DataTemplate.LoadContent 方法

定義

命名空間:

Microsoft.UI.Xaml

在DataTemplate中建立UIElement物件。

public:
 virtual DependencyObject ^ LoadContent() = LoadContent;

DependencyObject LoadContent();

public DependencyObject LoadContent();

function loadContent()

Public Function LoadContent () As DependencyObject

傳回

DependencyObject

DataTemplate的根UIElement。

範例

下列範例示範如何使用 LoadContent 方法來變更 執行時間的 Border 外觀。 此範例會建立 ListView ，其中包含數位 1 到 10。 當使用者在 ListView中選取專案時， Border 會顯示選取的數位。 如果使用者選取偶數，數位會是紅色，且周圍有綠色圓圈。 如果使用者選取奇數，則數位為藍色，且周圍有紫色方塊。

<StackPanel x:Name="rootStackPanel">
    <StackPanel.Resources>
        <DataTemplate x:Key="oddNumberTemplate">
            <Grid>
                <Rectangle Stroke="Purple" StrokeThickness="4"/>
                <TextBlock HorizontalAlignment="Center" 
                           VerticalAlignment="Center" 
                           FontSize="24" Foreground="Blue" 
                           FontWeight="Bold"/>
            </Grid>
        </DataTemplate>

        <DataTemplate x:Key="evenNumberTemplate">
            <Grid>
                <Ellipse Stroke="Green" StrokeThickness="4"/>
                <TextBlock HorizontalAlignment="Center" 
                           VerticalAlignment="Center" 
                           FontSize="24" Foreground="Red" 
                           FontWeight="Bold"  />
            </Grid>
        </DataTemplate>
    </StackPanel.Resources>

    <ListView x:Name="numberList" 
              SelectionChanged="ListView_SelectionChanged" 
              HorizontalAlignment="Center">
        <ListViewItem Content="1"/>
        <ListViewItem Content="2"/>
        <ListViewItem Content="3"/>
        <ListViewItem Content="4"/>
        <ListViewItem Content="5"/>
        <ListViewItem Content="6"/>
        <ListViewItem Content="7"/>
        <ListViewItem Content="8"/>
        <ListViewItem Content="9"/>
        <ListViewItem Content="10"/>
    </ListView>

    <Border x:Name="selectedItemDisplay" 
            Width="50" Height="50"/>
</StackPanel>

private void ListView_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    ListViewItem lvi = ((sender as ListView).SelectedItem as ListViewItem);
    SelectDataTemplate(lvi.Content);
}

private void SelectDataTemplate(object value)
{
    string numberStr = value as string;

    if (numberStr != null)
    {
        int num;

        try
        {
            num = Convert.ToInt32(numberStr);
        }
        catch
        {
            return;
        }

        DataTemplate template;

        // Select one of the DataTemplate objects, based on the 
        // value of the selected item in the ListView.
        if (num % 2 != 0)
        {
            template = rootStackPanel.Resources["oddNumberTemplate"] as DataTemplate;
        }
        else
        {
            template = rootStackPanel.Resources["evenNumberTemplate"] as DataTemplate;
        }

        selectedItemDisplay.Child = template.LoadContent() as UIElement;
        TextBlock tb = FindVisualChild<TextBlock>(selectedItemDisplay);
        tb.Text = numberStr;
    }
}

private childItem FindVisualChild<childItem>(DependencyObject obj)
    where childItem : DependencyObject
{
    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
    {
        DependencyObject child = VisualTreeHelper.GetChild(obj, i);

        if (child != null && child is childItem)
        {
            return (childItem)child;
        }
        else
        {
            childItem childOfChild = FindVisualChild<childItem>(child);
            if (childOfChild != null)
                return childOfChild;
        }
    }
    return null;
}

備註

當您呼叫 LoadContent 時，會建立 DataTemplate中的UIElement物件，並將它們新增至另一個UIElement的視覺化樹狀結構。