| /* |
| * Copyright 2019 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.ui.framework.samples |
| |
| import androidx.annotation.Sampled |
| import androidx.compose.Composable |
| import androidx.ui.core.Constraints |
| import androidx.ui.core.Dp |
| import androidx.ui.core.Layout |
| import androidx.ui.core.Modifier |
| import androidx.ui.core.OnChildPositioned |
| import androidx.ui.core.OnPositioned |
| import androidx.ui.core.coerceAtLeast |
| import androidx.ui.core.coerceIn |
| import androidx.ui.core.dp |
| import androidx.ui.core.globalPosition |
| import androidx.ui.core.ipx |
| import androidx.ui.core.max |
| import androidx.ui.core.positionInRoot |
| import androidx.ui.foundation.shape.DrawShape |
| import androidx.ui.foundation.shape.RectangleShape |
| import androidx.ui.graphics.Color |
| |
| @Sampled |
| @Composable |
| fun OnPositionedSample() { |
| Column { |
| SizedRectangle(color = Color.Green, width = 20.dp, height = 20.dp) |
| SizedRectangle(color = Color.Blue, width = 20.dp, height = 20.dp) |
| OnPositioned(onPositioned = { coordinates -> |
| // This will be the size of the Column. |
| coordinates.size |
| // This will be the position of Column inside its parent. |
| coordinates.position |
| // The position of the Column relative to the application window. |
| coordinates.globalPosition |
| // The position of the Column relative to the Compose root. |
| coordinates.positionInRoot |
| // These will be the alignment lines provided to the layout (empty here for Column). |
| coordinates.providedAlignmentLines |
| // This will a LayoutCoordinates instance corresponding to the parent of Column. |
| coordinates.parentCoordinates |
| }) |
| } |
| } |
| |
| @Sampled |
| @Composable |
| fun OnChildPositionedSample() { |
| Column { |
| SizedRectangle(color = Color.Green, width = 20.dp, height = 20.dp) |
| OnChildPositioned(onPositioned = { coordinates -> |
| // This will be the size of the child SizedRectangle. |
| coordinates.size |
| // This will be the position of SizedRectangle inside its Column parent. |
| coordinates.position |
| // The position of the SizedRectangle relative to the application window. |
| coordinates.globalPosition |
| // The position of the SizedRectangle relative to the Compose root. |
| coordinates.positionInRoot |
| // These will be the alignment lines provided to the layout (empty for SizedRectangle) |
| coordinates.providedAlignmentLines |
| // This will a LayoutCoordinates instance corresponding to the Column. |
| coordinates.parentCoordinates |
| }) { |
| SizedRectangle(color = Color.Blue, width = 20.dp, height = 20.dp) |
| } |
| } |
| } |
| |
| /** |
| * Simple Column implementation. |
| */ |
| @Composable |
| fun Column(children: @Composable() () -> Unit) { |
| Layout(children) { measurables, constraints -> |
| val placeables = measurables.map { measurable -> |
| measurable.measure( |
| Constraints(minWidth = constraints.minWidth, maxWidth = constraints.maxWidth) |
| ) |
| } |
| val columnWidth = (placeables.maxBy { it.width.value }?.width ?: 0.ipx) |
| .coerceAtLeast(constraints.minWidth) |
| val columnHeight = placeables.sumBy { it.height.value }.ipx.coerceIn( |
| constraints.minHeight, |
| constraints.maxHeight |
| ) |
| layout(columnWidth, columnHeight) { |
| var top = 0.ipx |
| placeables.forEach { placeable -> |
| placeable.place(0.ipx, top) |
| top += placeable.height |
| } |
| } |
| } |
| } |
| |
| /** |
| * A rectangle layout that tries to size itself to specified width and height, subject to |
| * the incoming constraints. The composable also draws a color in the space of the rectangle |
| * layout. If the width and/or height of the rectangle are not specified, the rectangle will |
| * be sized to the incoming max constraints. |
| */ |
| @Composable |
| fun SizedRectangle( |
| modifier: Modifier = Modifier.None, |
| color: Color, |
| width: Dp? = null, |
| height: Dp? = null |
| ) { |
| Layout(children = { DrawRectangle(color = color) }, modifier = modifier) { _, constraints -> |
| val widthPx = max(width?.toIntPx() ?: constraints.maxWidth, constraints.minWidth) |
| val heightPx = max(height?.toIntPx() ?: constraints.maxHeight, constraints.minHeight) |
| layout(widthPx, heightPx) {} |
| } |
| } |
| |
| /** |
| * Draws a rectangle of a given color in the space of the parent layout. |
| */ |
| @Composable |
| fun DrawRectangle(color: Color) { |
| DrawShape(shape = RectangleShape, color = color) |
| } |