ArcLayout

@UiThread
public class ArcLayout extends ViewGroup

Container which will lay its elements out on an arc. Elements will be relative to a given anchor angle (where 0 degrees = 12 o clock), where the layout relative to the anchor angle is controlled using anchorAngleDegrees and anchorType. The thickness of the arc is calculated based on the child element with the greatest height (in the case of Android widgets), or greatest thickness (for curved widgets). By default, the container lays its children one by one in clockwise direction. The attribute 'clockwise' can be set to false to make the layout direction as anti-clockwise. These two types of widgets will be drawn as follows.

Standard Android Widgets:

These widgets will be drawn as usual, but placed at the correct position on the arc, with the correct amount of rotation applied. As an example, for an Android Text widget, the text baseline would be drawn at a tangent to the arc. The arc length of a widget is obtained by measuring the width of the widget, and transforming that to the length of an arc on a circle.

A standard Android widget will be measured as usual, but the maximum height constraint will be capped at the minimum radius of the arc (i.e. width / 2).

"Curved" widgets:

Widgets which implement ArcLayout.Widget are expected to draw themselves within an arc automatically. These widgets will be measured with the full dimensions of the arc container. They are also expected to provide their thickness (used when calculating the thickness of the arc) and the current sweep angle (used for laying out when drawing). Note that the ArcLayout will apply a rotation transform to the canvas before drawing this child; the inner child need not perform any rotations itself.

An example of a widget which implements this interface is CurvedTextView, which will lay itself out along the arc.

Summary