Intrinsic.kt
/*
* Copyright 2019 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.foundation.layout
import androidx.compose.runtime.Stable
import androidx.compose.ui.layout.LayoutModifier
import androidx.compose.ui.layout.Measurable
import androidx.compose.ui.layout.MeasureScope
import androidx.compose.ui.Modifier
import androidx.compose.ui.layout.IntrinsicMeasurable
import androidx.compose.ui.layout.IntrinsicMeasureScope
import androidx.compose.ui.layout.MeasureResult
import androidx.compose.ui.unit.Constraints
import androidx.compose.ui.unit.IntOffset
import androidx.compose.ui.unit.constrain
/**
* Declare the preferred width of the content to be the same as the min or max intrinsic width of
* the content. The incoming measurement [Constraints] may override this value, forcing the content
* to be either smaller or larger.
*
* See [preferredHeight] for options of sizing to intrinsic height.
* Also see [preferredWidth] and [preferredWidthIn] for other options to set the preferred width.
*
* Example usage for min intrinsic:
* @sample androidx.compose.foundation.layout.samples.SameWidthBoxes
*
* Example usage for max intrinsic:
* @sample androidx.compose.foundation.layout.samples.SameWidthTextBoxes
*/
@ExperimentalLayout
@Stable
fun Modifier.preferredWidth(intrinsicSize: IntrinsicSize) = when (intrinsicSize) {
IntrinsicSize.Min -> this.then(PreferredMinIntrinsicWidthModifier)
IntrinsicSize.Max -> this.then(PreferredMaxIntrinsicWidthModifier)
}
/**
* Declare the preferred height of the content to be the same as the min or max intrinsic height of
* the content. The incoming measurement [Constraints] may override this value, forcing the content
* to be either smaller or larger.
*
* See [preferredWidth] for other options of sizing to intrinsic width.
* Also see [preferredHeight] and [preferredHeightIn] for other options to set the preferred height.
*
* Example usage for min intrinsic:
* @sample androidx.compose.foundation.layout.samples.MatchParentDividerForText
*
* Example usage for max intrinsic:
* @sample androidx.compose.foundation.layout.samples.MatchParentDividerForAspectRatio
*/
@ExperimentalLayout
@Stable
fun Modifier.preferredHeight(intrinsicSize: IntrinsicSize) = when (intrinsicSize) {
IntrinsicSize.Min -> this.then(PreferredMinIntrinsicHeightModifier)
IntrinsicSize.Max -> this.then(PreferredMaxIntrinsicHeightModifier)
}
/**
* Intrinsic size used in [preferredWidth] or [preferredHeight] which can refer to width or height.
*/
enum class IntrinsicSize { Min, Max }
private object PreferredMinIntrinsicWidthModifier : PreferredIntrinsicSizeModifier {
override fun MeasureScope.calculateContentConstraints(
measurable: Measurable,
constraints: Constraints
): Constraints {
val width = measurable.minIntrinsicWidth(constraints.maxHeight)
return Constraints.fixedWidth(width)
}
override fun IntrinsicMeasureScope.maxIntrinsicWidth(
measurable: IntrinsicMeasurable,
height: Int
) = measurable.minIntrinsicWidth(height)
}
private object PreferredMinIntrinsicHeightModifier : PreferredIntrinsicSizeModifier {
override fun MeasureScope.calculateContentConstraints(
measurable: Measurable,
constraints: Constraints
): Constraints {
val height = measurable.minIntrinsicHeight(constraints.maxWidth)
return Constraints.fixedHeight(height)
}
override fun IntrinsicMeasureScope.maxIntrinsicHeight(
measurable: IntrinsicMeasurable,
width: Int
) = measurable.minIntrinsicHeight(width)
}
private object PreferredMaxIntrinsicWidthModifier : PreferredIntrinsicSizeModifier {
override fun MeasureScope.calculateContentConstraints(
measurable: Measurable,
constraints: Constraints
): Constraints {
val width = measurable.maxIntrinsicWidth(constraints.maxHeight)
return Constraints.fixedWidth(width)
}
override fun IntrinsicMeasureScope.minIntrinsicWidth(
measurable: IntrinsicMeasurable,
height: Int
) = measurable.maxIntrinsicWidth(height)
}
private object PreferredMaxIntrinsicHeightModifier : PreferredIntrinsicSizeModifier {
override fun MeasureScope.calculateContentConstraints(
measurable: Measurable,
constraints: Constraints
): Constraints {
val height = measurable.maxIntrinsicHeight(constraints.maxWidth)
return Constraints.fixedHeight(height)
}
override fun IntrinsicMeasureScope.minIntrinsicHeight(
measurable: IntrinsicMeasurable,
width: Int
) = measurable.maxIntrinsicHeight(width)
}
private interface PreferredIntrinsicSizeModifier : LayoutModifier {
fun MeasureScope.calculateContentConstraints(
measurable: Measurable,
constraints: Constraints
): Constraints
override fun MeasureScope.measure(
measurable: Measurable,
constraints: Constraints
): MeasureResult {
val placeable = measurable.measure(
constraints.constrain(calculateContentConstraints(measurable, constraints))
)
return layout(placeable.width, placeable.height) {
placeable.placeRelative(IntOffset.Zero)
}
}
override fun IntrinsicMeasureScope.minIntrinsicWidth(
measurable: IntrinsicMeasurable,
height: Int
) = measurable.minIntrinsicWidth(height)
override fun IntrinsicMeasureScope.minIntrinsicHeight(
measurable: IntrinsicMeasurable,
width: Int
) = measurable.minIntrinsicHeight(width)
override fun IntrinsicMeasureScope.maxIntrinsicWidth(
measurable: IntrinsicMeasurable,
height: Int
) = measurable.maxIntrinsicWidth(height)
override fun IntrinsicMeasureScope.maxIntrinsicHeight(
measurable: IntrinsicMeasurable,
width: Int
) = measurable.maxIntrinsicHeight(width)
}