The scale Labels object has a property called TextProvider that controls how the label value will be formatted and presented as text to the user. There are two types of label text providers:

NFormattedScaleLabelTextProvider

The formatted scale label text provider takes the value associated with the label and formats it as a user readable string. It has an associated value formatter object (check out the Numeric Value Formatting and DateTime Value Formatting sections below). The following code snippet shows how to alter the default formatting on a linear scale:

scale.Labels.TextProvider = new NFormattedScaleLabelTextProvider(new NNumericValueFormatter("0.000"));

Different scales by default have an associated formatted scale label text provider with different value formatter as shown on the following table:

NOrdinalScaleLabelTextProvider

The ordinal scale label text provider takes the value of label and maps it to a set to a set of predefined constant strings. It is commonly used in ordinal (categorical) scales where each value on the scale represents a different category. The following code snippet for example create a simple categorical bar chart with custom category labels:

NBarSeries bar = new NBarSeries();
bar.DataPoints.Add(new NBarDataPoint(10));
bar.DataPoints.Add(new NBarDataPoint(18));
bar.DataPoints.Add(new NBarDataPoint(25));
chart.Series.Add(bar);
NOrdinalScale scaleX = (NOrdinalScale)chart.Axes[ENCartesianAxis.PrimaryX].Scale;
scaleX.Labels.TextProvider = new NOrdinalScaleLabelTextProvider(new string[] { "Cars", "Busses", "Airplanes" });

NDateTimeUnitSensitiveLabelTextProvider

The date time unit sensitive label text provider takes the unit and value of the label and applies formatting to the value which is dependent on the date time unit that generated itl. This allows you to specify unit sensitive formatting, which is dependent on the date/time unit selected by the scale for the major ticks.

For example consider that you display date/time data which is gathered from a real time device at 5 second intervals. In this case the scale will choose a smaller date time unit depending on the number of data points - for example second or minute. Most likely you'll not need date or year information when you display data for one or two hours span. On the other hand if you display data for monthly or yearly sales the scale will choose a bigger date time unit (week, month, quarter, half year or year) and chances are you'll not need time information.

Unit sensitive formatting allows you to specify a date time formatting string depending on the date time unit selected by the scale for the major ticks.

Unit sensitive formatting is also very useful when you use DateTime scales with zooming and scrolling. In this case when you zoom in the scale will select smaller units (that show time information), respectively when you zoom out, the scale will select bigger units (with date information).

Creating a Date Time Unit Sensitive Label Text Provider

The following code snippet shows how to create a date time unit sensitive text provider:

scale.Labels.TextProvider = new NDateTimeUnitSensitiveLabelTextProvider();

Configuring the allowed date time units for decoration

Date time units are implemented as singleton objects, which are accessible from the NDateaTimeUnit base abstract class. The following table lists the date time units supported by the date time, value timeline and range timeline scales:

At any point you may enable / disable the date time units that the scale can use for the major ticks. This is achieved by modifying the AutoDateTimeUnits array:

 dateTimeScale.AutoDateTimeUnits = new NDomArray<NDateTimeUnit>(new NDateTimeUnit[] { NDateTimeUnit.Day, NDateTimeUnit.Month });

This code will limit the scale to choose only from a day and month date time units.

You can also change the format string associated with a particular date time unit:

NDateTimeUnitSensitiveLabelTextProvider textProvider = new NDateTimeUnitSensitiveLabelTextProvider();
textProvider.DayFormatter = new NDateTimeValueFormatter(ENDateTimeValueFormat.ShortDateShortTime24Hour);
textProvider.MonthFormatter = new NDateTimeValueFormatter(ENDateTimeValueFormat.Date);
dateTimeScale.Labels.TextProvider = textProvider;

Now when the scale decides to generate major ticks for days (at say each day, each fifth day etc.) it will use a formatting string with short date and short time information. Otherwise if it chooses to generate ticks on a per month basis it will display just date information.

The numeric value formatter supports all standard .NET format strings and also features support for a number of predefined format strings. The following table shows the predefined numeric format strings:

The following code snippets show how to apply different predefined numeric formats:

Display Value as Currency

scale.Labels.TextProvider = new NFormattedScaleLabelTextProvider(new NNumericValueFormatter(ENNumericValueFormat.Currency));

Display Value as Percentage

scale.Labels.TextProvider = new NFormattedScaleLabelTextProvider(new NNumericValueFormatter(ENNumericValueFormat.Percentage));

The date time value formatter supports all standard .NET date time format strings and extends it further to add support for week and quarter formatting. The predefined format strings in the control are contained in the ENDateTimeValueFormat enumeration. The following table list the available options:

 The following code shows how to apply one of the predefined date time value formats:

dateTimeScale.Labels.TextProvider = new NFormattedScaleLabelTextProvider(new NDateTimeValueFormatter(ENDateTimeValueFormat.ShortTime24Hour));