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Compose Material Design Components library
/*
* Copyright 2018 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.compose.material
import androidx.compose.animation.animateColorAsState
import androidx.compose.animation.core.animateFloat
import androidx.compose.animation.core.snap
import androidx.compose.animation.core.spring
import androidx.compose.animation.core.tween
import androidx.compose.animation.core.updateTransition
import androidx.compose.foundation.Canvas
import androidx.compose.foundation.interaction.Interaction
import androidx.compose.foundation.interaction.MutableInteractionSource
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.requiredSize
import androidx.compose.foundation.layout.wrapContentSize
import androidx.compose.foundation.selection.triStateToggleable
import androidx.compose.runtime.Composable
import androidx.compose.runtime.Immutable
import androidx.compose.runtime.Stable
import androidx.compose.runtime.State
import androidx.compose.runtime.getValue
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberUpdatedState
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.CornerRadius
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.geometry.Size
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.Path
import androidx.compose.ui.graphics.PathMeasure
import androidx.compose.ui.graphics.StrokeCap
import androidx.compose.ui.graphics.drawscope.DrawScope
import androidx.compose.ui.graphics.drawscope.Fill
import androidx.compose.ui.graphics.drawscope.Stroke
import androidx.compose.ui.semantics.Role
import androidx.compose.ui.state.ToggleableState
import androidx.compose.ui.unit.dp
import androidx.compose.ui.util.lerp
import kotlin.math.floor
import kotlin.math.max
/**
* Material Design checkbox.
*
* Checkboxes allow users to select one or more items from a set. Checkboxes can turn an option on
* or off.
*
* 
*
* @sample androidx.compose.material.samples.CheckboxSample
*
* @see [TriStateCheckbox] if you require support for an indeterminate state, or more advanced
* color customization between states.
*
* @param checked whether Checkbox is checked or unchecked
* @param onCheckedChange callback to be invoked when checkbox is being clicked,
* therefore the change of checked state in requested. If null, then this is passive
* and relies entirely on a higher-level component to control the "checked" state.
* @param modifier Modifier to be applied to the layout of the checkbox
* @param enabled whether the component is enabled or grayed out
* @param interactionSource an optional hoisted [MutableInteractionSource] for observing and
* emitting [Interaction]s for this checkbox. You can use this to change the checkbox's
* appearance or preview the checkbox in different states. Note that if `null` is provided,
* interactions will still happen internally.
* @param colors [CheckboxColors] that will be used to determine the color of the checkmark / box
* / border in different states. See [CheckboxDefaults.colors].
*/
@Composable
fun Checkbox(
checked: Boolean,
onCheckedChange: ((Boolean) -> Unit)?,
modifier: Modifier = Modifier,
enabled: Boolean = true,
interactionSource: MutableInteractionSource? = null,
colors: CheckboxColors = CheckboxDefaults.colors()
) {
TriStateCheckbox(
state = ToggleableState(checked),
onClick = if (onCheckedChange != null) { { onCheckedChange(!checked) } } else null,
interactionSource = interactionSource,
enabled = enabled,
colors = colors,
modifier = modifier
)
}
/**
* Material Design checkbox parent.
*
* Checkboxes can have a parent-child relationship with other checkboxes. When the parent checkbox
* is checked, all child checkboxes are checked. If a parent checkbox is unchecked, all child
* checkboxes are unchecked. If some, but not all, child checkboxes are checked, the parent checkbox
* becomes an indeterminate checkbox.
*
* 
*
* @sample androidx.compose.material.samples.TriStateCheckboxSample
*
* @see [Checkbox] if you want a simple component that represents Boolean state
*
* @param state whether TriStateCheckbox is checked, unchecked or in indeterminate state
* @param onClick callback to be invoked when checkbox is being clicked,
* therefore the change of ToggleableState state is requested. If null, then this is passive
* and relies entirely on a higher-level component to control the state.
* @param modifier Modifier to be applied to the layout of the checkbox
* @param enabled whether the component is enabled or grayed out
* @param interactionSource an optional hoisted [MutableInteractionSource] for observing and
* emitting [Interaction]s for this checkbox. You can use this to change the checkbox's
* appearance or preview the checkbox in different states. Note that if `null` is provided,
* interactions will still happen internally.
* @param colors [CheckboxColors] that will be used to determine the color of the checkmark / box
* / border in different states. See [CheckboxDefaults.colors].
*/
@Composable
fun TriStateCheckbox(
state: ToggleableState,
onClick: (() -> Unit)?,
modifier: Modifier = Modifier,
enabled: Boolean = true,
interactionSource: MutableInteractionSource? = null,
colors: CheckboxColors = CheckboxDefaults.colors()
) {
val toggleableModifier =
if (onClick != null) {
Modifier.triStateToggleable(
state = state,
onClick = onClick,
enabled = enabled,
role = Role.Checkbox,
interactionSource = interactionSource,
indication = rippleOrFallbackImplementation(
bounded = false,
radius = CheckboxRippleRadius
)
)
} else {
Modifier
}
CheckboxImpl(
enabled = enabled,
value = state,
modifier = modifier
.then(
if (onClick != null) {
Modifier.minimumInteractiveComponentSize()
} else {
Modifier
}
)
.then(toggleableModifier)
.padding(CheckboxDefaultPadding),
colors = colors
)
}
/**
* Represents the colors used by the three different sections (checkmark, box, and border) of a
* [Checkbox] or [TriStateCheckbox] in different states.
*
* See [CheckboxDefaults.colors] for the default implementation that follows Material
* specifications.
*/
@Stable
interface CheckboxColors {
/**
* Represents the color used for the checkmark inside the checkbox, depending on [state].
*
* @param state the [ToggleableState] of the checkbox
*/
@Composable
fun checkmarkColor(state: ToggleableState): State
/**
* Represents the color used for the box (background) of the checkbox, depending on [enabled]
* and [state].
*
* @param enabled whether the checkbox is enabled or not
* @param state the [ToggleableState] of the checkbox
*/
@Composable
fun boxColor(enabled: Boolean, state: ToggleableState): State
/**
* Represents the color used for the border of the checkbox, depending on [enabled] and [state].
*
* @param enabled whether the checkbox is enabled or not
* @param state the [ToggleableState] of the checkbox
*/
@Composable
fun borderColor(enabled: Boolean, state: ToggleableState): State
}
/**
* Defaults used in [Checkbox] and [TriStateCheckbox].
*/
object CheckboxDefaults {
/**
* Creates a [CheckboxColors] that will animate between the provided colors according to the
* Material specification.
*
* @param checkedColor the color that will be used for the border and box when checked
* @param uncheckedColor color that will be used for the border when unchecked
* @param checkmarkColor color that will be used for the checkmark when checked
* @param disabledColor color that will be used for the box and border when disabled
* @param disabledIndeterminateColor color that will be used for the box and
* border in a [TriStateCheckbox] when disabled AND in an [ToggleableState.Indeterminate] state.
*/
@Composable
fun colors(
checkedColor: Color = MaterialTheme.colors.secondary,
uncheckedColor: Color = MaterialTheme.colors.onSurface.copy(alpha = 0.6f),
checkmarkColor: Color = MaterialTheme.colors.surface,
disabledColor: Color = MaterialTheme.colors.onSurface.copy(alpha = ContentAlpha.disabled),
disabledIndeterminateColor: Color = checkedColor.copy(alpha = ContentAlpha.disabled)
): CheckboxColors {
return remember(
checkedColor,
uncheckedColor,
checkmarkColor,
disabledColor,
disabledIndeterminateColor,
) {
DefaultCheckboxColors(
checkedBorderColor = checkedColor,
checkedBoxColor = checkedColor,
checkedCheckmarkColor = checkmarkColor,
uncheckedCheckmarkColor = checkmarkColor.copy(alpha = 0f),
uncheckedBoxColor = checkedColor.copy(alpha = 0f),
disabledCheckedBoxColor = disabledColor,
disabledUncheckedBoxColor = disabledColor.copy(alpha = 0f),
disabledIndeterminateBoxColor = disabledIndeterminateColor,
uncheckedBorderColor = uncheckedColor,
disabledBorderColor = disabledColor,
disabledIndeterminateBorderColor = disabledIndeterminateColor,
)
}
}
}
@Composable
private fun CheckboxImpl(
enabled: Boolean,
value: ToggleableState,
modifier: Modifier,
colors: CheckboxColors
) {
val transition = updateTransition(value)
val checkDrawFraction by transition.animateFloat(
transitionSpec = {
when {
initialState == ToggleableState.Off -> tween(CheckAnimationDuration)
targetState == ToggleableState.Off -> snap(BoxOutDuration)
else -> spring()
}
}
) {
when (it) {
ToggleableState.On -> 1f
ToggleableState.Off -> 0f
ToggleableState.Indeterminate -> 1f
}
}
val checkCenterGravitationShiftFraction by transition.animateFloat(
transitionSpec = {
when {
initialState == ToggleableState.Off -> snap()
targetState == ToggleableState.Off -> snap(BoxOutDuration)
else -> tween(durationMillis = CheckAnimationDuration)
}
}
) {
when (it) {
ToggleableState.On -> 0f
ToggleableState.Off -> 0f
ToggleableState.Indeterminate -> 1f
}
}
val checkCache = remember { CheckDrawingCache() }
val checkColor by colors.checkmarkColor(value)
val boxColor by colors.boxColor(enabled, value)
val borderColor by colors.borderColor(enabled, value)
Canvas(modifier.wrapContentSize(Alignment.Center).requiredSize(CheckboxSize)) {
val strokeWidthPx = floor(StrokeWidth.toPx())
drawBox(
boxColor = boxColor,
borderColor = borderColor,
radius = RadiusSize.toPx(),
strokeWidth = strokeWidthPx
)
drawCheck(
checkColor = checkColor,
checkFraction = checkDrawFraction,
crossCenterGravitation = checkCenterGravitationShiftFraction,
strokeWidthPx = strokeWidthPx,
drawingCache = checkCache
)
}
}
private fun DrawScope.drawBox(
boxColor: Color,
borderColor: Color,
radius: Float,
strokeWidth: Float
) {
val halfStrokeWidth = strokeWidth / 2.0f
val stroke = Stroke(strokeWidth)
val checkboxSize = size.width
if (boxColor == borderColor) {
drawRoundRect(
boxColor,
size = Size(checkboxSize, checkboxSize),
cornerRadius = CornerRadius(radius),
style = Fill
)
} else {
drawRoundRect(
boxColor,
topLeft = Offset(strokeWidth, strokeWidth),
size = Size(checkboxSize - strokeWidth * 2, checkboxSize - strokeWidth * 2),
cornerRadius = CornerRadius(max(0f, radius - strokeWidth)),
style = Fill
)
drawRoundRect(
borderColor,
topLeft = Offset(halfStrokeWidth, halfStrokeWidth),
size = Size(checkboxSize - strokeWidth, checkboxSize - strokeWidth),
cornerRadius = CornerRadius(radius - halfStrokeWidth),
style = stroke
)
}
}
private fun DrawScope.drawCheck(
checkColor: Color,
checkFraction: Float,
crossCenterGravitation: Float,
strokeWidthPx: Float,
drawingCache: CheckDrawingCache
) {
val stroke = Stroke(width = strokeWidthPx, cap = StrokeCap.Square)
val width = size.width
val checkCrossX = 0.4f
val checkCrossY = 0.7f
val leftX = 0.2f
val leftY = 0.5f
val rightX = 0.8f
val rightY = 0.3f
val gravitatedCrossX = lerp(checkCrossX, 0.5f, crossCenterGravitation)
val gravitatedCrossY = lerp(checkCrossY, 0.5f, crossCenterGravitation)
// gravitate only Y for end to achieve center line
val gravitatedLeftY = lerp(leftY, 0.5f, crossCenterGravitation)
val gravitatedRightY = lerp(rightY, 0.5f, crossCenterGravitation)
with(drawingCache) {
checkPath.reset()
checkPath.moveTo(width * leftX, width * gravitatedLeftY)
checkPath.lineTo(width * gravitatedCrossX, width * gravitatedCrossY)
checkPath.lineTo(width * rightX, width * gravitatedRightY)
// TODO: replace with proper declarative non-android alternative when ready (b/158188351)
pathMeasure.setPath(checkPath, false)
pathToDraw.reset()
pathMeasure.getSegment(
0f, pathMeasure.length * checkFraction, pathToDraw, true
)
}
drawPath(drawingCache.pathToDraw, checkColor, style = stroke)
}
@Immutable
private class CheckDrawingCache(
val checkPath: Path = Path(),
val pathMeasure: PathMeasure = PathMeasure(),
val pathToDraw: Path = Path()
)
/**
* Default [CheckboxColors] implementation.
*/
@Stable
private class DefaultCheckboxColors(
private val checkedCheckmarkColor: Color,
private val uncheckedCheckmarkColor: Color,
private val checkedBoxColor: Color,
private val uncheckedBoxColor: Color,
private val disabledCheckedBoxColor: Color,
private val disabledUncheckedBoxColor: Color,
private val disabledIndeterminateBoxColor: Color,
private val checkedBorderColor: Color,
private val uncheckedBorderColor: Color,
private val disabledBorderColor: Color,
private val disabledIndeterminateBorderColor: Color
) : CheckboxColors {
@Composable
override fun checkmarkColor(state: ToggleableState): State {
val target = if (state == ToggleableState.Off) {
uncheckedCheckmarkColor
} else {
checkedCheckmarkColor
}
val duration = if (state == ToggleableState.Off) BoxOutDuration else BoxInDuration
return animateColorAsState(target, tween(durationMillis = duration))
}
@Composable
override fun boxColor(enabled: Boolean, state: ToggleableState): State {
val target = if (enabled) {
when (state) {
ToggleableState.On, ToggleableState.Indeterminate -> checkedBoxColor
ToggleableState.Off -> uncheckedBoxColor
}
} else {
when (state) {
ToggleableState.On -> disabledCheckedBoxColor
ToggleableState.Indeterminate -> disabledIndeterminateBoxColor
ToggleableState.Off -> disabledUncheckedBoxColor
}
}
// If not enabled 'snap' to the disabled state, as there should be no animations between
// enabled / disabled.
return if (enabled) {
val duration = if (state == ToggleableState.Off) BoxOutDuration else BoxInDuration
animateColorAsState(target, tween(durationMillis = duration))
} else {
rememberUpdatedState(target)
}
}
@Composable
override fun borderColor(enabled: Boolean, state: ToggleableState): State {
val target = if (enabled) {
when (state) {
ToggleableState.On, ToggleableState.Indeterminate -> checkedBorderColor
ToggleableState.Off -> uncheckedBorderColor
}
} else {
when (state) {
ToggleableState.Indeterminate -> disabledIndeterminateBorderColor
ToggleableState.On, ToggleableState.Off -> disabledBorderColor
}
}
// If not enabled 'snap' to the disabled state, as there should be no animations between
// enabled / disabled.
return if (enabled) {
val duration = if (state == ToggleableState.Off) BoxOutDuration else BoxInDuration
animateColorAsState(target, tween(durationMillis = duration))
} else {
rememberUpdatedState(target)
}
}
}
private const val BoxInDuration = 50
private const val BoxOutDuration = 100
private const val CheckAnimationDuration = 100
private val CheckboxRippleRadius = 24.dp
private val CheckboxDefaultPadding = 2.dp
private val CheckboxSize = 20.dp
private val StrokeWidth = 2.dp
private val RadiusSize = 2.dp
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