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[英]How to create numeric Textbox Custom Control with dependency Property in WPF?
[英]How to create DataSource dependency property on a wpf User Control
我有一个包装网格的用户控件。 我希望能够设置底层网格的数据源,但是通过用户控件,如下所示:
<my:CustomGrid DataSource="{Binding Path=CollectionView}" />
我在网格中设置了这样:
private static readonly DependencyProperty DataSourceProperty
= DependencyProperty.Register("DataSource", typeof(IEnumerable), typeof(CustomGrid));
public IEnumerable DataSource
{
get { return (IEnumerable)GetValue(DataSourceProperty); }
set
{
SetValue(DataSourceProperty, value);
underlyingGrid.DataSource = value;
}
}
但这不起作用(它也没有给我一个错误)。 永远不会设置数据源。 我错过了什么?
当WPF加载您的控件并遇到XAML中指定的DependencyProperty时,它使用DependencyObject.SetValue来设置属性值而不是类的属性。 这使得作为依赖属性的属性设置器中的自定义代码几乎无用。
你应该做的是覆盖OnPropertyChanged方法(来自DependencyObject):
protected override void OnPropertyChanged( DependencyPropertyChangedEventArgs e ) {
base.OnPropertyChanged( e );
if( e.Property == DataSourceProperty ) {
underlyingGrid.DataSource = e.NewValue;
}
}
或者,您可以在注册DependencyProperty时指定回调:
public static readonly DependencyProperty DataSourceProperty =
DependencyProperty.Register( "DataSource", typeof( IEnumerable ), typeof( MyGridControl ), new PropertyMetadata( DataSourceChanged ) );
并且在回调中的OnPropertyChanged中有效地与上面相同:
public static void DataSourceChanged( DependencyObject element, DependencyPropertyChangedEventArgs e ) {
MyGridControl c = (MyGridControl) element;
c.underlyingGrid.DataSource = e.NewValue;
}
还行吧:
public static readonly DependencyProperty ItemsSourceProperty =
DependencyProperty.Register("ItemsSource", typeof(IList), typeof(YourControl),
newFrameworkPropertyMetadata(null,FrameworkPropertyMetadataOptions.AffectsArrange,new PropertyChangedCallback(OnIsChanged)));
private static void OnIsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
YourControl c = (YourControl)d;
c.OnPropertyChanged("ItemsSource");
}
public IList ItemsSource
{
get
{
return (IList)GetValue(ItemsSourceProperty);
}
set
{
SetValue(ItemsSourceProperty, value);
}
}
问题在于:当你设置
MyGridControl c = (MyGridControl) element;
c.underlyingGrid.DataSource = e.NewValue;
你设置了值,但删除你的绑定!
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