Axis Ticks - TickProvider and DeltaCalculator API

It is possible to further customize the MajorDelta, MinorDelta and affect the tick frequency of an axis, to have a totally custom set of axis ticks (gridlines, label intervals) on the chart. That can be achieved quite easily through DeltaCalculator and TickProvider APIs.

Creating your own DeltaCalculator

To have full control over the calculations of MajorDelta and MinorDelta you will need to create a custom IDeltaCalculator. By default each ITickProvider has a DeltaCalculator created for it. The type of DeltaCalculator depends on the TickProvider. Below is a table of the DeltaCalculator already defined in SciChart Android.

Delta Calculator Type Used By
NumericDeltaCalculator NumericTickProvider and CategoryTickProvider
LogarithmicDeltaCalculator LogarithmicNumericTickProvider
DateDeltaCalculator DateTickProvider

To create a custom IDeltaCalculator, you need to inherit from the correct class, according to the table above, then override getDeltaFromRange(Comparable<?> min, Comparable<?> max, int minorsPerMajor, int maxTicks) method. This method is called internally by ITickProvider for every axis when it needs to recalculate AxisDelta<T>.

Let's create a custom IDeltaCalculator and use it with NumericTickProvider for NumericAxis.

class CustomNumericDeltaCalculator extends NumericDeltaCalculator {
    @Override
    public IAxisDelta<Double> getDeltaFromRange(Comparable min, Comparable max, int minorsPerMajor, int maxTicks) {
        // For the sake of simplicity, we will use simple constants.
        // But you might want to have some complex calculations here.
        double minorDelta = 0.07;
        double majorDelta = 0.1;
        return new AxisDelta<>(minorDelta, majorDelta);
    }
}

// create a NumericTickProvider with CustomNumericDeltaCalculator and assign it to the axis
final NumericAxis axis = new NumericAxis(getContext());
axis.setTickProvider(new NumericTickProvider(new CustomNumericDeltaCalculator()));

Numeric Delta Calculator

Creating your own TickProvider

If you need to have fine grained control over axis ticks output, and custom Delta Calculator isn't enough - you might want to use tickProvider property, which is available for all Axis Types. To use it - you will need to provide a custom ITickProvider and set it on your axis.

By default each axis has a ITickProvider created and assigned to it. The type of TickProvider depends on the type of Axis. Below is a table of the TickProviders already defined in SciChart Android.

Tick Provider Type Provide ticks For
NumericTickProvider NumericAxis
LogarithmicNumericTickProvider LogarithmicNumericAxis
DateTickProvider DateAxis
CategoryTickProvider CategoryDateAxis

To create a custom TickProvider, you need to inherit from the correct class, according to the Axis Type you have, and override updateTicks(DoubleValues minorTicks, DoubleValues majorTicks) method which is called internally for every axis when it needs to recalculate major and minor ticks for drawing.

Let's create custom NumericTickProvider for NumericAxis

class CustomNumericTickProvider extends NumericTickProvider {
    @Override
    protected void updateTicks(DoubleValues minorTicks, DoubleValues majorTicks) {
        double min = axis.getVisibleRange().getMinAsDouble();
        double max = axis.getVisibleRange().getMaxAsDouble();
        majorTicks.add(min);
        majorTicks.add((min + max) / 2);
        majorTicks.add(max);
    }
}

final NumericAxis axis = new NumericAxis(getContext());
// create a CustomNumericTickProvider and assign it to the axis
axis.setTickProvider(new CustomNumericTickProvider());

Numeric Tick Provider