xref: /compose/ui/ui/src/commonMain/kotlin/androidx/compose/ui/node/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.Modifier
import androidx.compose.ui.graphics.GraphicsLayerScope
import androidx.compose.ui.layout.AlignmentLine
import androidx.compose.ui.layout.ApproachIntrinsicMeasureScope
import androidx.compose.ui.layout.ApproachIntrinsicsMeasureScope
import androidx.compose.ui.layout.ApproachMeasureScope
import androidx.compose.ui.layout.IntrinsicMeasurable
import androidx.compose.ui.layout.IntrinsicMeasureScope
import androidx.compose.ui.layout.IntrinsicsMeasureScope
import androidx.compose.ui.layout.LargeDimension
import androidx.compose.ui.layout.Measurable
import androidx.compose.ui.layout.MeasureResult
import androidx.compose.ui.layout.MeasureScope
import androidx.compose.ui.layout.Placeable
import androidx.compose.ui.unit.Constraints
import androidx.compose.ui.unit.IntOffset
import androidx.compose.ui.unit.IntSize

/**
 * A [Modifier.Node] that changes how its wrapped content is measured and laid out. It has the same
 * measurement and layout functionality as the [androidx.compose.ui.layout.Layout] component, while
 * wrapping exactly one layout due to it being a modifier. In contrast, the
 * [androidx.compose.ui.layout.Layout] component is used to define the layout behavior of multiple
 * children.
 *
 * This is the [androidx.compose.ui.Modifier.Node] equivalent of
 * [androidx.compose.ui.layout.LayoutModifier]
 *
 * @sample androidx.compose.ui.samples.LayoutModifierNodeSample
 * @see androidx.compose.ui.layout.Layout
 */
interface LayoutModifierNode : DelegatableNode {
    /**
     * 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
     * [androidx.compose.ui.layout.Layout], the only difference is that they apply to exactly one
     * child. For a more detailed explanation of measurement and layout, see
     * [androidx.compose.ui.layout.MeasurePolicy].
     */
    fun MeasureScope.measure(measurable: Measurable, constraints: Constraints): MeasureResult

    /** The function used to calculate [IntrinsicMeasurable.minIntrinsicWidth]. */
    fun IntrinsicMeasureScope.minIntrinsicWidth(measurable: IntrinsicMeasurable, height: Int): Int =
        NodeMeasuringIntrinsics.minWidth(
            { intrinsicMeasurable, constraints -> measure(intrinsicMeasurable, constraints) },
            this,
            measurable,
            height
        )

    /** The lambda used to calculate [IntrinsicMeasurable.minIntrinsicHeight]. */
    fun IntrinsicMeasureScope.minIntrinsicHeight(measurable: IntrinsicMeasurable, width: Int): Int =
        NodeMeasuringIntrinsics.minHeight(
            { intrinsicMeasurable, constraints -> measure(intrinsicMeasurable, constraints) },
            this,
            measurable,
            width
        )

    /** The function used to calculate [IntrinsicMeasurable.maxIntrinsicWidth]. */
    fun IntrinsicMeasureScope.maxIntrinsicWidth(measurable: IntrinsicMeasurable, height: Int): Int {
        return NodeMeasuringIntrinsics.maxWidth(
            { intrinsicMeasurable, constraints -> measure(intrinsicMeasurable, constraints) },
            this,
            measurable,
            height
        )
    }

    /** The lambda used to calculate [IntrinsicMeasurable.maxIntrinsicHeight]. */
    fun IntrinsicMeasureScope.maxIntrinsicHeight(measurable: IntrinsicMeasurable, width: Int): Int =
        NodeMeasuringIntrinsics.maxHeight(
            { intrinsicMeasurable, constraints -> measure(intrinsicMeasurable, constraints) },
            this,
            measurable,
            width
        )
}

/**
 * Performs the node remeasuring synchronously even if the node was not marked as needs remeasure
 * before. Useful for cases like when during scrolling you need to re-execute the measure block to
 * consume the scroll offset and remeasure your children in a blocking way.
 */
fun LayoutModifierNode.remeasureSync() = requireLayoutNode().forceRemeasure()

/**
 * This will invalidate the current node's layer, and ensure that the layer is redrawn for the next
 * frame.
 */
fun LayoutModifierNode.invalidateLayer() = requireCoordinator(Nodes.Layout).invalidateLayer()

/**
 * This will invalidate the current node's placement result, and ensure that relayout (the placement
 * block rerun) of this node will happen for the next frame .
 */
fun LayoutModifierNode.invalidatePlacement() = requireLayoutNode().requestRelayout()

/**
 * This invalidates the current node's measure result, and ensures that a re-measurement (the
 * measurement block rerun) of this node will happen for the next frame.
 */
fun LayoutModifierNode.invalidateMeasurement() = requireLayoutNode().invalidateMeasurements()

internal fun LayoutModifierNode.requestRemeasure() = requireLayoutNode().requestRemeasure()

internal object NodeMeasuringIntrinsics {
    // Fun interface for measure block to avoid autoBoxing of Constraints
    internal fun interface MeasureBlock {
        fun MeasureScope.measure(measurable: Measurable, constraints: Constraints): MeasureResult
    }

    internal fun interface ApproachMeasureBlock {
        fun ApproachMeasureScope.measure(
            measurable: Measurable,
            constraints: Constraints
        ): MeasureResult
    }

    internal fun minWidth(
        measureBlock: ApproachMeasureBlock,
        intrinsicMeasureScope: ApproachIntrinsicMeasureScope,
        intrinsicMeasurable: IntrinsicMeasurable,
        h: Int
    ): Int {
        val measurable =
            DefaultIntrinsicMeasurable(
                intrinsicMeasurable,
                IntrinsicMinMax.Min,
                IntrinsicWidthHeight.Width
            )
        val constraints = Constraints(maxHeight = h)
        val layoutResult =
            with(measureBlock) {
                ApproachIntrinsicsMeasureScope(
                        intrinsicMeasureScope,
                        intrinsicMeasureScope.layoutDirection
                    )
                    .measure(measurable, constraints)
            }
        return layoutResult.width
    }

    internal fun minHeight(
        measureBlock: ApproachMeasureBlock,
        intrinsicMeasureScope: ApproachIntrinsicMeasureScope,
        intrinsicMeasurable: IntrinsicMeasurable,
        w: Int
    ): Int {
        val measurable =
            DefaultIntrinsicMeasurable(
                intrinsicMeasurable,
                IntrinsicMinMax.Min,
                IntrinsicWidthHeight.Height
            )
        val constraints = Constraints(maxWidth = w)
        val layoutResult =
            with(measureBlock) {
                ApproachIntrinsicsMeasureScope(
                        intrinsicMeasureScope,
                        intrinsicMeasureScope.layoutDirection
                    )
                    .measure(measurable, constraints)
            }
        return layoutResult.height
    }

    internal fun maxWidth(
        measureBlock: ApproachMeasureBlock,
        intrinsicMeasureScope: ApproachIntrinsicMeasureScope,
        intrinsicMeasurable: IntrinsicMeasurable,
        h: Int
    ): Int {
        val measurable =
            DefaultIntrinsicMeasurable(
                intrinsicMeasurable,
                IntrinsicMinMax.Max,
                IntrinsicWidthHeight.Width
            )
        val constraints = Constraints(maxHeight = h)
        val layoutResult =
            with(measureBlock) {
                ApproachIntrinsicsMeasureScope(
                        intrinsicMeasureScope,
                        intrinsicMeasureScope.layoutDirection
                    )
                    .measure(measurable, constraints)
            }
        return layoutResult.width
    }

    internal fun maxHeight(
        measureBlock: ApproachMeasureBlock,
        intrinsicMeasureScope: ApproachIntrinsicMeasureScope,
        intrinsicMeasurable: IntrinsicMeasurable,
        w: Int
    ): Int {
        val measurable =
            DefaultIntrinsicMeasurable(
                intrinsicMeasurable,
                IntrinsicMinMax.Max,
                IntrinsicWidthHeight.Height
            )
        val constraints = Constraints(maxWidth = w)
        val layoutResult =
            with(measureBlock) {
                ApproachIntrinsicsMeasureScope(
                        intrinsicMeasureScope,
                        intrinsicMeasureScope.layoutDirection
                    )
                    .measure(measurable, constraints)
            }
        return layoutResult.height
    }

    internal fun minWidth(
        measureBlock: MeasureBlock,
        intrinsicMeasureScope: IntrinsicMeasureScope,
        intrinsicMeasurable: IntrinsicMeasurable,
        h: Int
    ): Int {
        val measurable =
            DefaultIntrinsicMeasurable(
                intrinsicMeasurable,
                IntrinsicMinMax.Min,
                IntrinsicWidthHeight.Width
            )
        val constraints = Constraints(maxHeight = h)
        val layoutResult =
            with(measureBlock) {
                IntrinsicsMeasureScope(intrinsicMeasureScope, intrinsicMeasureScope.layoutDirection)
                    .measure(measurable, constraints)
            }

        return layoutResult.width
    }

    internal fun minHeight(
        measureBlock: MeasureBlock,
        intrinsicMeasureScope: IntrinsicMeasureScope,
        intrinsicMeasurable: IntrinsicMeasurable,
        w: Int
    ): Int {
        val measurable =
            DefaultIntrinsicMeasurable(
                intrinsicMeasurable,
                IntrinsicMinMax.Min,
                IntrinsicWidthHeight.Height
            )
        val constraints = Constraints(maxWidth = w)
        val layoutResult =
            with(measureBlock) {
                IntrinsicsMeasureScope(intrinsicMeasureScope, intrinsicMeasureScope.layoutDirection)
                    .measure(measurable, constraints)
            }
        return layoutResult.height
    }

    internal fun maxWidth(
        measureBlock: MeasureBlock,
        intrinsicMeasureScope: IntrinsicMeasureScope,
        intrinsicMeasurable: IntrinsicMeasurable,
        h: Int
    ): Int {
        val measurable =
            DefaultIntrinsicMeasurable(
                intrinsicMeasurable,
                IntrinsicMinMax.Max,
                IntrinsicWidthHeight.Width
            )
        val constraints = Constraints(maxHeight = h)
        val layoutResult =
            with(measureBlock) {
                IntrinsicsMeasureScope(intrinsicMeasureScope, intrinsicMeasureScope.layoutDirection)
                    .measure(measurable, constraints)
            }
        return layoutResult.width
    }

    internal fun maxHeight(
        measureBlock: MeasureBlock,
        intrinsicMeasureScope: IntrinsicMeasureScope,
        intrinsicMeasurable: IntrinsicMeasurable,
        w: Int
    ): Int {
        val measurable =
            DefaultIntrinsicMeasurable(
                intrinsicMeasurable,
                IntrinsicMinMax.Max,
                IntrinsicWidthHeight.Height
            )
        val constraints = Constraints(maxWidth = w)
        val layoutResult =
            with(measureBlock) {
                IntrinsicsMeasureScope(intrinsicMeasureScope, intrinsicMeasureScope.layoutDirection)
                    .measure(measurable, constraints)
            }
        return layoutResult.height
    }

    private class DefaultIntrinsicMeasurable(
        val measurable: IntrinsicMeasurable,
        val minMax: IntrinsicMinMax,
        val widthHeight: IntrinsicWidthHeight
    ) : Measurable {
        override val parentData: Any?
            get() = measurable.parentData

        override fun measure(constraints: Constraints): Placeable {
            if (widthHeight == IntrinsicWidthHeight.Width) {
                val width =
                    if (minMax == IntrinsicMinMax.Max) {
                        measurable.maxIntrinsicWidth(constraints.maxHeight)
                    } else {
                        measurable.minIntrinsicWidth(constraints.maxHeight)
                    }
                val height =
                    if (constraints.hasBoundedHeight) constraints.maxHeight else LargeDimension
                return EmptyPlaceable(width, height)
            }
            val height =
                if (minMax == IntrinsicMinMax.Max) {
                    measurable.maxIntrinsicHeight(constraints.maxWidth)
                } else {
                    measurable.minIntrinsicHeight(constraints.maxWidth)
                }
            val width = if (constraints.hasBoundedWidth) constraints.maxWidth else LargeDimension
            return EmptyPlaceable(width, height)
        }

        override fun minIntrinsicWidth(height: Int): Int {
            return measurable.minIntrinsicWidth(height)
        }

        override fun maxIntrinsicWidth(height: Int): Int {
            return measurable.maxIntrinsicWidth(height)
        }

        override fun minIntrinsicHeight(width: Int): Int {
            return measurable.minIntrinsicHeight(width)
        }

        override fun maxIntrinsicHeight(width: Int): Int {
            return measurable.maxIntrinsicHeight(width)
        }
    }

    private class EmptyPlaceable(width: Int, height: Int) : Placeable() {
        init {
            measuredSize = IntSize(width, height)
        }

        override fun get(alignmentLine: AlignmentLine): Int = AlignmentLine.Unspecified

        override fun placeAt(
            position: IntOffset,
            zIndex: Float,
            layerBlock: (GraphicsLayerScope.() -> Unit)?
        ) {}
    }

    private enum class IntrinsicMinMax {
        Min,
        Max
    }

    private enum class IntrinsicWidthHeight {
        Width,
        Height
    }
}