Blazor Data Legend

    In Ignite UI for Blazor, the IgbDataLegend is highly-customizable version of the Legend, that shows values of series and provides many configuration properties for filtering series rows and values columns, styling and formatting values. This legend updates when moving the mouse inside of the plot area of the IgbCategoryChart, IgbFinancialChart, and IgbDataChart. Also, it has a persistent state that remembers the last hovered point when the user's mouse pointer exits the plot area. It displays this content using a set of three type of rows (header, series, summary) and four types of columns (title, label, value, unit).

    Blazor Data Legend Rows

    The rows of the IgbDataLegend include the header row, series row(s), and the summary row. The header row displays the axis label of the point that is hovered, and can be changed using the HeaderText property.

    Header Row

    The header row displays the current label of x-axis when hovering mouse over category series and financial series. You can use HeaderFormatDate and HeaderFormatTime properties to format date and time in the IgbDataLegend if the x-axis shows dates. For other types of series, the IgbDataLegend does not render the header row.

    Series Row

    The series row represents each series plotted in the chart. These rows will display the legend badge, series title, actual/abbreviated value of the the series, and abbreviation symbol or unit of measurement, if specified. You can filter series rows by setting IncludedSeries or ExcludedSeries properties to a collection of series' indexes (1, 2, 3) or series' titles (Tesla, Microsoft).

    Summary Row

    Finally, there is a summary row that displays the total of all series values. The default summary title can be changed using the SummaryTitleText property of the legend. Also, you can use the SummaryType property to customize whether you display the Total, Min, Max, or Average of series values in the summary row.

    Blazor Data Legend Columns

    The columns of the IgbDataLegend include the series title, label, value of data column, and optional unit associated with the value. Some series in the chart can have multiple columns for label, value, and units. For example, financial price series has High, Low, Open, and Close data columns which can be filtered in the IgbDataLegend using the IncludedColumns or ExcludedColumns properties.

    Setting values on the IncludedColumns and ExcludedColumns properties, depends on type of series and how many data columns they support. For example, you can set IncludedColumns property to a collection of Open and Close strings and the legend will show only open and close values for stock prices when the chart is plotting financial series. The following table lists all column names that can be use to filter columns in data legend.

    Type of Series Column Names
    Category Series Value
    Radial Series Value
    Polar Series Radius, Angle
    Bubble Series X, Y, Radius
    Scatter Series X, Y
    Range Series High, Low
    Financial Series High, Low, Open, Close, Change, TypicalPrice, Volume

    Where the TypicalPrice and percentage Change of OHLC prices are automatically calculated by financial series so you do not need to include them in your data sources.

    Title Column

    The title column displays legend badges and series titles, which come from the Title property of the different IgbSeries plotted in the chart.

    Label Column

    The label column displays short name on the left side of value column, e.g. "O" for Open stock price. You can toggle visibility of this column using the LabelDisplayMode property.

    Value Column

    The value column displays values of series as abbreviated text which can be formatted using the ValueFormatAbbreviation property to apply the same abbreviation for all numbers by setting this property to Shared. Alternatively, a user can select other abbreviations such as Independent, Kilo, Million, etc. Precision of abbreviated values is controlled using the ValueFormatMinFractions and ValueFormatMaxFractions for minimum and maximum digits, respectively.

    Unit Column

    The unit column displays an abbreviation symbol on the right side of value column. The unit symbol depends on the ValueFormatAbbreviation property, e.g. "M" for the Million abbreviation.

    Customizing Columns

    You can customize text displayed in the Label and Unit columns using properties that end with MemberAsLegendLabel and MemberAsLegendUnit on each series. The following table shows some possible customizations of the Label and Unit columns.

    Type of Series Series Properties
    Category Series ValueMemberAsLegendLabel="$"
    ValueMemberAsLegendUnit="M"
    Radial Series ValueMemberAsLegendLabel="Distance:"
    ValueMemberAsLegendUnit="KM"
    Polar Series RadiusMemberAsLegendLabel="Radius:"
    RadiusMemberAsLegendUnit="KM"
    AngleMemberAsLegendLabel="Angle:"
    AngleMemberAsLegendUnit="°"
    Range Series HighMemberAsLegendLabel="H:"
    HighMemberAsLegendUnit="K"
    LowMemberAsLegendLabel="L:"
    LowMemberAsLegendUnit="K"
    Financial Series OpenMemberAsLegendLabel="O:"
    OpenMemberAsLegendUnit="K"
    HighMemberAsLegendLabel="H:"
    HighMemberAsLegendUnit="K"
    LowMemberAsLegendLabel="L:"
    LowMemberAsLegendUnit="K"
    CloseMemberAsLegendLabel="C:"
    CloseMemberAsLegendUnit="K"

    Also, you can use the UnitText property on the IgbDataLegend to change text displayed in all Unit columns.

    Blazor Data Legend Styling

    The IgbDataLegend provides properties for styling each type of column. Each of these properties begins with Title, Label, Value, or Units. You can style the text's color, font, and margin. For example, if you wanted to set the text color of all columns, you would set the TitleTextColor, LabelTextColor, ValueTextColor, and UnitsTextColor properties. The following example demonstrates a utilization of the styling properties mentioned above:

    Blazor Data Legend Value Formatting

    The IgbDataLegend provides automatic abbreviation of large numbers using its ValueFormatAbbreviation property. This adds a multiplier in the units column such as kilo, million, billion, etc. You can customize the number of fractional digits that are displayed by setting the ValueFormatMinFractions and ValueFormatMaxFractions. This will allow you to determine the minimum and maximum number of digits that appear after the decimal point, respectively. The following example demonstrates how to use those properties:

    Blazor Data Legend Value Mode

    You have the ability to change the default decimal display of values within the IgbDataLegend to a currency by changing the ValueFormatMode property. Also, you can change the culture of the displayed currency symbol by setting the ValueFormatCulture property a culture tag. For example, the following example data legend with the ValueFormatCulture set to "en-GB" to display British Pounds (£) symbol:

    Blazor Data Legend Styling Events

    The IgbDataLegend has three events that fire when rendering their corresponding row. These events are listed below with a description of what they are designed to be used for:

    • StyleHeaderRow: This event fires once when rendering the header row.
    • StyleSeriesRow: This event fires once for each series row, which allows conditional styling of the values of the series.
    • StyleSeriesColumn: This event fires once for each series column, which allows conditional styling of the different columns for the series in the chart.
    • StyleSummaryRow: This event fires once when rendering the summary row.
    • StyleSummaryColumn: This event fires once when rendering the summary column.

    Each of the above events exposes a IgbDataLegendStylingRowEventArgs parameter as its arguments, which lets you customize each item's text, text color, and the overall visibility of the row. The event arguments also expose event-specific properties. For example, since the StyleSeriesRow event fires for each series, the event arguments will return the series index and series title for the row that represents the series.

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