ConstraintLayout

Pacchetto	spark.layouts
Classe	public class ConstraintLayout
Ereditarietà	ConstraintLayout LayoutBase OnDemandEventDispatcher Object
Sottoclassi	FormItemLayout

Versione linguaggio:

ActionScript 3.0

Versione prodotto:

Flex 4.5

Versioni runtime:

Flash Player 10, AIR 1.5

The ConstraintLayout class arranges the layout elements based on their individual settings and a set of constraint regions defined by constraint columns and constraint rows. Although you can use all of the properties and constraints from BasicLayout to position and size elements, ConstraintLayout gives you the ability to create sibling-relative layouts by constraining elements to the specified columns and rows.

Note: The Spark list-based controls (the Spark List control and its subclasses such as ButtonBar, ComboBox, DropDownList, and TabBar) do not support the ConstraintLayout class. Do not use ConstraintLayout with the Spark list-based controls.

Per-element supported constraints are left, right, top, bottom, baseline, percentWidth, and percentHeight. Element's minimum and maximum sizes will always be respected.

Columns and rows may have an explicit size or content size (no explicit size). Explicit size regions will be fixed at their specified size, while content size regions will stretch to fit only the elements constrained to them. If multiple content size regions are spanned by an element, the space will be divided equally among the content size regions.

The measured size of the container is calculated from the elements, their constraints, their preferred sizes, and the sizes of the rows and columns. The size of each row and column is just big enough to hold all of the elements constrained to it at their preferred sizes with constraints satisfied. The measured size of the container is big enough to hold all of the columns and rows as well as any other elements left at their preferred sizes with constraints satisfied.

During a call to the updateDisplayList() method, the element's size is determined according to the rules in the following order of precedence (the element's minimum and maximum sizes are always respected):

If the element has percentWidth or percentHeight set, then its size is calculated as a percentage of the available size, where the available size is the region or container size minus any left, right, top, or bottom constraints.
If the element has both left and right constraints, it's width is set to be the region's or container's width minus the left and right constraints.
If the element has both top and bottom constraints, it's height is set to be the container's height minus the top and bottom constraints.
The element is set to its preferred width and/or height.

The element's position is determined according to the rules in the following order of precedence:

If element's baseline is specified, then the element is positioned in the vertical direction such that its baselinePosition (usually the base line of its first line of text) is aligned with baseline constraint.
If element's top or left constraints are specified, then the element is positioned such that the top-left corner of the element's layout bounds is offset from the top-left corner of the container by the specified values.
If element's bottom or right constraints are specified, then the element is positioned such that the bottom-right corner of the element's layout bounds is offset from the bottom-right corner of the container by the specified values.
When no constraints determine the position in the horizontal or vertical direction, the element is positioned according to its x and y coordinates.

The content size of the container is calculated as the maximum of the coordinates of the bottom-right corner of all the layout elements and constraint regions.

Proprietà pubbliche

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	Proprietà		Definito da
		clipAndEnableScrolling : Boolean If true, specifies to clip the children to the boundaries of the viewport.	LayoutBase
		constraintColumns : Vector.<ConstraintColumn> A Vector of ConstraintColumn instances that partition the target container.	ConstraintLayout
		constraintRows : Vector.<ConstraintRow> A Vector of ConstraintRow instances that partition the target container.	ConstraintLayout
		constructor : Object Un riferimento all'oggetto classe o alla funzione di costruzione per una determinata istanza di oggetto.	Object
		dropIndicator : DisplayObject The DisplayObject that this layout uses for the drop indicator during a drag-and-drop operation.	LayoutBase
		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
		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
		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

Metodi pubblici

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	Metodo		Definito da
		ConstraintLayout() Constructor.	ConstraintLayout
		addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event.	OnDemandEventDispatcher
		calculateDropLocation(dragEvent:DragEvent):DropLocation Calculates the drop location in the data provider of the drop target for the specified dragEvent.	LayoutBase
		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 Dispatches an event into the event flow.	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
		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
		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 vertical scroll position to handle different scrolling options.	LayoutBase
		hasEventListener(type:String):Boolean Checks whether the EventDispatcher object has any listeners registered for a specific type of event.	OnDemandEventDispatcher
		hasOwnProperty(name:String):Boolean Indica se per un oggetto è definita una proprietà specifica.	Object
		hideDropIndicator():void Hides the previously shown drop indicator, created by the showDropIndicator() method, removes it from the display list and also stops the drag scrolling.	LayoutBase
		isPrototypeOf(theClass:Object):Boolean Indica se un'istanza della classe Object si trova nella catena di prototipi dell'oggetto specificato come parametro.	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 Indica se la proprietà specificata esiste ed è enumerabile.	Object
		removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void Removes a listener from the EventDispatcher object.	OnDemandEventDispatcher
		setPropertyIsEnumerable(name:String, isEnum:Boolean = true):void Imposta la disponibilità di una proprietà dinamica per le operazioni cicliche.	Object
		showDropIndicator(dropLocation:DropLocation):void Sizes, positions and parents the drop indicator based on the specified drop location.	LayoutBase
		toLocaleString():String Restituisce la rappresentazione in formato stringa di questo oggetto, formattato in base alle convenzioni specifiche per le versioni localizzate.	Object
		toString():String Restituisce la rappresentazione in formato stringa dell'oggetto specificato.	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 Restituisce il valore di base dell'oggetto specificato.	Object
		willTrigger(type:String):Boolean Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type.	OnDemandEventDispatcher

Metodi protetti

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	Metodo		Definito da
		calculateDragScrollDelta(dropLocation:DropLocation, elapsedTime:Number):Point Calculates how much to scroll for the specified dropLocation during a drag and drop gesture.	LayoutBase
		calculateDropIndex(x:Number, y:Number):int Returns the index where a new item should be inserted if the user releases the mouse at the specified coordinates while completing a drag and drop gesture.	LayoutBase
		calculateDropIndicatorBounds(dropLocation:DropLocation):Rectangle Calculates the bounds for the drop indicator that provides visual feedback to the user of where the items will be inserted at the end of a drag and drop gesture.	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
		layoutContent(unscaledWidth:Number, unscaledHeight:Number):void Lays out the elements of the layout target using the current widths and heights of the columns and rows.	ConstraintLayout
		measureAndPositionColumnsAndRows(constrainedWidth:Number = NaN, constrainedHeight:Number = NaN):void Used by FormItemLayout to measure and set new column widths and row heights before laying out the elements.	ConstraintLayout
		scrollPositionChanged():void Called when the verticalScrollPosition or horizontalScrollPosition properties change.	LayoutBase

Descrizione delle proprietà

constraintColumns

proprietà

constraintColumns:Vector.<ConstraintColumn>

Versione linguaggio:

ActionScript 3.0

Versione prodotto:

Flex 4.5

Versioni runtime:

Flash Player 10, AIR 1.5

A Vector of ConstraintColumn instances that partition the target container. The ConstraintColumn instance at index 0 is the left-most column; indices increase from left to right.

Implementazione
public function get constraintColumns():Vector.<ConstraintColumn>
public function set constraintColumns(value:Vector.<ConstraintColumn>):void

constraintRows

proprietà

constraintRows:Vector.<ConstraintRow>

Versione linguaggio:

ActionScript 3.0

Versione prodotto:

Flex 4.5

Versioni runtime:

Flash Player 10, AIR 1.5

A Vector of ConstraintRow instances that partition the target container. The ConstraintRow instance at index 0 is the top-most column; indices increase from top to bottom.

Implementazione
public function get constraintRows():Vector.<ConstraintRow>
public function set constraintRows(value:Vector.<ConstraintRow>):void

Descrizione della funzione di costruzione

()

Funzione di costruzione

public function ConstraintLayout()

Versione linguaggio:

ActionScript 3.0

Versione prodotto:

Flex 4.5

Versioni runtime:

Flash Player 10, AIR 1.5

Constructor.

Descrizione dei metodi

layoutContent

()

metodo

protected function layoutContent(unscaledWidth:Number, unscaledHeight:Number):void

Versione linguaggio:

ActionScript 3.0

Versione prodotto:

Flex 4.5

Versioni runtime:

Flash Player 10, AIR 1.5

Lays out the elements of the layout target using the current widths and heights of the columns and rows. Used by FormItemLayout after setting new column widths to lay elements using those new widths.

Parametri

	`unscaledWidth:Number` — Specifies the width of the component, in pixels, in the component's coordinates, regardless of the value of the `scaleX` property of the component.

	`unscaledHeight:Number` — Specifies the height of the component, in pixels, in the component's coordinates, regardless of the value of the `scaleY` property of the component.

measureAndPositionColumnsAndRows

()

metodo

protected function measureAndPositionColumnsAndRows(constrainedWidth:Number = NaN, constrainedHeight:Number = NaN):void

Versione linguaggio:

ActionScript 3.0

Versione prodotto:

Flex 4.5

Versioni runtime:

Flash Player 10, AIR 1.5

Used by FormItemLayout to measure and set new column widths and row heights before laying out the elements.

Parametri

	`constrainedWidth:Number` (default = `NaN`) — The total width available for columns to stretch or shrink their percent width columns. If NaN, percent width columns are unconstrained and fit to their content.

	`constrainedHeight:Number` (default = `NaN`) — The total height available for rows to stretch or shrink their percent height rows. If NaN, percent height rows are unconstrained and fit to their content.

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ConstraintLayout - AS3 Flex

Classi x

constraintColumns

constraintRows