Placeholder

Artifact: androidx.constraintlayout:constraintlayout-core

Added in 1.1.0

Kotlin |Java

public class Placeholder extends VirtualLayout

java.lang.Object
↳	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 methods
`void`	`addToSolver(LinearSystem system, boolean optimize)` Add this widget to the solver
`void`	`measure(int widthMode, int widthSize, int heightMode, int heightSize)`

Inherited Constants

From androidx.constraintlayout.core.widgets.ConstraintWidget

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

Inherited fields

From androidx.constraintlayout.core.widgets.ConstraintWidget

`static float`	`DEFAULT_BIAS`
`WidgetFrame`	`frame`
`ChainRun`	`horizontalChainRun`
`int`	`horizontalGroup`
`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`
`ConstraintAnchor[]`	`mListAnchors`
`ConstraintWidget.DimensionBehaviour[]`	`mListDimensionBehaviors`
`ConstraintWidget[]`	`mListNextMatchConstraintsWidget`
`int`	`mMatchConstraintDefaultHeight`
`int`	`mMatchConstraintDefaultWidth`
`int`	`mMatchConstraintMaxHeight`
`int`	`mMatchConstraintMaxWidth`
`int`	`mMatchConstraintMinHeight`
`int`	`mMatchConstraintMinWidth`
`float`	`mMatchConstraintPercentHeight`
`float`	`mMatchConstraintPercentWidth`
`int`	`mMinHeight`
`int`	`mMinWidth`
`ConstraintWidget[]`	`mNextChainWidget`
`int`	`mOffsetX`
`int`	`mOffsetY`
`ConstraintWidget`	`mParent`
`int[]`	`mResolvedMatchConstraintDefault`
`ConstraintAnchor`	`mRight`
`ConstraintAnchor`	`mTop`
`int`	`mVerticalResolution`
`VerticalWidgetRun`	`mVerticalRun`
`float[]`	`mWeight`
`int`	`mX`
`int`	`mY`
`boolean`	`measured`
`WidgetRun[]`	`run`
`String`	`stringId`
`ChainRun`	`verticalChainRun`
`int`	`verticalGroup`

From androidx.constraintlayout.core.widgets.HelperWidget

`ConstraintWidget[]`	`mWidgets`
`int`	`mWidgetsCount`

From androidx.constraintlayout.core.widgets.VirtualLayout

BasicMeasure.Measure

mMeasure

Inherited methods

From androidx.constraintlayout.core.widgets.ConstraintWidget

`void`	`addChildrenToSolverByDependency( ConstraintWidgetContainer container, LinearSystem system, HashSet<ConstraintWidget> widgets, int orientation, boolean addSelf )`
`boolean`	`allowedInBarrier()` Returns true if this widget should be used in a barrier
`void`	`connect( ConstraintAnchor.Type constraintFrom, ConstraintWidget target, ConstraintAnchor.Type constraintTo )` Connect a given anchor of this widget to another anchor of a target widget
`void`	`connect(ConstraintAnchor from, ConstraintAnchor to, int margin)` Connect the given anchors together (the from anchor should be owned by this widget)
`void`	`connect( ConstraintAnchor.Type constraintFrom, ConstraintWidget target, ConstraintAnchor.Type constraintTo, int margin )` Connect a given anchor of this widget to another anchor of a target widget
`void`	`connectCircularConstraint( ConstraintWidget target, float angle, int radius )` Set a circular constraint
`void`	`createObjectVariables(LinearSystem system)` Create all the system variables for this widget
`void`	`ensureMeasureRequested()`
`void`	`ensureWidgetRuns()`
`ConstraintAnchor`	`getAnchor(ConstraintAnchor.Type anchorType)` 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(int orientation)` 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
`Object`	`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(int orientation)` 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(int orientation)` 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(int orientation)` 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(int orientation)` 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(int orientation)`
`void`	`getSceneString(StringBuilder ret)`
`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(int orientation)`
`boolean`	`hasDependencies()`
`boolean`	`hasDimensionOverride()`
`boolean`	`hasResolvedTargets(int orientation, int size)`
`void`	`immediateConnect( ConstraintAnchor.Type startType, ConstraintWidget target, ConstraintAnchor.Type endType, int margin, int goneMargin )` 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(int orientation)`
`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
`void`	`markHorizontalSolvingPassDone()`
`void`	`markVerticalSolvingPassDone()`
`boolean`	`oppositeDimensionDependsOn(int orientation)`
`boolean`	`oppositeDimensionsTied()`
`void`	`reset()`
`void`	`resetAllConstraints()` Reset all the constraints set on this widget
`void`	`resetAnchor(ConstraintAnchor anchor)` Reset the given anchor
`void`	`resetAnchors()` Reset all connections
`void`	`resetFinalResolution()`
`void`	`resetSolverVariables(Cache cache)` Reset the solver variables of the anchors
`void`	`resetSolvingPassFlag()`
`StringBuilder`	`serialize(StringBuilder ret)` Serialize the anchors for JSON5 output
`void`	`setAnimated(boolean animated)` Set if this widget is animated.
`void`	`setBaselineDistance(int baseline)` Set the baseline distance relative to the top of the widget
`void`	`setCompanionWidget(Object companion)` Set the companion widget.
`void`	`setContainerItemSkip(int skip)` Set the skip value for this widget.
`void`	`setDebugName(String name)` Set the debug name of this widget
`void`	`setDebugSolverName(LinearSystem system, String name)` Utility debug function.
`void`	`setDimension(int w, int h)` Set both width and height of the widget
`void`	`setDimensionRatio(String ratio)` Set the ratio of the widget
`void`	`setDimensionRatio(float ratio, int dimensionRatioSide)` 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.
`void`	`setFinalBaseline(int baselineValue)`
`void`	`setFinalFrame( int left, int top, int right, int bottom, int baseline, int orientation )`
`void`	`setFinalHorizontal(int x1, int x2)`
`void`	`setFinalLeft(int x1)`
`void`	`setFinalTop(int y1)`
`void`	`setFinalVertical(int y1, int y2)`
`void`	`setFrame(int start, int end, int orientation)` Set the position+dimension of the widget based on starting/ending positions on one dimension.
`void`	`setFrame(int left, int top, int right, int bottom)` Set the position+dimension of the widget given left/top/right/bottom
`void`	`setGoneMargin(ConstraintAnchor.Type type, int goneMargin)` Set the margin to be used when connected to a widget with a visibility of GONE
`void`	`setHasBaseline(boolean hasBaseline)`
`void`	`setHeight(int h)` Set the height of the widget
`void`	`setHeightWrapContent(boolean heightWrapContent)` Keep track of wrap_content for height
`void`	`setHorizontalBiasPercent(float horizontalBiasPercent)` Set the horizontal bias percent to apply when we have two opposite constraints of equal strength
`void`	`setHorizontalChainStyle(int horizontalChainStyle)` Set the chain starting from this widget to be packed.
`void`	`setHorizontalDimension(int left, int right)` Set the positions for the horizontal dimension only
`void`	`setHorizontalDimensionBehaviour( ConstraintWidget.DimensionBehaviour behaviour )` Set the widget's behaviour for the horizontal dimension
`void`	`setHorizontalMatchStyle( int horizontalMatchStyle, int min, int max, float percent )` Set the horizontal style when MATCH_CONSTRAINT is set
`void`	`setHorizontalWeight(float horizontalWeight)` Set the horizontal weight (only used in chains)
`void`	`setInBarrier(int orientation, boolean value)`
`void`	`setInPlaceholder(boolean inPlaceholder)`
`void`	`setInVirtualLayout(boolean inVirtualLayout)`
`void`	`setLastMeasureSpec(int horizontal, int vertical)`
`void`	`setLength(int length, int orientation)` Set the dimension of a widget in a particular orientation.
`void`	`setMaxHeight(int maxHeight)`
`void`	`setMaxWidth(int maxWidth)`
`void`	`setMeasureRequested(boolean measureRequested)`
`void`	`setMinHeight(int h)` Set the minimum height of the widget
`void`	`setMinWidth(int w)` Set the minimum width of the widget
`void`	`setOffset(int x, int y)` Set the offset of this widget relative to the root widget
`void`	`setOrigin(int x, int y)` Set both the origin in (x, y) of the widget, relative to its container
`void`	`setParent(ConstraintWidget widget)` Set the parent of this widget
`void`	`setType(String type)` Set the type of the widget (as a String)
`void`	`setVerticalBiasPercent(float verticalBiasPercent)` Set the vertical bias percent to apply when we have two opposite constraints of equal strength
`void`	`setVerticalChainStyle(int verticalChainStyle)` Set the chain starting from this widget to be packed.
`void`	`setVerticalDimension(int top, int bottom)` Set the positions for the vertical dimension only
`void`	`setVerticalDimensionBehaviour( ConstraintWidget.DimensionBehaviour behaviour )` Set the widget's behaviour for the vertical dimension
`void`	`setVerticalMatchStyle( int verticalMatchStyle, int min, int max, float percent )` Set the vertical style when MATCH_CONSTRAINT is set
`void`	`setVerticalWeight(float verticalWeight)` Set the vertical weight (only used in chains)
`void`	`setVisibility(int visibility)` Set the visibility for this widget
`void`	`setWidth(int w)` Set the width of the widget
`void`	`setWidthWrapContent(boolean widthWrapContent)` Keep track of wrap_content for width
`void`	`setWrapBehaviorInParent(int behavior)`
`void`	`setX(int x)` Set the x position of the widget, relative to its container
`void`	`setY(int y)` Set the y position of the widget, relative to its container
`void`	`setupDimensionRatio( boolean hParentWrapContent, boolean vParentWrapContent, boolean horizontalDimensionFixed, boolean verticalDimensionFixed )` Resolves the dimension ratio parameters (mResolvedDimensionRatioSide &mDimensionRatio)
`String`	`toString()` Returns a string representation of the ConstraintWidget
`void`	`updateFromRuns(boolean updateHorizontal, boolean updateVertical)`
`void`	`updateFromSolver(LinearSystem system, boolean optimize)` Update the widget from the values generated by the solver

From androidx.constraintlayout.core.widgets.HelperWidget

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

From androidx.constraintlayout.core.widgets.VirtualLayout

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

Public constructors

Placeholder

Added in 1.1.0

public Placeholder()

Public methods

addToSolver

public void addToSolver(LinearSystem system, boolean optimize)

Add this widget to the solver

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

measure

public void measure(int widthMode, int widthSize, int heightMode, int heightSize)