sp：什么是 Android 中可缩放的文本像素

// 在 Kotlin 中以编程方式获取 scaledDensity
val scaledDensity = with(context.resources) {
    displayMetrics.scaledDensity
}

// 将 sp 转换为 px
fun spToPx(sp: Float, context: Context): Float {
    return TypedValue.applyDimension(
        TypedValue.COMPLEX_UNIT_SP,
        sp,
        context.resources.displayMetrics
    )
}

// 将 px 转换为 sp
fun pxToSp(px: Float, context: Context): Float {
    return px / context.resources.displayMetrics.scaledDensity
}

<!-- 带有 textSize sp 的 TextView 布局 -->
<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="@string/hello"
    android:textSize="16sp"
    android:padding="12dp"
    android:lineSpacingExtra="4dp" />

<!-- 使用 dimens 资源 -->
<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textSize="@dimen/text_body_large" />

<!-- res/values/dimens.xml -->
<resources>
    <!-- Material Design Type Scale -->
    <dimen name="text_display_large">34sp</dimen>
    <dimen name="text_display_medium">28sp</dimen>
    <dimen name="text_headline_large">24sp</dimen>
    <dimen name="text_headline_medium">20sp</dimen>
    <dimen name="text_title_large">18sp</dimen>
    <dimen name="text_body_large">16sp</dimen>
    <dimen name="text_body_medium">14sp</dimen>
    <dimen name="text_label_large">14sp</dimen>
    <dimen name="text_label_small">11sp</dimen>
</resources>

// 通过 Typography API 实现自定义排版
val AppTypography = Typography(
    displayLarge = TextStyle(
        fontWeight = FontWeight.Normal,
        fontSize = 34.sp,
        lineHeight = 40.sp,
        letterSpacing = 0.sp
    ),
    headlineLarge = TextStyle(
        fontWeight = FontWeight.SemiBold,
        fontSize = 24.sp,
        lineHeight = 32.sp
    ),
    titleLarge = TextStyle(
        fontWeight = FontWeight.Medium,
        fontSize = 18.sp,
        lineHeight = 24.sp
    ),
    bodyLarge = TextStyle(
        fontWeight = FontWeight.Normal,
        fontSize = 16.sp,
        lineHeight = 24.sp,
        letterSpacing = 0.5.sp
    ),
    labelSmall = TextStyle(
        fontWeight = FontWeight.Medium,
        fontSize = 11.sp,
        lineHeight = 16.sp,
        letterSpacing = 0.5.sp
    )
)

// Compose 中的 TextUnit — 安全使用 sp
@Composable
fun ArticleCard(title: String, description: String) {
    Card(modifier = Modifier
        .fillMaxWidth()
        .padding(16.dp)
    ) {
        Text(
            text = title,
            style = MaterialTheme.typography.titleLarge
        )
        Spacer(modifier = Modifier.height(8.dp))
        Text(
            text = description,
            style = MaterialTheme.typography.bodyMedium
        )
    }
}

// 在 sp 中显式设置 fontSize
Text(
    text = "自定义大小",
    fontSize = 20.sp,
    fontWeight = FontWeight.Bold,
    color = MaterialTheme.colorScheme.primary
)