DateTime Axis

This example shows creation of a DateTime Axis, for rendering XY-series where either/both of X/Y dimensions can present time. This doesn't affect the input of data - format remains as {x: number, y: number} - however, DateTime-axes format their values from number to a date and time. This affects axis labels, markers and cursors.

A DateTime-Axis is created by specifying its TickStrategy. Here's how it looks when creating a new Axis:

const bottomAxisDateTime = chart.addAxisX(false, AxisTickStrategies.DateTime())

If you want to specify the TickStrategy of a default Axis, you must do it when constructing the ChartXY using ChartXYOptions interface:

const chart = lightningChart().ChartXY({
    // ChartXYOptions
    defaultAxisXTickStrategy: AxisTickStrategies.DateTime()

The above mentioned examples will provide an Axis that will format its scale values to their DateTime-representations. This conversion relies on a reference date, further referred to as origin-date. This origin-date specifies the DateTime value that is equal to zero as a numeric representation. Incremental values will result in progressive DateTimes by milliseconds. For example, given origin-date is equal to the 1st of January 2002, 2PM, a numeric value of 7,200,000 would be translated to 1st of January 2002 4PM.

As such, the origin-date must be able to be specified to whichever DateTime is desired. It is done by passing a javascript Date object to the function that creates the DateTime TickStrategy:

// Define the origin-date. (y, m [0-11], d [1-31], h [0-23])
const originDate = new Date(2002, 0, 1, 13)
// Create DateTime AxisTickStrategy with specified originDate.
const dateTimeTickStrategy = AxisTickStrategies.DateTime(originDate)

If this TickStrategy would be supplied to an X-Axis, it would effectively mean that its scale would start from 1st of January 2002 14PM, so a XY-point with coordinates { x: 0, y: 0 } would be formated as { x: 1.1.2002 14:00, y: 0 }.

It is worth mentioning that big DateTime-intervals can produce severe precision problems (eq. when zooming in). The only way to battle this is by reducing the distance of timestamps from the active origin-date.

© Arction Ltd 2009-2020. All rights reserved.