依赖项属性-未指定默认值的元数据选项

Question

public double FontSize
{
    get { return (double)GetValue(FontSizeProperty); }
    set { SetValue(FontSizeProperty, value); }
}
public static readonly DependencyProperty FontSizeProperty =
    TextElement.FontSizeProperty.AddOwner(typeof(OutlineTextBlock),
    new FrameworkPropertyMetadata(XXX, FrameworkPropertyMetadataOptions.AffectsRender));

I don't want to specify XXX and there is no override to specify only AffectsRender .

If I do like this

    new FrameworkPropertyMetadata()

then property will take default value from somewhere.

How to specify AffectsRender without default value?

Answer 1

Try the following

new FrameworkPropertyMetadata { AffectsRender = true; }

By not specifying a default value, the base PropertyMetadata does not get flagged as the default value being modified. This ensures when the metadata is merged, the original default value is used but the AffectsRender flag is added.