Shadow：本质，在移动应用中创建阴影

// UIKit：通过CALayer配置阴影
import UIKit

let cardView = UIView()
cardView.backgroundColor = .systemBackground
cardView.layer.cornerRadius = 12

// 配置阴影
cardView.layer.shadowColor = UIColor.black.cgColor
cardView.layer.shadowOpacity = 0.15
cardView.layer.shadowOffset = CGSize(width: 0, height: 4)
cardView.layer.shadowRadius = 8

"> 优化：显式 shadowPath
cardView.layer.shadowPath = UIBezierPath(
    roundedRect: cardView.bounds,
    cornerRadius: 12
).cgPath

// SwiftUI：通过shadow修饰符设置阴影
import SwiftUI

VStack {
    Text("带阴影的卡片")
        .padding()
        .background(Color.white)
        .cornerRadius(16)
        .shadow(
            color: .black.opacity(0.15),
            radius: 10,
            x: 0,
            y: 4
        )
}

<!-- XML：通过属性设置elevation -->
<androidx.cardview.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:cardCornerRadius="12dp"
    app:cardElevation="6dp">
    <!-- 卡片内容 -->
</androidx.cardview.widget.CardView>

// Kotlin：用于阴影的自定义OutlineProvider
import android.graphics.Outline
import android.view.View
import android.view.ViewOutlineProvider

val myView: View = findViewById(R.id.myView)
myView.outlineProvider = object : ViewOutlineProvider() {
    override fun getOutline(view: View, outline: Outline) {
        outline.setRoundRect(
            0, 0, view.width, view.height,
            12f  // 圆角半径
        )
    }
}
myView.elevation = 8f  // 阴影高度（px）
myView.translationZ = 4f  // 按下时额外高度

// Jetpack Compose：通过Modifier.shadow设置阴影
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp

Card(
    modifier = Modifier.shadow(
        elevation = 6.dp,
        shape = RoundedCornerShape(12.dp),
        clip = false
    ),
    colors = CardDefaults.cardColors(containerColor = Color.White)
) {
    Text("带自定义阴影的Card")
}

// Flutter：通过BoxDecoration + BoxShadow设置阴影
import 'package:flutter/material.dart';

Container(
    decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.circular(12.0),
        boxShadow: [
            BoxShadow(
                color: Colors.black.withOpacity(0.15),
                offset: Offset(0, 4),
                blurRadius: 8.0,
                spreadRadius: 0,
            ),
        ],
    ),
    child: Text('带阴影的容器'),
)

// 用于物理阴影的PhysicalModel
PhysicalModel(
    color: Colors.white,
    elevation: 6.0,
    shadowColor: Colors.black.withOpacity(0.2),
    borderRadius: BorderRadius.circular(12.0),
    child: Text('带阴影的物理模型'),
)