问题背景
本文将初步介绍jetpeck库之camerax的初步基本使用，包括实现取景器、拍摄照片、录制视频三个功能用例。
问题分析
话不多说，直接上代码。
（1）项目中添加camerax相关依赖；
def camerax_version = "1.1.0-beta01"
implementation "androidx.camera:camera-core:${camerax_version}"
implementation "androidx.camera:camera-camera2:${camerax_version}"
implementation "androidx.camera:camera-lifecycle:${camerax_version}"
implementation "androidx.camera:camera-video:${camerax_version}"
implementation "androidx.camera:camera-view:${camerax_version}"
implementation "androidx.camera:camera-extensions:${camerax_version}"
（2）项目中使用到了viewbinding，需要相应配置；
android {
compileSdkVersion 31
defaultConfig {
applicationId "composer.kotlin"
...
}
...
buildFeatures{
// 配置开启viewbinding
viewBinding = true
}
}
（3）新建activity，代码如下：
import android.Manifest
import android.content.ContentValues
import android.content.pm.PackageManager
import android.os.Build
import android.os.Bundle
import android.provider.MediaStore
import android.util.Log
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.camera.core.*
import androidx.camera.lifecycle.ProcessCameraProvider
import androidx.camera.video.*
import androidx.camera.video.VideoCapture
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import androidx.core.content.PermissionChecker
import composer.R
import composer.databinding.ActivityCameraxBinding
import kotlinx.android.synthetic.main.activity_camerax.*
import java.nio.ByteBuffer
import java.text.SimpleDateFormat
import java.util.*
import java.util.concurrent.ExecutorService
import java.util.concurrent.Executors
typealias LumaListener = (luma: Double) -> Unit
class CameraxActivity : AppCompatActivity() {
private lateinit var viewBinding: ActivityCameraxBinding
private var imageCapture: ImageCapture? = null
private var videoCapture: VideoCapture<Recorder>? = null
private var recording: Recording? = null
private lateinit var cameraExecutor: ExecutorService
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
viewBinding = ActivityCameraxBinding.inflate(layoutInflater)
setContentView(viewBinding.root)
if (allPermissionsGranted()) {
startCamera()
} else {
ActivityCompat.requestPermissions(
this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS)
}
viewBinding.imageCaptureButton.setOnClickListener { takePhoto() }
viewBinding.videoCaptureButton.setOnClickListener { captureVideo() }
cameraExecutor = Executors.newSingleThreadExecutor()
}
/**
* 捕获图片
*/
private fun takePhoto() {
val imageCapture = imageCapture ?: return
val name = SimpleDateFormat(FILENAME_FORMAT, Locale.US)
.format(System.currentTimeMillis())
val contentValues = ContentValues().apply {
put(MediaStore.MediaColumns.DISPLAY_NAME, name)
put(MediaStore.MediaColumns.MIME_TYPE, "image/jpeg")
if(Build.VERSION.SDK_INT > Build.VERSION_CODES.P) {
put(MediaStore.Images.Media.RELATIVE_PATH, "Pictures/CameraX-Image")
}
}
val outputOptions = ImageCapture.OutputFileOptions
.Builder(contentResolver,
MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
contentValues)
.build()
imageCapture.takePicture(
outputOptions,
ContextCompat.getMainExecutor(this),
object : ImageCapture.OnImageSavedCallback {
override fun onError(exc: ImageCaptureException) {
Log.e(TAG, "Photo capture failed: ${exc.message}", exc)
}
override fun
onImageSaved(output: ImageCapture.OutputFileResults){
val msg = "Photo capture succeeded: ${output.savedUri}"
Toast.makeText(baseContext, msg, Toast.LENGTH_SHORT).show()
Log.d(TAG, msg)
}
}
)
}
/**
* 捕获视频
*/
private fun captureVideo() {
val videoCapture = this.videoCapture ?: return
viewBinding.videoCaptureButton.isEnabled = false
val curRecording = recording
if (curRecording != null) {
// 停止当前录制
curRecording.stop()
recording = null
return
}
val name = SimpleDateFormat(FILENAME_FORMAT, Locale.US)
.format(System.currentTimeMillis())
val contentValues = ContentValues().apply {
put(MediaStore.MediaColumns.DISPLAY_NAME, name)
put(MediaStore.MediaColumns.MIME_TYPE, "video/mp4")
if (Build.VERSION.SDK_INT > Build.VERSION_CODES.P) {
put(MediaStore.Video.Media.RELATIVE_PATH, "Movies/CameraX-Video")
}
}
val mediaStoreOutputOptions = MediaStoreOutputOptions
.Builder(contentResolver, MediaStore.Video.Media.EXTERNAL_CONTENT_URI)
.setContentValues(contentValues)
.build()
recording = videoCapture.output
.prepareRecording(this, mediaStoreOutputOptions)
.apply {
if (PermissionChecker.checkSelfPermission(this@CameraxActivity,
Manifest.permission.RECORD_AUDIO) ==
PermissionChecker.PERMISSION_GRANTED)
{
withAudioEnabled()
}
}
.start(ContextCompat.getMainExecutor(this)) { recordEvent ->
when(recordEvent) {
is VideoRecordEvent.Start -> {
viewBinding.videoCaptureButton.apply {
text = getString(R.string.stop_capture)
isEnabled = true
}
}
is VideoRecordEvent.Finalize -> {
if (!recordEvent.hasError()) {
val msg = "Video capture succeeded: " +
"${recordEvent.outputResults.outputUri}"
Toast.makeText(baseContext, msg, Toast.LENGTH_SHORT)
.show()
Log.d(TAG, msg)
} else {
recording?.close()
recording = null
Log.e(TAG, "Video capture ends with error: " +
"${recordEvent.error}")
}
viewBinding.videoCaptureButton.apply {
text = getString(R.string.start_capture)
isEnabled = true
}
}
}
}
}
/**
* 启动相机，开机相机取景预览
*/
private fun startCamera() {
val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
cameraProviderFuture.addListener({
val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()
// 开启相机取景预览
val preview = Preview.Builder()
.build()
.also {
it.setSurfaceProvider(viewFinder.surfaceProvider)
}
imageCapture = ImageCapture.Builder()
.build()
val recorder = Recorder.Builder()
.setQualitySelector(QualitySelector.from(Quality.HIGHEST))
.build()
videoCapture = VideoCapture.withOutput(recorder)
val imageAnalyzer = ImageAnalysis.Builder()
.build()
.also {
it.setAnalyzer(cameraExecutor, LuminosityAnalyzer { luma ->
Log.d(TAG, "Average luminosity: $luma")
})
}
// 默认使用后置摄像头
val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA
try {
cameraProvider.unbindAll()
// 混合使用preview、imageCapture、和videoCapture三个用例
cameraProvider.bindToLifecycle(
this, cameraSelector, preview, imageCapture, videoCapture)
// 注意：不支持 preview + imageCapture + videoCapture + imageAnalysis 组合
// cameraProvider.bindToLifecycle(
// this, cameraSelector, preview, imageAnalyzer, imageCapture, videoCapture)
} catch(exc: Exception) {
Log.e(TAG, "Use case binding failed", exc)
}
}, ContextCompat.getMainExecutor(this))
}
private fun allPermissionsGranted() = REQUIRED_PERMISSIONS.all {
ContextCompat.checkSelfPermission(
baseContext, it) == PackageManager.PERMISSION_GRANTED
}
override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String>, grantResults: IntArray) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults)
if (requestCode == REQUEST_CODE_PERMISSIONS) {
if (allPermissionsGranted()) {
startCamera()
} else {
Toast.makeText(this,
"Permissions not granted by the user.",
Toast.LENGTH_SHORT).show()
finish()
}
}
}
override fun onDestroy() {
super.onDestroy()
cameraExecutor.shutdown()
}
companion object {
private const val TAG = "baorant"
private const val FILENAME_FORMAT = "yyyy-MM-dd-HH-mm-ss-SSS"
private const val REQUEST_CODE_PERMISSIONS = 10
private val REQUIRED_PERMISSIONS =
mutableListOf (
Manifest.permission.CAMERA,
Manifest.permission.RECORD_AUDIO
).apply {
if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.P) {
add(Manifest.permission.WRITE_EXTERNAL_STORAGE)
}
}.toTypedArray()
}
private class LuminosityAnalyzer(private val listener: LumaListener) : ImageAnalysis.Analyzer {
private fun ByteBuffer.toByteArray(): ByteArray {
rewind()
val data = ByteArray(remaining())
get(data)
return data
}
override fun analyze(image: ImageProxy) {
val buffer = image.planes[0].buffer
val data = buffer.toByteArray()
val pixels = data.map { it.toInt() and 0xFF }
val luma = pixels.average()
listener(luma)
image.close()
}
}
}
（4）activity对应layout布局文件如下
<?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"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".view.CameraxActivity">
<androidx.camera.view.PreviewView
android:id="@+id/viewFinder"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<Button
android:id="@+id/image_capture_button"
android:layout_width="110dp"
android:layout_height="110dp"
android:layout_marginBottom="50dp"
android:layout_marginEnd="50dp"
android:elevation="2dp"
android:text="@string/take_photo"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintEnd_toStartOf="@id/vertical_centerline" />
<Button
android:id="@+id/video_capture_button"
android:layout_width="110dp"
android:layout_height="110dp"
android:layout_marginBottom="50dp"
android:layout_marginStart="50dp"
android:elevation="2dp"
android:text="@string/start_capture"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toEndOf="@id/vertical_centerline" />
<androidx.constraintlayout.widget.Guideline
android:id="@+id/vertical_centerline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent=".50" />
</androidx.constraintlayout.widget.ConstraintLayout>
（5）使用到的字符串资源如下：
<string name="take_photo">拍照</string>
<string name="start_capture">开始捕捉</string>
<string name="stop_capture">停止捕获</string>
（6）运行结果如下：
实现取景器功能，点击拍照功能可以捕捉图像存入手机本地。
点击开始捕获按钮开始视频捕获，停止后视频保存到本地。
问题总结
本文初步介绍了jetpeck库之camerax的初步基本使用，包括实现取景器、拍摄照片、录制视频三个功能用例，有兴趣的同学可以进一步深入研究。