Series: Labels

• Dec 18, 2018
• 4 minutes to read

Labels can accompany series points to provide various additional information about them.

Use the label property to customize settings specifying the content, position and appearance of series point labels. Note that series label settings depend on the series type. The following table lists series and the corresponding label types:

Series type	Label type
DXPieSeries	DXPieSeriesLabel
DXDonutSeries	DXPieSeriesLabel
DXAreaSeries	DXMarkerSeriesLabel
DXStackedAreaSeries	DXMarkerSeriesLabel
DXFullStackedAreaSeries	DXMarkerSeriesLabel
DXStepAreaSeries	DXMarkerSeriesLabel
DXBarSeries	DXBarSeriesLabel
DXStackedBarSeries	DXStackedBarSeriesLabel
DXFullStackedBarSeries	DXStackedBarSeriesLabel
DXSideBySideStackedBarSeries	DXStackedBarSeriesLabel
DXSideBySideFullStackedBarSeries	DXStackedBarSeriesLabel
DXPointSeries	DXMarkerSeriesLabel
DXBubbleSeries	DXBubbleSeriesLabel
DXLineSeries	DXMarkerSeriesLabel
DXStepLineSeries	DXMarkerSeriesLabel
DXScatterLineSeries	DXMarkerSeriesLabel
DXCandleStickSeries	DXFinancialSeriesLabel
DXStockSeries	DXFinancialSeriesLabel

This guide shows the main customization scenarios.

How to: Format series labels

The following code snippet demonstrates how to specify a Point series point label pattern:

Objective C

MarkerSeriesLabel *seriesLabel = [[MarkerSeriesLabel alloc] init];
seriesLabel.textPattern = @"{A$tb}: {V$.0f}°C";
seriesLabel.hidden = DXDefaultBooleanNo;
series.label = seriesLabel;

Swift

let seriesLabel = MarkerSeriesLabel();
seriesLabel.textPattern = "{A$tb}: {V$.0f}°C";
seriesLabel.hidden = DXDefaultBoolean.no;
series.label = seriesLabel;

C#

series.Label = new MarkerSeriesLabel {
    Hidden = DXDefaultBoolean.No,
    TextPattern = "{A$tb}: {V$.0f}°C"
};

The DXSeriesLabel.textPattern property allows you to modify label text for a series.

In the code above, series label placeholders (A and V) specify a series point value that should be added to a label. The following label placeholders are available:

Placeholder	Description
{S}	Displays a series name.
{A}	Displays a series point argument.
{L}	Displays a pie series point label.
{V}	Displays a series point value.
{VP}	Displays a series point value as percentages.
{W}	Displays a Bubble series point weight.
{O}	Displays a financial series point open value.
{H}	Displays a financial series point high value.
{L}	Displays a financial series point low value.
{C}	Displays a financial series point close value.
{HV}	Displays a range bar series point max value.
{LV}	Displays a range bar series point min value.

Note

These values can be formatted using default format strings after the $ sign. For example, in the {VP$#.##} string, VP is a placeholder, $ is a format string separator, and #.## is a format string.

How to: Use a series label’s text provider

If you need extra customization, for example, to calculate values shown by a label, write code to develop a class that adopts the series label text provider protocol:

Objective C

BarSeriesLabel *seriesLabel = [[BarSeriesLabel alloc] init];
seriesLabel.textProvider = BarSeriesLabelTextProvider();
series.label = seriesLabel;


@interface SeriesLabelTextProvider : NSObject<DXSeriesLabelTextProvider>
-(NSString *)format : (DXSeriesLabelValuesBase *) value;
@end

@implementation SeriesLabelTextProvider
-(NSString *)format : (SeriesLabelValues *) value {
    DXSeriesLabelValues * xyValues = (DXSeriesLabelValues *)value;
    return [NSString stringWithFormat:@"%.0fM", xyValues.value/1000000.0];
}
@end

Swift

let seriesLabel = BarSeriesLabel();
seriesLabel.textProvider = BarSeriesLabelTextProvider();
series.label = seriesLabel;

// The series label text provider implementation.
class GdpLabelTextProvider : NSObject, DXSeriesLabelTextProvider {
    public func format(_ value: DXSeriesLabelValuesBase) -> String {
        let xyValues = value as! DXSeriesLabelValues;
        return String(format: "%.0fM", arguments: [xyValues.value / 1000000]);
    }
}

C#

series.Label = new BarSeriesLabel {
    TextProvider = new BarSeriesLabelTextProvider();
};

// The series label text provider implementation.
public class BarSeriesLabelTextProvider : DXSeriesLabelTextProvider {
    public string Format(SeriesLabelValues seriesLabelValues) {
        DXSeriesLabelValues xyValues = (DXSeriesLabelValues)value;
        return String.format:("{0:.0}M", xyValues.value / 1000000);
    }
}

Use the following symbols to implement a series label text provider:

Symbol	Description
DXSeriesLabelTextProvider	The protocol that a class should adopt to provide series labels’ text.
DXSeriesLabelTextProvider::format:	Prepares series label text for the specified series point values.
DXPieSeriesLabelValues	Provides values available to build a pie series’ label text.
DXSeriesLabelValues	Provides values available to build a common Cartesian series’ label text.
DXFullStackedLabelValues	Provides values available to build a full-stacked series’ label text.
DXFinancialSeriesLabelValues	Provides values available to build a financial series’ label text.

How to: Customize series labels’ appearance

You can customize labels’ appearance like any other chart elements’ appearance. The image below highlights the appearance parameters that you can modify.

See this code snippet to learn how to change this label text’s appearance:

Objective C

DXPieSeriesLabelStyle *labelStyle = [[DXPieSeriesLabelStyle alloc] init];
labelStyle.connectorThickness = 2;

DXTextStyle *textStyle = [[DXTextStyle alloc] init];
textStyle.foregroundColor = [UIColor colorWithWhite: 0.2 alpha: 1];
textStyle.backgroundColor = [UIColor colorWithWhite: 0.9 alpha: 1];
textStyle.size = 30.0;
labelStyle.textStyle = textStyle;

pieLabel.style = labelStyle;

Swift

let labelStyle = DXPieSeriesLabelStyle();
labelStyle.connectorThickness = 2;

let textStyle = DXTextStyle();
textStyle.foregroundColor = UIColor(white: 0.2, alpha: 1);
textStyle.backgroundColor = UIColor(white: 0.9, alpha: 1);
textStyle.size = 30.0;
labelStyle.textStyle = textStyle;

pieLabel.style = labelStyle;

C#

pieLabel.style = new DXPieSeriesLabelStyle {
    ConnectorThickness = 2,
    TextStyle = new DXTextStyle {
        ForegroundColor = UIColor.FromWhiteAlpha(0.2, 1),
        BackgroundColor = UIColor.FromWhiteAlpha(0.9, 1),
        Size = 30.0
    }
}

Symbols that are used to customize a label’s text.

Symbol	Description
DXPieSeriesLabelStyle	A Pie series points’ label appearance settings’ storage.
DXSeriesLabelStyle	A Cartesian series points’ label appearance settings’ storage.
DXSeriesLabelStyle.textStyle	Gets or sets labels’ text appearance settings.
DXTextStyle	The text’s appearance settings storage.