Contex.Axis represents the visual appearance of a Contex.Scale

In general terms, an Axis is responsible for rendering a Contex.Scale where the scale is used to position a graphical element.

As an end-user of the Contex you won't need to worry too much about Axes - the specific plot types take care of them. Things like styling and scales are handled elsewhere. However, if you are building a new plot type you will need to understand how they work.

Axes can be drawn with ticks in different locations relative to the Axis based on the orientation. For example, when :orientation is :top, the axis is drawn as a horizontal line with the ticks above and the tick text above that.

:rotation is used to optionally rotate the labels and can either by 45 or 90 (anything else is considered to be 0).

:tick_size_inner and :tick_size_outer control the line lengths of the ticks.

:tick_padding controls the gap between the end of the tick mark and the tick text.

:flip_factor is for internal use. Whatever you set it to will be ignored.

An offset relative to the containing SVG element's origin is used to position the axis line. For example, an x-axis drawn at the bottom of the plot will typically be offset by the height of the plot content. The different plot types look after this internally.

There are some layout heuristics to calculate text sizes and offsets based on axis orientation and whether the tick labels are rotated.