《Jetpack Compose从入门到实战》第三章 定制 UI 视图

配置颜色、字体与形状

-ui.theme.Color.kt

val pink100 = Color(0xFFFFF1F1)
val pink900 = Color(0xFF3F2C2C)
val white = Color(0xFFFFFFFF)
val white850 = Color(0xD9FFFFFF)
val gray = Color(0xFF232323)

• ui.theme.Type.kt
  先将Nunito Sans字体家族放入 res/font，再根据设计稿写代码

val nunitoSansFamily = FontFamily(
    Font(R.font.nunitosans_light, FontWeight.Light),
    Font(R.font.nunitosans_semibold, FontWeight.SemiBold),
    Font(R.font.nunitosans_bold, FontWeight.Bold)
)

val h1 = TextStyle(
    fontSize = 18.sp,
    fontFamily = nunitoSansFamily,
    fontWeight = FontWeight.Bold
)
val h2 = TextStyle(
    fontSize = 14.sp,
    letterSpacing = 0.15.sp,
    fontFamily = nunitoSansFamily,
    fontWeight = FontWeight.Bold
)
val subtitle1 = TextStyle(
    fontSize = 16.sp,
    fontFamily = nunitoSansFamily,
    fontWeight = FontWeight.Light
)
val body1 = TextStyle(
    fontSize = 14.sp,
    fontFamily = nunitoSansFamily,
    fontWeight = FontWeight.Light
)
val body2 = TextStyle(
    fontSize = 12.sp,
    fontFamily = nunitoSansFamily,
    fontWeight = FontWeight.Light
)
val button = TextStyle(
    fontSize = 14.sp,
    letterSpacing = 1.sp,
    fontFamily = nunitoSansFamily,
    fontWeight = FontWeight.SemiBold,
    color = white
)
val caption = TextStyle(
    fontSize = 12.sp,
    fontFamily = nunitoSansFamily,
    fontWeight = FontWeight.SemiBold
)

• ui.theme/Shape.kt

Welcome Page

@Preview(showBackground = true)
@Composable
fun WelcomeTitle() {
    Column(
        horizontalAlignment = Alignment.CenterHorizontally,
        modifier = Modifier.fillMaxWidth()
    ) {
        Image(
            painter = rememberVectorPainter(image = ImageVector.vectorResource(id = R.drawable.ic_light_logo)),
            contentDescription = "weclome_logo",
            modifier = Modifier
                .wrapContentWidth()
                .height(32.dp)
        )
        Box(
            modifier = Modifier
                .fillMaxWidth()
                .height(32.dp),
            contentAlignment = Alignment.BottomCenter
        ) {
            Text(
                text = "Beautiful home garden solutions",
                textAlign = TextAlign.Center,
                style = subtitle1,
                color = gray
            )
        }
    }
}

@Preview(showBackground = true)
@Composable
fun WelcomeButtons() {
    Column(
        horizontalAlignment = Alignment.CenterHorizontally,
        modifier = Modifier.fillMaxWidth()
    ){
        Button(
            onClick = { },
            modifier = Modifier
                .height(48.dp)
                .padding(horizontal = 16.dp)
                .fillMaxWidth()
                .clip(medium),
            colors = ButtonDefaults.buttonColors(backgroundColor = pink900)
        ) {
            Text(
                text = "Create account",
                style = button,
                color = white
            )
        }
        Spacer(modifier = Modifier.height(24.dp))
        TextButton(
            onClick = { },
        ) {
            Text(
                text = "Log in",
                style = button,
                color = pink900,
            )
        }
    }
}

@Preview(showBackground = true)
@Composable
fun LeafImage() {
    Image(
        painter = rememberVectorPainter(image = ImageVector.vectorResource(id = R.drawable.ic_light_welcome_illos)),
        contentDescription = "weclome_illos",
        modifier = Modifier
            .wrapContentSize()
            .padding(start = 88.dp)
    )
}

@Preview(showBackground = true)
@Composable
fun WelcomeContent() {
    Column(modifier = Modifier
        .fillMaxSize()
    ) {
        Spacer(Modifier.height(72.dp))
        LeafImage()
        Spacer(modifier = Modifier.height(48.dp))
        WelcomeTitle()
        Spacer(modifier = Modifier.height(40.dp))
        WelcomeButtons()
    }
}

@Composable
fun WelcomePage() {
    Box(
        modifier = Modifier
            .fillMaxSize()
            .background(pink100)
    ) {
        Image(
            painter = rememberVectorPainter(image = ImageVector.vectorResource(id = R.drawable.ic_light_welcome_bg)),
            contentDescription = "weclome_bg",
            modifier = Modifier.fillMaxSize()
        )
        WelcomeContent()
    }
}

Login Page

@Preview(showBackground = true)
@Composable
fun TopText() {
    Row(
        modifier = Modifier.fillMaxWidth(),
        horizontalArrangement = Arrangement.SpaceBetween
    ) {
        var keywordPre = "By Clicking below you agree to our".split(" ")
        var keywordPost = "and consent".split(" ")
        for (word in keywordPre) {
            Text(
                text = word,
                style = body2,
                color = gray,
            )
        }
        Text(
            text = "Terms of Use",
            style = body2,
            color = gray,
            textDecoration = TextDecoration.Underline
        )
        for (word in keywordPost) {
            Text(
                text = word,
                style = body2,
                color = gray,
            )
        }
    }
}

@Preview(showBackground = true)
@Composable
fun BottomText() {
    Row(
        modifier = Modifier.fillMaxWidth(),
        horizontalArrangement = Arrangement.Center
    ) {
        Text(text = " to Our ",
            style = body2,
            color = gray
        )
        Text(text = "Privacy Policy.",
            style = body2,
            color = gray,
            textDecoration = TextDecoration.Underline
        )
    }
}

@Preview(showBackground = true)
@Composable
fun HintWithUnderline() {
    Column(
        modifier = Modifier.paddingFromBaseline(top = 24.dp, bottom = 16.dp)
    ){
        TopText()
        BottomText()
    }
}

@Preview(showBackground = true)
@Composable
fun LoginInputBox() {
    Column {
        OutlinedTextField(
            value = "",
            onValueChange = {},
            modifier = Modifier
                .fillMaxWidth()
                .height(56.dp)
                .clip(small),
            placeholder = {
                Text(
                    text = "Email address",
                    style = body1,
                    color = gray
                )
            }
        )
        Spacer(modifier = Modifier.height(8.dp))
        OutlinedTextField(
            value = "",
            onValueChange = {},
            modifier = Modifier
                .fillMaxWidth()
                .height(56.dp)
                .clip(small),
            placeholder = {
                Text(
                    text = "Password(8+ Characters)",
                    style = body1,
                    color = gray
                )
            }
        )
    }
}

@Preview(showBackground = true, showSystemUi = false)
@Composable
fun LoginTitle() {
    Text(
        text = "Log in with email",
        modifier = Modifier
            .fillMaxWidth()
            .paddingFromBaseline(top = 184.dp, bottom = 16.dp),
        style = h1,
        color = gray,
        textAlign = TextAlign.Center
    )
}

@Preview(showBackground = true)
@Composable
fun LoginButton() {
    Button(
        onClick = { },
        modifier = Modifier
            .height(48.dp)
            .fillMaxWidth()
            .clip(medium),
        colors = ButtonDefaults.buttonColors(backgroundColor = pink900)
    ) {
        Text(
            text = "Log in",
            style = button,
            color = white
        )
    }
}

@Composable
fun LoginPage() {
    Column(
        Modifier
            .fillMaxSize()
            .background(white)
            .padding(horizontal = 16.dp)
    ) {
        LoginTitle()
        LoginInputBox()
        HintWithUnderline()
        LoginButton()
    }
}

@Composable
@Preview
fun LoginPageLightPreview() {
    BloomTheme() {
        LoginPage()
    }
}

Home Page

val small = RoundedCornerShape(4.dp)
val medium = RoundedCornerShape(24.dp)

val shapes = Shapes(
    small = RoundedCornerShape(4.dp),
    medium = RoundedCornerShape(4.dp),
    large = RoundedCornerShape(0.dp)
)

data class ImageItem(val name: String, val resId: Int)

val bloomBannerList = listOf(
    ImageItem("Desert chic", R.drawable.desert_chic),
    ImageItem("Tiny terrariums", R.drawable.tiny_terrariums),
    ImageItem("Jungle Vibes", R.drawable.jungle_vibes)
)

val bloomInfoList = listOf(
    ImageItem("Monstera", R.drawable.monstera),
    ImageItem("Aglaonema", R.drawable.aglaonema),
    ImageItem("Peace lily", R.drawable.peace_lily),
    ImageItem("Fiddle leaf tree", R.drawable.fiddle_leaf),
    ImageItem("Desert chic", R.drawable.desert_chic),
    ImageItem("Tiny terrariums", R.drawable.tiny_terrariums),
    ImageItem("Jungle Vibes", R.drawable.jungle_vibes)
)

val navList = listOf(
    ImageItem("Home", R.drawable.ic_home),
    ImageItem("Favorites", R.drawable.ic_favorite_border),
    ImageItem("Profile", R.drawable.ic_account_circle),
    ImageItem("Cart", R.drawable.ic_shopping_cart)
)

@Preview(showBackground = true)
@Composable
fun BloomRowBanner() {
    Column {
        Box(
            Modifier.fillMaxWidth()
        ) {
            Text(
                text = "Browse themes",
                style = h1,
                color = gray,
                modifier = Modifier
                    .fillMaxWidth()
                    .paddingFromBaseline(top = 32.dp)
            )
        }
        Spacer(modifier = Modifier.height(16.dp))
        LazyRow(
            modifier = Modifier.height(136.dp)
        ) {
            items(bloomBannerList.size) {
                if (it != 0) {
                    Spacer(modifier = Modifier.width(8.dp))
                }
                PlantCard(bloomBannerList[it])
            }
        }
    }
}


@Preview(showBackground = true)
@Composable
fun BloomInfoList() {
    Column {
        Row(
            Modifier.fillMaxWidth(),
            horizontalArrangement = Arrangement.SpaceBetween
        ) {
            Text(
                text = "Design your home garden",
                style = h1,
                color = gray,
                modifier = Modifier.paddingFromBaseline(top = 40.dp)
            )
            Icon(
                painterResource(id = R.drawable.ic_filter_list),
                "filter",
                modifier = Modifier
                    .padding(top = 24.dp)
                    .size(24.dp)
            )
        }
        Spacer(modifier = Modifier.height(16.dp))
        LazyColumn(
            modifier = Modifier
                .fillMaxWidth(),
            contentPadding = PaddingValues(bottom = 56.dp)
        ) {
            items(bloomInfoList.size) {
                if (it != 0) {
                    Spacer(modifier = Modifier.height(8.dp))
                }
                DesignCard(bloomInfoList[it])
            }
        }
    }
}

@Preview(showBackground = true)
@Composable
fun SearchBar() {
    Box {
        TextField(
            value = "",
            onValueChange = {},
            modifier = Modifier
                .fillMaxWidth()
                .height(56.dp)
                .clip(RoundedCornerShape(4.dp))
                .border(BorderStroke(1.dp, Color.Black)),
            leadingIcon = {
                Icon(
                    painter = rememberVectorPainter(image = ImageVector.vectorResource(id = R.drawable.ic_search)),
                    contentDescription = "search",
                    modifier = Modifier.size(18.dp)
                )
            },
            placeholder = {
                Text(
                    text = "Search",
                    style = body1,
                    color = gray
                )
            },
            colors = TextFieldDefaults.outlinedTextFieldColors(
                backgroundColor = white,
                unfocusedBorderColor = white,
                focusedBorderColor = white,
            ),
        )
    }
}

@Composable
fun HomePage() {
    Scaffold(
        bottomBar = {
            BottomBar()
        }
    ) {
        Column(
            Modifier
                .fillMaxSize()
                .background(white)
                .padding(horizontal = 16.dp)
        ) {
            Spacer(modifier = Modifier.height(40.dp))
            SearchBar()
            BloomRowBanner()
            BloomInfoList()
        }
    }
}

@Composable
fun DesignCard(plant: ImageItem) {
    Row(
        modifier = Modifier.fillMaxWidth()
    ) {
        Image(
            painterResource(id = plant.resId),
            contentScale = ContentScale.Crop,
            contentDescription = "image",
            modifier = Modifier
                .size(64.dp)
                .clip(RoundedCornerShape(4.dp))
        )
        Spacer(modifier = Modifier.width(16.dp))
        Column {
            Row(modifier = Modifier.fillMaxWidth(), horizontalArrangement = Arrangement.SpaceBetween) {
                Column {
                    Text(
                        text = plant.name,
                        style = h2,
                        color = gray,
                        modifier = Modifier.paddingFromBaseline(top = 24.dp)
                    )
                    Text(
                        text = "This is a description",
                        style = body1,
                        color = gray,
                        modifier = Modifier
                    )
                }
                Checkbox(
                    modifier = Modifier
                        .padding(top = 24.dp)
                        .size(24.dp),
                    checked = false,
                    onCheckedChange = {
                        // plant.enable = it
                    },
                    colors = CheckboxDefaults.colors(
                        checkmarkColor = white
                    )
                )
            }
            Divider(color = gray, modifier = Modifier.padding(top = 16.dp), thickness = 0.5.dp)
        }
    }
}


@Composable
fun PlantCard(plant: ImageItem) {
    Card(
        modifier = Modifier
            .size(136.dp)
            .clip(RoundedCornerShape(4.dp))
    ) {
        Column {
            Image(
                painterResource(id = plant.resId),
                contentScale = ContentScale.Crop,
                contentDescription = "image",
                modifier = Modifier
                    .fillMaxWidth()
                    .height(96.dp)
            )
            Box(
                Modifier
                    .fillMaxWidth()
                    .padding(start = 16.dp)
            ) {
                Text(
                    text = plant.name,
                    style = h2,
                    color = gray,
                    modifier = Modifier
                        .fillMaxWidth()
                        .paddingFromBaseline(top = 24.dp, bottom = 16.dp)
                )
            }
        }
    }
}

@Composable
fun BottomBar() {
    BottomNavigation(
        elevation = 16.dp,
        modifier = Modifier
            .fillMaxWidth()
            .height(56.dp)
            .background(pink100)
    ) {
        navList.forEach {
            BottomNavigationItem(
                onClick = {},
                icon = {
                    Icon(
                        painterResource(id = it.resId),
                        contentDescription = null,
                        modifier = Modifier.size(24.dp),
                    )
                },
                label = {
                    Text(
                        it.name,
                        style = caption,
                        color = gray,
                    )
                },
                selected = ("Home" == it.name)
            )
        }
    }
}

@Preview(showBackground = true)
@Composable
fun BottomBarPreview() {
    BloomTheme() {
        BottomBar()
    }
}

@Preview(showBackground = true)
@Composable
fun DesignCardPreview() {
    BloomTheme() {
        DesignCard(bloomInfoList[0])
    }
}

@Preview(showBackground = true)
@Composable
fun PlantCardPreview() {
    BloomTheme() {
        PlantCard(bloomBannerList[0])
    }
}

@Preview(showBackground = true)
@Composable
fun HomePageLightPreview() {
    BloomTheme() {
        HomePage()
    }
}

主题

private val BloomLightColorPaltte = lightColors(
    primary = pink100,
    secondary = pink900,
    background = white,
    surface = white850,
    onPrimary = gray,
    onSecondary = white,
    onBackground = gray,
    onSurface = gray,
)

private val BloomDarkColorPaltte = darkColors(
    primary = green900,
    secondary = green300,
    background = gray,
    surface = white150,
    onPrimary = white,
    onSecondary = gray,
    onBackground = white,
    onSurface = white850
)

open class WelcomeAssets private constructor(
    var background: Int,
    var illos: Int,
    var logo: Int
) {
    object LightWelcomeAssets : WelcomeAssets(
        background = R.drawable.ic_light_welcome_bg,
        illos = R.drawable.ic_light_welcome_illos,
        logo = R.drawable.ic_light_logo
    )

    object DarkWelcomeAssets : WelcomeAssets(
        background = R.drawable.ic_dark_welcome_bg,
        illos = R.drawable.ic_dark_welcome_illos,
        logo = R.drawable.ic_dark_logo
    )
}

internal var LocalWelcomeAssets = staticCompositionLocalOf { WelcomeAssets.LightWelcomeAssets as WelcomeAssets }

val MaterialTheme.welcomeAssets
    @Composable
    @ReadOnlyComposable
    get() = LocalWelcomeAssets.current

enum class BloomTheme {
    LIGHT, DARK
}


@Composable
fun BloomTheme(theme: BloomTheme = BloomTheme.LIGHT, content: @Composable() () -> Unit) {
    CompositionLocalProvider(
        LocalWelcomeAssets provides if (theme == BloomTheme.DARK) WelcomeAssets.DarkWelcomeAssets else WelcomeAssets.LightWelcomeAssets,
    ) {
        MaterialTheme(
            colors = if (theme == BloomTheme.DARK) BloomDarkColorPaltte else BloomLightColorPaltte,
            typography = bloomTypoGraphy,
            shapes = shapes,
            content = content
        )
    }
}

CompositionLocal

CompositionLocal 是 Jetpack Compose 中的一种数据传递方式。它可以在组合组件之间传递可变数据，而无需通过 props 或 state 管理器来传递数据。这个特性比传统的数据传递方式更为高效和方便。
例如，我们可以通过 CompositionLocal 在应用程序的不同部分中传递数据，如主题、语言环境、字体等。这个特性可以让我们在组合应用程序中更轻松地使用全局状态，而不必每次都传递数据。
此外，CompositionLocal 还可以用于实现本地化和自定义主题等功能的高效性。因此，它是 Jetpack Compose 中非常重要的一个组成部分。

• 如果CompositonLocal提供得知发生更改的可能性很小或永远无法改变，利用staticCompositionLocal能显著提升性能

总结

• 所有视图组件建议用顶级函数声明

随笔：

• 简历 遇到什么问题，用了什么方法，如何进行优化

《Jetpack Compose从入门到实战》第一章 全新的 Android UI 框架

《Jetpack Compose从入门到实战》 第二章 了解常用UI组件

《Jetpack Compose从入门到实战》第三章 定制 UI 视图

《Jetpack Compose从入门到实战》第八章 Compose页面 导航

《Jetpack Compose从入门到实战》第九章 Accompanist 与第三方组件库文章来源地址https://www.toymoban.com/news/detail-729725.html

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