Android 摄像头预览悬浮窗，可拖动，可显示在其他app上方
市面上常见的摄像头悬浮窗，如微信、手机QQ的视频通话功能，有如下特点：
- 整屏页面能切换到一个小的悬浮窗
- 悬浮窗能运行在其他app上方
- 悬浮窗能跳回整屏页面，并且悬浮窗消失
我们探讨过用CameraX打开摄像头预览，结合可改变大小和浮动的activity，实现了应用内摄像头预览悬浮Activity。这个悬浮Activity是在应用内使用的。要让悬浮窗在其他app上，需要结合悬浮窗 System Alert Window。
本文用CameraX实现摄像头预览悬浮窗，能显示在其他app上方，可拖动，可跳回activity。
这个例子的相关代码放进了单独的模块。使用时注意gradle里的细微差别。
引入依赖
模块gradle的一些配置，使用的Android SDK版本为31，启用databinding
plugins {
id 'com.android.library'
id 'kotlin-android'
id 'kotlin-android-extensions'
id 'kotlin-kapt'
}
android {
compileSdk 31
defaultConfig {
minSdk 21
targetSdk 31
versionCode 1
versionName "1.0"
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
consumerProguardFiles "consumer-rules.pro"
}
dataBinding {
enabled = true
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}
}
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}
}
dependencies {
implementation 'androidx.appcompat:appcompat:1.4.0'
implementation 'com.google.android.material:material:1.4.0'
implementation project(path: ':baselib')
testImplementation 'junit:junit:4.+'
androidTestImplementation 'androidx.test.ext:junit:1.1.3'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
implementation "androidx.camera:camera-core:1.1.0-alpha11"
implementation "androidx.camera:camera-camera2:1.1.0-alpha11"
implementation "androidx.camera:camera-lifecycle:1.1.0-alpha11"
implementation "androidx.camera:camera-view:1.0.0-alpha31"
implementation "androidx.camera:camera-extensions:1.0.0-alpha31"
}
引入CameraX依赖（CameraX 核心库是用camera2实现的），目前主要用1.1.0-alpha11版本
权限
manifest中申请权限
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera.any" />
<!-- 悬浮窗的权限 -->
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
动态申请相机权限 Manifest.permission.CAMERA
private static final int REQ_CAMERA = 2;
if (PackageManager.PERMISSION_GRANTED != ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, REQ_CAMERA);
}
后面需要MeFloatingCameraXAct与FloatingCameraXService配合使用。
manifest中注册Activity和Service
<activity
android:name=".camera.MeFloatingCameraXAct"
android:exported="true"
android:launchMode="singleTop" />
<service android:name=".camera.FloatingCameraXService" />
MeFloatingCameraXAct
这个activity提供一个简单的摄像头预览界面，并且提供入口启动悬浮窗。
layout me_act_floating_preivew_x.xml
<?xml version="1.0" encoding="utf-8"?>
<layout>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.camera.view.PreviewView
android:id="@+id/previewView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</FrameLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:gravity="center"
android:orientation="vertical"
android:padding="4dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="@+id/start"
style="@style/NormalBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="打开摄像头" />
<Button
android:id="@+id/end"
style="@style/NormalBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="4dp"
android:text="停止摄像头" />
<Button
android:id="@+id/go_floating"
style="@style/NormalBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="4dp"
android:text="切换到悬浮窗" />
<Button
android:id="@+id/close_act"
style="@style/NormalBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="4dp"
android:text="关闭" />
</LinearLayout>
</LinearLayout>
</RelativeLayout>
</layout>
完整代码如下
// package com.rustfisher.mediasamples.camera;
import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.camera.core.CameraSelector;
import androidx.camera.core.Preview;
import androidx.camera.lifecycle.ProcessCameraProvider;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.databinding.DataBindingUtil;
import com.google.common.util.concurrent.ListenableFuture;
import com.rustfisher.mediasamples.R;
import com.rustfisher.mediasamples.databinding.MeActFloatingPreivewXBinding;
import java.util.concurrent.ExecutionException;
/**
* @author an.rustfisher.com
* @date 2022-1-06 23:53
*/
public class MeFloatingCameraXAct extends AppCompatActivity {
private static final String TAG = "rfDevX";
private static final int REQ_CAMERA = 2;
public static final String K_START_CAMERA = "start_camera"; // 直接启动摄像头
private MeActFloatingPreivewXBinding mBinding;
private ListenableFuture<ProcessCameraProvider> mCameraProviderFuture;
private ProcessCameraProvider mCameraProvider;
private boolean mRunning = false;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mBinding = DataBindingUtil.setContentView(this, R.layout.me_act_floating_preivew_x);
final boolean startNow = getIntent().getBooleanExtra(K_START_CAMERA, false);
mCameraProviderFuture = ProcessCameraProvider.getInstance(this);
mCameraProviderFuture.addListener(() -> {
try {
mCameraProvider = mCameraProviderFuture.get();
Log.d(TAG, "获取到了 cameraProvider");
if (startNow) {
bindPreview(mCameraProvider);
}
} catch (ExecutionException | InterruptedException e) {
// 这里不用处理
}
}, ContextCompat.getMainExecutor(this));
mBinding.start.setOnClickListener(v -> {
if (mCameraProvider != null && !mRunning) {
bindPreview(mCameraProvider);
}
});
mBinding.end.setOnClickListener(v -> {
mCameraProvider.unbindAll();
mRunning = false;
});
mBinding.goFloating.setOnClickListener(v -> {
startService(new Intent(getApplicationContext(), FloatingCameraXService.class));
finish();
});
mBinding.closeAct.setOnClickListener(v -> {
Toast.makeText(getApplicationContext(), "关闭摄像头示例", Toast.LENGTH_SHORT).show();
stopService(new Intent(getApplicationContext(), FloatingCameraXService.class));
finish();
});
if (PackageManager.PERMISSION_GRANTED != ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, REQ_CAMERA);
}
}
@Override
public void onBackPressed() {
Toast.makeText(getApplicationContext(), "请点击关闭按钮", Toast.LENGTH_SHORT).show();
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == REQ_CAMERA) {
if (grantResults[0] != PackageManager.PERMISSION_GRANTED) {
Toast.makeText(getApplicationContext(), "请允许相机权限", Toast.LENGTH_SHORT).show();
}
}
}
private void bindPreview(ProcessCameraProvider cameraProvider) {
if (cameraProvider == null) {
Toast.makeText(getApplicationContext(), "没获取到相机", Toast.LENGTH_SHORT).show();
return;
}
Toast.makeText(getApplicationContext(), "相机启动", Toast.LENGTH_SHORT).show();
Preview preview = new Preview.Builder().build();
CameraSelector cameraSelector = new CameraSelector.Builder()
.requireLensFacing(CameraSelector.LENS_FACING_BACK)
.build();
preview.setSurfaceProvider(mBinding.previewView.getSurfaceProvider());
cameraProvider.bindToLifecycle(this, cameraSelector, preview);
mRunning = true;
}
}
CameraX启动预览的代码可以参考 https://an.rustfisher.com/android/jetpack/camerax/simple-preview/
悬浮窗
layout
先给悬浮窗准备一个layout
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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="match_parent"
android:background="#000">
<androidx.camera.view.PreviewView
android:id="@+id/preview_view"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<ImageView
android:id="@+id/to_big"
android:layout_width="40dp"
android:layout_height="40dp"
android:padding="4dp"
android:src="@drawable/me_to_big"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
图片请自备
FloatingCameraXService
FloatingCameraXService实现LifecycleOwner接口，为了方便CameraX绑定生命周期组件。
// package com.rustfisher.mediasamples.camera;
import android.app.Service;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.os.Build;
import android.os.IBinder;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.camera.core.CameraSelector;
import androidx.camera.core.Preview;
import androidx.camera.lifecycle.ProcessCameraProvider;
import androidx.camera.view.PreviewView;
import androidx.core.content.ContextCompat;
import androidx.lifecycle.Lifecycle;
import androidx.lifecycle.LifecycleOwner;
import androidx.lifecycle.LifecycleRegistry;
import com.google.common.util.concurrent.ListenableFuture;
import com.rustfisher.mediasamples.R;
import java.util.concurrent.ExecutionException;
/**
* 摄像头预览悬浮窗的服务
*
* @author an.rustfisher.com
* @date 2022-01-06 23:53
*/
public class FloatingCameraXService extends Service implements LifecycleOwner {
private static final String TAG = "rfDevFloatingCameraX";
private WindowManager mWM;
private View mFloatView;
private LifecycleRegistry mLifecycleRegistry;
private ListenableFuture<ProcessCameraProvider> mCameraProviderFuture;
private ProcessCameraProvider mCameraProvider;
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public void onCreate() {
super.onCreate();
mLifecycleRegistry = new LifecycleRegistry(this);
mLifecycleRegistry.setCurrentState(Lifecycle.State.CREATED);
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand , " + startId);
if (mFloatView == null) {
Log.d(TAG, "onStartCommand: 创建悬浮窗");
initUi();
}
mLifecycleRegistry.setCurrentState(Lifecycle.State.STARTED);
return super.onStartCommand(intent, flags, startId);
}
@Override
public void onDestroy() {
Log.d(TAG, "onDestroy");
if (mFloatView != null) {
mWM.removeView(mFloatView);
}
mLifecycleRegistry.setCurrentState(Lifecycle.State.DESTROYED);
super.onDestroy();
}
private void initUi() {
DisplayMetrics metrics = getApplicationContext().getResources().getDisplayMetrics();
int width = metrics.widthPixels;
int height = metrics.heightPixels;
mWM = (WindowManager) getSystemService(WINDOW_SERVICE);
LayoutInflater inflater = (LayoutInflater) getBaseContext().getSystemService(LAYOUT_INFLATER_SERVICE);
mFloatView = inflater.inflate(R.layout.me_floating_camerax, null);
int layoutType;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
layoutType = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
} else {
layoutType = WindowManager.LayoutParams.TYPE_TOAST;
}
WindowManager.LayoutParams floatLp = new WindowManager.LayoutParams(
(int) (width * (0.4f)), // 这里可以定小一点
(int) (height * (0.3f)),// 为方便展示 这里给的尺寸比较大
layoutType,
WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
PixelFormat.TRANSLUCENT
);
floatLp.gravity = Gravity.CENTER;
floatLp.x = 0;
floatLp.y = 0;
mFloatView.findViewById(R.id.to_big).setOnClickListener(v -> {
stopSelf();
Intent intent = new Intent(getApplicationContext(), MeFloatingCameraXAct.class);
intent.putExtra(MeFloatingCameraXAct.K_START_CAMERA, true);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
});
mWM.addView(mFloatView, floatLp);
mFloatView.setOnTouchListener(new View.OnTouchListener() {
final WindowManager.LayoutParams floatWindowLayoutUpdateParam = floatLp;
double x;
double y;
double px;
double py;
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
x = floatWindowLayoutUpdateParam.x;
y = floatWindowLayoutUpdateParam.y;
px = event.getRawX();
py = event.getRawY();
break;
case MotionEvent.ACTION_MOVE:
floatWindowLayoutUpdateParam.x = (int) ((x + event.getRawX()) - px);
floatWindowLayoutUpdateParam.y = (int) ((y + event.getRawY()) - py);
mWM.updateViewLayout(mFloatView, floatWindowLayoutUpdateParam);
break;
}
return false;
}
});
mCameraProviderFuture = ProcessCameraProvider.getInstance(this);
mCameraProviderFuture.addListener(() -> {
try {
mCameraProvider = mCameraProviderFuture.get();
Log.d(TAG, "[service]获取到了cameraProvider");
bindPreview(mCameraProvider, mFloatView.findViewById(R.id.preview_view));
} catch (ExecutionException | InterruptedException e) {
// 这里不用处理
}
}, ContextCompat.getMainExecutor(this));
}
@NonNull
@Override
public Lifecycle getLifecycle() {
return mLifecycleRegistry;
}
private void bindPreview(ProcessCameraProvider cameraProvider, PreviewView previewView) {
if (cameraProvider == null) {
Toast.makeText(getApplicationContext(), "没获取到相机", Toast.LENGTH_SHORT).show();
return;
}
Toast.makeText(getApplicationContext(), "相机启动", Toast.LENGTH_SHORT).show();
Preview preview = new Preview.Builder().build();
CameraSelector cameraSelector = new CameraSelector.Builder()
.requireLensFacing(CameraSelector.LENS_FACING_BACK)
.build();
preview.setSurfaceProvider(previewView.getSurfaceProvider());
cameraProvider.bindToLifecycle(this, cameraSelector, preview);
}
}
这里悬浮窗view创建完毕后，再去请求摄像头和打开预览。
LifeCycle
生命周期请参考LifeCycle
WindowManager
创建悬浮窗view，并且添加到窗口中。主要使用WindowManager提供的方法。
创建WindowManager.LayoutParams的时候，指定宽高，根据API版本选择layoutType。
启动预览
启动预览部分bindPreview代码与前面的类似。用bindToLifecycle方法。
运行测试
运行到手机上，打开这个Activity就可以看到摄像头预览。图像宽高比正常，没有拉伸现象。
缩小成悬浮窗后，可以拖动。可从悬浮窗跳回Activity。
- 荣耀 EMUI 3.1 Lite，Android 5.1 运行正常
- Redmi 9A，MIUI 12.5.1稳定版，Android 10 运行正常
小结
结合悬浮窗功能与摄像头得到的预览悬浮窗，可以运行在其他app上方。
注意引导用户开启悬浮窗权限和摄像头权限。
参考
一个软件工程师的记录
