LayoutCoordinates.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.ui.layout
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.geometry.Rect
import androidx.compose.ui.node.LayoutNodeWrapper
import androidx.compose.ui.unit.IntSize
import kotlin.jvm.JvmDefaultWithCompatibility
/**
* A holder of the measured bounds for the layout (MeasureBox).
*/
@JvmDefaultWithCompatibility
interface LayoutCoordinates {
/**
* The size of this layout in the local coordinates space.
*/
val size: IntSize
/**
* The alignment lines provided for this layout, not including inherited lines.
*/
val providedAlignmentLines: Set<AlignmentLine>
/**
* The coordinates of the parent layout. Null if there is no parent.
*/
val parentLayoutCoordinates: LayoutCoordinates?
/**
* The coordinates of the parent layout modifier or parent layout if there is no
* parent layout modifier, or `null` if there is no parent.
*/
val parentCoordinates: LayoutCoordinates?
/**
* Returns false if the corresponding layout was detached from the hierarchy.
*/
val isAttached: Boolean
/**
* Converts [relativeToWindow] relative to the window's origin into an [Offset] relative to
* this layout.
*/
fun windowToLocal(relativeToWindow: Offset): Offset
/**
* Converts [relativeToLocal] position within this layout into an [Offset] relative to the
* window's origin.
*/
fun localToWindow(relativeToLocal: Offset): Offset
/**
* Converts a local position within this layout into an offset from the root composable.
*/
fun localToRoot(relativeToLocal: Offset): Offset
/**
* Converts an [relativeToSource] in [sourceCoordinates] space into local coordinates.
* [sourceCoordinates] may be any [LayoutCoordinates] that belong to the same
* compose layout hierarchy.
*/
fun localPositionOf(sourceCoordinates: LayoutCoordinates, relativeToSource: Offset): Offset
/**
* Returns the bounding box of [sourceCoordinates] in the local coordinates.
* If [clipBounds] is `true`, any clipping that occurs between [sourceCoordinates] and
* this layout will affect the returned bounds, and can even result in an empty rectangle
* if clipped regions do not overlap. If [clipBounds] is false, the bounding box of
* [sourceCoordinates] will be converted to local coordinates irrespective of any clipping
* applied between the layouts.
*
* When rotation or scaling is applied, the bounding box of the rotated or scaled value
* will be computed in the local coordinates. For example, if a 40 pixels x 20 pixel layout
* is rotated 90 degrees, the bounding box will be 20 pixels x 40 pixels in its parent's
* coordinates.
*/
fun localBoundingBoxOf(sourceCoordinates: LayoutCoordinates, clipBounds: Boolean = true): Rect
/**
* Returns the position in pixels of an [alignment line][AlignmentLine],
* or [AlignmentLine.Unspecified] if the line is not provided.
*/
operator fun get(alignmentLine: AlignmentLine): Int
}
/**
* The position of this layout inside the root composable.
*/
fun LayoutCoordinates.positionInRoot(): Offset = localToRoot(Offset.Zero)
/**
* The position of this layout relative to the window.
*/
fun LayoutCoordinates.positionInWindow(): Offset = localToWindow(Offset.Zero)
/**
* The boundaries of this layout inside the root composable.
*/
fun LayoutCoordinates.boundsInRoot(): Rect =
findRoot().localBoundingBoxOf(this)
/**
* The boundaries of this layout relative to the window's origin.
*/
fun LayoutCoordinates.boundsInWindow(): Rect {
val root = findRoot()
val bounds = boundsInRoot()
val topLeft = root.localToWindow(Offset(bounds.left, bounds.top))
val topRight = root.localToWindow(Offset(bounds.right, bounds.top))
val bottomRight = root.localToWindow(Offset(bounds.right, bounds.bottom))
val bottomLeft = root.localToWindow(Offset(bounds.left, bounds.bottom))
val left = minOf(topLeft.x, topRight.x, bottomLeft.x, bottomRight.x)
val top = minOf(topLeft.y, topRight.y, bottomLeft.y, bottomRight.y)
val right = maxOf(topLeft.x, topRight.x, bottomLeft.x, bottomRight.x)
val bottom = maxOf(topLeft.y, topRight.y, bottomLeft.y, bottomRight.y)
return Rect(left, top, right, bottom)
}
/**
* Returns the position of the top-left in the parent's content area or (0, 0)
* for the root.
*/
fun LayoutCoordinates.positionInParent(): Offset =
parentLayoutCoordinates?.localPositionOf(this, Offset.Zero) ?: Offset.Zero
/**
* Returns the bounding box of the child in the parent's content area, including any clipping
* done with respect to the parent. For the root, the bounds is positioned at (0, 0) and sized
* to the size of the root.
*/
fun LayoutCoordinates.boundsInParent(): Rect =
parentLayoutCoordinates?.localBoundingBoxOf(this)
?: Rect(0f, 0f, size.width.toFloat(), size.height.toFloat())
/**
* Returns the [LayoutCoordinates] of the root layout element in the hierarchy. This will have
* the size of the entire compose UI.
*/
internal fun LayoutCoordinates.findRoot(): LayoutCoordinates {
var root = this
var parent = root.parentLayoutCoordinates
while (parent != null) {
root = parent
parent = root.parentLayoutCoordinates
}
var rootLayoutNodeWrapper = root as? LayoutNodeWrapper ?: return root
var parentLayoutNodeWrapper = rootLayoutNodeWrapper.wrappedBy
while (parentLayoutNodeWrapper != null) {
rootLayoutNodeWrapper = parentLayoutNodeWrapper
parentLayoutNodeWrapper = parentLayoutNodeWrapper.wrappedBy
}
return rootLayoutNodeWrapper
}