Cannot set CornerRadius value from static resource

Cannot set CornerRadius value from static resource

I have defined a static resource:

<UserControl x:Class="MyProject.MainPage"    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"     xmlns:sys="clr-namespace:System;assembly=mscorlib"     mc:Ignorable="d"     Width="255"     Height="300">     <UserControl.Resources>       <sys:Double x:Key="CornerRadiusValue">5</sys:Double>    </UserControl.Resources> ... 

Later on in XAML file, I am trying to use that value when setting top left corner radius for a border:

<Border     Width="40"    Height="30"    BorderThickness="1,1,0,0"     BorderBrush="Red">       <Border.CornerRadius>          <CornerRadius TopLeft="{StaticResource CornerRadiusValue}" />       </Border.CornerRadius> </Border> 

In design time, everything works fine and changing the value for CornerRadiusValue static resource changes the corner radius on a border. However, when I want to run this, I get an XamlParseException exception with the message:

Cannot set read-only property `System.Windows.CornerRadius.TopLeft'.

What am I doing wrong? How do I make it work? Thanks.

Answers & Comments...

Answer: 1

I believe CornerRadius properties are not DependencyProperties, so they cannot be set through a binding.

The two alternatives I can think of is to use a MultiConverter which accepts the parameters of the Border object, and desired CornerRadius, or to create a custom DependencyProperty for the CornerRadius. Both methods would require you to set the value in code-behind.

by : Rachelhttp://stackoverflow.com/users/302677

Answer: 2

MSDN:

You can set this value in XAML, but only as part of the attribute syntax for properties that take a CornerRadius, or as initialization text of a CornerRadius object element. See XAML sections and Remarks sections of CornerRadius.

You could try to bind the whole CornerRadius property and use a converter to get all the resources and create a CornerRadius instance from them using the constructor.

e.g. using only one value:

<Border Name="bd" BorderBrush="Red" BorderThickness="1">     <Border.Resources>         <sys:Double x:Key="CR_TopLeft">5</sys:Double>     </Border.Resources>     <Border.CornerRadius>         <Binding ElementName="bd">             <Binding.Converter>                 <vc:CornerRadiusConverter />             </Binding.Converter>         </Binding>     </Border.CornerRadius>     <Button>!</Button> </Border> 

public class CornerRadiusConverter : IValueConverter {     public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)     {         var resourceSource = (FrameworkElement)value;         var topLeft = (double)resourceSource.Resources["CR_TopLeft"];         return new CornerRadius(topLeft, 0, 0, 0);     }      public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)     {         throw new NotSupportedException();     } } 

You could propbably make this more generic by searching for the resources going up the tree and not directly targeting the object on which the resources are defined.

(This is a Silverlight-only problem, in WPF your code works just fine, if you have a Silverlight question please avoid the WPF tag unless the problem actually exists in WPF)

by : H.B.http://stackoverflow.com/users/546730

Answer: 3

<sys:Double x:Key="ScrollbarHandleCrValue">3</sys:Double> <CornerRadius x:Key="ScrollbarHandleCornerRadius"     TopLeft="{StaticResource ScrollbarHandleCrValue}"     TopRight="{StaticResource ScrollbarHandleCrValue}"     BottomRight="{StaticResource ScrollbarHandleCrValue}"     BottomLeft="{StaticResource ScrollbarHandleCrValue}" />  ... <Border Name="Border"    CornerRadius="{StaticResource ScrollbarHandleCornerRadius}"     Background="{StaticResource ScrollbarHandleColor}"    BorderBrush="Transparent"    BorderThickness="1" /> ... 

by : Dirk Schillerhttp://stackoverflow.com/users/1756246

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