Binding Exception but i don t know why? - wpf

Question

I have a custom usercontrol with that code:
public partial class AudioControl : UserControl
{
public AudioControl()
{
InitializeComponent();
Value = 0.1;
DataContext = this;
}
public event RoutedPropertyChangedEventHandler<double> ValueChanged = delegate { };
public int TextWidth
{
get { return (int)GetValue(TextWidthProperty); }
set { SetValue(TextWidthProperty, value); }
}
public int SliderWidth
{
get { return (int)GetValue(SliderWidthProperty); }
set { SetValue(SliderWidthProperty, value); }
}
public string Header
{
get { return (string)GetValue(TextBlock.TextProperty); }
set { SetValue(TextBlock.TextProperty, value); }
}
//public double Value
//{
// get { return (double)GetValue(Slider.ValueProperty); }
// set { SetValue(Slider.ValueProperty, value); }
//}
public double Value
{
get {
return (double)GetValue(ValueProperty);
}
set {
SetValue(ValueProperty, value);
}
}
public static readonly DependencyProperty ValueProperty =
DependencyProperty.Register("Value", typeof(double), typeof(AudioControl), new UIPropertyMetadata(0));
public static readonly DependencyProperty TextWidthProperty =
DependencyProperty.Register("TextWidth", typeof(int), typeof(AudioControl), new UIPropertyMetadata(0));
public static readonly DependencyProperty SliderWidthProperty =
DependencyProperty.Register("SliderWidth", typeof(int), typeof(AudioControl), new UIPropertyMetadata(0));
private void Slider_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
{
ValueChanged(this, e);
}
}
And this XAML:
<UserControl x:Class="Controller.Audio.AudioControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:Audio="clr-namespace:Controller.Audio"
mc:Ignorable="d"
d:DesignHeight="23" d:DesignWidth="500" x:Name="audioControl">
<UserControl.Resources>
<Audio:DoubleToIntConverter x:Key="doubleToInt"/>
</UserControl.Resources>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="{Binding TextWidth}"/>
<ColumnDefinition Width="40"/>
<ColumnDefinition Width="{Binding SliderWidth}"/>
</Grid.ColumnDefinitions>
<Label x:Name="txtBlock" Margin="0,0,10,0">
<Binding Path="Header"/>
</Label>
<Label Grid.Column="1" Content="{Binding ElementName=slider, Path=Value, Converter={StaticResource doubleToInt}}"/>
<Slider x:Name="slider" Grid.Column="2" Style="{StaticResource Office2010SilverSliderStyle}"
Value="{Binding Path=Value, ElementName=audioControl}" Minimum="0.0" Maximum="1.0" LargeChange="0.25" TickFrequency="0.01" ValueChanged="Slider_ValueChanged"/>
</Grid>
So if i start it I get an exception that something with the value binding is wrong. I also tried the commented version (the value-Property). There is no exception but if i set the value of that property my slider does not change.
Does anyone has any idea why? I ve never done something like that :(

Answer 1

There's an error in the following dependency property declaration:
public static readonly DependencyProperty ValueProperty =
DependencyProperty.Register("Value", typeof(double), typeof(AudioControl), new UIPropertyMetadata(0));
The problem here is that you're defining the dependency property to be of type double, but giving it a default value 0 that is an int. Try changing 0 to 0.0.
I ran your code and encountered an exception. The innermost exception contained the following message:
Default value type does not match type of property 'Value'.
I changed the 0 in the line above to 0.0 and the problem went away.