wpf NullToVisibilityConverter 如果不为空则使可见
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NullToVisibilityConverter make visible if not null
提问by Roar
Want to hide and show property grid for SelectedItemin listview
想要在列表视图中隐藏和显示SelectedItem 的属性网格
<UserControl xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit"
<ListView>
<!--here is list view-->
</ListView>
<xctk:PropertyGrid SelectedObject="{Binding Active}" Visibility="{Binding Active, Converter=NullToVisibilityConverter}" >
</xctk:PropertyGrid>
</UserControl>
So I need converter and use it in visibility property converter. Any help?
所以我需要转换器并在可见性属性转换器中使用它。有什么帮助吗？
回答by 123 456 789 0
public class NullVisibilityConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return value == null ? Visibility.Hidden : Visibility.Visible;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
Then reference the NullVisibilityConverter in your XAML Resources.
然后在 XAML 资源中引用 NullVisibilityConverter。
<StackPanel.Resources>
<simpleXamlContent:NullVisibilityConverter x:Key="NullToVisibilityConverter"/>
</StackPanel.Resources>
回答by WPFUser
To use the converter we can create one in the resources, and refer to it as a static resource in the binding statement.
要使用转换器，我们可以在资源中创建一个，并在绑定语句中将其称为静态资源。
<UserControl xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit">
<UserControl.Resources>
<yournamespace:NullVisibilityConverter x:Key="NullToVisibilityConverter"/>
</UserControl.Resources>
<ListView>
<!--here is list view-->
</ListView>
<xctk:PropertyGrid SelectedObject="{Binding Active}" Visibility="{Binding Active, Converter={StaticResource NullToVisibilityConverter}}" >
</xctk:PropertyGrid>
</UserControl>
and Converter class itself
和转换器类本身
public class NullVisibilityConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return value == null ? Visibility.Hidden : Visibility.Visible;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
回答by ApceH Hypocrite
There is little more useful version allows to set default invisibility value:
有一些更有用的版本允许设置默认的隐身值：
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
string defaultInvisibility = parameter as string;
Visibility invisibility = (defaultInvisibility != null) ?
(Visibility)Enum.Parse(typeof(Visibility), defaultInvisibility)
: Visibility.Collapsed;
return value == null ? invisibility : Visibility.Visible;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return DependencyProperty.UnsetValue;
}
Where ever in resources add:
在资源中的任何地方添加：
<converters:NullReferenceToVisibilityConverter x:Key="NullToVis" />
And use it like there:
并像那里一样使用它：
<StackPanel Visibility="{Binding MyObject, Converter={StaticResource NullToVis}}">
<StackPanel Visibility="{Binding MyObject, Converter={StaticResource NullToVis}, ConverterParameter=Hidden}">
