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我在我的组合框中的自定义下拉列表或弹出模板中连接一些事件时遇到问题。

顺便说一下，这个自定义模板看起来像 IE 10 中的那个。这是 在此处输入图像描述 我得到的部分图片（下面是我的）。但我在删除历史列表中的项目时遇到问题。下面是我的 PART_Popup 模板

<Popup x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
    <Themes:SystemDropShadowChrome x:Name="Shdw" Color="Transparent" MinWidth="{Binding ActualWidth, ElementName=Placement}">
        <Border x:Name="DropDownBorder" BorderBrush="{DynamicResource {x:Static SystemColors.WindowFrameBrushKey}}" BorderThickness="1" Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}">
            <!--<ScrollViewer>-->
            <Grid>
                <Grid.RowDefinitions>
                    <RowDefinition Height="*" />
                    <RowDefinition Height="Auto" />
                </Grid.RowDefinitions>

                <StackPanel>
                    <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>

                    <Border Padding="5">
                        <StackPanel>
                            <Grid>
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition Width="Auto" />
                                    <ColumnDefinition Width="*" />
                                </Grid.ColumnDefinitions>
                                <TextBlock Text="History" Foreground="{StaticResource SeparatorLine}" />
                                <Border Height="2" Grid.Column="1" Margin="5,0,0,0" BorderBrush="{StaticResource SeparatorLine}" BorderThickness="0.5" />
                            </Grid>
                            <ListBox x:Name="listHistory"  BorderThickness="0" Margin="0" Padding="0" HorizontalContentAlignment="Stretch">
                                <ListBox.ItemTemplate>
                                    <DataTemplate>
                                        <Grid>
                                            <TextBlock Text="{Binding }" />
                                            <Button Grid.Column="1" HorizontalAlignment="Right" x:Name="btnDeleteHistoryItem" Content="r" FontFamily="Marlett" Style="{DynamicResource ButtonStyle}" Visibility="Hidden" Opacity="0.75" />
                                        </Grid>

                                        <DataTemplate.Triggers>
                                            <Trigger Property="IsMouseOver" Value="True">
                                                <Setter Property="Visibility" TargetName="btnDeleteHistoryItem" Value="Visible" />
                                            </Trigger>
                                        </DataTemplate.Triggers>
                                    </DataTemplate>
                                </ListBox.ItemTemplate>
                            </ListBox>
                    </StackPanel>
                    </Border>
                </StackPanel>

                <Border Grid.Row="1" BorderBrush="{StaticResource SeparatorLine}" BorderThickness="0,1,0,0" Padding="5" Height="30">
                    <Border.Background>
                        <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                            <GradientStop Color="#33000000" Offset="0"/>
                            <GradientStop Offset="1"/>
                            <GradientStop Offset="0.375"/>
                        </LinearGradientBrush>
                    </Border.Background>

                    <StackPanel Orientation="Horizontal" HorizontalAlignment="Right">
                        <Button x:Name="btnClearHistory" Content=" Clear History " Style="{DynamicResource ButtonStyle}" />
                    </StackPanel>
                </Border>
            </Grid>
            <!--</ScrollViewer>-->
        </Border>
    </Themes:SystemDropShadowChrome>
</Popup>

好吧，在Listbox(listHistory)中我有一个名为btnDeleteHistoryItem的按钮，但我无法钩住它。它在我的代码中返回 Null 错误

protected override void OnSourceInitialized(EventArgs e)
{
    ListBox lb = (ListBox)cbSearch.Template.FindName("listHistory", cbSearch);
    lb.ItemsSource = this.SearchHistory;
    lb.SelectionChanged += cbResults_SelectionChanged;

    Button btnDeleteHistoryItem = (Button)lb.Template.FindName("btnDeleteHistoryItem", lb);
    // if (btnDeleteHistoryItem != null)
    {
        btnDeleteHistoryItem.Click += DeleteHistoryItem_Click;
    }

    // or --------------

    Button btnDeleteHistoryItem = (Button)cbSearch.Template.FindName("btnDeleteHistoryItem", cbSearch);
    // if (btnDeleteHistoryItem != null)
    {
        btnDeleteHistoryItem.Click += DeleteHistoryItem_Click;
    }
}

编码在这里有点经典，所以没有在事件挂钩中实现 MVVM。所以问题是这个Button btnDeleteHistoryItem = (Button)lb.Template.FindName("btnDeleteHistoryItem", lb); 或按钮 btnDeleteHistoryItem = (Button)cbSearch.Template.FindName("btnDeleteHistoryItem", cbSearch); 无法找到该 btnDeleteHistoryItem 的行。

我该如何解决这个问题？

- 更新 - 

lb.Loaded += (a, b) =>
{
    Button btnDeleteHistoryItem = (Button)lb.Template.FindName("btnDeleteHistoryItem", lb);
    //if (btnDeleteHistoryItem != null)
    {
        btnDeleteHistoryItem.Click += DeleteHistoryItem_Click;
    }
};

也不起作用

4

1 回答 1

2

使用命令可能是这里最简单的解决方案。您可以将命令连接到删除按钮并将当前项目作为参数传递。这是一个简单的示例来说明。

public partial class MainWindow : Window {
    public MainWindow() {
        InitializeComponent();
        SomeCommand = new MySampleCommand();

        cbo.Items.Add("Hello");
        cbo.Items.Add("Item 1");
        cbo.Items.Add("Another Item");
        cbo.Items.Add("Something else");
        cbo.Items.Add("Yet another item");
    }

    public MySampleCommand SomeCommand { get; set; }
}

public class MySampleCommand : ICommand {
    public bool CanExecute(object parameter) {
        return true;
    }

    public event EventHandler CanExecuteChanged;

    public void Execute(object parameter) {
        MessageBox.Show(string.Format("You are trying to remove {0}", parameter.ToString()));
    }
}

您的组合框绑定看起来像：

<Window x:Class="SOComboWithEmbeddedButton2.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    x:Name="Window"
    Title="MainWindow" Height="350" Width="525">
<Window.Resources>
    <DataTemplate x:Key="ListBoxItemTemplate">
        <StackPanel Orientation="Horizontal">
            <TextBlock Text="{Binding}" />
            <Button Command="{Binding SomeCommand, ElementName=Window}" CommandParameter="{Binding}" Content="Remove" />
        </StackPanel>
    </DataTemplate>
</Window.Resources>
<StackPanel>
    <ComboBox ItemTemplate="{StaticResource ListBoxItemTemplate}" x:Name="cbo" />
</StackPanel>

只需调整 DataTemplate 上的 Command 绑定以指向具有命令对象实例的适当对象。希望有帮助！

于 2013-02-05T02:41:36.180 回答