Question

我有一个自定义控件，我想告诉每个TextBlock内部使用TextBlock.TextTrimming = CharacterEllipsis，但我不想单独设置每个属性。我的意思是，即使稍后用户定义了ContentTemplate并将其置于我的自定义控件中并且ContentTemplate包含一些Textblocks，他们也应该自动设置TextBlock.TextTrimming = CharacterEllipsis。

我该怎么做？有什么帮助吗？

Answer 1

您可以使用attached property创建property value inheritance并将其应用于自定义控件，例如在其构造函数中。只要目标对象是TextBlock，附加属性就会将其值复制到目标对象。

public class CustomControl : ContentControl
{
    public CustomControl()
    {
        SetTextTrimming(this, TextTrimming.CharacterEllipsis);
    }

    public static readonly DependencyProperty TextTrimmingProperty =
        DependencyProperty.RegisterAttached(
            "TextTrimming", typeof(TextTrimming), typeof(CustomControl),
            new FrameworkPropertyMetadata(
                default(TextTrimming),
                FrameworkPropertyMetadataOptions.Inherits,
                TextTrimmingPropertyChanged));

    public static TextTrimming GetTextTrimming(DependencyObject obj)
    {
        return (TextTrimming)obj.GetValue(TextTrimmingProperty);
    }

    public static void SetTextTrimming(DependencyObject obj, TextTrimming value)
    {
        obj.SetValue(TextTrimmingProperty, value);
    }

    private static void TextTrimmingPropertyChanged(
        DependencyObject obj, DependencyPropertyChangedEventArgs e)
    {
        var textBlock = obj as TextBlock;

        if (textBlock != null)
        {
            textBlock.TextTrimming = (TextTrimming)e.NewValue;
        }
    }
}

请注意，无需在派生控件类中定义此TextTrimming附加属性。您也可以在一个特殊的帮助器类中定义它，它甚至不需要从DependencyObject派生。

该属性也适用于在其可视化树中使用TextBoxes的任何其他控件，例如标准的ContentControl：

<ContentControl local:CustomControl.TextTrimming="WordEllipsis"
                Content="Some sample text to be trimmed"/>

启用TextBlock.TextTrimming的继承

1 个答案: