AnchoredDraggableState
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class AnchoredDraggableState<T : Any?>
State of the anchoredDraggable modifier. Use the constructor overload with anchors if the anchors are defined in composition, or update the anchors using updateAnchors.
This contains necessary information about any ongoing drag or animation and provides methods to change the state either immediately or by starting an animation.
Summary
Public companion functions |
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Saver<AnchoredDraggableState<T>, T> |
The default |
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Saver<AnchoredDraggableState<T>, T> |
This function is deprecated. confirmValueChange is deprecated without replacement. |
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Saver<AnchoredDraggableState<T>, T> |
<T : Any> This function is deprecated. This constructor of AnchoredDraggableState has been deprecated. |
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Public constructors |
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<T : Any?> AnchoredDraggableState(initialValue: T) |
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<T : Any?> AnchoredDraggableState(Construct an |
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<T : Any?> This function is deprecated. confirmValueChange is deprecated without replacement. |
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<T : Any?> This function is deprecated. confirmValueChange is deprecated without replacement. |
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Public functions |
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suspend Unit |
anchoredDrag(Call this function to take control of drag logic and perform anchored drag with the latest anchors. |
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suspend Unit |
anchoredDrag(Call this function to take control of drag logic and perform anchored drag with the latest anchors and target. |
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Float |
dispatchRawDelta(delta: Float)Drag by the |
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@FloatRange(from = 0.0, to = 1.0) Float |
progress(from: T, to: T)The fraction of the offset between |
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Float |
Require the current offset. |
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suspend Unit |
settle(animationSpec: AnimationSpec<Float>)Find the closest anchor and settle at it with the given |
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suspend Float |
This function is deprecated. settle does not accept a velocity anymore. |
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Unit |
updateAnchors(newAnchors: DraggableAnchors<T>, newTarget: T)Update the anchors. |
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Public properties |
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DraggableAnchors<T> |
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T |
The current value of the |
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lateinit DecayAnimationSpec<Float> |
This property is deprecated. This constructor of AnchoredDraggableState has been deprecated. |
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Boolean |
Whether an animation is currently in progress. |
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Float |
The velocity of the last known animation. |
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Float |
The current offset, or |
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Float |
This property is deprecated. Use the progress function to query the progress between two specified anchors. |
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T |
The value the |
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lateinit AnimationSpec<Float> |
This property is deprecated. This constructor of AnchoredDraggableState has been deprecated. |
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T |
The target value. |
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Extension functions |
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suspend Unit |
<T : Any?> AnchoredDraggableState<T>.animateTo(Animate to a |
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suspend Float |
<T : Any?> AnchoredDraggableState<T>.animateToWithDecay(Attempt to animate using decay Animation to a |
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suspend Unit |
<T : Any?> AnchoredDraggableState<T>.snapTo(targetValue: T)Snap to a |
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Public companion functions
Saver
fun <T : Any> Saver(): Saver<AnchoredDraggableState<T>, T>
The default Saver implementation for AnchoredDraggableState.
Saver
fun <T : Any>Saver(confirmValueChange: (T) -> Boolean = { true }): Saver<AnchoredDraggableState<T>, T>
The default Saver implementation for AnchoredDraggableState.
Saver
fun <T : Any>Saver(
snapAnimationSpec: AnimationSpec<Float>,
decayAnimationSpec: DecayAnimationSpec<Float>,
positionalThreshold: (distance: Float) -> Float,
velocityThreshold: () -> Float,
confirmValueChange: (T) -> Boolean = { true }
): Saver<AnchoredDraggableState<T>, T>
The default Saver implementation for AnchoredDraggableState.
Public constructors
AnchoredDraggableState
<T : Any?> AnchoredDraggableState(initialValue: T)
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initialValue: T |
The initial value of the state. |
AnchoredDraggableState
<T : Any?> AnchoredDraggableState(
initialValue: T,
anchors: DraggableAnchors<T>
)
Construct an AnchoredDraggableState instance with anchors.
| Parameters | |
|---|---|
initialValue: T |
The initial value of the state. |
anchors: DraggableAnchors<T> |
The anchors of the state. Use |
AnchoredDraggableState
<T : Any?>AnchoredDraggableState(
initialValue: T,
confirmValueChange: (newValue) -> Boolean
)
Construct an AnchoredDraggableState instance with anchors.
import androidx.compose.foundation.gestures.AnchoredDraggableState
import androidx.compose.foundation.gestures.DraggableAnchors
import androidx.compose.foundation.gestures.Orientation
import androidx.compose.foundation.gestures.anchoredDraggable
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.offset
import androidx.compose.foundation.layout.width
import androidx.compose.material.Button
import androidx.compose.material.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.mutableStateListOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.saveable.rememberSaveable
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.layout.onSizeChanged
import androidx.compose.ui.unit.IntOffset
val open = "Open"
val closed = "Closed"
@Composable
fun DrawerLayout(
state: AnchoredDraggableState<String>,
activePositions: List<String> = listOf(open, closed),
modifier: Modifier = Modifier,
drawerContent: @Composable () -> Unit,
content: @Composable () -> Unit
) {
Box(modifier) {
Box(Modifier.anchoredDraggable(state, Orientation.Horizontal)) { content() }
Box(
Modifier.onSizeChanged { measuredSize ->
state.updateAnchors(
DraggableAnchors {
if (closed in activePositions) {
closed at -measuredSize.width.toFloat()
}
if (open in activePositions) {
open at 0f
}
}
)
}
.offset { IntOffset(x = state.requireOffset().roundToInt(), y = 0) }
) {
drawerContent()
}
}
}
val state =
rememberSaveable(saver = AnchoredDraggableState.Saver()) {
AnchoredDraggableState(initialValue = closed)
}
val activePositions = remember { mutableStateListOf(open, closed) }
DrawerLayout(
state,
activePositions,
drawerContent = {
Button(
onClick = {
if (closed in activePositions) {
activePositions.remove(closed)
} else {
activePositions.add(closed)
}
}
) {
val text =
if (closed in activePositions) {
"Click to disallow closing drawer"
} else {
"Click to allow closing"
}
Text(text)
}
},
) {
Text("Swipe to expand Drawer")
}
For an example of using dynamic anchors to replace confirmValueChange.
| Parameters | |
|---|---|
initialValue: T |
The initial value of the state. |
confirmValueChange: (newValue) -> Boolean |
Optional callback invoked to confirm or veto a pending state change. |
AnchoredDraggableState
<T : Any?>AnchoredDraggableState(
initialValue: T,
anchors: DraggableAnchors<T>,
confirmValueChange: (newValue) -> Boolean = { true }
)
Construct an AnchoredDraggableState instance with anchors.
import androidx.compose.foundation.gestures.AnchoredDraggableState
import androidx.compose.foundation.gestures.DraggableAnchors
import androidx.compose.foundation.gestures.Orientation
import androidx.compose.foundation.gestures.anchoredDraggable
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.offset
import androidx.compose.foundation.layout.width
import androidx.compose.material.Button
import androidx.compose.material.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.mutableStateListOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.saveable.rememberSaveable
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.layout.onSizeChanged
import androidx.compose.ui.unit.IntOffset
val open = "Open"
val closed = "Closed"
@Composable
fun DrawerLayout(
state: AnchoredDraggableState<String>,
activePositions: List<String> = listOf(open, closed),
modifier: Modifier = Modifier,
drawerContent: @Composable () -> Unit,
content: @Composable () -> Unit
) {
Box(modifier) {
Box(Modifier.anchoredDraggable(state, Orientation.Horizontal)) { content() }
Box(
Modifier.onSizeChanged { measuredSize ->
state.updateAnchors(
DraggableAnchors {
if (closed in activePositions) {
closed at -measuredSize.width.toFloat()
}
if (open in activePositions) {
open at 0f
}
}
)
}
.offset { IntOffset(x = state.requireOffset().roundToInt(), y = 0) }
) {
drawerContent()
}
}
}
val state =
rememberSaveable(saver = AnchoredDraggableState.Saver()) {
AnchoredDraggableState(initialValue = closed)
}
val activePositions = remember { mutableStateListOf(open, closed) }
DrawerLayout(
state,
activePositions,
drawerContent = {
Button(
onClick = {
if (closed in activePositions) {
activePositions.remove(closed)
} else {
activePositions.add(closed)
}
}
) {
val text =
if (closed in activePositions) {
"Click to disallow closing drawer"
} else {
"Click to allow closing"
}
Text(text)
}
},
) {
Text("Swipe to expand Drawer")
}
For an example of using dynamic anchors to replace confirmValueChange.
| Parameters | |
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initialValue: T |
The initial value of the state. |
anchors: DraggableAnchors<T> |
The anchors of the state. Use |
confirmValueChange: (newValue) -> Boolean = { true } |
Optional callback invoked to confirm or veto a pending state change. |
Public functions
anchoredDrag
suspend fun anchoredDrag(
dragPriority: MutatePriority = MutatePriority.Default,
block: suspend AnchoredDragScope.(anchors: DraggableAnchors<T>) -> Unit
): Unit
Call this function to take control of drag logic and perform anchored drag with the latest anchors.
All actions that change the offset of this AnchoredDraggableState must be performed within an anchoredDrag block (even if they don't call any other methods on this object) in order to guarantee that mutual exclusion is enforced.
If anchoredDrag is called from elsewhere with the dragPriority higher or equal to ongoing drag, the ongoing drag will be cancelled.
If the anchors change while the block is being executed, it will be cancelled and re-executed with the latest anchors and target. This allows you to target the correct state.
| Parameters | |
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dragPriority: MutatePriority = MutatePriority.Default |
of the drag operation |
block: suspend AnchoredDragScope.(anchors: DraggableAnchors<T>) -> Unit |
perform anchored drag given the current anchor provided |
anchoredDrag
suspend fun anchoredDrag(
targetValue: T,
dragPriority: MutatePriority = MutatePriority.Default,
block: suspend AnchoredDragScope.(anchor: DraggableAnchors<T>, targetValue) -> Unit
): Unit
Call this function to take control of drag logic and perform anchored drag with the latest anchors and target.
All actions that change the offset of this AnchoredDraggableState must be performed within an anchoredDrag block (even if they don't call any other methods on this object) in order to guarantee that mutual exclusion is enforced.
This overload allows the caller to hint the target value that this anchoredDrag is intended to arrive to. This will set AnchoredDraggableState.targetValue to provided value so consumers can reflect it in their UIs.
If the anchors or AnchoredDraggableState.targetValue change while the block is being executed, it will be cancelled and re-executed with the latest anchors and target. This allows you to target the correct state.
If anchoredDrag is called from elsewhere with the dragPriority higher or equal to ongoing drag, the ongoing drag will be cancelled.
| Parameters | |
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targetValue: T |
hint the target value that this |
dragPriority: MutatePriority = MutatePriority.Default |
of the drag operation |
block: suspend AnchoredDragScope.(anchor: DraggableAnchors<T>, targetValue) -> Unit |
perform anchored drag given the current anchor provided |
dispatchRawDelta
fun dispatchRawDelta(delta: Float): Float
Drag by the delta, coerce it in the bounds and dispatch it to the AnchoredDraggableState.
| Returns | |
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Float |
The delta the consumed by the |
progress
fun progress(from: T, to: T): @FloatRange(from = 0.0, to = 1.0) Float
The fraction of the offset between from and to, as a fraction between 0f..1f, or 1f if from is equal to to.
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from: T |
The starting value used to calculate the distance |
to: T |
The end value used to calculate the distance |
requireOffset
fun requireOffset(): Float
Require the current offset.
| Throws | |
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kotlin.IllegalStateException |
If the offset has not been initialized yet |
| See also | |
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offset |
settle
suspend fun settle(animationSpec: AnimationSpec<Float>): Unit
Find the closest anchor and settle at it with the given animationSpec.
| Parameters | |
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animationSpec: AnimationSpec<Float> |
The animation spec that will be used to animate to the closest anchor. |
settle
suspend funsettle(velocity: Float): Float
Find the closest anchor, taking into account the velocityThreshold and positionalThreshold, and settle at it with an animation.
If the velocity is lower than the velocityThreshold, the closest anchor by distance and positionalThreshold will be the target. If the velocity is higher than the velocityThreshold, the positionalThreshold will not be considered and the next anchor in the direction indicated by the sign of the velocity will be the target.
Based on the velocity, either snapAnimationSpec or decayAnimationSpec will be used to animate towards the target.
| Returns | |
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Float |
The velocity consumed in the animation |
updateAnchors
fun updateAnchors(
newAnchors: DraggableAnchors<T>,
newTarget: T = if (!offset.isNaN()) { newAnchors.closestAnchor(offset) ?: targetValue } else targetValue
): Unit
Update the anchors. If there is no ongoing anchoredDrag operation, snap to the newTarget, otherwise restart the ongoing anchoredDrag operation (e.g. an animation) with the new anchors.
If your anchors depend on the size of the layout, updateAnchors should be called in the layout (placement) phase, e.g. through Modifier.onSizeChanged. This ensures that the state is set up within the same frame. For static anchors, or anchors with different data dependencies, updateAnchors is safe to be called from side effects or layout.
| Parameters | |
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newAnchors: DraggableAnchors<T> |
The new anchors. |
newTarget: T = if (!offset.isNaN()) {
newAnchors.closestAnchor(offset) ?: targetValue
} else targetValue |
The new target, by default the closest anchor or the current target if there are no anchors. |
Public properties
currentValue
val currentValue: T
The current value of the AnchoredDraggableState.
That is the closest anchor point that the state has passed through.
lastVelocity
val lastVelocity: Float
The velocity of the last known animation. Gets reset to 0f when an animation completes successfully, but does not get reset when an animation gets interrupted. You can use this value to provide smooth reconciliation behavior when re-targeting an animation.
offset
val offset: Float
The current offset, or Float.NaN if it has not been initialized yet.
The offset will be initialized when the anchors are first set through updateAnchors.
Strongly consider using requireOffset which will throw if the offset is read before it is initialized. This helps catch issues early in your workflow.
progress
val progress: Float
The fraction of the progress going from settledValue to targetValue, within 0f..1f bounds, or 1f if the AnchoredDraggableState is in a settled state.
settledValue
val settledValue: T
The value the AnchoredDraggableState is currently settled at.
When progressing through multiple anchors, e.g. A -> B -> C, settledValue will stay the same until settled at an anchor, while currentValue will update to the closest anchor.
targetValue
val targetValue: T
The target value. This is the closest value to the current offset. If no interactions like animations or drags are in progress, this will be the current value.
Extension functions
animateTo
suspend fun <T : Any?> AnchoredDraggableState<T>.animateTo(
targetValue: T,
animationSpec: AnimationSpec<Float> = if (usePreModifierChangeBehavior) { @Suppress("DEPRECATION") this.snapAnimationSpec } else AnchoredDraggableDefaults.SnapAnimationSpec
): Unit
Animate to a targetValue. If the targetValue is not in the set of anchors, the AnchoredDraggableState.currentValue will be updated to the targetValue without updating the offset.
| Parameters | |
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targetValue: T |
The target value of the animation |
animationSpec: AnimationSpec<Float> = if (usePreModifierChangeBehavior) {
@Suppress("DEPRECATION") this.snapAnimationSpec
} else AnchoredDraggableDefaults.SnapAnimationSpec |
The animation spec used to perform the animation |
| Throws | |
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kotlinx.coroutines.CancellationException |
if the interaction interrupted by another interaction like a gesture interaction or another programmatic interaction like a |
animateToWithDecay
suspend fun <T : Any?> AnchoredDraggableState<T>.animateToWithDecay(
targetValue: T,
velocity: Float,
snapAnimationSpec: AnimationSpec<Float> = if (usePreModifierChangeBehavior) { @Suppress("DEPRECATION") this.snapAnimationSpec } else AnchoredDraggableDefaults.SnapAnimationSpec,
decayAnimationSpec: DecayAnimationSpec<Float> = if (usePreModifierChangeBehavior) { @Suppress("DEPRECATION") this.decayAnimationSpec } else AnchoredDraggableDefaults.DecayAnimationSpec
): Float
Attempt to animate using decay Animation to a targetValue. If the velocity is high enough to get to the target offset, we'll use decayAnimationSpec to get to that offset and return the consumed velocity. If the velocity is not high enough, we'll use snapAnimationSpec to reach the target offset.
If the targetValue is not in the set of anchors, AnchoredDraggableState.currentValue will be updated ro the targetValue without updating the offset.
| Parameters | |
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targetValue: T |
The target value of the animation |
velocity: Float |
The velocity the animation should start with, in px/s |
snapAnimationSpec: AnimationSpec<Float> = if (usePreModifierChangeBehavior) {
@Suppress("DEPRECATION") this.snapAnimationSpec
} else AnchoredDraggableDefaults.SnapAnimationSpec |
The animation spec used if the velocity is not high enough to perform a decay to the |
decayAnimationSpec: DecayAnimationSpec<Float> = if (usePreModifierChangeBehavior) {
@Suppress("DEPRECATION") this.decayAnimationSpec
} else AnchoredDraggableDefaults.DecayAnimationSpec |
The animation spec used if the velocity is high enough to perform a decay to the |
| Returns | |
|---|---|
Float |
The velocity consumed in the animation |
| Throws | |
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kotlinx.coroutines.CancellationException |
if the interaction interrupted bt another interaction like a gesture interaction or another programmatic interaction like |
snapTo
suspend fun <T : Any?> AnchoredDraggableState<T>.snapTo(targetValue: T): Unit
Snap to a targetValue without any animation. If the targetValue is not in the set of anchors, the AnchoredDraggableState.currentValue will be updated to the targetValue without updating the offset.
| Parameters | |
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targetValue: T |
The target value of the animation |
| Throws | |
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kotlinx.coroutines.CancellationException |
if the interaction interrupted by another interaction like a gesture interaction or another programmatic interaction like a |