當datagrid爲空時顯示消息

Question

我想在datagrid中沒有項目顯示時在datagrid中顯示一條簡單消息。現在我有以下XAML代碼：

<xcdg:DataGridControl x:Name="lsvSleutels" 
          ItemsSourceName="Registratiesleutels" 
          ItemsSource="{Binding Source={StaticResource DataViewSource}}" 
          Style="{StaticResource SmbDataGridControlStyle}" 
          IsRefreshCommandEnabled="False" 
          rf:XceedGridService.SettingsKeyName="RegistratieSleutelOverzichtGridKey" 
          rf:XceedGridService.IsGroupingEnabled="True" 
          rf:XceedGridService.ItemContextMenu="{StaticResource ItemContextMenu}" 
          rf:XceedGridService.ItemsContextMenu="{StaticResource ItemsContextMenu}" 
          rf:XceedGridService.GroupBarVisibility="Collapsed" 
          rf:XceedGridService.LoadUserSettings="True" > 
      *columns and stuff* 
    </xcdg:DataGridControl> 

     <TextBlock x:Name="txtNoDataFound" 
        FontSize="18" 
        Foreground="Blue" 
        Text="No items found" 
        Margin="10,25,20,10" 
        VerticalAlignment="Top" 
        HorizontalAlignment="Center" 
        Visibility="Hidden"> 
      <TextBlock.Style> 
       <Style TargetType="{x:Type TextBlock}"> 
        <Style.Triggers> 
         <DataTrigger Binding="{Binding ElementName=lsvSleutels, Path=Items.Count}" 
            Value="0"> 
          <Setter Property="Visibility" 
            Value="Visible"/> 
         </DataTrigger> 
        </Style.Triggers> 
       </Style> 
      </TextBlock.Style> 
     </TextBlock> 

但是，該消息未顯示。我的第一個猜測是DataTrigger有問題，但我不知道是什麼。有任何想法嗎？提前致謝！

Answer 1

下面是一個示例代碼ListBox控件：

<ListBox x:Name="lsvSleutels"> 
       <ListBoxItem>asdasdasd</ListBoxItem> 
       <ListBoxItem>asdasdasd</ListBoxItem> 
       <ListBoxItem>asdasdasd</ListBoxItem> 
       <ListBoxItem>asdasdasd</ListBoxItem> 
       <ListBoxItem>asdasdasd</ListBoxItem> 
       <ListBoxItem>asdasdasd</ListBoxItem> 
       <ListBoxItem>asdasdasd</ListBoxItem> 
       <ListBox.Style> 
        <Style TargetType="{x:Type ListBox}"> 
         <Style.Setters> 
          <Setter Property="Template"> 
           <Setter.Value> 
            <ControlTemplate TargetType="ListBox"> 
             <Grid> 
              <ItemsPresenter/> 
              <TextBlock x:Name="txtNoDataFound" 
                FontSize="18" 
                Foreground="Blue" 
                Text="No items found" 
                Margin="10,25,20,10" 
                VerticalAlignment="Top" 
                HorizontalAlignment="Center" 
                Visibility="Hidden"> 

              </TextBlock> 
             </Grid> 
             <ControlTemplate.Triggers> 
              <DataTrigger Binding="{Binding Path=Items.Count, RelativeSource={RelativeSource Self}}" Value="0"> 
               <Setter TargetName="txtNoDataFound" Property="Visibility" Value="Visible" /> 
              </DataTrigger> 
             </ControlTemplate.Triggers> 
            </ControlTemplate> 
           </Setter.Value> 
          </Setter> 
         </Style.Setters> 
        </Style> 
       </ListBox.Style> 
      </ListBox> 

希望這有助於你。

Answer 2

這是因爲WPF屬性heirarchy的工作方式而發生的。在根級設置的屬性不能被樣式覆蓋。

您需要將可見性=「隱藏」屬性從文本框聲明中移出並將其移至樣式中的設置器。

像這樣：

<utils:InvertBoolToVisibilityConverter x:Key="BoolToVisibility" /> 

在C＃：

<TextBlock x:Name="txtNoDataFound" 
       FontSize="18" 
       Foreground="Blue" 
       Text="No items found" 
       Margin="10,25,20,10" 
       VerticalAlignment="Top" 
       HorizontalAlignment="Center"> 
     <TextBlock.Style> 
      <Style TargetType="{x:Type TextBlock}"> 
       <Setter Property="Visibility" Value="Hidden" /> 
       <Style.Triggers> 
        <DataTrigger Binding="{Binding ElementName=lsvSleutels, Path=Items.Count}" 
           Value="0"> 
         <Setter Property="Visibility" 
           Value="Visible"/> 
        </DataTrigger> 
       </Style.Triggers> 
      </Style> 
     </TextBlock.Style> 
    </TextBlock>a 

Answer 3

在XAML中添加InvertBoolToVisibility轉換器

public object Convert(object value, Type targetType, object parameter, CultureInfo culture) 
    { 
     var hasItems = (bool) value; 

     return hasItems ? Visibility.Collapsed : Visibility.Visible; 
    } 

添加行控件模板：

<Setter Property="Template"> 
      <Setter.Value> 
       <ControlTemplate TargetType="{x:Type DataGrid}"> 
        <Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="True"> 
         <ScrollViewer x:Name="DG_ScrollViewer" Focusable="false"> 
          <ScrollViewer.Template> 
           <ControlTemplate TargetType="{x:Type ScrollViewer}"> 
            <Grid> 
             <Grid.ColumnDefinitions> 
              <ColumnDefinition Width="Auto"/> 
              <ColumnDefinition Width="*"/> 
              <ColumnDefinition Width="Auto"/> 
             </Grid.ColumnDefinitions> 
             <Grid.RowDefinitions> 
              <RowDefinition Height="Auto"/> 
              <RowDefinition Height="*"/> 
              <RowDefinition Height="Auto"/> 
             </Grid.RowDefinitions> 
             <Button Command="{x:Static DataGrid.SelectAllCommand}" Focusable="false" Style="{DynamicResource {ComponentResourceKey ResourceId=DataGridSelectAllButtonStyle, TypeInTargetAssembly={x:Type DataGrid}}}" Visibility="{Binding HeadersVisibility, ConverterParameter={x:Static DataGridHeadersVisibility.All}, Converter={x:Static DataGrid.HeadersVisibilityConverter}, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" Width="{Binding CellsPanelHorizontalOffset, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}"/> 
             <DataGridColumnHeadersPresenter x:Name="PART_ColumnHeadersPresenter" Grid.Column="1" Visibility="{Binding HeadersVisibility, ConverterParameter={x:Static DataGridHeadersVisibility.Column}, Converter={x:Static DataGrid.HeadersVisibilityConverter}, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}"/> 
             <ScrollContentPresenter x:Name="PART_ScrollContentPresenter" CanContentScroll="{TemplateBinding CanContentScroll}" Grid.ColumnSpan="2" Grid.Row="1"/> 
             <ScrollBar x:Name="PART_VerticalScrollBar" Grid.Column="2" Maximum="{TemplateBinding ScrollableHeight}" Orientation="Vertical" Grid.Row="1" Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}" Value="{Binding VerticalOffset, Mode=OneWay, RelativeSource={RelativeSource TemplatedParent}}" ViewportSize="{TemplateBinding ViewportHeight}"/> 
             <Grid Grid.Column="1" Grid.Row="2"> 
              <Grid.ColumnDefinitions> 
               <ColumnDefinition Width="{Binding NonFrozenColumnsViewportHorizontalOffset, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}"/> 
               <ColumnDefinition Width="*"/> 
              </Grid.ColumnDefinitions> 
              <ScrollBar x:Name="PART_HorizontalScrollBar" Grid.Column="1" Maximum="{TemplateBinding ScrollableWidth}" Orientation="Horizontal" Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}" Value="{Binding HorizontalOffset, Mode=OneWay, RelativeSource={RelativeSource TemplatedParent}}" ViewportSize="{TemplateBinding ViewportWidth}"/>            
             </Grid> 
             <!--<TextBlock Grid.ColumnSpan="2" Grid.Row="1" VerticalAlignment="Center" HorizontalAlignment="Center" Foreground="#FFD9DEE3" Text="No Data Shown" Visibility="{Binding HasItems, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}, Converter={StaticResource BoolToVisibility}}" />--> 
            </Grid> 
           </ControlTemplate> 
          </ScrollViewer.Template> 
          <ItemsPresenter SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/> 
         </ScrollViewer> 
        </Border> 
       </ControlTemplate> 
      </Setter.Value> 
     </Setter>