Question

我需要更新用于在运行时加载listview的DataTemplate中的文本块。每次用户单击“递增”或“递减”按钮时，必须相应地增加或减少lblRepeatNum。

我很难从按钮的click事件中访问文本块。请帮忙。

XAML＆amp; c＃代码如下。

<ListView x:Name="lvBuildYourRuqya" Grid.Row="1">

        <ListView.ItemContainerStyle>
            <Style TargetType="ListViewItem">
                <Setter Property="HorizontalContentAlignment" Value="Stretch" />
            </Style>
        </ListView.ItemContainerStyle>

        <ListView.ItemTemplate>
            <DataTemplate>

                <RelativePanel>
                    <TextBlock x:Uid="lblVerseName" x:Name="lblVerseName" Height="35" Text="{Binding RuqyaName}" RelativePanel.AlignLeftWithPanel="True" VerticalAlignment="Center" Margin="15,15,0,0" HorizontalAlignment="Center"/>
                    <StackPanel Orientation="Horizontal" RelativePanel.AlignRightWithPanel="True" Padding="0,0,20,0" RelativePanel.RightOf="lblVerseName" HorizontalAlignment="Right">
                        <TextBlock x:Uid="lblRepeatNum" x:Name="lblRepeatNum" Text="{Binding NumOfTimes}" HorizontalAlignment="Right" Margin="0,0,20,0" VerticalAlignment="Center"/>
                        <Button x:Name="btnIncrement" Width="35" Height="35" Tag="{Binding index}" Click="btnIncrement_Click" Content="+" Margin="0,0,10,0"/>
                        <Button x:Name="btnDecrement" Width="35" Height="35" Tag="{Binding index}" Click="btnDecrement_Click" Content="-"/>
                    </StackPanel>
                </RelativePanel>

            </DataTemplate>
        </ListView.ItemTemplate>

    </ListView>

private void btnDecrement_Click(object sender, RoutedEventArgs e)
    {

        //get index of selected row
        int index = (int)((Button)sender).Tag;

        //get object at this index
        Ruqya rq = (Ruqya) lvBuildYourRuqya.Items[index];

        //decrement 
        rq.NumOfTimes -= 1;

        //update lblRepeatNum
        ????????
    }

Answer 1

正如Justin XL所说，您需要为要动态更改的属性实现INotifyPropertyChanged接口。因此，一旦NumOfTimes由代码行rq.NumOfTimes -= 1;更改，lblRepeatNum将自动更改。例如，您的Ruqya类可以继承INotifyPropertyChanged，如下所示：

public class Ruqya : INotifyPropertyChanged
{
   private int _numOfTimes;
   public int NumOfTimes
   {
       get
       {
           return _numOfTimes;
       }

       set
       {
           this._numOfTimes = value;
           this.OnPropertyChanged();
       }
   }
   public string RuqyaName { get; set; }
   public int index { get; set; }

   public event PropertyChangedEventHandler PropertyChanged =delegate { };

   public void OnPropertyChanged([CallerMemberName] string propertyName = null)
   {
       // Raise the PropertyChanged event, passing the name of the property whose value has changed.
       this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
   }
}

更多详情请参阅Data binding in depth。对于您的场景，我还建议您使用ICommand界面来显示按钮点击事件句柄，有关详细信息，请参阅this sample。

UWP Listview - 在运行时更新DataTemplate中的文本块

1 个答案: