Row="1" />
 
        <Button 
            Foreground="White" 
            Content="Изменить" 
            Click="Button_Click" 
            Background="Black"
            BorderBrush="Silver" 
            Grid.Column="2" 
            Grid.Row="2" />
    </Grid>
</Window>

using System.ComponentModel;
using System.Runtime.CompilerServices;
 
class Phone : INotifyPropertyChanged
{
    private string title;
    private string company;
    private int price;
 
    public string Title
    {
        get { return title; }
        set
        {
            title = value;
            OnPropertyChanged("Title");
        }
    }
    public string Company
    {
        get { return company; }
        set
        {
            company = value;
            OnPropertyChanged("Company");
        }
    }
    public int Price
    {
        get { return price; }
        set
        {
            price = value;
            OnPropertyChanged("Price");
        }
    }
 
    public event PropertyChangedEventHandler PropertyChanged;
    public void OnPropertyChanged([CallerMemberName]string prop = "")
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(prop));
    }
}

Форматирование значений привязки и конвертеры значений

class Phone
{
    public string Title { get; set; }
    public string Company { get; set; }
    public int Price { get; set; }
}

<Window 
    x:Class="ValueConventerApp.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:ValueConventerApp"
    mc:Ignorable="d"
    Title="MainWindow" 
    Height="150" 
    Width="300"
>
    <Window.Resources>
        <local:Phone 
            x:Key="nexusPhone" 
            Title="Nexus X5" 
            Company="Google" 
            Price="25000" />
    </Window.Resources>
    <Grid>
        <TextBlock 
            Text="{Binding 
                StringFormat=Итоговая цена {0} рублей, 
                Source={StaticResource nexusPhone}, 
                Path=Price}" />
    </Grid>
</Window>

Конвертеры значений

public class DateTimeToDateConverter : IValueConverter
{
    public object Convert(
        object value, 
        Type targetType, 
        object parameter, 
        CultureInfo culture)
    {
        if(parameter!=null && parameter.ToString()=="EN")
            return ((DateTime)value).ToString("MM-dd-yyyy");
         
        return ((DateTime)value).ToString("dd.MM.yyyy");
    }
         
    public object ConvertBack(
        object value, 
        Type targetType, 
        object parameter, 
        CultureInfo culture)
    {
        return DependencyProperty.UnsetValue;
    }
}

<StackPanel>
    <TextBlock 
        Text="{Binding 
            Source={StaticResource myDate},
            Converter={StaticResource myDateConverter}}" />
    <TextBlock 
        Text="{Binding 
            Source={StaticResource myDate}, 
            ConverterParameter=EN, 
            Converter={StaticResource myDateConverter}}" />
    <TextBlock 
        Text="{Binding 
            Source={StaticResource myDate}}" />
</StackPanel>