How do I add Items to a Legend in WPF

[BabaGoud]

I have added a Grpah with three plots. Added a Legend and wanted to have 3 plots of the graph as the Items to my Legend. Is there any way I can add the Legend items at design time?

<ni:Graph>

<ni:Graph.Plots>

<ni.Plot x:name="x1"/>

<ni.Plot x:name="x2"/>

<ni.Plot x:name="x3"/>

</ni.Graph.Plots>

</ni:Graph>

<ni:Legend items{???} />

Seems Items is read only collection....

[phansen · Accepted solution]

You can use the ItemsSource property to populate the Legend. You can show all items by using the graph itself, or you can limit it to a specific collection, as in this XAML from the Standard\DefaultPlotRenderers example installed with Measurement Studio:

<ni:Legend ItemsSource="{Binding AllPlots, ElementName=graph}"
           ItemBackground="{Binding Background, ElementName=graph}"
           BorderBrush="{Binding BorderBrush, ElementName=graph}"
           IsTabStop="False" />

[BabaGoud]

Hi Paul,

I have 2 graphs on the window. the first graph has only one plot and the second graph has 3 plots.

My Legend needs to contain one item as a source from the first graph and only 2 of the plots as two more items from the second graph. Is there a way to mention plots from 2 different graphs as Itemsource of the Legend?

[phansen]

Because of the amount of filtering involved, I think the simplest approach would be to initialize a collection in code-behind to contain the specific plots you were interested in. (If you had wanted to combine all items from multiple collections, then a WPF CompositeCollection could work as a purely declarative solution.)

The Legend will try to display the items from any collection you provide to ItemsSource, so based on your description:

XAML:
<ni:Graph x:Name="graph1">
    <ni:Graph.Plots>
        <ni:Plot Label="Graph 1, Plot 1" />
    </ni:Graph.Plots>
</ni:Graph>

<ni:Graph x:Name="graph2">
    <ni:Graph.Plots>
        <ni:Plot Label="Graph 2, Plot 1" />
        <ni:Plot Label="Graph 2, Plot 2" />
        <ni:Plot Label="Graph 2, Plot 3" />
    </ni:Graph.Plots>
</ni:Graph>

<ni:Legend x:Name="legend" />


Code:
var plots = new List<Plot>( );
plots.Add( graph1.Plots[0] );
plots.AddRange( graph2.Plots.Take( 2 ) );
legend.ItemsSource = plots;

[ranger007]

Hi Paul,

I have an application where I have to plot data based on user selection and show them in a legend. So I have to create plots dynamically and add plot labels from a ViewModel

Then I have binded Legend to these plots and got the labels displayed on legend.

 The problem is - clicking on the legend items no longer change the visibility of the plots. 

 Can you please help?

Thanks,

[phansen]

[I see you posted a new question, so I have moved my answer there]

[phansen]

This sounds like how you would customize the legend in Windows Forms, not WPF?