| /* |
| * 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.ui.core.samples |
| |
| import androidx.annotation.Sampled |
| import androidx.compose.Composable |
| import androidx.compose.remember |
| import androidx.ui.core.HorizontalAlignmentLine |
| import androidx.ui.core.Layout |
| import kotlin.math.min |
| |
| @Sampled |
| @Composable |
| fun AlignmentLineSample() { |
| // Create a horizontal alignment line. Note it is not common for alignment lines to be created |
| // in the scope of one composable, since they are usually used across more than one function. |
| // We use ::min as merging strategy, which means that the parent will have the minimum of |
| // the values of the alignment line, when this is inherited from more than one child. |
| val exampleLine = remember { HorizontalAlignmentLine(::min) } |
| |
| // A layout with a fixed size, and a given position for the exampleLine alignment line. |
| @Composable |
| fun LineProviderLayout(exampleLinePosition: Int) { |
| val size: Int = 20 |
| Layout({}) { _, _ -> |
| layout(size, size, mapOf(exampleLine to exampleLinePosition)) {} |
| } |
| } |
| |
| Layout({ |
| LineProviderLayout(exampleLinePosition = 5) |
| LineProviderLayout(exampleLinePosition = 10) |
| }) { measurables, constraints -> |
| val placeables = measurables.map { it.measure(constraints) } |
| // placeables[0][line] will be 5 |
| // placeables[1][line] will be 10 |
| layout(constraints.maxWidth, constraints.maxHeight) { |
| placeables[0].placeAbsolute(0, 3) |
| placeables[1].placeAbsolute(constraints.maxWidth / 2, 0) |
| } |
| } |
| // Note that if the parent of this Layout (the parent of AlignmentLineSample) was able to |
| // query its position of exampleLine (assuming this was in a shared scope), its position would |
| // be 8. This is because the Layout positioned its first child at 3 from the top, |
| // and because of the ::min merging strategy the position of exampleLine will be |
| // min(5 + 3, 10 + 0). |
| } |