We are normally bind the IValueConverter value like as below,
<Button x:Name="myButton" Content="ClickMe" />
<Image Opacity="{Binding ElementName=myButton, Path=IsEnabled, Converter={StaticResource BoolToOpacityConverter}, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay, ConverterParameter = 1}" />
But my requirement is, without using xaml bind the IValueConverter. Please anyone suggest me how to bind the IValueConverter using c# without using xaml
You would use it in c# exactly the same as if you were using any other class.
So if your value converter is like this:
public class CustomConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
// ... your custom value converter
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
// ... your custom value converter
}
}
you would use it like this:
var customConverter = new CustomConverter();
customConverter.Convert( .. );
Related
I am working on a windows universal app and I'm trying to work out data binding.
I have a listview which has an item template and data template in which a property of a custom class is bound.
<ListView>
<ListView.ItemTemplate>
<DataTemplate>
<Textblock Text="{Binding Name}"/>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
This works fine an displays the names all instances of my custom class in the ObservableCollection I bind to the listview. I was wondering however if there is some way of modifying what is being bound before it is bound without changing the class itself.
I'm trying to bind a capitalisation of the string property Name so if the name was Test I want to bind TEST instead. Currently the way I'm doing this is to have a separate property called NameLabel which I populate like this
NameLabel = Name.ToUpper();
However this seems very messy and I was wondering if there's a neater way of doing it without creating a separate property?
You can use a Converter.
Create a StringToUpper.cs File with a StringToUpper Class which inherits form IValueConverter:
public class StringToUpper: IValueConverter
{
public object Convert(object value, Type targetType,
object parameter, CultureInfo culture)
{
var valueString = value.ToString();
if (!string.IsNullOrEmpty(valueString))
{
return valueString.ToUpper();
}
return string.Empty;
}
public object ConvertBack(object value, Type targetType,
object parameter, CultureInfo culture)
{
// do nothing.
}
}
Add the resource of your created Converter:
...
xmlns:converter="clr-namespace:StringToUpper"
...>
<Window.Resources>
<converter:StringToUpper x:Key="StringToUpperConverter" />
</Window.Resources>
Add the converter:
<Textblock Text="{Binding Name, Converter={StaticResource StringToUpperConverter}}"/>
Here is a good Tutorial about Converters in WPF.
You could create a converter, that turns the value of a property into a form desired for the view (in your case, a simple capitalisation of the string).
Your converter class might look like this:
public class StringToUpperStringConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
var valueString = value.ToString();
if (!string.IsNullOrEmpty(valueString))
{
return valueString.ToUpper();
}
return string.Empty;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
Your xaml might have this defined in the resource section:
<converters:StringToUpperStringConverter x:Key="StringToUpperStringConverter" />
And your binding would then look like this:
<Textblock Text="{Binding Name, Converter={StaticResource StringToUpperStringConverter}}"/>
I'm auto-generating a grid from a DataTable, and some of the columns need to be converted to more complex layouts than just text. I've successfully applied DataTemplates dynamically where needed, however I cannot run a converter (IValueConverter) because the value it is being given is the DataRow, so I have no way to tell which piece of data I need from the array.
I can't seem to figure out what I'm doing wrong.
Here is relevant code:
<DataTemplate x:Key="DateColumn">
<ContentControl Content="{Binding Converter={StaticResource DateConverter}}" />
</DataTemplate>
public class DateConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return value;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
Any help is greatly appreciated.
I was able to get this working by setting the converter in the code instead of trying to select the template in the xaml. Here is what it looks like now:
column.DataMemberBinding.Converter = new DateConverter();
Note that this is for a Telerik grid. I believe the syntax on a normal data grid is "Binding.Converter" instead of "DataMemberBinding.Converter".
Want to hide and show property grid for SelectedItem in listview
<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?
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.
<StackPanel.Resources>
<simpleXamlContent:NullVisibilityConverter x:Key="NullToVisibilityConverter"/>
</StackPanel.Resources>
To use the converter we can create one in the resources, and refer to it as a static resource in the binding statement.
<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
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();
}
}
There is little more useful version allows to set default invisibility value:
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:
<converters:NullReferenceToVisibilityConverter x:Key="NullToVis" />
And use it like there:
<StackPanel Visibility="{Binding MyObject, Converter={StaticResource NullToVis}}">
<StackPanel Visibility="{Binding MyObject, Converter={StaticResource NullToVis}, ConverterParameter=Hidden}">
I need to calculate/change form of input between textbox to its bindable source. The way i trying to achive this, is with help of converters.
Converter:
public class ParameterConverter : IValueConverter
{
public object Convert(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (value == null)
return string.Empty;
string originalParameValue = value.ToString();
string fixedParameterValue = string.Format("#_{0}", originalParameValue);
return fixedParameterValue;
}
public object ConvertBack(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new System.NotImplementedException();
}
}
XAML:
<Window.Resources>
<converters:ParameterConverter x:Key="parameterConverter" />
</Window.Resources>
<Grid>
<TextBox Text="{Binding ParameterA, Converter={StaticResource parameterConverter}}"/>
</Grid>
The problem is, that converter is functioning only once. Is it approach correct (i mean with converter) or there are another approaches ?
Perhaps the binding Mode is not two way, and did your property fire property changed.
Does your data context implement INotifyPropertyChanged and is PropertyChanged being called whenever ParameterA is changed? It seems as if nobody is notifying the textbox that it needs to update its contents.
I would like to dynamic do the columnSpan on the userControl. I created the converter class, but it didn’t work. Would you show me how to do it correctly? Thanks.
The code on my UserControl:
<TextBlock x:Name="txtSumary" Grid.Row="0" Grid.Column="1" Text="{Binding summary}"
TextWrapping="Wrap" Style="{StaticResource PhoneTextAccentStyle}" Grid.ColumnSpan="{Binding isSpan, Converter={StaticResource ColumSpanConverter}}" />
It is reference on the UserControl.Resources
<local:VisibilityConverter x:Key="ColumSpanConverter"/>
There is the Converter Class:
public class ColumSpanConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
bool isSpan = (bool)value;
return isSpan ? 2 : 0;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotSupportedException();
}
}
The converter is referencing the wrong converter:
<local:VisibilityConverter x:Key="ColumSpanConverter"/>
Should be:
<local:ColumSpanConverter x:Key="ColumSpanConverter" />