/
ModifierSnippets.kt
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/
ModifierSnippets.kt
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/*
* 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.
*/
package com.example.compose.snippets.modifiers
import androidx.compose.animation.core.AnimationState
import androidx.compose.foundation.background
import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.fillMaxHeight
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.offset
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.paddingFromBaseline
import androidx.compose.foundation.layout.requiredSize
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.foundation.shape.CircleShape
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.State
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clip
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.unit.dp
private object Padding {
// [START android_compose_modifiers_padding]
@Composable
private fun Greeting(name: String) {
Column(modifier = Modifier.padding(24.dp)) {
Text(text = "Hello,")
Text(text = name)
}
}
// [END android_compose_modifiers_padding]
}
private object PaddingAndFill {
// [START android_compose_modifiers_paddingandfill]
@Composable
private fun Greeting(name: String) {
Column(
modifier = Modifier
.padding(24.dp)
.fillMaxWidth()
) {
Text(text = "Hello,")
Text(text = name)
}
}
// [END android_compose_modifiers_paddingandfill]
}
private object Order1 {
val onClick = {}
// [START android_compose_modifiers_order1]
@Composable
fun ArtistCard(/*...*/) {
val padding = 16.dp
Column(
Modifier
.clickable(onClick = onClick)
.padding(padding)
.fillMaxWidth()
) {
// rest of the implementation
}
}
// [END android_compose_modifiers_order1]
}
private object Order2 {
val onClick = {}
// [START android_compose_modifiers_order2]
@Composable
fun ArtistCard(/*...*/) {
val padding = 16.dp
Column(
Modifier
.padding(padding)
.clickable(onClick = onClick)
.fillMaxWidth()
) {
// rest of the implementation
}
}
// [END android_compose_modifiers_order2]
}
private object Size {
// [START android_compose_modifiers_size]
@Composable
fun ArtistCard(/*...*/) {
Row(
modifier = Modifier.size(width = 400.dp, height = 100.dp)
) {
Image(/*...*/)
Column { /*...*/ }
}
}
// [END android_compose_modifiers_size]
}
private object RequiredSize {
// [START android_compose_modifiers_requiredsize]
@Composable
fun ArtistCard(/*...*/) {
Row(
modifier = Modifier.size(width = 400.dp, height = 100.dp)
) {
Image(
/*...*/
modifier = Modifier.requiredSize(150.dp)
)
Column { /*...*/ }
}
}
// [END android_compose_modifiers_requiredsize]
}
private object FillMaxHeight {
// [START android_compose_modifiers_fillmaxheight]
@Composable
fun ArtistCard(/*...*/) {
Row(
modifier = Modifier.size(width = 400.dp, height = 100.dp)
) {
Image(
/*...*/
modifier = Modifier.fillMaxHeight()
)
Column { /*...*/ }
}
}
// [END android_compose_modifiers_fillmaxheight]
}
private object PaddingFromBaseline {
// [START android_compose_modifiers_paddingfrombaseline]
@Composable
fun ArtistCard(artist: Artist) {
Row(/*...*/) {
Column {
Text(
text = artist.name,
modifier = Modifier.paddingFromBaseline(top = 50.dp)
)
Text(artist.lastSeenOnline)
}
}
}
// [END android_compose_modifiers_paddingfrombaseline]
}
private object Offset {
// [START android_compose_modifiers_offset]
@Composable
fun ArtistCard(artist: Artist) {
Row(/*...*/) {
Column {
Text(artist.name)
Text(
text = artist.lastSeenOnline,
modifier = Modifier.offset(x = 4.dp)
)
}
}
}
// [END android_compose_modifiers_offset]
}
private object MatchParentSize {
// [START android_compose_modifiers_matchparentsize]
@Composable
fun MatchParentSizeComposable() {
Box {
Spacer(
Modifier
.matchParentSize()
.background(Color.LightGray)
)
ArtistCard()
}
}
// [END android_compose_modifiers_matchparentsize]
}
private object Weight {
// [START android_compose_modifiers_weight]
@Composable
fun ArtistCard(/*...*/) {
Row(
modifier = Modifier.fillMaxWidth()
) {
Image(
/*...*/
modifier = Modifier.weight(2f)
)
Column(
modifier = Modifier.weight(1f)
) {
/*...*/
}
}
}
// [END android_compose_modifiers_weight]
}
private object ReusingModifiers {
// [START android_compose_modifiers_reusingmodifiers]
val reusableModifier = Modifier
.fillMaxWidth()
.background(Color.Red)
.padding(12.dp)
// [END android_compose_modifiers_reusingmodifiers]
}
private object AnimationInline {
// [START android_compose_modifiers_animationinline]
@Composable
fun LoadingWheelAnimation() {
val animatedState = animateFloatAsState(/*...*/)
LoadingWheel(
// Creation and allocation of this modifier will happen on every frame of the animation!
modifier = Modifier
.padding(12.dp)
.background(Color.Gray),
animatedState = animatedState
)
}
// [END android_compose_modifiers_animationinline]
}
private object AnimationExtracted {
// [START android_compose_modifiers_animationextracted]
// Now, the allocation of the modifier happens here:
val reusableModifier = Modifier
.padding(12.dp)
.background(Color.Gray)
@Composable
fun LoadingWheelAnimation() {
val animatedState = animateFloatAsState(/*...*/)
LoadingWheel(
// No allocation, as we're just reusing the same instance
modifier = reusableModifier,
animatedState = animatedState
)
}
// [END android_compose_modifiers_animationextracted]
}
private object UnscopedModifiers1 {
// [START android_compose_modifiers_unscopedmodifiers1]
val reusableModifier = Modifier
.fillMaxWidth()
.background(Color.Red)
.padding(12.dp)
@Composable
fun AuthorField() {
HeaderText(
// ...
modifier = reusableModifier
)
SubtitleText(
// ...
modifier = reusableModifier
)
}
// [END android_compose_modifiers_unscopedmodifiers1]
}
private object UnscopedModifiers2 {
// [START android_compose_modifiers_unscopedmodifiers2]
val reusableItemModifier = Modifier
.padding(bottom = 12.dp)
.size(216.dp)
.clip(CircleShape)
@Composable
private fun AuthorList(authors: List<Author>) {
LazyColumn {
items(authors) {
AsyncImage(
// ...
modifier = reusableItemModifier,
)
}
}
}
// [END android_compose_modifiers_unscopedmodifiers2]
}
@Composable
private fun ScopedModifiers1() {
// [START android_compose_modifiers_scopedmodifiers1]
Column(/*...*/) {
val reusableItemModifier = Modifier
.padding(bottom = 12.dp)
// Align Modifier.Element requires a ColumnScope
.align(Alignment.CenterHorizontally)
.weight(1f)
Text1(
modifier = reusableItemModifier,
// ...
)
Text2(
modifier = reusableItemModifier
// ...
)
// ...
}
// [END android_compose_modifiers_scopedmodifiers1]
}
@Composable
private fun ScopedModifiers2() {
// [START android_compose_modifiers_scopedmodifiers2]
Column(modifier = Modifier.fillMaxWidth()) {
// Weight modifier is scoped to the Column composable
val reusableItemModifier = Modifier.weight(1f)
// Weight will be properly assigned here since this Text is a direct child of Column
Text1(
modifier = reusableItemModifier
// ...
)
Box {
Text2(
// Weight won't do anything here since the Text composable is not a direct child of Column
modifier = reusableItemModifier
// ...
)
}
}
// [END android_compose_modifiers_scopedmodifiers2]
}
private object ChainingExtractedModifiers {
val otherModifier = Modifier
@Composable
private fun Snippet() {
// Note: In a real app, you would define the modifier outside of the composable where it is
// needed. For the snippet in the documentation, putting it in one place is clearer.
// [START android_compose_modifiers_chainingextractedmodifiers]
val reusableModifier = Modifier
.fillMaxWidth()
.background(Color.Red)
.padding(12.dp)
// Append to your reusableModifier
reusableModifier.clickable { /*...*/ }
// Append your reusableModifier
otherModifier.then(reusableModifier)
// [END android_compose_modifiers_chainingextractedmodifiers]
}
}
// ----- Classes and functions below are to simplify snippets above ----- //
private data class Artist(val name: String, val lastSeenOnline: String)
private data class Author(val name: String)
@Composable
private fun Image(modifier: Modifier = Modifier) {
// Empty to allow Image(/*...*/) in snippets
}
@Composable
private fun ArtistCard() {
// Empty for snippets
}
@Composable
private fun LoadingWheel(modifier: Modifier, animatedState: State<Float>) {
// Empty for snippets
}
@Composable
private fun animateFloatAsState(): State<Float> {
return AnimationState(initialValue = 0f)
}
@Composable
private fun HeaderText(modifier: Modifier = Modifier) {
// Empty for snippets
}
@Composable
private fun SubtitleText(modifier: Modifier = Modifier) {
// Empty for snippets
}
@Composable
private fun AsyncImage(modifier: Modifier = Modifier) {
// Empty for snippets
}
@Composable
private fun Text1(modifier: Modifier = Modifier) {
// Empty for snippets
}
@Composable
private fun Text2(modifier: Modifier = Modifier) {
// Empty for snippets
}