I got the following code:
namespace SomeApp
{
public partial class MyClass : PhoneApplicationPage, IValueConverter
{
SOME METHODS...
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return true;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return true;
}
}
}
I would like to bind this class to a ValueConverter of a RadioButton. Is there any way to reference to the current class I'm working with? For example:
<phone:PhoneApplicationPage
x:Class="SomeApp.MyClass"
xmlns:local="clr-namespace:SomeApp">
<phone:PhoneApplicationPage.Resources>
<local:MyClass x:Key="myClass"/>
</phone:PhoneApplicationPage.Resources>
<RadioButton IsChecked="{Binding Converter={StaticResource myClass}}"/>
Thanks in advance =)
First using your page as a converter don't seem like a good idea, it's better practice to separate the converter fonctionality in a separate class. Particularly it would be a very bad idea to create a StaticResources of a converter created that way as it will use a lot of unessessary memory to create the whole page.
The only thing a converter can be binded in xaml is a StaticResource so you will not be able to do it in xaml but if you really want to do it you could do it by creating the binding from code behind (for example in the constructor of the page):
Binding binding=new Binding();
binding.Converter = this;
myRadioButton.SetBinding(CheckBox.IsCheckedProperty, binding);
Related
I am trying to access to method class from XAML file.
My class is on folder: project.Utils.
Adding on xaml Content Page:
xmlns:local="project.Utils"
I try to use myConverterMethod class inside Utils folder and use it as:
Converter={StaticResource myConverterMethod}
but error Type myConverterMethod not found in xmlns project.Utils.
Where is my fault?
You can use
xmlns:local="clr-namespace:project.Utils;assembly=project"
It is not possible to refer to a Method within a specific class but to a IValueConverter.
In order to achieve what you want, you need to define a class that implements IValueConverter:
public class IntToBoolConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return (int)value != 0;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return (bool)value ? 1 : 0;
}
}
Define the created converter in accessible scope: Page/View or Application. By scope I mean resources:
<ContentPage.Resources>
<ResourceDictionary>
<local:IntToBoolConverter x:Key="intToBool" />
</ResourceDictionary>
</ContentPage.Resources>
and finally consume the converter in the next way:
<Button Text="Search"
HorizontalOptions="Center"
VerticalOptions="CenterAndExpand"
IsEnabled="{Binding Source={x:Reference entry1},
Path=Text.Length,
Converter={StaticResource intToBool}}" />
Xamarin has a very nice documentation that will answer all your questions and it usually has a good code samples.
I wanna bind my element height to another element height plus 20 pixel...
Is it possible to do such a thing?
<ScrollViewer Height="{Binding Height, ElementName=AnotherElement}">
Yes, by using a value converter
public class IncreaseByValueConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, string language)
{
var passedInValue = System.Convert.ToDouble(value);
var increaseByValue = System.Convert.ToDouble(parameter);
return passedInValue + increaseByValue;
}
public object ConvertBack(object value, Type targetType, object parameter, string language)
{
throw new NotImplementedException();
}
}
defined as a static resource somewhere in your resources:
<local:IncreaseByValueConverter x:Key="IncreaseByValueConverter" />
used like this:
<ScrollViewer Height="{Binding Height, ElementName=AnotherElement, Converter={StaticResource IncreaseByValueConverter}", ConverterParameter="20">
You'll probably want to handle the converter parameter better by using some try/catch code in the IncreaseByValueConverter.Convert method. For example, make the parameter optional, so if it's not passed in, use a default value, or something like that...
I am trying to format my string to have commas every 3 places, and a decimal if it is not a whole number. I have checked roughly 20 examples, and this is the closest I have come:
<TextBlock x:Name="countTextBlock" Text="{Binding Count, StringFormat={0:n}}" />
But I get a The property 'StringFormat' was not found in type 'Binding'. error.
Any ideas what is wrong here? Windows Phone 8.1 appears to differ from WPF, because all of the WPF resources say that this is how it is done.
(The string is updated constantly, so I need the code to be in the XAML. I also need it to remain binded. Unless of course I cannot have my cake and eat it too.)
It seems that, similar to Binding in WinRT, Binding in Windows Phone Universal Apps doesn't have StringFormat property. One possible way to work around this limitation is using Converter as explained in this blog post,
To summarize the post, you can create an IValueConverter implmentation that accept string format as parameter :
public sealed class StringFormatConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, string language)
{
if (value == null)
return null;
if (parameter == null)
return value;
return string.Format((string)parameter, value);
}
public object ConvertBack(object value, Type targetType, object parameter,
string language)
{
throw new NotImplementedException();
}
}
Create a resource of above converter in your XAML, then you can use it like this for example :
<TextBlock x:Name="countTextBlock"
Text="{Binding Count,
Converter={StaticResource StringFormatConverter},
ConverterParameter='{}{0:n}'}" />
I'm seeing an error trying to use a custom converter in my WP8 app.
I defined my converter in a namespace: standrighthere.Utilities:
namespace standrighthere.Utilities
{
public class NonNullVisibilityConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return value == null ? Visibility.Collapsed : Visibility.Visible;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
}
I then included it in the App.xaml manifest as so:
<Application.Resources>
<utilities:NonNullVisibilityConverter x:Key="NonNullVisibiltyConverter" />
</Application.Resources>
I then tried to use it in my phone application page like this:
<Button Visibility="{Binding Source={Binding User}, Converter={StaticResource ResourceKey=NonNullVisibilityConverter}}" />
However, it keeps giving the error:
Error 1 The resource "NonNonNullVisibilityConverter" could not be resolved.
I feel like I must be missing something really obvious here.
Looks like a simple typo. You called your converter "NonNullVisibiltyConverter" in the resources and NonNonNullVisibil*i*tyConverter in the binding.
I have a piece of code for a Text Box in a XAML File. The text box takes as input Numeric Value.Below is the piece of code:-
<TextBox Text="{Binding Path=Revenue, StringFormat=c0, Mode=TwoWay, Converter={StaticResource NullableConverter}, NotifyOnValidationError=True, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}" Grid.Column="3" Grid.Row="2"/>
However if I input 5 and tab out the input does not become 5 $. However, on saving the data in the page and loading the page the formatting is intact. Any thoughts on this ??
please remove the converter and try it, you should get it. should be something wrong with converter.
this is what I tried for Nullable Converter it worked.
public class NullableConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value == null)
return 0;
else
return value;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return value;
}
}
If you are using SL5 I think this is a bug, the StringFormat is not triggered when the binding is updated. For more details here is the MS connect issue. You can check the workaround it might help you solving the problem.