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Extensions for the Kotlin standard library and third-party libraries.
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/*
* Copyright (C) 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.constraintlayout.compose
import androidx.compose.foundation.layout.LayoutScopeMarker
import androidx.compose.runtime.Stable
import androidx.compose.ui.graphics.TransformOrigin
import androidx.compose.ui.layout.FirstBaseline
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.LayoutDirection
import androidx.compose.ui.unit.dp
import androidx.constraintlayout.compose.AnchorFunctions.baselineAnchorFunction
import androidx.constraintlayout.core.state.ConstraintReference
/**
* Scope that can be used to constrain a layout.
*
* Used within `Modifier.constrainAs` from the inline DSL API. And within `constrain` from the
* ConstraintSet-based API.
*/
@LayoutScopeMarker
@Stable
class ConstrainScope internal constructor(internal val id: Any) {
internal val tasks = mutableListOf<(State) -> Unit>()
internal fun applyTo(state: State) = tasks.forEach { it(state) }
/**
* Reference to the [ConstraintLayout] itself, which can be used to specify constraints
* between itself and its children.
*/
val parent = ConstrainedLayoutReference(SolverState.PARENT)
/**
* The start anchor of the layout - can be constrained using [VerticalAnchorable.linkTo].
*/
val start: VerticalAnchorable = ConstraintVerticalAnchorable(id, -2, tasks)
/**
* The left anchor of the layout - can be constrained using [VerticalAnchorable.linkTo].
*/
val absoluteLeft: VerticalAnchorable = ConstraintVerticalAnchorable(id, 0, tasks)
/**
* The top anchor of the layout - can be constrained using [HorizontalAnchorable.linkTo].
*/
val top: HorizontalAnchorable = ConstraintHorizontalAnchorable(id, 0, tasks)
/**
* The end anchor of the layout - can be constrained using [VerticalAnchorable.linkTo].
*/
val end: VerticalAnchorable = ConstraintVerticalAnchorable(id, -1, tasks)
/**
* The right anchor of the layout - can be constrained using [VerticalAnchorable.linkTo].
*/
val absoluteRight: VerticalAnchorable = ConstraintVerticalAnchorable(id, 1, tasks)
/**
* The bottom anchor of the layout - can be constrained using [HorizontalAnchorable.linkTo].
*/
val bottom: HorizontalAnchorable = ConstraintHorizontalAnchorable(id, 1, tasks)
/**
* The [FirstBaseline] of the layout - can be constrained using [BaselineAnchorable.linkTo].
*/
val baseline: BaselineAnchorable = ConstraintBaselineAnchorable(id, tasks)
/**
* The width of the [ConstraintLayout] child.
*/
var width: Dimension = Dimension.wrapContent
set(value) {
field = value
tasks.add { state ->
state.constraints(id)?.width(
(value as DimensionDescription).toSolverDimension(state)
)
}
}
/**
* The height of the [ConstraintLayout] child.
*/
var height: Dimension = Dimension.wrapContent
set(value) {
field = value
tasks.add { state ->
state.constraints(id)?.height(
(value as DimensionDescription).toSolverDimension(state)
)
}
}
/**
* The overall visibility of the [ConstraintLayout] child.
*
* [Visibility.Visible] by default.
*/
var visibility: Visibility = Visibility.Visible
set(value) {
field = value
tasks.add { state ->
with(state.constraints(id)) {
this?.visibility(value.solverValue)
if (value == Visibility.Invisible) {
// A bit of a hack, this behavior is not defined in :core
// Invisible should override alpha
this?.alpha(0f)
}
}
}
}
/**
* The transparency value when rendering the content.
*/
var alpha: Float = 1.0f
set(value) {
field = value
addTransform {
if (visibility != Visibility.Invisible) {
// A bit of a hack, this behavior is not defined in :core
// Invisible should override alpha
alpha(value)
}
}
}
/**
* The percent scaling value on the horizontal axis. Where 1 is 100%.
*/
var scaleX: Float = 1.0f
set(value) {
field = value
addTransform { scaleX(value) }
}
/**
* The percent scaling value on the vertical axis. Where 1 is 100%.
*/
var scaleY: Float = 1.0f
set(value) {
field = value
addTransform { scaleY(value) }
}
/**
* The degrees to rotate the content over the horizontal axis.
*/
var rotationX: Float = 0.0f
set(value) {
field = value
addTransform { rotationX(value) }
}
/**
* The degrees to rotate the content over the vertical axis.
*/
var rotationY: Float = 0.0f
set(value) {
field = value
addTransform { rotationY(value) }
}
/**
* The degrees to rotate the content on the screen plane.
*/
var rotationZ: Float = 0.0f
set(value) {
field = value
addTransform { rotationZ(value) }
}
/**
* The distance to offset the content over the X axis.
*/
var translationX: Dp = 0.dp
set(value) {
field = value
addFloatTransformFromDp(value) { floatValue -> translationX(floatValue) }
}
/**
* The distance to offset the content over the Y axis.
*/
var translationY: Dp = 0.dp
set(value) {
field = value
addFloatTransformFromDp(value) { floatValue -> translationY(floatValue) }
}
/**
* The distance to offset the content over the Z axis.
*/
var translationZ: Dp = 0.dp
set(value) {
field = value
addFloatTransformFromDp(value) { floatValue -> translationZ(floatValue) }
}
/**
* The X axis offset percent where the content is rotated and scaled.
*
* @see [TransformOrigin]
*/
var pivotX: Float = 0.5f
set(value) {
field = value
addTransform { pivotX(value) }
}
/**
* The Y axis offset percent where the content is rotated and scaled.
*
* @see [TransformOrigin]
*/
var pivotY: Float = 0.5f
set(value) {
field = value
addTransform { pivotY(value) }
}
/**
* Whenever the width is not fixed, this weight may be used by an horizontal Chain to decide how
* much space assign to this widget.
*/
var horizontalChainWeight: Float = Float.NaN
set(value) {
field = value
tasks.add { state ->
state.constraints(id)?.horizontalChainWeight = value
}
}
/**
* Whenever the height is not fixed, this weight may be used by a vertical Chain to decide how
* much space assign to this widget.
*/
var verticalChainWeight: Float = Float.NaN
set(value) {
field = value
tasks.add { state ->
state.constraints(id)?.verticalChainWeight = value
}
}
private fun addTransform(change: ConstraintReference.() -> Unit) =
tasks.add { state -> state.constraints(id)?.let { change(it) } }
private fun addFloatTransformFromDp(dpValue: Dp, change: ConstraintReference.(Float) -> Unit) =
tasks.add { state ->
(state as? State)?.also {
state.constraints(id)?.change(state.convertDimension(dpValue).toFloat())
}
}
/**
* Adds both start and end links towards other [ConstraintLayoutBaseScope.VerticalAnchor]s.
*/
fun linkTo(
start: ConstraintLayoutBaseScope.VerticalAnchor,
end: ConstraintLayoutBaseScope.VerticalAnchor,
startMargin: Dp = 0.dp,
endMargin: Dp = 0.dp,
startGoneMargin: Dp = 0.dp,
endGoneMargin: Dp = 0.dp,
bias: Float = 0.5f
) {
[email protected](
anchor = start,
margin = startMargin,
goneMargin = startGoneMargin
)
[email protected](anchor = end, margin = endMargin, goneMargin = endGoneMargin)
tasks.add { state ->
val resolvedBias = if (state.layoutDirection == LayoutDirection.Rtl) 1 - bias else bias
state.constraints(id)?.horizontalBias(resolvedBias)
}
}
/**
* Adds both top and bottom links towards other [ConstraintLayoutBaseScope.HorizontalAnchor]s.
*/
fun linkTo(
top: ConstraintLayoutBaseScope.HorizontalAnchor,
bottom: ConstraintLayoutBaseScope.HorizontalAnchor,
topMargin: Dp = 0.dp,
bottomMargin: Dp = 0.dp,
topGoneMargin: Dp = 0.dp,
bottomGoneMargin: Dp = 0.dp,
bias: Float = 0.5f
) {
[email protected](anchor = top, margin = topMargin, goneMargin = topGoneMargin)
[email protected](
anchor = bottom,
margin = bottomMargin,
goneMargin = bottomGoneMargin
)
tasks.add { state ->
state.constraints(id)?.verticalBias(bias)
}
}
/**
* Adds all start, top, end, bottom links towards
* other [ConstraintLayoutBaseScope.HorizontalAnchor]s.
*/
fun linkTo(
start: ConstraintLayoutBaseScope.VerticalAnchor,
top: ConstraintLayoutBaseScope.HorizontalAnchor,
end: ConstraintLayoutBaseScope.VerticalAnchor,
bottom: ConstraintLayoutBaseScope.HorizontalAnchor,
startMargin: Dp = 0.dp,
topMargin: Dp = 0.dp,
endMargin: Dp = 0.dp,
bottomMargin: Dp = 0.dp,
startGoneMargin: Dp = 0.dp,
topGoneMargin: Dp = 0.dp,
endGoneMargin: Dp = 0.dp,
bottomGoneMargin: Dp = 0.dp,
horizontalBias: Float = 0.5f,
verticalBias: Float = 0.5f
) {
linkTo(
start = start,
end = end,
startMargin = startMargin,
endMargin = endMargin,
startGoneMargin = startGoneMargin,
endGoneMargin = endGoneMargin,
bias = horizontalBias
)
linkTo(
top = top,
bottom = bottom,
topMargin = topMargin,
bottomMargin = bottomMargin,
topGoneMargin = topGoneMargin,
bottomGoneMargin = bottomGoneMargin,
bias = verticalBias
)
}
/**
* Adds all start, top, end, bottom links towards the corresponding anchors of [other].
* This will center the current layout inside or around (depending on size) [other].
*/
fun centerTo(other: ConstrainedLayoutReference) {
linkTo(other.start, other.top, other.end, other.bottom)
}
/**
* Adds start and end links towards the corresponding anchors of [other].
* This will center horizontally the current layout inside or around (depending on size)
* [other].
*/
fun centerHorizontallyTo(
other: ConstrainedLayoutReference,
bias: Float = 0.5f
) {
linkTo(start = other.start, end = other.end, bias = bias)
}
/**
* Adds top and bottom links towards the corresponding anchors of [other].
* This will center vertically the current layout inside or around (depending on size)
* [other].
*/
fun centerVerticallyTo(
other: ConstrainedLayoutReference,
bias: Float = 0.5f
) {
linkTo(other.top, other.bottom, bias = bias)
}
/**
* Adds start and end links towards a vertical [anchor].
* This will center the current layout around the vertical [anchor].
*/
fun centerAround(anchor: ConstraintLayoutBaseScope.VerticalAnchor) {
linkTo(anchor, anchor)
}
/**
* Adds top and bottom links towards a horizontal [anchor].
* This will center the current layout around the horizontal [anchor].
*/
fun centerAround(anchor: ConstraintLayoutBaseScope.HorizontalAnchor) {
linkTo(anchor, anchor)
}
/**
* Set a circular constraint relative to the center of [other].
* This will position the current widget at a relative angle and distance from [other].
*/
fun circular(other: ConstrainedLayoutReference, angle: Float, distance: Dp) {
tasks.add { state ->
state.constraints(id)?.circularConstraint(other.id, angle, state.convertDimension(distance).toFloat())
}
}
/**
* Clear the constraints on the horizontal axis (left, right, start, end).
*
* Useful when extending another [ConstraintSet] with unwanted constraints on this axis.
*/
fun clearHorizontal() {
tasks.add { state ->
state.constraints(id)?.clearHorizontal()
}
}
/**
* Clear the constraints on the vertical axis (top, bottom, baseline).
*
* Useful when extending another [ConstraintSet] with unwanted constraints on this axis.
*/
fun clearVertical() {
tasks.add { state ->
state.constraints(id)?.clearVertical()
}
}
/**
* Clear all constraints (vertical, horizontal, circular).
*
* Useful when extending another [ConstraintSet] with unwanted constraints applied.
*/
fun clearConstraints() {
tasks.add { state ->
state.constraints(id)?.clear()
}
}
/**
* Resets the [width] and [height] to their default values.
*
* Useful when extending another [ConstraintSet] with unwanted dimensions.
*/
fun resetDimensions() {
tasks.add { state ->
val defaultDimension =
(Dimension.wrapContent as DimensionDescription).toSolverDimension(state)
state.constraints(id)
?.width(defaultDimension)
?.height(defaultDimension)
}
}
/**
* Reset all render-time transforms of the content to their default values.
*
* Does not modify the [visibility] property.
*
* Useful when extending another [ConstraintSet] with unwanted transforms applied.
*/
fun resetTransforms() {
tasks.add { state ->
state.constraints(id)
?.alpha(Float.NaN)
?.scaleX(Float.NaN)
?.scaleY(Float.NaN)
?.rotationX(Float.NaN)
?.rotationY(Float.NaN)
?.rotationZ(Float.NaN)
?.translationX(Float.NaN)
?.translationY(Float.NaN)
?.translationZ(Float.NaN)
?.pivotX(Float.NaN)
?.pivotY(Float.NaN)
}
}
}
/**
* Represents a vertical side of a layout (i.e start and end) that can be anchored using
* [linkTo] in their `Modifier.constrainAs` blocks.
*/
private class ConstraintVerticalAnchorable constructor(
val id: Any,
index: Int,
tasks: MutableList<(State) -> Unit>
) : BaseVerticalAnchorable(tasks, index) {
override fun getConstraintReference(state: State): ConstraintReference =
state.constraints(id)!!
}
/**
* Represents a horizontal side of a layout (i.e top and bottom) that can be anchored using
* [linkTo] in their `Modifier.constrainAs` blocks.
*/
private class ConstraintHorizontalAnchorable constructor(
val id: Any,
index: Int,
tasks: MutableList<(State) -> Unit>
) : BaseHorizontalAnchorable(tasks, index) {
override fun getConstraintReference(state: State): ConstraintReference =
state.constraints(id)!!
}
/**
* Represents the [FirstBaseline] of a layout that can be anchored
* using [linkTo] in their `Modifier.constrainAs` blocks.
*/
private class ConstraintBaselineAnchorable constructor(
val id: Any,
val tasks: MutableList<(State) -> Unit>
) : BaselineAnchorable {
/**
* Adds a link towards a [ConstraintLayoutBaseScope.BaselineAnchor].
*/
override fun linkTo(
anchor: ConstraintLayoutBaseScope.BaselineAnchor,
margin: Dp,
goneMargin: Dp
) {
tasks.add { state ->
(state as? State)?.let {
it.baselineNeededFor(id)
it.baselineNeededFor(anchor.id)
}
with(state.constraints(id)) {
this?.let { baselineAnchorFunction.invoke(it, anchor.id).margin(margin)?.marginGone(goneMargin) }
}
}
}
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