The title of an axis Caption texts The distance between the title text and axis marks Title font Font.Orientation is by default set to 900 (90 degrees to the left) for vertical axises. Title is shown if Visible is true and Caption is not empty Determines the side of the chart to which the axis is aligned Left- and right-aligned axises are vertical, top- and bottom-aligned axises are horizontal. Pen used for grid drawing Grid lines are drawn across the chart from each axis mark Inverts the axis scale from increasing to decreasing. If true, the axis is drawn on the chart Invisible axis might still be used for series transformation Source of mark positions

If the source is set, marks are determined by X or Y coordinates of Source items for horizontal and vertical axises correspondingly.

Otherwise, marks are created automatically.

Axis of a chart

TAChart uses four coordinate systems:

Axis coordinates (known in some other applications as object coordinates) -- this is the "raw" coordinate values obtained from the data. As the name implies, axis coordinates are interpreted in terms of specific axis -- the same coordinate value may have different meaning depending on the axis it is applied to.
Graph coordinates are converted from the axis coordinates using axis transformations, such as logarithmic scale. Graph coordinates are common for all objects in the chart.
Image coordinates (aka screen coordinates) are converted from graph coordinates based on the chart viewport. This transformation is always linear and can be influenced by chart tools such as zooming and panning.
Device coordinates are usually equal to screen coordinates, but may be adjusted to the drawing back-end to accommodate different physical resolutions (DPI values). See, for example, printer drawer.

You can add or remove an arbitrary number of axes by editing the AxisList property of the chart. By default, a chart has two axes: one horizontal and one vertical. They are accessible via the BottomAxis and LeftAxis properties. Note that those properties are aliases to AxisList[0] and AxisList[1], so if you remove those default axes, accessing BottomAxis and LeftAxis will return nil.

Visually, an axis consists of the axis line (drawn by AxisPen), grid lines (drawn by GridPen), ticks, marks and an arrow.

Each axis is drawn inside its own rectangle, determined by the size of mark labels and ticks. By assigning several axes the same positive Group number, you can have them share the same rectangular area. Grouped axes can be used to achieve a "panes" look, when several series are drawn on different portions of the same graph.

Axes with the same alignment, but different groups, are stacked alongside each other. You can use the Margin property to control the spacing between such axes.