LayoutModifierNode.kt
/*
* Copyright 2022 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.ui.node
import androidx.compose.ui.ExperimentalComposeUiApi
import androidx.compose.ui.layout.IntrinsicMeasurable
import androidx.compose.ui.layout.IntrinsicMeasureScope
import androidx.compose.ui.layout.Measurable
import androidx.compose.ui.layout.MeasureResult
import androidx.compose.ui.layout.MeasureScope
import androidx.compose.ui.layout.Remeasurement
import androidx.compose.ui.unit.Constraints
import androidx.compose.ui.unit.IntSize
@ExperimentalComposeUiApi
interface LayoutModifierNode : Remeasurement, DelegatableNode {
// NOTE(lmr): i guess RemeasurementModifier was created because there are some use
// cases where we want to call forceRemeasure but we don't want to implement MeasureNode.
// I think maybe we should just add this as an API on DelegatingNode. I don't think we need
// to burn a NodeType on this...
override fun forceRemeasure() = requireLayoutNode().forceRemeasure()
/**
* The function used to measure the modifier. The [measurable] corresponds to the
* wrapped content, and it can be measured with the desired constraints according
* to the logic of the [LayoutModifierNode]. The modifier needs to choose its own
* size, which can depend on the size chosen by the wrapped content (the obtained
* [Placeable]), if the wrapped content was measured. The size needs to be returned
* as part of a [MeasureResult], alongside the placement logic of the
* [Placeable], which defines how the wrapped content should be positioned inside
* the [LayoutModifierNode]. A convenient way to create the [MeasureResult]
* is to use the [MeasureScope.layout] factory function.
*
* A [LayoutModifierNode] uses the same measurement and layout concepts and principles as a
* [Layout], the only difference is that they apply to exactly one child. For a more detailed
* explanation of measurement and layout, see [MeasurePolicy].
*/
fun MeasureScope.measure(
measurable: Measurable,
constraints: Constraints
): MeasureResult
/**
* The function used to calculate [IntrinsicMeasurable.minIntrinsicWidth].
*/
fun IntrinsicMeasureScope.minIntrinsicWidth(
measurable: IntrinsicMeasurable,
height: Int
): Int
/**
* The lambda used to calculate [IntrinsicMeasurable.minIntrinsicHeight].
*/
fun IntrinsicMeasureScope.minIntrinsicHeight(
measurable: IntrinsicMeasurable,
width: Int
): Int
/**
* The function used to calculate [IntrinsicMeasurable.maxIntrinsicWidth].
*/
fun IntrinsicMeasureScope.maxIntrinsicWidth(
measurable: IntrinsicMeasurable,
height: Int
): Int
/**
* The lambda used to calculate [IntrinsicMeasurable.maxIntrinsicHeight].
*/
fun IntrinsicMeasureScope.maxIntrinsicHeight(
measurable: IntrinsicMeasurable,
width: Int
): Int
}
@ExperimentalComposeUiApi
internal fun LayoutModifierNode.invalidateLayer() =
requireCoordinator(Nodes.Layout).invalidateLayer()
@ExperimentalComposeUiApi
internal fun LayoutModifierNode.requestRelayout() = requireLayoutNode().requestRelayout()
@ExperimentalComposeUiApi
internal fun LayoutModifierNode.requestRemeasure() = requireLayoutNode().requestRemeasure()
@ExperimentalComposeUiApi
interface IntermediateLayoutModifierNode : LayoutModifierNode {
var targetSize: IntSize
}