« Converter » : différence entre les versions
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| Ligne 2 : | Ligne 2 : | ||
= ValueConverter = | = ValueConverter = | ||
<kode lang="xaml"> | <kode lang="xaml"> | ||
<UserControl xmlns: | <UserControl xmlns:conversion="clr-namespace:MyNamespace.Conversion"> | ||
<UserControl.Resources> | <UserControl.Resources> | ||
< | <conversion:EnumerableToVisibilityConverter x:Key="EnumerableToVisibilityConverter" /> | ||
</UserControl.Resources> | </UserControl.Resources> | ||
<TextBlock Text="{Binding | <TextBlock Text="{Binding MyProperty, Converter={StaticResource EnumerableToVisibilityConverter}}" /> | ||
</kode> | </kode> | ||
<kode lang="csharp"> | <kode lang="csharp"> | ||
namespace | namespace MyNamespace.Conversion | ||
{ | { | ||
// L'attribut ValueConversion est optionel, | // L'attribut ValueConversion est optionel, | ||
// il permet de spécifier le type d'entrée et le type de sortie | // il permet de spécifier le type d'entrée et le type de sortie | ||
[ValueConversion(typeof( | [ValueConversion(typeof(IEnumerable), typeof(Visibility))] | ||
public class | public class EnumerableToVisibilityConverter : IValueConverter | ||
{ | { | ||
public object Convert(object values, Type targetType, object parameter, CultureInfo culture) | public object Convert(object values, Type targetType, object parameter, CultureInfo culture) | ||
{ | { | ||
if (value is IEnumerable itemCollection) | |||
... | { | ||
return | return itemCollection.Cast<object>().Any() ? Visibility.Visible : Visibility.Collapsed; | ||
} | |||
return Visibility.Collapsed; | |||
} | } | ||
| Ligne 29 : | Ligne 32 : | ||
public object ConvertBack(object value, Type targetTypes, object parameter, CultureInfo culture) | public object ConvertBack(object value, Type targetTypes, object parameter, CultureInfo culture) | ||
{ | { | ||
throw new NotSupportedException(); | |||
throw new NotImplementedException(); | throw new NotImplementedException(); | ||
return null; | |||
} | } | ||
} | } | ||
Version du 15 avril 2020 à 16:24
ValueConverter
|
<UserControl xmlns:conversion="clr-namespace:MyNamespace.Conversion">
<UserControl.Resources>
<conversion:EnumerableToVisibilityConverter x:Key="EnumerableToVisibilityConverter" />
</UserControl.Resources>
<TextBlock Text="{Binding MyProperty, Converter={StaticResource EnumerableToVisibilityConverter}}" />
|
|
namespace MyNamespace.Conversion
{
// L'attribut ValueConversion est optionel,
// il permet de spécifier le type d'entrée et le type de sortie
[ValueConversion(typeof(IEnumerable), typeof(Visibility))]
public class EnumerableToVisibilityConverter : IValueConverter
{
public object Convert(object values, Type targetType, object parameter, CultureInfo culture)
{
if (value is IEnumerable itemCollection)
{
return itemCollection.Cast<object>().Any() ? Visibility.Visible : Visibility.Collapsed;
}
return Visibility.Collapsed;
}
// Conversion inverse non-implémentée
public object ConvertBack(object value, Type targetTypes, object parameter, CultureInfo culture)
{
throw new NotSupportedException();
throw new NotImplementedException();
return null;
}
}
}
|
Inverted convertion
|
|
<TextBlock Visibility="{Binding MyProperty, Converter={StaticResource BooleanToVisibilityConverter}, ConverterParameter=Inverted}" />
|
| BooleanToVisibilityConverter.cs |
[ValueConversion(typeof(bool), typeof(Visibility))]
public sealed class BooleanToVisibilityConverter : IValueConverter
{
public object IValueConverter.Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
bool visibleFlag;
if (value is bool b)
{
visibleFlag = b;
}
else
{
return DependencyProperty.UnsetValue;
}
if (parameter != null)
{
if (Enum.TryParse(parameter.ToString(), true, out Parameters invert) && invert == Parameters.Inverted)
{
visibleFlag = !visibleFlag;
}
}
return visibleFlag ? Visibility.Visible : Visibility.Collapsed;
}
public object IValueConverter.ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotSupportedException();
}
private enum Parameters
{
Normal,
Inverted
}
|
MultiValueConverter
|
|
<UserControl xmlns:my="clr-namespace:CurrentNameSpace">
<UserControl.Resources>
<my:MyConverter x:Key="myConverter"/>
</UserControl.Resources>
<TextBlock.Text>
<MultiBinding Converter="{StaticResource ResourceKey=myConverter}">
<Binding ... />
<Binding ... />
</MultiBinding>
</TextBlock.Text>
|
|
|
namespace CurrentNameSpace
{
// L'attribut ValueConversion n'est pas utilisé ici car il n'est pas adapté
// au MultiValueConverter : il ne peut définir qu'un seul type d'entrée
public class MyConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
var binding1Value = (int)values[0];
var binding2Value = (string)values[1];
...
return ""; // un string
}
// Conversion inverse non-implémentée
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
}
|
