WPF / XAML - hide image if other control text property is empty / not set
I am new to wpf and this is my first attempt at creating a custom control. its purpose is to display two values (myText1 and myText2) with their respective images (myimage1, myimage2). sometimes one of these values is not specified and therefore one image must also be hidden. here's my code:
Window1.xaml
<local:myControl myText2="Hello World!" />
myControl.xaml
<TextBlock Text="{Binding ElementName=myControl,Path=myText1}" />
<Image Source="myimage1.jpg" />
<TextBlock Text="{Binding ElementName=myControl,Path=myText2}" />
<Image Source="myimage2.jpg" />
myText1 was not set to window1.xaml, so the text block remains empty. but the image is still displayed. what lines of code am I missing to hide the image if myText1 (or myText2) was not set in window1.xaml?
You have a post converter for text visibility
public class TextToVisibilityConverter : IValueConverter
{
public object Convert(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (value is string && targetType == typeof(bool))
{
if (value.ToString().Equals(string.Empty))
return Visibility.Hidden;
else
return Visibility.Hidden;
}
else
{
return null;
}
}
public object ConvertBack(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (value is Visibility && targetType == typeof(string))
{
if ((Visibility)value == Visibility.Visible)
{
return "Text";
}
else
{
return string.Empty;
}
}
else
{
return null;
}
}
}
And in XAML <TextToVisibilityConverter x: Key = "myCnverter" / ">
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A couple of small mistakes in there:
if (value is string && targetType == typeof(bool))
{
if (value.ToString().Equals(string.Empty))
return Visibility.Hidden;
else
return Visibility.Hidden;
}
Should be
if (value is string && targetType == typeof(Visibility))
{
if (value.ToString().Equals(string.Empty))
return Visibility.Hidden;
else
return Visibility.Visible;
}
You will need the following messages:
using System.Windows;
using System.Windows.Data;
You may also consider returning Visibility.Collapsed
rather thanVisibility.Hidden
Once you create the right converter, it's easy for you. And not many answers also got that Text.IsEmpty is available for the TextBlock Text property
I created a BooleanVisibilityConverter which depends on the boolean parameter being True or False. Gives you true flexibility not found in xaml.
public class BooleanVisibilityConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
Visibility v = Visibility.Collapsed;
bool checkValue = true;
if(parameter != null)
{
checkValue = Boolean.Parse(parameter.ToString());
}
if(value.Equals(checkValue))
{
v = Visibility.Visible;
}
return v;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
Then in your xaml, import that namespace into:
xmlns:conv="clr-namespace:ConvertersNamespace"
Create a converter in Resources:
<UserControl.Resources>
<conv:BooleanVisibilityConverter x:Key="bool2vis" />
</UserControl.Resources>
Then just use in your design:
<TextBlock Text="{Binding ElementName=myControl,Path=myText1}" x:Name="txtBlock"/>
<Image Source="myimage1.jpg"
Visibility="{Binding ElementName=txtBlock,Path=Text.IsEmpty,
Converter={StaticResource bool2vis},ConverterParameter=False}"/>
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