为一些特定天气添加背景动画

比如晴天、下雨、下雪及多云，别的极端天气，类似雾霾等等没有做

Author: zhujiang2

.idea/gradle.xml

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+/build

animate/.gitignore

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+plugins {
+    id("com.android.library")
+    id("org.jetbrains.kotlin.android")
+}
+
+android {
+    namespace = "com.zui.animate"
+    val sdkVersion = rootProject.extra["sdkVersion"] as Int?
+    val minSdkVersion = rootProject.extra["minSdkVersion"] as Int?
+    compileSdk = sdkVersion
+
+    defaultConfig {
+        minSdk = minSdkVersion
+        targetSdk = sdkVersion
+
+        testInstrumentationRunner = rootProject.extra["testInstrumentationRunner"] as String?
+        rootProject.extra["consumerProguardFiles"]?.let { consumerProguardFiles(it) }
+        resourceConfigurations += listOf("en", "zh", "zh-rCN", "zh-rHK", "zh-rTW")
+    }
+
+    buildTypes {
+        release {
+            // 开启混淆
+            isMinifyEnabled = true
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
+        }
+    }
+    val javaVersion = rootProject.extra["javaVersion"] as JavaVersion
+    val javaVersionName = javaVersion.toString()
+
+    kotlin {
+        jvmToolchain {
+            languageVersion.set(JavaLanguageVersion.of(javaVersionName))
+        }
+    }
+
+    compileOptions {
+        sourceCompatibility = javaVersion
+        targetCompatibility = javaVersion
+    }
+    buildFeatures {
+        compose = true
+        viewBinding = true
+    }
+
+    composeOptions {
+        kotlinCompilerExtensionVersion = rootProject.extra["kotlinCompiler"] as String?
+    }
+}
+
+dependencies {
+
+    implementation("${rootProject.extra["coreKtx"] as String?}")
+    implementation("${rootProject.extra["appcompat"] as String?}")
+
+    val composeVersion = rootProject.extra["composeVersion"] as String?
+    implementation("androidx.compose.ui:ui:$composeVersion")
+    implementation("androidx.compose.ui:ui-tooling-preview:$composeVersion")
+    implementation("androidx.compose.runtime:runtime-livedata:$composeVersion")
+    implementation("androidx.compose.material:material:$composeVersion")
+    testImplementation("${rootProject.extra["junit"] as String?}")
+    androidTestImplementation("${rootProject.extra["extJunit"] as String?}")
+    androidTestImplementation("${rootProject.extra["espressoCore"] as String?}")
+}

animate/build.gradle.kts

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+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

animate/consumer-rules.pro

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+package com.zui.animate
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("com.zui.animate.test", appContext.packageName)
+    }
+}

animate/proguard-rules.pro

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+</manifest>

animate/src/androidTest/java/com/zui/animate/ExampleInstrumentedTest.kt

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+package com.zui.animate
+
+import androidx.compose.animation.core.LinearEasing
+import androidx.compose.animation.core.RepeatMode
+import androidx.compose.animation.core.animateFloat
+import androidx.compose.animation.core.infiniteRepeatable
+import androidx.compose.animation.core.rememberInfiniteTransition
+import androidx.compose.animation.core.tween
+import androidx.compose.foundation.Image
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.offset
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.rotate
+import androidx.compose.ui.platform.LocalConfiguration
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.unit.dp
+
+@Composable
+fun Cloudy(modifier: Modifier = Modifier, durationMillis: Int = 20000) {
+    val screenWidthDp = LocalConfiguration.current.screenWidthDp
+    val transition = rememberInfiniteTransition(label = "")
+    val rotate by transition.animateFloat(
+        initialValue = 0f,
+        targetValue = 40f,
+        animationSpec = infiniteRepeatable(
+            tween(durationMillis, easing = LinearEasing),
+            RepeatMode.Reverse
+        ), label = ""
+    )
+    val offset by transition.animateFloat(
+        initialValue = 0f,
+        targetValue = screenWidthDp.toFloat(),
+        animationSpec = infiniteRepeatable(
+            tween(durationMillis, easing = LinearEasing),
+            RepeatMode.Reverse
+        ), label = ""
+    )
+    Box(modifier = modifier) {
+        Image(
+            modifier = Modifier
+                .rotate(rotate),
+            painter = painterResource(id = R.drawable.ic_yun1), contentDescription = ""
+        )
+        Image(
+            modifier = Modifier
+                .offset(offset.dp),
+            painter = painterResource(id = R.drawable.ic_yun2), contentDescription = ""
+        )
+    }
+}

animate/src/main/AndroidManifest.xml

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+package com.zui.animate
+
+import androidx.annotation.IntDef
+import androidx.compose.animation.core.FastOutLinearInEasing
+import androidx.compose.animation.core.RepeatMode
+import androidx.compose.animation.core.animateFloat
+import androidx.compose.animation.core.infiniteRepeatable
+import androidx.compose.animation.core.rememberInfiniteTransition
+import androidx.compose.animation.core.tween
+import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.layout.size
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.ImageBitmap
+import androidx.compose.ui.graphics.StrokeCap
+import androidx.compose.ui.layout.Layout
+import androidx.compose.ui.res.imageResource
+import androidx.compose.ui.unit.dp
+import kotlin.math.roundToInt
+import kotlin.random.Random
+
+/**
+ * 定制四种雨，分别对应不同数量的雨滴，数值直接表示雨滴数量
+ */
+@IntDef(
+    value = [
+        Rains.LIGHT_RAIN,
+        Rains.MODERATE_RAIN,
+        Rains.HEAVY_RAIN,
+        Rains.RAINSTORM,
+    ],
+)
+annotation class RainsValue
+
+object Rains {
+    // 小雨
+    const val LIGHT_RAIN = 100
+
+    // 中雨
+    const val MODERATE_RAIN = 150
+
+    // 大雨
+    const val HEAVY_RAIN = 200
+
+    // 暴雨
+    const val RAINSTORM = 300
+}
+
+@Composable
+fun Rain(modifier: Modifier = Modifier, @RainsValue rainType: Int = Rains.LIGHT_RAIN) {
+    val bitmap = ImageBitmap.imageResource(id = R.drawable.ic_rain)
+
+    Layout(
+        modifier = modifier,
+        content = {
+            // 摆放雪花，分别设置不同duration，增加随机性
+            repeat(rainType) {
+                RainDrop(
+                    modifier.size(1.dp, Random.nextInt(8, 20).dp),
+                    bitmap,
+                    Random.nextInt(1000, 2500)
+                )
+            }
+        }
+    ) { measures, constraints ->
+        val placeableList = measures.mapIndexed { _, measurable ->
+            constraints.maxHeight * Random.nextFloat()
+            val height = constraints.maxHeight * Random.nextFloat()
+            measurable.measure(
+                constraints.copy(
+                    minWidth = 0,
+                    minHeight = 0,
+                    maxWidth = 10.dp.toPx().toInt(), // snowdrop width
+                    maxHeight = height.roundToInt(),
+                )
+            )
+        }
+
+        layout(constraints.maxWidth, constraints.maxHeight) {
+            var xPosition = constraints.maxWidth / ((placeableList.size + 1))
+
+            placeableList.forEachIndexed { _, placeable ->
+                placeable.place(x = xPosition, y = -(constraints.maxHeight * 0.2).roundToInt())
+
+                xPosition += (constraints.maxWidth / ((placeableList.size + 1) * 0.9f)).roundToInt()
+            }
+        }
+    }
+}
+
+@Composable
+fun RainDrop(modifier: Modifier = Modifier, bitmap: ImageBitmap, durationMillis: Int = 100) {
+    // 循环播放
+    val transition = rememberInfiniteTransition(label = "")
+
+    // 下降动画：restart动画
+    val animateY by transition.animateFloat(
+        initialValue = 0f,
+        targetValue = 18f,
+        animationSpec = infiniteRepeatable(
+            tween(durationMillis, easing = FastOutLinearInEasing),
+            RepeatMode.Restart
+        ), label = ""
+    )
+
+    Canvas(modifier) {
+        // 位置随AnimationState改变，实现雪花飘落的效果
+        val topLeft = center.copy(
+            x = center.x,
+            y = center.y + center.y * animateY
+        )
+        drawImage(bitmap, topLeft = topLeft)
+    }
+}