commonMain.androidx.compose.ui.node.InnerNodeCoordinator.kt Maven / Gradle / Ivy

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Compose UI primitives. This library contains the primitives that form the Compose UI Toolkit, such as drawing, measurement and layout.
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/*
 * 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.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.graphics.Canvas
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.GraphicsLayerScope
import androidx.compose.ui.graphics.Paint
import androidx.compose.ui.graphics.PaintingStyle
import androidx.compose.ui.graphics.layer.GraphicsLayer
import androidx.compose.ui.layout.AlignmentLine
import androidx.compose.ui.layout.Placeable
import androidx.compose.ui.unit.Constraints
import androidx.compose.ui.unit.IntOffset

internal class TailModifierNode : Modifier.Node() {
    init {
        // aggregateChildKindSet defaults to all bits being set, and is expected to be set later.
        // We can deterministically set the tail's because the tail will never have children by
        // definition.
        aggregateChildKindSet = 0
    }

    // BackwardsCompatNode uses this to determine if it is in a "chain update" or not. If attach
    // has been run on the tail node, then we can assume that it is a chain update. Importantly,
    // this is different than using isAttached.
    var attachHasBeenRun = false
    override fun toString(): String {
        return ""
    }

    override fun onAttach() {
        attachHasBeenRun = true
    }

    override fun onDetach() {
        attachHasBeenRun = false
    }
}

internal class InnerNodeCoordinator(
    layoutNode: LayoutNode
) : NodeCoordinator(layoutNode) {
    @OptIn(ExperimentalComposeUiApi::class)
    override val tail = TailModifierNode()

    init {
        @OptIn(ExperimentalComposeUiApi::class)
        tail.updateCoordinator(this)
    }

    override var lookaheadDelegate: LookaheadDelegate? =
        if (layoutNode.lookaheadRoot != null) LookaheadDelegateImpl() else null

    private inner class LookaheadDelegateImpl : LookaheadDelegate(this@InnerNodeCoordinator) {

        // Lookahead measure
        override fun measure(constraints: Constraints): Placeable =
            performingMeasure(constraints) {
                // before rerunning the user's measure block reset previous measuredByParent for children
                layoutNode.forEachChild {
                    it.lookaheadPassDelegate!!.measuredByParent =
                        LayoutNode.UsageByParent.NotUsed
                }
                val measureResult = with(layoutNode.measurePolicy) {
                    measure(
                        layoutNode.childLookaheadMeasurables,
                        constraints
                    )
                }
                measureResult
            }

        override fun calculateAlignmentLine(alignmentLine: AlignmentLine): Int {
            return (alignmentLinesOwner
                .calculateAlignmentLines()[alignmentLine] ?: AlignmentLine.Unspecified).also {
                cachedAlignmentLinesMap[alignmentLine] = it
            }
        }

        override fun placeChildren() {
            layoutNode.lookaheadPassDelegate!!.onNodePlaced()
        }

        override fun minIntrinsicWidth(height: Int) =
            layoutNode.minLookaheadIntrinsicWidth(height)

        override fun minIntrinsicHeight(width: Int) =
            layoutNode.minLookaheadIntrinsicHeight(width)

        override fun maxIntrinsicWidth(height: Int) =
            layoutNode.maxLookaheadIntrinsicWidth(height)

        override fun maxIntrinsicHeight(width: Int) =
            layoutNode.maxLookaheadIntrinsicHeight(width)
    }

    override fun ensureLookaheadDelegateCreated() {
        if (lookaheadDelegate == null) {
            lookaheadDelegate = LookaheadDelegateImpl()
        }
    }

    override fun measure(constraints: Constraints): Placeable {
        @Suppress("NAME_SHADOWING") val constraints =
            if (forceMeasureWithLookaheadConstraints) {
                lookaheadDelegate!!.constraints
            } else {
                constraints
            }
        return performingMeasure(constraints) {
            // before rerunning the user's measure block reset previous measuredByParent for children
            layoutNode.forEachChild {
                it.measurePassDelegate.measuredByParent = LayoutNode.UsageByParent.NotUsed
            }

            measureResult = with(layoutNode.measurePolicy) {
                measure(layoutNode.childMeasurables, constraints)
            }
            onMeasured()
            this
        }
    }

    override fun minIntrinsicWidth(height: Int) =
        layoutNode.minIntrinsicWidth(height)

    override fun minIntrinsicHeight(width: Int) =
        layoutNode.minIntrinsicHeight(width)

    override fun maxIntrinsicWidth(height: Int) =
        layoutNode.maxIntrinsicWidth(height)

    override fun maxIntrinsicHeight(width: Int) =
        layoutNode.maxIntrinsicHeight(width)

    override fun placeAt(
        position: IntOffset,
        zIndex: Float,
        layer: GraphicsLayer
    ) {
        super.placeAt(position, zIndex, layer)
        onAfterPlaceAt()
    }

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

    private fun onAfterPlaceAt() {
        // The coordinator only runs their placement block to obtain our position, which allows them
        // to calculate the offset of an alignment line we have already provided a position for.
        // No need to place our wrapped as well (we might have actually done this already in
        // get(line), to obtain the position of the alignment line the coordinator currently needs
        // our position in order ot know how to offset the value we provided).
        if (isShallowPlacing) return

        onPlaced()

        layoutNode.measurePassDelegate.onNodePlaced()
    }

    override fun calculateAlignmentLine(alignmentLine: AlignmentLine): Int {
        return lookaheadDelegate?.calculateAlignmentLine(alignmentLine)
            ?: alignmentLinesOwner
                .calculateAlignmentLines()[alignmentLine]
            ?: AlignmentLine.Unspecified
    }

    override fun performDraw(canvas: Canvas, graphicsLayer: GraphicsLayer?) {
        val owner = layoutNode.requireOwner()
        layoutNode.zSortedChildren.forEach { child ->
            if (child.isPlaced) {
                child.draw(canvas, graphicsLayer)
            }
        }
        if (owner.showLayoutBounds) {
            drawBorder(canvas, innerBoundsPaint)
        }
    }

    @OptIn(ExperimentalComposeUiApi::class)
    override fun hitTestChild(
        hitTestSource: HitTestSource,
        pointerPosition: Offset,
        hitTestResult: HitTestResult,
        isTouchEvent: Boolean,
        isInLayer: Boolean
    ) {
        var inLayer = isInLayer
        var hitTestChildren = false

        if (hitTestSource.shouldHitTestChildren(layoutNode)) {
            if (withinLayerBounds(pointerPosition)) {
                hitTestChildren = true
            } else if (isTouchEvent &&
                distanceInMinimumTouchTarget(pointerPosition, minimumTouchTargetSize).isFinite()
            ) {
                inLayer = false
                hitTestChildren = true
            }
        }

        if (hitTestChildren) {
            hitTestResult.siblingHits {
                // Any because as soon as true is returned, we know we have found a hit path and we must
                // not add hit results on different paths so we should not even go looking.
                layoutNode.zSortedChildren.reversedAny { child ->
                    if (child.isPlaced) {
                        hitTestSource.childHitTest(
                            child,
                            pointerPosition,
                            hitTestResult,
                            isTouchEvent,
                            inLayer
                        )
                        val wasHit = hitTestResult.hasHit()
                        val continueHitTest: Boolean
                        if (!wasHit) {
                            continueHitTest = true
                        } else if (hitTestResult.shouldSharePointerInputWithSibling) {
                            hitTestResult.acceptHits()
                            continueHitTest = true
                        } else {
                            continueHitTest = false
                        }
                        !continueHitTest
                    } else {
                        false
                    }
                }
            }
        }
    }

    internal companion object {
        val innerBoundsPaint = Paint().also { paint ->
            paint.color = Color.Red
            paint.strokeWidth = 1f
            paint.style = PaintingStyle.Stroke
        }
    }
}