spark.layouts.HorizontalLayout (Flex 4 Beta)

Package	spark.layouts
Class	public class HorizontalLayout
Inheritance	HorizontalLayout LayoutBase OnDemandEventDispatcher Object

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

The HorizontalLayout class arranges the layout elements in a horizontal sequence, left to right, with optional gaps between the elements and optional padding around the elements.

The horizontal position of the elements is determined by arranging them in a horizontal sequence, left to right, taking into account the padding before the first element and the gaps between the elements.

The vertical position of the elements is determined by the layout's verticalAlign property.

During the execution of the measure() method, the default size of the container is calculated by accumulating the preferred sizes of the elements, including gaps and padding. When the requestedColumnCount property is set to a value other than -1, only the space for that many elements is measured, starting from the first element.

During the execution of the updateDisplayList() method, the width of each element is calculated according to the following rules, listed in their respective order of precedence (element's minimum width and maximum width are always respected):

If variableColumnWidth is false, then set the element's width to the value of the columnWidth property.
If the element's percentWidth is set, then calculate the element's width by distributing the available container width between all elements with percentWidth setting. The available container width is equal to the container width minus the gaps, the padding and the space occupied by the rest of the elements. The element's precentWidth property is ignored when the layout is virtualized.
Set the element's width to its preferred width.

The height of each element is calculated according to the following rules, listed in their respective order of precedence (element's minimum height and maximum height are always respected):

If the verticalAlign property is "justify", then set the element's height to the container height.
If the verticalAlign property is "contentJustify", then set the element's height to the maximum between the container's height and all elements' preferred height.
If the element's percentHeight property is set, then calculate the element's height as a percentage of the container's height.
Set the element's height to its preferred height.

MXML Syntax expanded

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The <s:HorizontalLayout> tag inherits all of the tag attributes of its superclass and adds the following tag attributes:

  <s:HorizontalLayout 
    Properties
    columnWidth="calculated"
    gap="6"
    paddingBottom="0"
    paddingLeft="0"
    paddingRight="0"
    paddingTop="0"
    requestedColumnCount="-1"
    variableColumnWidth="true"
    verticalAlign="top"
  />

	Property	Defined By
		clipAndEnableScrolling : Boolean If true, specifies to clip the children to the boundaries of the viewport.	LayoutBase
		columnCount : int [read-only] Returns the current number of elements in view.	HorizontalLayout
		columnWidth : Number If the variableColumnWidth property is false, then this property specifies the actual width of each layout element.	HorizontalLayout
		constructor : Object A reference to the class object or constructor function for a given object instance.	Object
		firstIndexInView : int [read-only] The index of the first column that is part of the layout and within the layout target's scroll rectangle, or -1 if nothing has been displayed yet.	HorizontalLayout
		gap : int The horizontal space between layout elements.	HorizontalLayout
		horizontalScrollPosition : Number The x coordinate of the origin of the viewport in the component's coordinate system, where the default value is (0,0) corresponding to the upper-left corner of the component.	LayoutBase
		lastIndexInView : int [read-only] The index of the last column that is part of the layout and within the layout target's scroll rectangle, or -1 if nothing has been displayed yet.	HorizontalLayout
		paddingBottom : Number The minimum number of pixels between the container's bottom edge and the bottom of all the container's layout elements.	HorizontalLayout
		paddingLeft : Number Number of pixels between the container's left edge and the left edge of the first layout element.	HorizontalLayout
		paddingRight : Number Number of pixels between the container's right edge and the right edge of the last layout element.	HorizontalLayout
		paddingTop : Number The minimum number of pixels between the container's top edge and the top of all the container's layout elements.	HorizontalLayout
		prototype : Object [static] A reference to the prototype object of a class or function object.	Object
		requestedColumnCount : int The measured size of this layout is wide enough to display the first requestedColumnCount layout elements.	HorizontalLayout
		target : GroupBase The GroupBase container whose elements are measured, sized and positioned by this layout.	LayoutBase
		typicalLayoutElement : ILayoutElement Used by layouts when fixed row/column sizes are requested but a specific size isn't specified.	LayoutBase
		useVirtualLayout : Boolean A container can hold any number of children.	LayoutBase
		variableColumnWidth : Boolean If true, specifies that layout elements are to be allocated their preferred width.	HorizontalLayout
		verticalAlign : String The vertical alignment of layout elements.	HorizontalLayout
		verticalScrollPosition : Number The y coordinate of the origin of the viewport in the component's coordinate system, where the default value is (0,0) corresponding to the upper-left corner of the component.	LayoutBase

	Method	Defined By
		HorizontalLayout() Constructor.	HorizontalLayout
		addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void	OnDemandEventDispatcher
		clearVirtualLayoutCache():void When useVirtualLayout is true, this method can be used by the layout target to clear cached layout information when the target changes.	LayoutBase
		dispatchEvent(event:Event):Boolean	OnDemandEventDispatcher
		elementAdded(index:int):void Called by the target after a layout element has been added and before the target's size and display list are validated.	LayoutBase
		elementRemoved(index:int):void This method must is called by the target after a layout element has been removed and before the target's size and display list are validated.	LayoutBase
		fractionOfElementInView(index:int):Number Returns 1.0 if the specified index is completely in view, 0.0 if it's not, or a value between 0.0 and 1.0 that represents the percentage of the if the index that is partially in view.	HorizontalLayout
		getHorizontalScrollPositionDelta(navigationUnit:uint):Number Returns the change to the horizontal scroll position to handle different scrolling options.	LayoutBase
		getNavigationDestinationIndex(currentIndex:int, navigationUnit:uint, arrowKeysWrapFocus:Boolean):int Delegation method that determines which item to navigate to based on the current item in focus and user input in terms of NavigationUnit.	LayoutBase
		getScrollPositionDeltaToElement(index:int):Point Computes the verticalScrollPosition and horizontalScrollPosition deltas needed to scroll the element at the specified index into view.	LayoutBase
		getVerticalScrollPositionDelta(navigationUnit:uint):Number Returns the change to the horizontal scroll position to handle different scrolling options.	LayoutBase
		hasEventListener(type:String):Boolean	OnDemandEventDispatcher
		hasOwnProperty(name:String):Boolean Indicates whether an object has a specified property defined.	Object
		isPrototypeOf(theClass:Object):Boolean Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.	Object
		measure():void Measures the target's default size based on its content, and optionally measures the target's default minimum size.	LayoutBase
		propertyIsEnumerable(name:String):Boolean Indicates whether the specified property exists and is enumerable.	Object
		removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void	OnDemandEventDispatcher
		setPropertyIsEnumerable(name:String, isEnum:Boolean = true):void Sets the availability of a dynamic property for loop operations.	Object
		toLocaleString():String Returns the string representation of this object, formatted according to locale-specific conventions.	Object
		toString():String Returns the string representation of the specified object.	Object
		updateDisplayList(width:Number, height:Number):void Sizes and positions the target's elements.	LayoutBase
		updateScrollRect(w:Number, h:Number):void Called by the target at the end of its updateDisplayList to have the layout update its scrollRect.	LayoutBase
		valueOf():Object Returns the primitive value of the specified object.	Object
		willTrigger(type:String):Boolean	OnDemandEventDispatcher

	Method	Defined By
		getElementBounds(index:int):Rectangle Returns the specified element's layout bounds as a Rectangle or null if the index is invalid, the corresponding element is null, includeInLayout=false, or if this layout's target property is null.	LayoutBase
		getElementBoundsAboveScrollRect(scrollRect:Rectangle):Rectangle Returns the bounds of the first layout element that either spans or is above the scrollRect's top edge.	LayoutBase
		getElementBoundsBelowScrollRect(scrollRect:Rectangle):Rectangle Returns the bounds of the first layout element that either spans or is below the scrollRect's bottom edge.	LayoutBase
		getElementBoundsLeftOfScrollRect(scrollRect:Rectangle):Rectangle Returns the bounds of the first layout element that either spans or is to the left of the scrollRect's left edge.	LayoutBase
		getElementBoundsRightOfScrollRect(scrollRect:Rectangle):Rectangle Returns the bounds of the first layout element that either spans or is to the right of the scrollRect's right edge.	LayoutBase
		getScrollRect():Rectangle Returns the bounds of the target's scroll rectangle in layout coordinates.	LayoutBase
		scrollPositionChanged():void Called when the verticalScrollPosition or horizontalScrollPosition properties change.	LayoutBase

Property Detail

columnCount

property

columnCount:int [read-only]

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

Returns the current number of elements in view.

The default value is -1.

This property can be used as the source for data binding. When this property is modified, it dispatches the propertyChange event.

Implementation
public function get columnCount():int

columnWidth

property

columnWidth:Number

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

If the variableColumnWidth property is false, then this property specifies the actual width of each layout element.

If the variableColumnWidth property is true, the default, then this property has no effect.

The default value of this property is the preferred width of the item specified by the typicalLayoutElement property.

Implementation
public function get columnWidth():Number
public function set columnWidth(value:Number):void

firstIndexInView

property

firstIndexInView:int [read-only]

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

The index of the first column that is part of the layout and within the layout target's scroll rectangle, or -1 if nothing has been displayed yet. Note that the column may only be partially in view.

This property can be used as the source for data binding. When this property is modified, it dispatches the propertyChange event.

Implementation
public function get firstIndexInView():int

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HorizontalLayout	Properties \| Methods