I used Microsoft's Chart Control of the WPF toolkit to write my own chart control. I blogged about it here . My Chart control stacks the yaxes in the chart on top of each other. As you can read in the article this all works quite well. Now I want to create a viewmodel that controls the data and axes in the chart. So far I'm able to add axes to the chart and show them in the chart. But I have a problem when I try to add the lineseries because it has one DependentAxis and one InDependentAxis property. I don't know how to assign the proper xAxis and yAxis controls to it.
Below you see part of the LineSeriesViewModel. It has a nested XAxisViewModel and YAxisViewModel property.
public class LineSeriesViewModel : ViewModelBase, IChartComponent
{
XAxisViewModel _xAxis;
public XAxisViewModel XAxis
{
get { return _xAxis; }
set
{
_xAxis = value;
RaisePropertyChanged(() => XAxis);
}
}
//The YAxis Property look the same
}
The viewmodels all have their own datatemplate. The xaml code looks like this:
<UserControl.Resources>
<DataTemplate x:Key="xAxisTemplate" DataType="{x:Type l:YAxisViewModel}">
<chart:LinearAxis x:Name="yAxis" Orientation="Y" Location="Left" Minimum="0" Maximum="10" IsHitTestVisible="False" Width="50" />
</DataTemplate>
<DataTemplate x:Key="yAxisTemplate" DataType="{x:Type l:XAxisViewModel}">
<chart:LinearAxis x:Name="xAxis" Orientation="X" Location="Bottom" Minimum="0" Maximum="100" IsHitTestVisible="False" Height="50" />
</DataTemplate>
<DataTemplate DataType="{x:Type l:LineSeriesViewModel}">
<!--Binding doesn't work on the Dependent and IndependentAxis! -->
<!--YAxis XAxis and Series are properties of the LineSeriesViewModel -->
<l:FastLineSeries DependentAxis="{Binding Path=YAxis}"
IndependentAxis="{Binding Path=XAxis}"
ItemsSource="{Binding Path=Series}"/>
</DataTemplate>
<Style TargetType="ItemsControl">
<Setter Property="ItemsPanel">
<Setter.Value>
<ItemsPanelTemplate>
<!--My stacked chart control -->
<l:StackedPanel x:Name="stackedPanel" Width="Auto" Height="Auto" Background="LightBlue">
</l:StackedPanel>
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
</Style>
</UserControl.Resources>
<Grid HorizontalAlignment="Stretch" VerticalAlignment="Stretch" ClipToBounds="True">
<!-- View is an ObservableCollection of all axes and series-->
<ItemsControl x:Name="chartItems" ItemsSource="{Binding Path=View}" Focusable="False">
</ItemsControl>
</Grid>
This code works quite well. When I add axes they get drawn. But the DependentAxis and InDependentAxis of the lineseries control stay null, so the series doesn't get drawn. How can I bind the nested viewmodels to the properties of a control?
It should work. A few things you can check:
Hope that helps,
Aelij.
You've probably already checked this but I find that when I'm debugging bindings the first and easiest place to start is running a debug session from VS as the debug output tells which objects and properties are failing to bind. I usually end up discovering I need to explicitly set a DataContext or something else like a typo. The output to look for start like this:
System.Windows.Data Error: 39 : BindingExpression path error:
this is followed by the property name you tried to bind to and usually most importantly the class against which its actually trying to bind. If this doesn't help there's a great article here on the debugging bindings: http://www.beacosta.com/blog/?p=52 which discusses the use of PresentationTraceSources.TraceLevel=High which Aelij mentioned, as well as a few other techniques. Hope this gets onto the right track.
Regards,
Mike
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