Used internally by a component, such as List, to set the number of virtualized items that appear after the items passed to layout(). Allows the array of items to be smaller than the full size. Does not work if the layout has variable item dimensions.

This property is meant to be set by the List or other component that uses the virtual layout. If you're simply creating a layout for a List or another component, do not use this property. It is meant for developers creating custom components only.

Used internally by a component, such as List, to set the number of virtualized items that appear before the items passed to layout(). Allows the array of items to be smaller than the full size. Does not work if the layout has variable item dimensions.

This property is meant to be set by the List or other component that uses the virtual layout. If you're simply creating a layout for a List or another component, do not use this property. It is meant for developers creating custom components only.

Determines if pages are positioned from left-to-right or from top-to-bottom.

The default value is feathers.layout.Direction.HORIZONTAL.

See also

The alignment of each item horizontally, on the x-axis.

The default value is feathers.layout.HorizontalAlign.CENTER.

See also

If the layout is virtualized, specifies the minimum total number of items that will be created, even if some are not currently visible in the view port.

The default value is 1.

See also

Quickly sets all padding properties to the same value. The padding getter always returns the value of paddingTop, but the other padding values may be different.

The default value is 0.

See also

The space, in pixels, that appears on the bottom of each item. item.

The default value is 0.

The minimum space, in pixels, to the left of each item.

The default value is 0.

The minimum space, in pixels, to the right of each item.

The default value is 0.

The space, in pixels, that appears on top of each item.

The default value is 0.

Determines if the container calls layout() when the scroll position changes. Useful for transforming items as the view port scrolls. This value should be true for layouts that implement the IVirtualLayout interface and the useVirtualLayout property is set to true. May also be used by layouts that toggle item visibility as the items scroll into and out of the view port.

Used internally by a component that supports layout virtualization, such as List, to provide a display object with dimensions that represent a "typical" item in the layout. These dimensions will be used to fill in blanks for the layout when an item is virtual and isn't actually on the display list. If you are simply passing a layout to a component, setting this property will have no effect. It is meant to be used by the component, and the component will replace any value you pass to this property.

Determines if virtual layout should be used. Some components don't support virtual layouts, and they will always change this property to false. In those cases, the virtual layout options will be ignored.

The default value is true.

The alignment of each item vertically, on the y-axis.

The default value is feathers.layout.VerticalAlign.MIDDLE.

See also

Constructor.

Using the current index and a key press, calculates the new index. This might be use to change a list's selectedIndex when a key is pressed.

Parameters

Calculates the scroll position nearest to the current scroll position that will display the full bounds of the item within the view port. If the item is already fully displayed in the view port, the current scroll position will be returned unchanged.

While the item will be displayed in the view port without being clipped in any way, it may not be placed in the most prominent position possible. To give the item a more prominent location, use getScrollPositionForIndex() instead.

This function should always be called after the layout() function. The width and height arguments are the final bounds of the view port, which may be calculated in the layout() function.

Parameters

Using the item dimensions, calculates a scroll position that will ensure that the item at a given index will be visible within the specified bounds.

Typically, this function is used to show the item in the most prominent way, such as centering. To scroll a minimum distance required to display the full bounds of the item in the view port, use getNearestScrollPositionForIndex() instead.

This function should always be called after the layout() function. The width and height arguments are the final bounds of the view port, which may be calculated in the layout() function.

Parameters

Used internally by a component, such as List, to determines which indices are visible with the specified view port bounds and scroll position. Indices that aren't returned are typically not displayed and can be replaced virtually. Uses the typical items dimensions, or cached dimensions, if available.

This function is meant to be called by the List or other component that uses the virtual layout. If you're simply creating a layout for a List or another component, do not call this function. It is meant for developers creating custom components only.

Parameters

Positions (and possibly resizes) the supplied items within the optional bounds argument. If no bounds are specified, the layout algorithm will assume that the bounds start a 0,0 and have unbounded dimensions. Returns the actual bounds of the content, which may be different than the specified bounds.

Note: The items are not absolutely restricted to appear only within the bounds. The bounds can affect positioning, but the algorithm may very well ignore them completely.

If a layout implementation needs to access accurate width and height values from items that are of type IFeathersControl, it must call validate() manually. For performance reasons, the container that is the parent of the items will not call validate() before passing the items to a layout implementation. Meeting this requirement may be as simple as looping through the items at the beginning of layout() and validating all items that are Feathers UI controls:

const itemCount:int = items.length;
for(var i:int = 0; i < itemCount; i++)
{
    var item:IFeathersControl = items[i] as IFeathersControl;
    if(item)
    {
        item.validate();
    }
}

Parameters

Used internally by a component, such as List, to measure the view port based on the typical item dimensions or cached dimensions, if available.

This function is meant to be called by the List or other component that uses the virtual layout. If you're simply creating a layout for a List or another component, do not call this function. It is meant for developers creating custom components only.

Parameters

Dispatched when a property of the layout changes, indicating that a redraw is probably needed.

The properties of the event object have the following values: