[移动开发]打开相机并获取相机流，并将yuv数据转换成nv21

1.导入依赖

在app下的build.gradle中加入

?def camerax_version ="1.0.1"

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-view:1.0.0-alpha28"

2.相机布局文件

使用androidx 的布局

<?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=".MainActivity">

? ? <androidx.camera.view.PreviewView

? ? ? ? android:id="@+id/textureView"

? ? ? ? android:layout_width="match_parent"

? ? ? ? android:layout_height="match_parent"

? ? ? ? tools:layout_editor_absoluteX="0dp"

? ? ? ? tools:layout_editor_absoluteY="0dp" />

</androidx.constraintlayout.widget.ConstraintLayout>

3.打开相机

private var textureView:PreviewView? =null

private val executor =Executors.newSingleThreadExecutor()

private val permissionsRequestCode =Random.nextInt(0,10000)

private var lensFacing:Int =CameraSelector.LENS_FACING_FRONT

//打开相机需要的权限

private val permissions =listOf(Manifest.permission.CAMERA,Manifest.permission.READ_EXTERNAL_STORAGE,Manifest.permission.WRITE_EXTERNAL_STORAGE)

override fun onCreate(savedInstanceState:Bundle?) {

????????super.onCreate(savedInstanceState)

????????setContentView(R.layout.activity_main)

? ? ? ? textureView = findViewById(R.id.textureView);

}

//先检测权限如果有权限就打开相机

override fun onResume() {

????????super.onResume()

? ? if (!hasPermissions(this)) { //检测权限

????????ActivityCompat.requestPermissions(

????????????????this,permissions.toTypedArray(),permissionsRequestCode

? ? ? ? )

????}else {

????????bindCameraUseCases()//打开相机

????}

}

/** 绑定预览和获取图片数据*/

@SuppressLint("UnsafeExperimentalUsageError","UnsafeOptInUsageError")

private fun bindCameraUseCases() =textureView?.post{

? ? ?val cameraProviderFuture =ProcessCameraProvider.getInstance(this)

? ? ?cameraProviderFuture.addListener(Runnable {

? ? ? ? ? val cameraProvider =cameraProviderFuture.get()

? ? ? ? ? val preview =textureView?.display?.let {

? ? ? ? ? ? ? ?Preview.Builder()

? ? ? ? ? ? ? .setTargetAspectRatio(AspectRatio.RATIO_4_3)

? ? ? ? ? ? ? .setTargetRotation(it.rotation)

? ? ? ? ? ? ? .build()

? ? ?}

? ? ?val imageAnalysis =ImageAnalysis.Builder()

? ? ? ? ? ?.setTargetAspectRatio(AspectRatio.RATIO_4_3)

? ? ? ? ? ?.setTargetRotation(textureView!!.display.rotation)

? ? ? ? ? ? .setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)

? ? ? ? ? ? .build()

? ? ? var frameCounter =0

? ? ? var lastFpsTimestamp =System.currentTimeMillis()

? ? ? var yuvBits:ByteBuffer? =null

? ? ? ?imageAnalysis.setAnalyzer(executor,ImageAnalysis.Analyzer{ image->

? ? ? ? ? ? val yuvBuffer = image.image?.let { YuvByteBuffer(it,yuvBits)} //获取相机流并转换成nv21

? ? ? ? ? ? image.close()

? ? ? ? ? //检测相机帧率

? ? ? ? ? ? val frameCount =10

? ? ? ? ? ? if (++frameCounter %frameCount ==0) {

? ? ? ? ? ? ? ? ?frameCounter =0

? ? ? ? ? ? ? ? val now =System.currentTimeMillis()

? ? ? ? ? ? ? ? val delta =now -lastFpsTimestamp

? ? ? ? ? ? ? ? val fps =1000 *frameCount.toFloat() /delta

? ? ? ? ? ? ? ? Log.d(TAG,"FPS: ${"%.02f".format(fps)}")

? ? ? ? ? ? ? ? ?lastFpsTimestamp =now

? ? ? ? ? ? }

? ? ? ?})

// Create a new camera selector each time, enforcing lens facing

? ?val cameraSelector =CameraSelector.Builder().requireLensFacing(lensFacing).build()

// Apply declared configs to CameraX using the same lifecycle owner

? ? cameraProvider.unbindAll()

? ? ? ? ?val camera =cameraProvider.bindToLifecycle(

????????????this as LifecycleOwner,cameraSelector,preview,imageAnalysis

? ? ? ? ? )

? ? val c:CameraInfo =camera.cameraInfo;

// Use the camera object to link our preview use case with the view

? ?preview?.setSurfaceProvider(textureView?.surfaceProvider)

? },ContextCompat.getMainExecutor(this))

? }

/** Convenience method used to check if all permissions required by this app are granted */

private fun hasPermissions(context:Context) =permissions.all {

? ? ContextCompat.checkSelfPermission(context,it) ==PackageManager.PERMISSION_GRANTED

}

override fun onRequestPermissionsResult(

requestCode:Int,

permissions:Array,

grantResults:IntArray

) {

super.onRequestPermissionsResult(requestCode, permissions, grantResults)

if (requestCode ==permissionsRequestCode && hasPermissions(this)) {

bindCameraUseCases()

}else {

finish()// If we don't have the required permissions, we can't run

? ? }

}

4.YUV转nv21工具

@kotlin.annotation.Retention(AnnotationRetention.SOURCE)

@IntDef(ImageFormat.NV21,ImageFormat.YUV_420_888)

annotation class YuvType

class YuvByteBuffer(image:Image, dstBuffer:ByteBuffer? =null) {

@YuvType

? ? val type:Int

? ? val buffer:ByteBuffer

? ? init {

val wrappedImage = ImageWrapper(image)

type =if (wrappedImage.u.pixelStride ==1) {

ImageFormat.YUV_420_888

? ? ? ? }else {

ImageFormat.NV21

? ? ? ? }

val size = image.width * image.height *3 /2

? ? ? ? buffer =if (

dstBuffer ==null ||dstBuffer.capacity()

dstBuffer.isReadOnly || !dstBuffer.isDirect

? ? ? ? ) {

ByteBuffer.allocateDirect(size) }

else {

dstBuffer

}

buffer.rewind()

removePadding(wrappedImage)

}

// Input buffers are always direct as described in

// https://developer.android.com/reference/android/media/Image.Plane#getBuffer()

? ? private fun removePadding(image:ImageWrapper) {

val sizeLuma = image.y.width * image.y.height

? ? ? ? val sizeChroma = image.u.width * image.u.height

? ? ? ? if (image.y.rowStride > image.y.width) {

removePaddingCompact(image.y,buffer,0)

}else {

buffer.position(0)

buffer.put(image.y.buffer)

}

if (type ==ImageFormat.YUV_420_888) {

if (image.u.rowStride > image.u.width) {

removePaddingCompact(image.u,buffer,sizeLuma)

removePaddingCompact(image.v,buffer,sizeLuma +sizeChroma)

}else {

buffer.position(sizeLuma)

buffer.put(image.u.buffer)

buffer.position(sizeLuma +sizeChroma)

buffer.put(image.v.buffer)

}

}else {

if (image.u.rowStride > image.u.width *2) {

removePaddingNotCompact(image,buffer,sizeLuma)

}else {

buffer.position(sizeLuma)

var uv = image.v.buffer

? ? ? ? ? ? ? ? val properUVSize = image.v.height * image.v.rowStride -1

? ? ? ? ? ? ? ? if (uv.capacity() >properUVSize) {

uv = clipBuffer(image.v.buffer,0,properUVSize)

}

buffer.put(uv)

val lastOne = image.u.buffer[image.u.buffer.capacity() -1]

buffer.put(buffer.capacity() -1,lastOne)

}

}

buffer.rewind()

}

private fun removePaddingCompact(

plane:PlaneWrapper,

dst:ByteBuffer,

offset:Int

? ? ) {

require(plane.pixelStride ==1){

? ? ? ? ? ? "use removePaddingCompact with pixelStride == 1"

? ? ? ? }

? ? ? ? val src = plane.buffer

? ? ? ? val rowStride = plane.rowStride

? ? ? ? var row:ByteBuffer

? ? ? ? dst.position(offset)

for (i in 0 until plane.height) {

row = clipBuffer(src,i *rowStride, plane.width)

dst.put(row)

}

}

private fun removePaddingNotCompact(

image:ImageWrapper,

dst:ByteBuffer,

offset:Int

? ? ) {

require(image.u.pixelStride ==2){

? ? ? ? ? ? "use removePaddingNotCompact pixelStride == 2"

? ? ? ? }

? ? ? ? val width = image.u.width

? ? ? ? val height = image.u.height

? ? ? ? val rowStride = image.u.rowStride

? ? ? ? var row:ByteBuffer

? ? ? ? dst.position(offset)

for (i in 0 until height -1) {

row = clipBuffer(image.v.buffer,i *rowStride,width *2)

dst.put(row)

}

row = clipBuffer(image.u.buffer, (height -1) *rowStride -1,width *2)

dst.put(row)

}

private fun clipBuffer(buffer:ByteBuffer, start:Int, size:Int):ByteBuffer {

val duplicate = buffer.duplicate()

duplicate.position(start)

duplicate.limit(start + size)

return duplicate.slice()

}

private class ImageWrapper(image:Image) {

val width= image.width

? ? ? ? val height = image.height

? ? ? ? val y = PlaneWrapper(width,height, image.planes[0])

val u = PlaneWrapper(width /2,height /2, image.planes[1])

val v = PlaneWrapper(width /2,height /2, image.planes[2])

// Check this is a supported image format

// https://developer.android.com/reference/android/graphics/ImageFormat#YUV_420_888

? ? ? ? init {

require(y.pixelStride ==1){

? ? ? ? ? ? ? ? "Pixel stride for Y plane must be 1 but got ${y.pixelStride}instead."

? ? ? ? ? ? }

? ? ? ? ? ? require(u.pixelStride ==v.pixelStride &&u.rowStride ==v.rowStride){

? ? ? ? ? ? ? ? "U and V planes must have the same pixel and row strides " +

"but got pixel=${u.pixelStride} row=${u.rowStride} for U " +

"and pixel=${v.pixelStride} and row=${v.rowStride}for V"

? ? ? ? ? ? }

? ? ? ? ? ? require(u.pixelStride ==1 ||u.pixelStride ==2){

? ? ? ? ? ? ? ? "Supported" +" pixel strides for U and V planes are 1 and 2"

? ? ? ? ? ? }

? ? ? ? }

}

private class PlaneWrapper(width:Int, height:Int, plane:Image.Plane) {

val width = width

val height = height

val buffer:ByteBuffer = plane.buffer

? ? ? ? val rowStride = plane.rowStride

? ? ? ? val pixelStride = plane.pixelStride

? ? }

}

5.AndroidManifest.xml

<!-- Declare features -->

<uses-feature android:name="android.hardware.camera" />

<!-- Declare permissions -->

<uses-permission android:name="android.permission.CAMERA" />

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />