ThinkingInComposeSnippets.kt

/*
 * Copyright 2023 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
 *
 *     https://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.
 */

@file:Suppress("unused")

package com.example.compose.snippets.mentalmodel

import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.material.Button
import androidx.compose.material.Checkbox
import androidx.compose.material.Divider
import androidx.compose.material.Text
import androidx.compose.material3.MaterialTheme
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier

// [START android_compose_thinking_in_compose_dynamic_content]
@Composable
fun Greeting(names: List<String>) {
    for (name in names) {
        Text("Hello $name")
    }
}
// [END android_compose_thinking_in_compose_dynamic_content]

// [START android_compose_thinking_in_compose_recomposition]
@Composable
fun ClickCounter(clicks: Int, onClick: () -> Unit) {
    Button(onClick = onClick) {
        Text("I've been clicked $clicks times")
    }
}
// [END android_compose_thinking_in_compose_recomposition]

// [START android_compose_thinking_in_compose_recomposition_logic]
@Composable
fun SharedPrefsToggle(
    text: String,
    value: Boolean,
    onValueChanged: (Boolean) -> Unit
) {
    Row {
        Text(text)
        Checkbox(checked = value, onCheckedChange = onValueChanged)
    }
}
// [END android_compose_thinking_in_compose_recomposition_logic]

@Suppress("UNUSED_PARAMETER")
@Composable
fun MyFancyNavigation(content: @Composable () -> Unit) {
}

@Composable
fun StartScreen() {
}

@Composable
fun MiddleScreen() {
}

@Composable
fun EndScreen() {
}

// [START android_compose_thinking_in_compose_order]
@Composable
fun ButtonRow() {
    MyFancyNavigation {
        StartScreen()
        MiddleScreen()
        EndScreen()
    }
}
// [END android_compose_thinking_in_compose_order]

// [START android_compose_thinking_in_compose_parallel]
@Composable
fun ListComposable(myList: List<String>) {
    Row(horizontalArrangement = Arrangement.SpaceBetween) {
        Column {
            for (item in myList) {
                Text("Item: $item")
            }
        }
        Text("Count: ${myList.size}")
    }
}
// [END android_compose_thinking_in_compose_parallel]

// [START android_compose_thinking_in_compose_incorrect]
@Composable
@Deprecated("Example with bug")
fun ListWithBug(myList: List<String>) {
    var items = 0

    Row(horizontalArrangement = Arrangement.SpaceBetween) {
        Column {
            for (item in myList) {
                Text("Item: $item")
                items++ // Avoid! Side-effect of the column recomposing.
            }
        }
        Text("Count: $items")
    }
}
// [END android_compose_thinking_in_compose_incorrect]

// [START android_compose_thinking_in_compose_skips]
/**
 * Display a list of names the user can click with a header
 */
@Composable
fun NamePicker(
    header: String,
    names: List<String>,
    onNameClicked: (String) -> Unit
) {
    Column {
        // this will recompose when [header] changes, but not when [names] changes
        Text(header, style = MaterialTheme.typography.bodyLarge)
        Divider()

        // LazyColumn is the Compose version of a RecyclerView.
        // The lambda passed to items() is similar to a RecyclerView.ViewHolder.
        LazyColumn {
            items(names) { name ->
                // When an item's [name] updates, the adapter for that item
                // will recompose. This will not recompose when [header] changes
                NamePickerItem(name, onNameClicked)
            }
        }
    }
}

/**
 * Display a single name the user can click.
 */
@Composable
private fun NamePickerItem(name: String, onClicked: (String) -> Unit) {
    Text(name, Modifier.clickable(onClick = { onClicked(name) }))
}
// [END android_compose_thinking_in_compose_skips]