Blazor Chart Overlays

    The Blazor IgbDataChart allows for placement of horizontal or vertical lines at a single numeric value that you define through usage of the IgbValueOverlay. This can help you to visualize data such as the mean or median of a particular series.

    Blazor Value Overlay Example

    The following example depicts a Column Chart with a few horizontal value overlays plotted.

    Blazor Value Overlay Properties

    Unlike other series types that use a DataSource 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.

    IgbValueOverlay 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 IgbValueOverlay to show the value of the overlay on the owning axis. In order to show this, you can set the IsAxisAnnotationEnabled property to true.

    Blazor Value Layer

    The Blazor 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 IgbValueLayer in the IgbCategoryChart and IgbFinancialChart 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 IgbDataChart, this is done by adding a IgbValueLayer 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 the ValueLayerValueMode enumeration.
    • 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 IgbValueLayer 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 IgbValueLayer elements within a single IgbDataChart as you want.

    The following sample demonstrates usage of the different ValueLines in the IgbCategoryChart:

    Blazor Financial Overlays

    You can also plot built-in financial overlays and indicators in Blazor Stock Chart.

    Additional Resources

    You can find more information about related chart types in these topics:

    API References

    The following is a list of API members mentioned in the above sections: