Placeholder

Artifact: androidx.constraintlayout:constraintlayout-core

Added in 1.1.0

Kotlin |Java

class Placeholder : VirtualLayout

kotlin.Any
↳	androidx.constraintlayout.core.widgets.ConstraintWidget
	↳	androidx.constraintlayout.core.widgets.HelperWidget
		↳	androidx.constraintlayout.core.widgets.VirtualLayout
			↳	androidx.constraintlayout.core.widgets.Placeholder

Simple VirtualLayout that center the first referenced widget onto itself.

Summary

Public constructors
`Placeholder()`

Public functions
`Unit`	`addToSolver(system: LinearSystem!, optimize: Boolean)` Add this widget to the solver
`Unit`	`measure(widthMode: Int, widthSize: Int, heightMode: Int, heightSize: Int)`

Inherited Constants

From androidx.constraintlayout.core.widgets.ConstraintWidget

`const Int`	`ANCHOR_BASELINE = 4`
`const Int`	`ANCHOR_BOTTOM = 3`
`const Int`	`ANCHOR_LEFT = 0`
`const Int`	`ANCHOR_RIGHT = 1`
`const Int`	`ANCHOR_TOP = 2`
`const Int`	`BOTH = 2`
`const Int`	`CHAIN_PACKED = 2`
`const Int`	`CHAIN_SPREAD = 0`
`const Int`	`CHAIN_SPREAD_INSIDE = 1`
`const Int`	`DIRECT = 2`
`const Int`	`GONE = 8`
`const Int`	`HORIZONTAL = 0`
`const Int`	`INVISIBLE = 4`
`const Int`	`MATCH_CONSTRAINT_PERCENT = 2`
`const Int`	`MATCH_CONSTRAINT_RATIO = 3`
`const Int`	`MATCH_CONSTRAINT_RATIO_RESOLVED = 4`
`const Int`	`MATCH_CONSTRAINT_SPREAD = 0`
`const Int`	`MATCH_CONSTRAINT_WRAP = 1`
`const Int`	`SOLVER = 1`
`const Int`	`UNKNOWN = -1`
`const Int`	`VERTICAL = 1`
`const Int`	`VISIBLE = 0`
`const Int`	`WRAP_BEHAVIOR_HORIZONTAL_ONLY = 1`
`const Int`	`WRAP_BEHAVIOR_INCLUDED = 0`
`const Int`	`WRAP_BEHAVIOR_SKIPPED = 3`
`const Int`	`WRAP_BEHAVIOR_VERTICAL_ONLY = 2`

Inherited functions

From androidx.constraintlayout.core.widgets.ConstraintWidget

`Unit`	`addChildrenToSolverByDependency( container: ConstraintWidgetContainer!, system: LinearSystem!, widgets: HashSet<ConstraintWidget!>!, orientation: Int, addSelf: Boolean )`
`Boolean`	`allowedInBarrier()` Returns true if this widget should be used in a barrier
`Unit`	`connect( constraintFrom: ConstraintAnchor.Type!, target: ConstraintWidget!, constraintTo: ConstraintAnchor.Type! )` Connect a given anchor of this widget to another anchor of a target widget
`Unit`	`connect(from: ConstraintAnchor!, to: ConstraintAnchor!, margin: Int)` Connect the given anchors together (the from anchor should be owned by this widget)
`Unit`	`connect( constraintFrom: ConstraintAnchor.Type!, target: ConstraintWidget!, constraintTo: ConstraintAnchor.Type!, margin: Int )` Connect a given anchor of this widget to another anchor of a target widget
`Unit`	`connectCircularConstraint( target: ConstraintWidget!, angle: Float, radius: Int )` Set a circular constraint
`Unit`	`createObjectVariables(system: LinearSystem!)` Create all the system variables for this widget
`Unit`	`ensureMeasureRequested()`
`Unit`	`ensureWidgetRuns()`
`ConstraintAnchor!`	`getAnchor(anchorType: ConstraintAnchor.Type!)` Given a type of anchor, returns the corresponding anchor.
`ArrayList<ConstraintAnchor!>!`	`getAnchors()` Return the array of anchors of this widget
`Int`	`getBaselineDistance()` Return the baseline distance relative to the top of the widget
`Float`	`getBiasPercent(orientation: Int)` Return the percentage bias that is used when two opposite connections exist of the same strength in a particular orientation.
`Int`	`getBottom()` Return the bottom position of the widget
`Any!`	`getCompanionWidget()` Return the companion widget.
`Int`	`getContainerItemSkip()` Accessor for the skip value
`String!`	`getDebugName()` Returns the name of this widget (used for debug purposes)
`ConstraintWidget.DimensionBehaviour!`	`getDimensionBehaviour(orientation: Int)` Get the widget's `DimensionBehaviour` in an specific orientation.
`Float`	`getDimensionRatio()` Return the current ratio of this widget
`Int`	`getDimensionRatioSide()` Return the current side on which ratio will be applied
`Boolean`	`getHasBaseline()`
`Int`	`getHeight()` Return the height of the widget
`Float`	`getHorizontalBiasPercent()` Return the horizontal percentage bias that is used when two opposite connections exist of the same strength.
`ConstraintWidget!`	`getHorizontalChainControlWidget()` if in a horizontal chain return the left most widget in the chain.
`Int`	`getHorizontalChainStyle()` get the chain starting from this widget to be packed.
`ConstraintWidget.DimensionBehaviour!`	`getHorizontalDimensionBehaviour()` Accessor for the horizontal dimension behaviour
`Int`	`getHorizontalMargin()` Returns all the horizontal margin of the widget.
`Int`	`getLastHorizontalMeasureSpec()`
`Int`	`getLastVerticalMeasureSpec()`
`Int`	`getLeft()` Return the left position of the widget (similar to `getX`)
`Int`	`getLength(orientation: Int)` Get a dimension of the widget in a particular orientation.
`Int`	`getMaxHeight()`
`Int`	`getMaxWidth()`
`Int`	`getMinHeight()` Return the minimum height of the widget
`Int`	`getMinWidth()` Return the minimum width of the widget
`ConstraintWidget!`	`getNextChainMember(orientation: Int)` Return the next chain member if one exists
`Int`	`getOptimizerWrapHeight()`
`Int`	`getOptimizerWrapWidth()`
`ConstraintWidget!`	`getParent()` Returns the parent of this widget if there is one
`ConstraintWidget!`	`getPreviousChainMember(orientation: Int)` Return the previous chain member if one exists
`Int`	`getRight()` Return the right position of the widget
`Int`	`getRootX()` Return the x position of the widget, relative to the root (without animation)
`Int`	`getRootY()` Return the y position of the widget, relative to the root (without animation)
`WidgetRun!`	`getRun(orientation: Int)`
`Unit`	`getSceneString(ret: StringBuilder!)`
`Int`	`getTop()` Return the top position of the widget (similar to `getY`)
`String!`	`getType()` Returns the type string if set
`Float`	`getVerticalBiasPercent()` Return the vertical percentage bias that is used when two opposite connections exist of the same strength.
`ConstraintWidget!`	`getVerticalChainControlWidget()` if in a vertical chain return the top most widget in the chain.
`Int`	`getVerticalChainStyle()` Set the chain starting from this widget to be packed.
`ConstraintWidget.DimensionBehaviour!`	`getVerticalDimensionBehaviour()` Accessor for the vertical dimension behaviour
`Int`	`getVerticalMargin()` Returns all the vertical margin of the widget
`Int`	`getVisibility()` Returns the current visibility value for this widget
`Int`	`getWidth()` Return the width of the widget
`Int`	`getWrapBehaviorInParent()`
`Int`	`getX()` Return the x position of the widget, relative to its container
`Int`	`getY()` Return the y position of the widget, relative to its container
`Boolean`	`hasBaseline()` Return true if this widget has a baseline
`Boolean`	`hasDanglingDimension(orientation: Int)`
`Boolean`	`hasDependencies()`
`Boolean`	`hasDimensionOverride()`
`Boolean`	`hasResolvedTargets(orientation: Int, size: Int)`
`Unit`	`immediateConnect( startType: ConstraintAnchor.Type!, target: ConstraintWidget!, endType: ConstraintAnchor.Type!, margin: Int, goneMargin: Int )` Immediate connection to an anchor without any checks.
`Boolean`	`isAnimated()` Returns if this widget is animated.
`Boolean`	`isHeightWrapContent()` Returns true if height is set to wrap_content
`Boolean`	`isHorizontalSolvingPassDone()`
`Boolean`	`isInBarrier(orientation: Int)`
`Boolean`	`isInHorizontalChain()` Test if you are in a Horizontal chain
`Boolean`	`isInPlaceholder()`
`Boolean`	`isInVerticalChain()` Test if you are in a vertical chain
`Boolean`	`isInVirtualLayout()`
`Boolean`	`isMeasureRequested()`
`Boolean`	`isResolvedHorizontally()`
`Boolean`	`isResolvedVertically()`
`Boolean`	`isRoot()` Returns true if the widget is the root widget
`Boolean`	`isSpreadHeight()`
`Boolean`	`isSpreadWidth()`
`Boolean`	`isVerticalSolvingPassDone()`
`Boolean`	`isWidthWrapContent()` Returns true if width is set to wrap_content
`Unit`	`markHorizontalSolvingPassDone()`
`Unit`	`markVerticalSolvingPassDone()`
`Boolean`	`oppositeDimensionDependsOn(orientation: Int)`
`Boolean`	`oppositeDimensionsTied()`
`Unit`	`reset()`
`Unit`	`resetAllConstraints()` Reset all the constraints set on this widget
`Unit`	`resetAnchor(anchor: ConstraintAnchor!)` Reset the given anchor
`Unit`	`resetAnchors()` Reset all connections
`Unit`	`resetFinalResolution()`
`Unit`	`resetSolverVariables(cache: Cache!)` Reset the solver variables of the anchors
`Unit`	`resetSolvingPassFlag()`
`StringBuilder!`	`serialize(ret: StringBuilder!)` Serialize the anchors for JSON5 output
`Unit`	`setAnimated(animated: Boolean)` Set if this widget is animated.
`Unit`	`setBaselineDistance(baseline: Int)` Set the baseline distance relative to the top of the widget
`Unit`	`setCompanionWidget(companion: Any!)` Set the companion widget.
`Unit`	`setContainerItemSkip(skip: Int)` Set the skip value for this widget.
`Unit`	`setDebugName(name: String!)` Set the debug name of this widget
`Unit`	`setDebugSolverName(system: LinearSystem!, name: String!)` Utility debug function.
`Unit`	`setDimension(w: Int, h: Int)` Set both width and height of the widget
`Unit`	`setDimensionRatio(ratio: String!)` Set the ratio of the widget
`Unit`	`setDimensionRatio(ratio: Float, dimensionRatioSide: Int)` Set the ratio of the widget The ratio will be applied if at least one of the dimension (width or height) is set to a behaviour of DimensionBehaviour.MATCH_CONSTRAINT -- the dimension's value will be set to the other dimension * ratio.
`Unit`	`setFinalBaseline(baselineValue: Int)`
`Unit`	`setFinalFrame( left: Int, top: Int, right: Int, bottom: Int, baseline: Int, orientation: Int )`
`Unit`	`setFinalHorizontal(x1: Int, x2: Int)`
`Unit`	`setFinalLeft(x1: Int)`
`Unit`	`setFinalTop(y1: Int)`
`Unit`	`setFinalVertical(y1: Int, y2: Int)`
`Unit`	`setFrame(start: Int, end: Int, orientation: Int)` Set the position+dimension of the widget based on starting/ending positions on one dimension.
`Unit`	`setFrame(left: Int, top: Int, right: Int, bottom: Int)` Set the position+dimension of the widget given left/top/right/bottom
`Unit`	`setGoneMargin(type: ConstraintAnchor.Type!, goneMargin: Int)` Set the margin to be used when connected to a widget with a visibility of GONE
`Unit`	`setHasBaseline(hasBaseline: Boolean)`
`Unit`	`setHeight(h: Int)` Set the height of the widget
`Unit`	`setHeightWrapContent(heightWrapContent: Boolean)` Keep track of wrap_content for height
`Unit`	`setHorizontalBiasPercent(horizontalBiasPercent: Float)` Set the horizontal bias percent to apply when we have two opposite constraints of equal strength
`Unit`	`setHorizontalChainStyle(horizontalChainStyle: Int)` Set the chain starting from this widget to be packed.
`Unit`	`setHorizontalDimension(left: Int, right: Int)` Set the positions for the horizontal dimension only
`Unit`	`setHorizontalDimensionBehaviour( behaviour: ConstraintWidget.DimensionBehaviour! )` Set the widget's behaviour for the horizontal dimension
`Unit`	`setHorizontalMatchStyle( horizontalMatchStyle: Int, min: Int, max: Int, percent: Float )` Set the horizontal style when MATCH_CONSTRAINT is set
`Unit`	`setHorizontalWeight(horizontalWeight: Float)` Set the horizontal weight (only used in chains)
`Unit`	`setInBarrier(orientation: Int, value: Boolean)`
`Unit`	`setInPlaceholder(inPlaceholder: Boolean)`
`Unit`	`setInVirtualLayout(inVirtualLayout: Boolean)`
`Unit`	`setLastMeasureSpec(horizontal: Int, vertical: Int)`
`Unit`	`setLength(length: Int, orientation: Int)` Set the dimension of a widget in a particular orientation.
`Unit`	`setMaxHeight(maxHeight: Int)`
`Unit`	`setMaxWidth(maxWidth: Int)`
`Unit`	`setMeasureRequested(measureRequested: Boolean)`
`Unit`	`setMinHeight(h: Int)` Set the minimum height of the widget
`Unit`	`setMinWidth(w: Int)` Set the minimum width of the widget
`Unit`	`setOffset(x: Int, y: Int)` Set the offset of this widget relative to the root widget
`Unit`	`setOrigin(x: Int, y: Int)` Set both the origin in (x, y) of the widget, relative to its container
`Unit`	`setParent(widget: ConstraintWidget!)` Set the parent of this widget
`Unit`	`setType(type: String!)` Set the type of the widget (as a String)
`Unit`	`setVerticalBiasPercent(verticalBiasPercent: Float)` Set the vertical bias percent to apply when we have two opposite constraints of equal strength
`Unit`	`setVerticalChainStyle(verticalChainStyle: Int)` Set the chain starting from this widget to be packed.
`Unit`	`setVerticalDimension(top: Int, bottom: Int)` Set the positions for the vertical dimension only
`Unit`	`setVerticalDimensionBehaviour( behaviour: ConstraintWidget.DimensionBehaviour! )` Set the widget's behaviour for the vertical dimension
`Unit`	`setVerticalMatchStyle( verticalMatchStyle: Int, min: Int, max: Int, percent: Float )` Set the vertical style when MATCH_CONSTRAINT is set
`Unit`	`setVerticalWeight(verticalWeight: Float)` Set the vertical weight (only used in chains)
`Unit`	`setVisibility(visibility: Int)` Set the visibility for this widget
`Unit`	`setWidth(w: Int)` Set the width of the widget
`Unit`	`setWidthWrapContent(widthWrapContent: Boolean)` Keep track of wrap_content for width
`Unit`	`setWrapBehaviorInParent(behavior: Int)`
`Unit`	`setX(x: Int)` Set the x position of the widget, relative to its container
`Unit`	`setY(y: Int)` Set the y position of the widget, relative to its container
`Unit`	`setupDimensionRatio( hParentWrapContent: Boolean, vParentWrapContent: Boolean, horizontalDimensionFixed: Boolean, verticalDimensionFixed: Boolean )` Resolves the dimension ratio parameters (mResolvedDimensionRatioSide &mDimensionRatio)
`String!`	`toString()` Returns a string representation of the ConstraintWidget
`Unit`	`updateFromRuns(updateHorizontal: Boolean, updateVertical: Boolean)`
`Unit`	`updateFromSolver(system: LinearSystem!, optimize: Boolean)` Update the widget from the values generated by the solver

From androidx.constraintlayout.core.widgets.HelperWidget

`Unit`	`add(widget: ConstraintWidget!)` Add a widget to the helper
`Unit`	`addDependents( dependencyLists: ArrayList<WidgetGroup!>!, orientation: Int, group: WidgetGroup! )`
`Unit`	`copy( src: ConstraintWidget!, map: HashMap<ConstraintWidget!, ConstraintWidget!>! )`
`Int`	`findGroupInDependents(orientation: Int)`
`Unit`	`removeAllIds()` Reset the widgets list contained by this helper

From androidx.constraintlayout.core.widgets.VirtualLayout

`Unit`	`applyRtl(isRtl: Boolean)`
`Unit`	`captureWidgets()`
`Boolean`	`contains(widgets: HashSet<ConstraintWidget!>!)`
`Int`	`getMeasuredHeight()`
`Int`	`getMeasuredWidth()`
`Int`	`getPaddingBottom()`
`Int`	`getPaddingLeft()`
`Int`	`getPaddingRight()`
`Int`	`getPaddingTop()`
`Unit`	`measure( widget: ConstraintWidget!, horizontalBehavior: ConstraintWidget.DimensionBehaviour!, horizontalDimension: Int, verticalBehavior: ConstraintWidget.DimensionBehaviour!, verticalDimension: Int )`
`Boolean`	`measureChildren()`
`Boolean`	`needSolverPass()`
`Unit`	`needsCallbackFromSolver(value: Boolean)`
`Unit`	`setMeasure(width: Int, height: Int)`
`Unit`	`setPadding(value: Int)`
`Unit`	`setPaddingBottom(value: Int)`
`Unit`	`setPaddingEnd(value: Int)`
`Unit`	`setPaddingLeft(value: Int)`
`Unit`	`setPaddingRight(value: Int)`
`Unit`	`setPaddingStart(value: Int)`
`Unit`	`setPaddingTop(value: Int)`
`Unit`	`updateConstraints(container: ConstraintWidgetContainer!)`

Inherited properties

From androidx.constraintlayout.core.widgets.ConstraintWidget

`java-static Float`	`DEFAULT_BIAS`
`WidgetFrame!`	`frame`
`ChainRun!`	`horizontalChainRun`
`Int`	`horizontalGroup`
`BooleanArray<Boolean>!`	`isTerminalWidget`
`ArrayList<ConstraintAnchor!>!`	`mAnchors`
`ConstraintAnchor!`	`mBaseline`
`ConstraintAnchor!`	`mBottom`
`ConstraintAnchor!`	`mCenter`
`Float`	`mCircleConstraintAngle`
`Float`	`mDimensionRatio`
`Int`	`mDimensionRatioSide`
`Int`	`mHorizontalResolution`
`HorizontalWidgetRun!`	`mHorizontalRun`
`Boolean`	`mIsHeightWrapContent`
`Boolean`	`mIsWidthWrapContent`
`ConstraintAnchor!`	`mLeft`
`Array<ConstraintAnchor!>!`	`mListAnchors`
`Array<ConstraintWidget.DimensionBehaviour!>!`	`mListDimensionBehaviors`
`Array<ConstraintWidget!>!`	`mListNextMatchConstraintsWidget`
`Int`	`mMatchConstraintDefaultHeight`
`Int`	`mMatchConstraintDefaultWidth`
`Int`	`mMatchConstraintMaxHeight`
`Int`	`mMatchConstraintMaxWidth`
`Int`	`mMatchConstraintMinHeight`
`Int`	`mMatchConstraintMinWidth`
`Float`	`mMatchConstraintPercentHeight`
`Float`	`mMatchConstraintPercentWidth`
`Int`	`mMinHeight`
`Int`	`mMinWidth`
`Array<ConstraintWidget!>!`	`mNextChainWidget`
`Int`	`mOffsetX`
`Int`	`mOffsetY`
`ConstraintWidget!`	`mParent`
`IntArray<Int>!`	`mResolvedMatchConstraintDefault`
`ConstraintAnchor!`	`mRight`
`ConstraintAnchor!`	`mTop`
`Int`	`mVerticalResolution`
`VerticalWidgetRun!`	`mVerticalRun`
`FloatArray<Float>!`	`mWeight`
`Int`	`mX`
`Int`	`mY`
`Boolean`	`measured`
`Array<WidgetRun!>!`	`run`
`String!`	`stringId`
`ChainRun!`	`verticalChainRun`
`Int`	`verticalGroup`

From androidx.constraintlayout.core.widgets.HelperWidget

`Array<ConstraintWidget!>!`	`mWidgets`
`Int`	`mWidgetsCount`

From androidx.constraintlayout.core.widgets.VirtualLayout

BasicMeasure.Measure!

mMeasure

Public constructors

Placeholder

Added in 1.1.0

Placeholder()

Public functions

addToSolver

fun addToSolver(system: LinearSystem!, optimize: Boolean): Unit

Add this widget to the solver

Parameters
`system: LinearSystem!`	the solver we want to add the widget to
`optimize: Boolean`	true if `OPTIMIZATION_GRAPH` is on

measure

fun measure(widthMode: Int, widthSize: Int, heightMode: Int, heightSize: Int): Unit