Angular Chart Overlays
The Angular DataChart allows for placement of horizontal or vertical lines at a single numeric value that you define through usage of the ValueOverlay. This can help you to visualize data such as the mean or median of a particular series.
Angular Value Overlay Example
The following example depicts a Column Chart with a few horizontal value overlays plotted.
Angular Value Overlay Properties
Unlike other series types that use a ItemsSource for data binding, the value overlay uses a ValueMemberPath property to bind a single numeric value. In addition, the value overlay requires you to define a single Axis to use. If you use an X-axis, the value overlay will be a vertical line, and if you use a Y-axis, it will be a horizontal line.
When using a numeric X or Y axis, the ValueMemberPath property should reflect the actual numeric value on the axis where you want the value overlay to be drawn. When using a category X or Y axis, the ValueMemberPath should reflect the index of the category at which you want the value overlay to appear.
When using the value overlay with a numeric angle axis, it will appear as a line from the center of the chart and when using a numeric radius axis, it will appear as a circle.
ValueOverlay appearance properties are inherited from Series and so Brush and Thickness for example are available and work the same way they do with other types of series.
It is also possible to show an axis annotation on a ValueOverlay to show the value of the overlay on the owning axis. In order to show this, you can set the IsAxisAnnotationEnabled property to true.
Angular Value Layer
The Angular charting components also expose the ability to use value lines to call out different focal points of your data, such as minimum, maximum, and average values.
Applying the ValueLayer in the CategoryChart and FinancialChart components is done by setting the ValueLines property on the chart. This property takes a collection of the ValueLayerValueMode enumeration. You can mix and match multiple value layers in the same chart by adding multiple ValueLayerValueMode enumerations to the ValueLines collection of the chart.
In the DataChart, this is done by adding a ValueLayer to the Series collection of the chart and then setting the ValueMode property to one of the ValueLayerValueMode enumerations. Each of these enumerations and what they mean is listed below:
Auto: The default value mode of theValueLayerValueModeenumeration.Average: Applies potentially multiple value lines to call out the average value of each series plotted in the chart.GlobalAverage: Applies a single value line to call out the average of all of the series values in the chart.GlobalMaximum: Applies a single value line to call out the absolute maximum value of all of the series values in the chart.GlobalMinimum: Applies a single value line to call out the absolute minimum value of all of the series values in the chart.Maximum: Applies potentially multiple value lines to call out the maximum value of each series plotted in the chart.Minimum: Applies potentially multiple value lines to call out the minimum value of each series plotted in the chart.
If you want to prevent any particular series from being taken into account when using the ValueLayer element, you can set the TargetSeries property on the layer. This will force the layer to target the series that you define. You can have as many ValueLayer elements within a single DataChart as you want.
The following sample demonstrates usage of the different ValueLines in the CategoryChart:
Angular Financial Overlays
You can also plot built-in financial overlays and indicators in Angular Stock Chart.
Chart Overlay Text Preview
The Angular ValueOverlay, ValueLayer, and all Data Annotation Layers can render custom overlay text inside plot area of the DataChart component. You can use this overlay text to annotate important events (e.g. company quarter reports) on x-axis or important values on y-axis in relationship to the layers.
For example, you can use DataAnnotationSliceLayer, ValueOverlay, and ValueLayer to show overlay text.
Styling Overlay Text
This code example shows how to style and customize Overlay Text on
the DataAnnotationSliceLayer, ValueOverlay, and ValueLayer.
Additional Resources
You can find more information about related chart types in these topics: