commonMain.androidx.compose.material3.TouchTarget.kt Maven / Gradle / Ivy
/*
* Copyright 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.compose.material3
import androidx.compose.runtime.ProvidableCompositionLocal
import androidx.compose.runtime.staticCompositionLocalOf
import androidx.compose.ui.Modifier
import androidx.compose.ui.composed
import androidx.compose.ui.layout.LayoutModifier
import androidx.compose.ui.layout.Measurable
import androidx.compose.ui.layout.MeasureResult
import androidx.compose.ui.layout.MeasureScope
import androidx.compose.ui.platform.LocalViewConfiguration
import androidx.compose.ui.platform.debugInspectorInfo
import androidx.compose.ui.unit.Constraints
import androidx.compose.ui.unit.DpSize
import kotlin.math.roundToInt
@OptIn(ExperimentalMaterial3Api::class)
@Suppress("ModifierInspectorInfo")
internal fun Modifier.minimumTouchTargetSize(): Modifier = composed(
inspectorInfo = debugInspectorInfo {
name = "minimumTouchTargetSize"
// TODO: b/214589635 - surface this information through the layout inspector in a better way
// - for now just add some information to help developers debug what this size represents.
properties["README"] = "Adds outer padding to measure at least 48.dp (default) in " +
"size to disambiguate touch interactions if the element would measure smaller"
}
) {
if (LocalMinimumTouchTargetEnforcement.current) {
// TODO: consider using a hardcoded value of 48.dp instead to avoid inconsistent UI if the
// LocalViewConfiguration changes across devices / during runtime.
val size = LocalViewConfiguration.current.minimumTouchTargetSize
MinimumTouchTargetModifier(size)
} else {
Modifier
}
}
/**
* CompositionLocal that configures whether Material components that have a visual size that is
* lower than the minimum touch target size for accessibility (such as Button) will include
* extra space outside the component to ensure that they are accessible. If set to false there
* will be no extra space, and so it is possible that if the component is placed near the edge of
* a layout / near to another component without any padding, there will not be enough space for
* an accessible touch target.
*/
@Suppress("OPT_IN_MARKER_ON_WRONG_TARGET")
@get:ExperimentalMaterial3Api
@ExperimentalMaterial3Api
val LocalMinimumTouchTargetEnforcement: ProvidableCompositionLocal =
staticCompositionLocalOf { true }
private class MinimumTouchTargetModifier(val size: DpSize) : LayoutModifier {
override fun MeasureScope.measure(
measurable: Measurable,
constraints: Constraints
): MeasureResult {
val placeable = measurable.measure(constraints)
// Be at least as big as the minimum dimension in both dimensions
val width = maxOf(placeable.width, size.width.roundToPx())
val height = maxOf(placeable.height, size.height.roundToPx())
return layout(width, height) {
val centerX = ((width - placeable.width) / 2f).roundToInt()
val centerY = ((height - placeable.height) / 2f).roundToInt()
placeable.place(centerX, centerY)
}
}
override fun equals(other: Any?): Boolean {
val otherModifier = other as? MinimumTouchTargetModifier ?: return false
return size == otherModifier.size
}
override fun hashCode(): Int {
return size.hashCode()
}
}