wheel

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po.wheel()

Constructs a mouse wheel control with default settings. This control uses the “mousewheel” event to provide smooth zooming around the mouse cursor, and is designed to support both discrete devices (such as the traditional mouse wheel) and continuous devices (such as trackpads).

wheel.map([x])

Adds this control to the specified map x, removes this control from its current map, or returns the current map. This method is typically not called directly, but is needed to support the map’s add method and remove methods.

If the argument x is specified, this method returns this. If x is null, this control is removed from its current map; otherwise, this control is added to the specified map. If no arguments are specified, this method returns the current map, which may be null. Whew!

wheel.smooth([x])

Sets or gets whether zooming is smooth. If the boolean argument x is specified, the method enables or disables smooth zooming accordingly, and returns this. If no arguments are specified, the method returns true if and only if smooth zooming is enabled.

Smooth zooming is enabled by default. It allows the map to be zoomed by arbitrary (fractional) amounts, rather than only at integer levels.

wheel.zoom([x[, l]])

Sets or gets the zoom mode of this control. If the argument x is specified, this method sets the zoom mode to the given named value and returns this. If no arguments are specified, this method returns the current named zoom mode.

The following zoom modes are supported: “mouse”, “center”, “location”. The default mode is “mouse”, which causes the control to zoom around the location at the mouse cursor. The “center” mode will zoom around the map center. The “location” mode requires the second argument l, which specifies the location around which to zoom.