Constraints

Kotlin |Java

@Immutable data class Constraints

kotlin.Any
↳	androidx.ui.core.Constraints

Immutable constraints used for measuring child Layouts. A parent Layout can measure their children using the measure method on the corresponding Measurables, method which takes the Constraints the child has to follow. A measured child is then responsible to choose for themselves and return a size which satisfies the received set of Constraints:

• minWidth <= chosenWidth <= maxWidth
• minHeight <= chosenHeight <= maxHeight The parent can then access the child chosen size on the resulting Placeable. The parent is responsible of defining a valid positioning of the children according to their sizes, so the parent needs to measure the children with appropriate Constraints, such that whatever valid sizes children choose, they can be laid out in a way that also respects the parent's incoming Constraints. Note that different children can be measured with different Constraints. A set of Constraints can have infinite maxWidth and/or maxHeight. This is a trick often used by parents to ask their children for their preferred size: unbounded constraints force children whose default behavior is to fill the available space (always size to maxWidth/maxHeight) to have an opinion about their preferred size. Most commonly, when measured with unbounded Constraints, these children will fallback to size themselves to wrap their content, instead of expanding to fill the available space (this is not always true as it depends on the child layout model, but is a common behavior for core layout components).

Summary

Public constructors
<init>(minWidth: IntPx = IntPx.Zero, maxWidth: IntPx = IntPx.Infinity, minHeight: IntPx = IntPx.Zero, maxHeight: IntPx = IntPx.Infinity) Immutable constraints used for measuring child Layouts.

Companion functions
Constraints	tightConstraints(width: IntPx, height: IntPx) Creates constraints tight in both dimensions.
Constraints	tightConstraintsForHeight(height: IntPx) Creates constraints with tight height and loose width.
Constraints	tightConstraintsForWidth(width: IntPx) Creates constraints with tight width and loose height.

Extension functions

From androidx.ui.core IntPxSize Constraints.constrain(size: IntPxSize) Takes a size and returns the closest size to it that satisfies the constraints. Constraints Constraints.enforce(otherConstraints: Constraints) Returns the result of coercing the current constraints in a different set of constraints. Constraints Constraints.looseMax() Returns a copy of the current instance with no max constraints. Constraints Constraints.looseMin() Returns a copy of the current instance with no min constraints. Constraints Constraints.offset(horizontal: IntPx = 0.ipx, vertical: IntPx = 0.ipx) Returns the Constraints obtained by offsetting the current instance with the given values. Boolean Constraints.satisfiedBy(size: IntPxSize) Takes a size and returns whether it satisfies the current constraints. Constraints Constraints.tightMax() Returns a copy of the current instance with the constraints tightened to their largest size. Constraints Constraints.tightMin() Returns a copy of the current instance with the constraints tightened to their smallest size. Constraints Constraints.withTight(width: IntPx? = null, height: IntPx? = null) Returns a copy of the current instance, overriding the specified values to be tight.

Properties
IntPx	maxHeight
IntPx	maxWidth
IntPx	minHeight
IntPx	minWidth

Extension properties

From androidx.ui.core Boolean hasBoundedHeight Whether or not the upper bound on the maximum height. Boolean hasBoundedWidth Whether or not the upper bound on the maximum width. Boolean hasTightHeight Whether there is exactly one height value that satisfies the constraints. Boolean hasTightWidth Whether there is exactly one width value that satisfies the constraints. Boolean isTight Whether there is exactly one size that satisfies the constraints. Boolean isZero Whether there is exactly one height value that satisfies the constraints.

Public constructors

<init>

Constraints(
    minWidth: IntPx = IntPx.Zero, 
    maxWidth: IntPx = IntPx.Infinity, 
    minHeight: IntPx = IntPx.Zero, 
    maxHeight: IntPx = IntPx.Infinity)

Immutable constraints used for measuring child Layouts. A parent Layout can measure their children using the measure method on the corresponding Measurables, method which takes the Constraints the child has to follow. A measured child is then responsible to choose for themselves and return a size which satisfies the received set of Constraints:

• minWidth <= chosenWidth <= maxWidth
• minHeight <= chosenHeight <= maxHeight The parent can then access the child chosen size on the resulting Placeable. The parent is responsible of defining a valid positioning of the children according to their sizes, so the parent needs to measure the children with appropriate Constraints, such that whatever valid sizes children choose, they can be laid out in a way that also respects the parent's incoming Constraints. Note that different children can be measured with different Constraints. A set of Constraints can have infinite maxWidth and/or maxHeight. This is a trick often used by parents to ask their children for their preferred size: unbounded constraints force children whose default behavior is to fill the available space (always size to maxWidth/maxHeight) to have an opinion about their preferred size. Most commonly, when measured with unbounded Constraints, these children will fallback to size themselves to wrap their content, instead of expanding to fill the available space (this is not always true as it depends on the child layout model, but is a common behavior for core layout components).

Properties

maxHeight

val maxHeight: IntPx

maxWidth

val maxWidth: IntPx

minHeight

val minHeight: IntPx

minWidth

val minWidth: IntPx

Companion functions

tightConstraints

fun tightConstraints(
    width: IntPx, 
    height: IntPx
): Constraints

Creates constraints tight in both dimensions.

tightConstraintsForHeight

fun tightConstraintsForHeight(height: IntPx): Constraints

Creates constraints with tight height and loose width.

tightConstraintsForWidth

fun tightConstraintsForWidth(width: IntPx): Constraints

Creates constraints with tight width and loose height.