使用 Overlay

必需依赖

本页可以独立使用。显示对话框必须引入单独的 Android Overlay 宿主产物：

build.gradle.kts

repositories { mavenCentral() }

dependencies {
    implementation("com.viewcompose:viewcompose-material3-android:0.1.0-alpha01")
    implementation("com.viewcompose:viewcompose-overlay-material3-android:0.1.0-alpha01")
    implementation("androidx.activity:activity:1.12.4")
    implementation("com.google.android.material:material:1.13.0")
}

缺少 viewcompose-overlay-material3-android 或 overlayHostFactory 时，Dialog 声明没有对应的 Android presenter，无法显示。

显示确认对话框

创建 OverlaysTutorialActivity.kt：

package com.viewcompose.samples.tutorials

import android.os.Bundle
import androidx.activity.ComponentActivity
import com.viewcompose.material3.android.setMaterial3UiContent
import com.viewcompose.overlay.material3.android.host.AndroidOverlayHost
import com.viewcompose.runtime.mutableStateOf
import com.viewcompose.ui.modifier.Modifier
import com.viewcompose.ui.modifier.fillMaxWidth
import com.viewcompose.ui.modifier.padding
import com.viewcompose.ui.unit.dp
import com.viewcompose.ui.foundation.Button
import com.viewcompose.ui.foundation.Column
import com.viewcompose.ui.foundation.Dialog
import com.viewcompose.ui.foundation.Surface
import com.viewcompose.ui.foundation.Text
import com.viewcompose.ui.foundation.remember

class OverlaysTutorialActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setMaterial3UiContent(overlayHostFactory = ::AndroidOverlayHost) {
            val dialogVisible = remember { mutableStateOf(false) }

            Button("Delete item", onClick = { dialogVisible.value = true })
            Dialog(
                visible = dialogVisible.value,
                requestKey = "delete-item",
                onDismissRequest = { dialogVisible.value = false },
            ) {
                Surface(modifier = Modifier.fillMaxWidth()) {
                    Column(spacing = 12.dp, modifier = Modifier.padding(20.dp)) {
                        Text("Delete this item?")
                        Button("Cancel", onClick = { dialogVisible.value = false })
                    }
                }
            }
        }
    }
}

Boolean 是应用状态，Dialog 只声明如何显示这个状态。requestKey 为请求提供跨重组的稳定身份。 取消按钮和平台关闭动作都更新同一个状态所有者。

验证结果

点击 Delete item，再通过 Cancel、Back 或点击外部关闭对话框。编译命令：

./gradlew :samples:tutorials:assembleDebug

Popup、BottomSheet、Snackbar、Toast 和队列行为请查看 Overlay 指南。