我不能讓自定義控件的所選項目

Question

Pager.xaml（查看）

<Grid xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
     x:Class="Client.View.Pager"> 
    ... 
    <ListBox x:Name="listBoxEntries" 
      ItemsSource="{Binding Path=ListCollectionView}" 
      BorderThickness="0" 
      Margin="0" 
      Style="{StaticResource common}" 
      HorizontalContentAlignment="Stretch" 
      VerticalContentAlignment="Stretch" 
      ItemTemplate="{StaticResource templateTableCategory}" 
      SelectedItem="{Binding Path=SelectedEntry, Mode=TwoWay}"> 
     <ListBox.ItemsPanel> 
      <ItemsPanelTemplate> 
       <UniformGrid Rows="{Binding Path=Rows}" 
          Columns="{Binding Path=Columns}" 
          IsItemsHost="True"/> 
      </ItemsPanelTemplate> 
     </ListBox.ItemsPanel> 
    </ListBox> 
    ... 
</Grid> 

Pager.xaml.cs（代碼隱藏）

using System; 
using System.Collections; 
using System.Collections.Generic; 
using System.Collections.ObjectModel; 
using System.Linq; 
using System.Text; 
using System.Threading.Tasks; 
using System.Windows; 
using System.Windows.Controls; 
using System.Windows.Input; 
using Client.Model; 
using Client.ViewModel; 

namespace Client.View 
{ 
    public partial class Pager 
    { 
     public static readonly DependencyProperty SelectedEntryProperty = DependencyProperty.Register("SelectedEntry", typeof(IPagableEntry), typeof(Pager)); 
     ... 
     public IPagableEntry SelectedEntry 
     { 
      get { return (DataContext as PagerViewModel).SelectedEntry; } 
      set { (DataContext as PagerViewModel).SelectedEntry = value; } 
     } 
     ... 
    } 
} 

PagerViewModel.cs

namespace Client.ViewModel 
{ 
    public class PagerViewModel : ViewModelBase 
    { 
     ... 

     IPagableEntry _selectedEntry; 
     public IPagableEntry SelectedEntry 
     { 
      get 
      { 
       return _selectedEntry; 
      } 

      set 
      { 
       _selectedEntry = value; 
       OnPropertyChanged("SelectedEntry"); 
      } 
     } 
     ... 
    } 
} 

MainPage.xaml（查看）

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
     x:Class="Client.View.MainPage" 
     Style="{StaticResource common}"> 
    <Page.DataContext> 
     <viewModel:MainPageViewModel/> 
    </Page.DataContext> 
    ... 

    <view:Pager x:Name="pagerTableCategories" 
      Grid.Row="0" 
      List="{Binding Path=PagerTableCategoriesItems}" 
      Rows="{Binding Path=PagerTableCategoriesRows}" 
      Columns="{Binding Path=PagerTableCategoriesColumns}" 
      SelectedEntry="{Binding Path=SelectedTableCategory, Mode=TwoWay}"> 
    </view:Pager> 
    ... 
</Page> 

個

MainPageViewModel.cs

using System.Collections; 
using System.Collections.Generic; 
using System.Collections.ObjectModel; 
using System.Linq; 
using System.Windows; 
using System.Windows.Controls; 
using System.Windows.Data; 
using System.Windows.Media; 
using Client.Model; 

namespace Client.ViewModel 
{ 
    public class MainPageViewModel : ViewModelBase 
    { 
     ... 
     IPagableEntry _selectedTableCategory; 

     public IPagableEntry SelectedTableCategory 
     { 
      get 
      { 
       return _selectedTableCategory; 
      } 
      set 
      { 
       _selectedTableCategory = value; 
       MessageBox.Show("Got it!"); 
      } 
     } 
     ... 
    } 
} 

我做了一個自定義面板 '尋呼機'，這就是視圖模型。 ，我想在我的MainPage中顯示尋呼機。 我期望我選擇一個項目，然後MainPageViewModel的屬性SelectTableCategory將會改變，並且一個消息框顯示爲字符串「Got it！」 但它不起作用... 我的問題是什麼？

ps。我不擅長英語。 我希望你的理解。

Answer 1

讓我們從第一原則開始工作。

你有一個叫做尋呼機的自定義控制，這是要使用這樣

<view:Pager x:Name="pagerTableCategories" 
     SelectedEntry="{Binding Path=SelectedTableCategory, Mode=TwoWay}"> 
</view:Pager> 

見SelectedEntry是如何分配的綁定？這告訴我們Pager必須實現SelectedEntry作爲依賴屬性。我們如何做到這一點？

public class Pager 
{ 
    // Using a DependencyProperty as the backing store for PrePend. 
    // This enables animation, styling, binding, etc... 
    public static readonly DependencyProperty SelectedEntryProperty = 
     DependencyProperty.Register("SelectedEntry", typeof(object), 
      typeof(Pager), 
      new PropertyMetadata(null, OnSelectedEntryChanged)); 

    public object SelectedEntry 
    { 
     get { return GetValue(SelectedEntryProperty); } 
     set { SetValue(SelectedEntryProperty, value); } 
    } 

    private static void OnSelectedEntryChanged(DependencyObject pager, DependencyPropertyChangedEventArgs e) 
    { 
     // TODO set the SelectedItem in the ListBox 
    } 
} 

接下來你需要顯示尋呼機。你的XAML看起來不錯。您應該在ListBox上添加一個事件處理程序來偵聽選擇已更改的事件。這樣，當發生這種情況時，您可以更新SelectedEntry。

public class Pager 
{ 
    // continued... 

    // *Updated* 
    private listBox_SelectionChanged(object sender, SelectionChangedEventArgs e) 
    { 
     this.SelectedEntry = (sender as ListBox).SelectedItem; 
    } 
}