LayoutOffset.kt
/*
* Copyright 2020 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.runtime.State
import androidx.compose.runtime.mutableStateOf
import androidx.compose.ui.LayoutModifier
import androidx.compose.ui.Measurable
import androidx.compose.ui.MeasureScope
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.Constraints
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.LayoutDirection
import androidx.compose.ui.unit.dp
import kotlin.math.roundToInt
/**
* Offset the content by ([x] dp, [y] dp). The offsets can be positive as well as non-positive.
*
* Example usage:
* @sample androidx.compose.foundation.layout.samples.LayoutOffsetModifier
*/
@Stable
fun Modifier.offset(x: Dp = 0.dp, y: Dp = 0.dp) = this.then(OffsetModifier(x, y, true))
/**
* Offset the content by ([x] dp, [y] dp). The offsets can be positive as well as non-positive.
* The offsets are applied without regard to the current [LayoutDirection], see [Modifier
* .offset] to apply relative offsets.
*
* Example usage:
* @sample androidx.compose.foundation.layout.samples.LayoutAbsoluteOffsetModifier
*/
@Stable
fun Modifier.absoluteOffset(x: Dp = 0.dp, y: Dp = 0.dp) =
this.then(OffsetModifier(x, y, false))
/**
* Offset the content by ([x] px, [y] px). The offsets can be positive as well as non-positive.
* This modifier is designed to be used for offsets that change, possibly due to user interactions.
*
* Example usage:
* @sample androidx.compose.foundation.layout.samples.LayoutOffsetPxModifier
*/
fun Modifier.offsetPx(
x: State<Float> = mutableStateOf(0f),
y: State<Float> = mutableStateOf(0f)
) = this.then(OffsetPxModifier(x, y, true))
/**
* Offset the content by ([x] px, [y] px). The offsets can be positive as well as non-positive.
* This modifier is designed to be used for offsets that change, possibly due to user interactions.
*
* The offsets are applied without regard to the current [LayoutDirection]. To apply relative
* offsets, use [Modifier.offsetPx] instead.
*
* Example usage:
* @sample androidx.compose.foundation.layout.samples.LayoutAbsoluteOffsetPxModifier
*/
fun Modifier.absoluteOffsetPx(
x: State<Float> = mutableStateOf(0f),
y: State<Float> = mutableStateOf(0f)
) = this.then(OffsetPxModifier(x, y, false))
private data class OffsetModifier(val x: Dp, val y: Dp, val rtlAware: Boolean) : LayoutModifier {
override fun MeasureScope.measure(
measurable: Measurable,
constraints: Constraints
): MeasureScope.MeasureResult {
val placeable = measurable.measure(constraints)
return layout(placeable.width, placeable.height) {
if (rtlAware) {
placeable.placeRelative(x.toIntPx(), y.toIntPx())
} else {
placeable.place(x.toIntPx(), y.toIntPx())
}
}
}
}
private data class OffsetPxModifier(
val x: State<Float>,
val y: State<Float>,
val rtlAware: Boolean
) : LayoutModifier {
override fun MeasureScope.measure(
measurable: Measurable,
constraints: Constraints
): MeasureScope.MeasureResult {
val placeable = measurable.measure(constraints)
return layout(placeable.width, placeable.height) {
if (rtlAware) {
placeable.placeRelative(x.value.roundToInt(), y.value.roundToInt())
} else {
placeable.place(x.value.roundToInt(), y.value.roundToInt())
}
}
}
}