ui/ui-layout/integration-tests/layout-demos/src/main/java/androidx/compose/foundation/layout/demos/RtlDemo.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.foundation.layout.demos

import androidx.compose.runtime.Composable
import androidx.compose.ui.Alignment
import androidx.compose.ui.Layout
import androidx.compose.ui.unit.LayoutDirection
import androidx.compose.ui.Modifier
import androidx.compose.ui.WithConstraints
import androidx.compose.foundation.Text
import androidx.compose.foundation.background
import androidx.compose.ui.graphics.Color
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.Stack
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.preferredSize
import androidx.compose.foundation.layout.wrapContentHeight
import androidx.compose.foundation.layout.wrapContentSize
import androidx.compose.runtime.Providers
import androidx.compose.ui.platform.LayoutDirectionAmbient
import androidx.compose.ui.unit.IntOffset
import androidx.compose.ui.unit.dp

@Composable
fun RtlDemo() {
    Column(verticalArrangement = Arrangement.SpaceEvenly) {
        Text("TEXT", Modifier.gravity(Alignment.CenterHorizontally))
        testText()
        Text("ROW", Modifier.gravity(Alignment.CenterHorizontally))
        testRow()
        Text("ROW WITH LTR ROW IN BETWEEN", Modifier.gravity(Alignment.CenterHorizontally))
        testRow_modifier()
        Text("RELATIVE TO SIBLINGS", Modifier.gravity(Alignment.CenterHorizontally))
        testSiblings()
        Text(
            "PLACE WITH AUTO RTL SUPPORT IN CUSTOM LAYOUT",
            Modifier.gravity(Alignment.CenterHorizontally)
        )
        CustomLayout(true)
        Text(
            "PLACE WITHOUT RTL SUPPORT IN CUSTOM LAYOUT",
            Modifier.gravity(Alignment.CenterHorizontally)
        )
        CustomLayout(false)
        Text("WITH CONSTRAINTS", Modifier.gravity(Alignment.CenterHorizontally))
        Providers(LayoutDirectionAmbient provides LayoutDirection.Ltr) {
            LayoutWithConstraints("LD: set LTR via ambient")
        }
        Providers(LayoutDirectionAmbient provides LayoutDirection.Rtl) {
            LayoutWithConstraints("LD: set RTL via ambient")
        }
        LayoutWithConstraints(text = "LD: locale")
        Text("STACK EXAMPLE", Modifier.gravity(Alignment.CenterHorizontally))
        StackExample()
    }
}

@Composable
fun StackExample() {
    Stack(Modifier.fillMaxSize().background(Color.LightGray)) {
        Stack(Modifier.fillMaxSize().wrapContentSize(Alignment.TopStart)) {
            Stack(boxSize.then(Modifier.background(Color.Red))) {}
        }
        Stack(Modifier.fillMaxSize().wrapContentHeight(Alignment.CenterVertically)) {
            Stack(boxSize.then(Modifier.background(Color.Green))) {}
        }
        Stack(Modifier.fillMaxSize().wrapContentSize(Alignment.BottomEnd)) {
            Stack(boxSize.then(Modifier.background(Color.Blue))) {}
        }
    }
}

private val boxSize = Modifier.preferredSize(50.dp, 20.dp)
private val size = Modifier.preferredSize(10.dp, 10.dp)

@Composable
private fun testRow() {
    Row {
        Stack(boxSize.background(color = Color.Red)) {}
        Stack(boxSize.background(color = Color.Green)) {}
        Row {
            Stack(boxSize.background(color = Color.Magenta)) {}
            Stack(boxSize.background(color = Color.Yellow)) {}
            Stack(boxSize.background(color = Color.Cyan)) {}
        }
        Stack(boxSize.background(color = Color.Blue)) {}
    }
}

@Composable
private fun testRow_modifier() {
    Row {
        Stack(boxSize.background(Color.Red)) {}
        Stack(boxSize.background(Color.Green)) {}
        Providers(LayoutDirectionAmbient provides LayoutDirection.Ltr) {
            Row {
                Stack(boxSize.background(Color.Magenta)) {}
                Stack(boxSize.background(Color.Yellow)) {}
                Stack(boxSize.background(Color.Cyan)) {}
            }
        }
        Stack(boxSize.background(color = Color.Blue)) {}
    }
}

@Composable
private fun testText() {
    Column {
        Text("Text.")
        Text("Text filling max width.", Modifier.fillMaxWidth())
        Text("שלום!")
        Text("שלום!", Modifier.fillMaxWidth())
        Text("-->")
        Text("-->", Modifier.fillMaxWidth())
    }
}

@Composable
private fun testSiblings() {
    Column {
        Stack(boxSize.background(color = Color.Red).alignWithSiblings { p -> p.width }
        ) {}
        Stack(boxSize.background(color = Color.Green).alignWithSiblings { p -> p.width / 2 }
        ) {}
        Stack(boxSize.background(color = Color.Blue).alignWithSiblings { p -> p.width / 4 }
        ) {}
    }
}

@Composable
private fun CustomLayout(rtlSupport: Boolean) {
    Layout(children = @Composable {
        Stack(boxSize.background(color = Color.Red)) {}
        Stack(boxSize.background(color = Color.Green)) {}
        Stack(boxSize.background(color = Color.Blue)) {}
    }) { measurables, constraints ->
        val p = measurables.map { e ->
            e.measure(constraints.copy(minWidth = 0, minHeight = 0))
        }
        val w = p.fold(0) { sum, e -> sum + e.width }
        val h = p.maxByOrNull { it.height }!!.height
        layout(w, h) {
            var xPosition = 0
            for (child in p) {
                child.place(IntOffset(xPosition, 0))
                if (rtlSupport) {
                    child.placeRelative(IntOffset(xPosition, 0))
                } else {
                    child.place(IntOffset(xPosition, 0))
                }
                xPosition += child.width
            }
        }
    }
}

@Composable
private fun LayoutWithConstraints(text: String) {
    WithConstraints {
        val w = maxWidth / 3
        val color = if (LayoutDirectionAmbient.current == LayoutDirection.Ltr) {
            Color.Red
        } else {
            Color.Magenta
        }
        Stack(Modifier.preferredSize(w, 20.dp).background(color)) {
            Text(text, Modifier.gravity(Alignment.Center))
        }
    }
}