Question

我有一个我添加项目的ListBox。每次我选择一个作为Person对象的项目时，这个人的属性应该在文本框中显示。此人具有年龄，姓名，性别等人物属性。

我的列表框选择更改事件仅触发一次或新添加的项目。当我点击并且不仅仅是添加它时，它不会触发。

Mainwindow.xaml.cs

namespace GUI_WPF_Eksamen
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
    Backlog bl = new Backlog();

    public MainWindow()
    {

        InitializeComponent();

        DataContext = bl;
        this.PriorityComboBox.Items.Add("High");
        this.PriorityComboBox.Items.Add("Medium");
        this.PriorityComboBox.Items.Add("Low");
    }


    private void AddToProductBackLogBtn_Click(object sender, RoutedEventArgs e)
    {
        this.ProductBacklogList.Items.Add(bl);
        this.NameTextBox.Text = String.Empty;
    }


    private void ProductBacklogList_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        var item = this.ProductBacklogList.SelectedItem as Backlog;
        this.NameLabel.Content = item.NAME;
        this.DescriptionTextBlock.Text = item.DESCRIPTION;
        this.PriorityLabel.Content = item.PRIORITY;
        this.TimeLabel.Content = item.TIME;
    }

    private void AddToSprint_Click(object sender, RoutedEventArgs e)
    {
        var currentItem = this.ProductBacklogList.SelectedItem as Backlog;
        this.SprintBacklogList.Items.Add(currentItem);

    }
}
}

Mainwindow.xaml

<Window x:Class="GUI_WPF_Eksamen.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:GUI_WPF_Eksamen"
    Title="GUI WPF application" Height="800" Width="1200">
<Window.Background>
    <ImageBrush ImageSource="Images/chalkboard.jpg"/>
</Window.Background>
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="69*"/>
        <RowDefinition Height="700*"/>
    </Grid.RowDefinitions>
    <Label x:Name="Title" Content="SCRUM-BOARD XXL" HorizontalAlignment="Center" HorizontalContentAlignment="Center" Margin="15,10,5,0" VerticalAlignment="Top" Width="1172" Height="56" FontSize="36" FontStyle="Italic" FontWeight="Bold" Foreground="White"/>

    <Grid HorizontalAlignment="Left" Height="680" Margin="15,10,0,0" Grid.Row="1" VerticalAlignment="Top" Width="354">
        <Grid.RowDefinitions>
            <RowDefinition Height="94*"/>
            <RowDefinition Height="44*"/>
            <RowDefinition Height="131*"/>
            <RowDefinition Height="53*"/>
            <RowDefinition Height="40*"/>
            <RowDefinition Height="46*"/>
            <RowDefinition Height="272*"/>
        </Grid.RowDefinitions>
        <Label Content="Navn" HorizontalAlignment="Left" Margin="0,44,0,0" VerticalAlignment="Top" Width="77" FontSize="16" Foreground="White"/>
        <Label Content="Beskrivelse&#xA;" HorizontalAlignment="Left" Margin="0,10,0,0" VerticalAlignment="Top" Foreground="White" FontSize="16" Height="31" Grid.Row="1"/>
        <Label Content="Prioritet" HorizontalAlignment="Left" Margin="0,7,0,0" VerticalAlignment="Top" Width="67" FontSize="16" Foreground="White" Grid.Row="3"/>
        <Label Content="Estimeret tidsforbrug" HorizontalAlignment="Left" Margin="0,10,0,0" VerticalAlignment="Top" Foreground="White" FontSize="16" Grid.Row="4" Grid.RowSpan="2"/>
        <TextBox x:Name="NameTextBox" HorizontalAlignment="Left" Height="23" Margin="51,52,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="303" Opacity="0.5" Text="{Binding Path=NAME}"/>
        <ComboBox x:Name="PriorityComboBox" HorizontalAlignment="Left" Margin="73,12,0,0" VerticalAlignment="Top" Width="152" RenderTransformOrigin="0.5,0.5" Opacity="0.5" Grid.Row="3" SelectedItem="{Binding Path=PRIORITY}">
            <ComboBox.RenderTransform>
                <TransformGroup>
                    <ScaleTransform/>
                    <SkewTransform/>
                    <RotateTransform Angle="0.036"/>
                    <TranslateTransform/>
                </TransformGroup>
            </ComboBox.RenderTransform>
        </ComboBox>
        <TextBox x:Name="TimeTextBox" HorizontalAlignment="Left" Height="23" Margin="0,6,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="204" Opacity="0.5" Grid.Row="5" Text="{Binding Path=TIME}"/>
        <Label Content="time(r)" HorizontalAlignment="Left" Margin="209,38,0,0" VerticalAlignment="Top" Foreground="White" FontSize="16" Width="57" Grid.Row="4" Grid.RowSpan="2"/>
        <TextBox x:Name="DescriptionTextBox" HorizontalAlignment="Left" Height="111" Margin="0,10,0,0" Grid.Row="2" TextWrapping="Wrap" VerticalAlignment="Top" Width="354" Opacity="0.5" Text="{Binding Path=DESCRIPTION}"/>
        <Button x:Name="AddToProductBackLogBtn" Content="Add Backlog item" HorizontalAlignment="Left" Grid.Row="6" VerticalAlignment="Top" Width="200" Height="27" Margin="66,0,0,0" Background="White" Opacity="0.7" Click="AddToProductBackLogBtn_Click"/>

    </Grid>

    <Grid HorizontalAlignment="Left" Height="680" Margin="374,10,0,0" Grid.Row="1" VerticalAlignment="Top" Width="808" RenderTransformOrigin="0.459,0.431">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="79*"/>
            <ColumnDefinition Width="47*"/>
            <ColumnDefinition Width="76*"/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="209*"/>
            <RowDefinition Height="131*"/>
        </Grid.RowDefinitions>
        <Label Content="Navn" HorizontalAlignment="Left" Margin="10,10,0,0" Grid.Row="1" VerticalAlignment="Top" FontSize="16" Foreground="White" Height="31" Width="47"/>
        <Label Content="Beskrivelse" HorizontalAlignment="Left" Margin="10,55,0,0" Grid.Row="1" VerticalAlignment="Top" Foreground="White" FontSize="16" Height="31" Width="87"/>
        <Label Content="Prioritet&#xD;&#xA;" HorizontalAlignment="Left" Margin="10,10,0,0" Grid.Row="1" VerticalAlignment="Top" Foreground="White" FontSize="16" Height="32" Grid.Column="1" Width="66"/>
        <Label Content="Estimeret tidsforbrug" Grid.Column="1" HorizontalAlignment="Left" Margin="10,55,0,0" Grid.Row="1" VerticalAlignment="Top" Foreground="White" FontSize="16" Height="31" Width="159"/>
        <Label x:Name="PriorityLabel" Content="" Grid.Column="1" HorizontalAlignment="Left" Margin="90,10,0,0" Grid.Row="1" VerticalAlignment="Top" FontSize="16" Foreground="White" Width="79" Height="31"/>
        <Label x:Name="TimeLabel" Grid.Column="2" HorizontalAlignment="Left" Margin="10,55,0,0" Grid.Row="1" VerticalAlignment="Top" Foreground="White" FontSize="16" Width="208" Height="31"/>
        <ListBox x:Name="ProductBacklogList" HorizontalAlignment="Left" Height="353" Margin="10,55,0,0" VerticalAlignment="Top" Width="292" DisplayMemberPath="NAME" Opacity="0.505" SelectionChanged="ProductBacklogList_SelectionChanged" RenderTransformOrigin="0.5,0.5">
            <ListBox.RenderTransform>
                <TransformGroup>
                    <ScaleTransform/>
                    <SkewTransform AngleY="-0.195"/>
                    <RotateTransform/>
                    <TranslateTransform Y="-0.497"/>
                </TransformGroup>
            </ListBox.RenderTransform>
        </ListBox>
        <ListBox x:Name="SprintBacklogList" HorizontalAlignment="Left" Height="353" Margin="10,55,0,0" VerticalAlignment="Top" Width="284" DisplayMemberPath="NAME" Grid.Column="2" Opacity="0.5"/>
        <Label x:Name="NameLabel" HorizontalAlignment="Left" Margin="62,14,0,0" Grid.Row="1" VerticalAlignment="Top" Width="244" Height="27" Content="{Binding Path=NAME}" Foreground="White"/>
        <Button x:Name="AddToSprint" Content="Add &gt;&gt;" Grid.Column="1" HorizontalAlignment="Left" Margin="54,201,0,0" VerticalAlignment="Top" Width="75" Height="20" Opacity="0.7" Click="AddToSprint_Click"/>
        <TextBlock x:Name="DescriptionTextBlock" HorizontalAlignment="Left" Margin="10,86,0,0" Grid.Row="1" TextWrapping="Wrap" VerticalAlignment="Top" Height="166" Width="296" Foreground="White"/>
    </Grid>
</Grid>

Answer 1

这种改变方式可以很容易地实现：

看看这里：

<Window x:Class="ListBoxSelection.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">
<DockPanel>
    <ListBox ItemsSource="{Binding persons}" IsSynchronizedWithCurrentItem="True" DockPanel.Dock="Top">
        <ListBox.ItemTemplate>
            <DataTemplate>
                <StackPanel Orientation="Horizontal">
                    <TextBlock Text="{Binding Name}" Margin="5,0"/>
                    <TextBlock Text="{Binding Age, StringFormat=is {0} years old}" Margin="5,0"/>
                </StackPanel>
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox>
    <StackPanel Orientation="Horizontal" DataContext="{Binding persons}" DockPanel.Dock="Top">
        <TextBlock Text="You have selected: " FontWeight="SemiBold"/>
        <TextBox Text="{Binding Name, UpdateSourceTrigger=PropertyChanged}" 
                 Margin="5,0" 
                 FontWeight="SemiBold" 
                 VerticalAlignment="Top"
                 HorizontalAlignment="Center"/>
        <TextBox Text="{Binding Age, UpdateSourceTrigger=PropertyChanged}"
                 Margin="5,0"
                 FontWeight="SemiBold" 
                 VerticalAlignment="Top" 
                 HorizontalAlignment="Left"/>
    </StackPanel> 
    <Button Content="Add Item" DockPanel.Dock="Top" Width="60" VerticalAlignment="Top" Margin="20" Click="btnAddItem_Click"/>
</DockPanel>

请注意这一点： IsSynchronizedWithCurrentItem="True"

来自MSDN：

获取或设置一个值，该值指示Selector是否应保留 SelectedItem与Items属性中的当前项同步。

下一步是什么？显示所选项目：

<StackPanel DataContext="{Binding persons}"/>

StackPanel不是ItemsControl，它不会尝试显示人物中的所有项目，而是会查找所选项目。

ICollectionView界面包含一个名为CurrentItem的成员。 IsSynchronizedWithCurrentItem的作用是：只要在ItemsControl上单击某个项目，它就会为集合视图设置CurrentItem。 ICollectionView还有两个事件：CurrentItemChanging和CurrentItemChanged。设置IsSynchronizedWithCurrentItem属性后，ItemsControl将根据ICollectionView的CurrentItem更新SelectedItem。

此外，使用UpdateSourceTrigger=PropertyChanged您可以更新所选项目，这将立即显示在ListBox。

好的，关于，这是代码的其余部分：

public class Person : INotifyPropertyChanged
{
    private string _Name;

    public string Name
    {
        get { return _Name; }
        set
        {
            _Name = value;
            PropertyChanged(this, new PropertyChangedEventArgs("Name"));
        }
    }

    private int _Age;

    public int Age
    {
        get { return _Age; }
        set
        {
            _Age = value;
            PropertyChanged(this, new PropertyChangedEventArgs("Age"));
        }
    }
    public event PropertyChangedEventHandler PropertyChanged = delegate { };
}

代码隐藏：

public partial class MainWindow : Window
{

    public ObservableCollection<Person> persons { get; set; }

    public Person SelectedPerson
    {
        get { return (Person)GetValue(SelectedPersonProperty); }
        set { SetValue(SelectedPersonProperty, value); }
    }

    // Using a DependencyProperty as the backing store for SelectedPerson.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty SelectedPersonProperty =
        DependencyProperty.Register("SelectedPerson", typeof(Person), typeof(MainWindow), new PropertyMetadata(null));

    public MainWindow()
    {
        InitializeComponent();
        persons = new ObservableCollection<Person>();
        persons.Add(new Person() { Name = "Name1", Age = 20 });
        persons.Add(new Person() { Name = "Name2", Age = 25 });
        persons.Add(new Person() { Name = "Name3", Age = 30 });
        this.DataContext = this;
    }

    private void btnAddItem_Click(object sender, RoutedEventArgs e)
    {
        persons.Add(new Person() { Name = "NameAdded", Age = 50 });
    }
}

如您所见，不再需要SelectionChanged处理程序。

您可能会问，后面代码中的SelectedPerson是什么：

在ListBox上添加此绑定：

SelectedItem="{Binding SelectedPerson}"

在AddToSprint_Click中使用SelectedPerson获取Person而不是直接访问ListBox。

ListBox SelectionChanged只有一次？

1 个答案: