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Android CameraX 使用教程

作者：花生_TL007 | 2024-04-21 06:16:12

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android camerax

Google 原来提供了Camera，后面又推出了Camera2，然后几年前在Jetpack里面推出了CameraX

CameraX其实内部是封装Camera2的。但是它比Camera2使用起来更加简便，性能也比Camera2提高了。

废话少说，直接上代码：

要用CameraX，第一是要引入其 dependencies

  1.     // CameraX core library
  2.     def camerax_version = '1.1.0-beta01'
  3.     implementation "androidx.camera:camera-core:$camerax_version"
  4.  
  5.     // CameraX Camera2 extensions
  6.     implementation "androidx.camera:camera-camera2:$camerax_version"
  7.  
  8.     // CameraX Lifecycle library
  9.     implementation "androidx.camera:camera-lifecycle:$camerax_version"
  10.  
  11.     // CameraX View class
  12.     implementation "androidx.camera:camera-view:$camerax_version"

进而上个布局；

  1. <?xml version="1.0" encoding="utf-8"?>
  2. <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
  3.     xmlns:app="http://schemas.android.com/apk/res-auto"
  4.     xmlns:tools="http://schemas.android.com/tools"
  5.     android:layout_width="match_parent"
  6.     android:layout_height="match_parent"
  7.     tools:context=".CameraActivity">
  8.  
  9.     <!--预览的控件-->
  10.     <androidx.camera.view.PreviewView
  11.         android:id="@+id/preview_view"
  12.         android:layout_width="0dp"
  13.         android:layout_height="0dp"
  14.         app:scaleType="fillCenter"
  15.         app:layout_constraintBottom_toBottomOf="parent"
  16.         app:layout_constraintLeft_toLeftOf="parent"
  17.         app:layout_constraintRight_toRightOf="parent"
  18.         app:layout_constraintTop_toTopOf="parent" />
  19.  
  20.     <androidx.appcompat.widget.AppCompatButton
  21.         android:id="@+id/switchCamera"
  22.         android:layout_width="100dp"
  23.         android:layout_height="50dp"
  24.         android:layout_marginTop="10dp"
  25.         android:text="切换相机"
  26.         app:layout_constraintLeft_toLeftOf="parent"
  27.         app:layout_constraintRight_toRightOf="parent"
  28.         app:layout_constraintTop_toTopOf="parent">
  29.     </androidx.appcompat.widget.AppCompatButton>
  30.  
  31.     <androidx.appcompat.widget.AppCompatTextView
  32.         android:id="@+id/tvFps"
  33.         android:layout_width="wrap_content"
  34.         android:layout_height="wrap_content"
  35.         app:layout_constraintTop_toBottomOf="@id/switchCamera"
  36.         app:layout_constraintLeft_toLeftOf="parent"
  37.         android:textSize="20sp"
  38.         android:gravity="center"
  39.         android:padding="5dp"
  40.         android:text="12456"
  41.         android:textColor="@color/white">
  42.     </androidx.appcompat.widget.AppCompatTextView>
  43.  
  44. </androidx.constraintlayout.widget.ConstraintLayout>

然后上个Activity代码：

  1.  
  2.  
  3. import androidx.appcompat.app.AppCompatActivity
  4. import android.os.Bundle
  5. import android.os.SystemClock
  6. import android.util.Log
  7. import android.view.View
  8. import androidx.appcompat.widget.AppCompatTextView
  9. import androidx.camera.core.*
  10. import androidx.camera.lifecycle.ProcessCameraProvider
  11. import androidx.camera.view.PreviewView
  12. import androidx.core.content.ContextCompat
  13.  
  14. class CameraActivity : AppCompatActivity() {
  15.  
  16.     companion object{
  17.         private const val TAG = "CameraActivity"
  18.     }
  19.  
  20.     private var cameraProvider: ProcessCameraProvider? = null
  21.     private var previewUseCase: Preview? = null
  22.     private lateinit var previewView: PreviewView
  23.     private lateinit var tvFps: AppCompatTextView
  24.     private var cameraSelector: CameraSelector? = null
  25.     private var lensFacing = CameraSelector.LENS_FACING_FRONT
  26.     private var camera: Camera? = null
  27.     private var analysisUseCase: ImageAnalysis? = null
  28.  
  29.     override fun onCreate(savedInstanceState: Bundle?) {
  30.         super.onCreate(savedInstanceState)
  31.         setContentView(R.layout.activity_camera)
  32.         previewView = findViewById(R.id.preview_view)
  33.         tvFps = findViewById(R.id.tvFps)
  34.         findViewById<View>(R.id.switchCamera).setOnClickListener {
  35.             switchCamera()
  36.         }
  37.         cameraSelector = CameraSelector.Builder().requireLensFacing(lensFacing).build()
  38.  
  39.         if (PermissionsUtil.allPermissionsGranted(this)){
  40.             start()
  41.         }else{
  42.             PermissionsUtil.requestPermission(this)
  43.         }
  44.     }
  45.  
  46.     private fun start() {
  47.         /*
  48.         通过 ProcessCameraProvider 获取 cameraProvider
  49.         cameraProvider 就是我们持有的相机实例
  50.         */
  51.         val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
  52.         cameraProviderFuture.addListener(Runnable {
  53.             cameraProvider = cameraProviderFuture.get()
  54.             startCamera()
  55.         }, ContextCompat.getMainExecutor(this))
  56.     }
  57.  
  58.     override fun onRequestPermissionsResult(
  59.         requestCode: Int,
  60.         permissions: Array<out String>,
  61.         grantResults: IntArray
  62.     ) {
  63.         super.onRequestPermissionsResult(requestCode, permissions, grantResults)
  64.         if (PermissionsUtil.allPermissionsGranted(this)){
  65.             start()
  66.         }
  67.     }
  68.  
  69.     /**
  70.      *      启动相机
  71.      * */
  72.     private fun startCamera() {
  73.         if (cameraProvider != null) {
  74.             cameraProvider!!.unbindAll()
  75.             /*
  76.             这一步是绑定预览界面，如果不需要预览界面，这一步克注释掉
  77.             CameraX优势体验之一：预览界面可以根据开发者需求去取舍，而Camera1和Camera2则必须要预览界面
  78.             */
  79.             bindPreviewUseCase()
  80.             // 这一步是绑定相机预览数据，可以获得相机每一帧的数据
  81.             bindAnalysisUseCase()
  82.         }
  83.     }
  84.  
  85.     /**
  86.      * 绑定预览界面。不需要预览界面可以不调用
  87.      * */
  88.     private fun bindPreviewUseCase() {
  89.         if (previewUseCase != null) {
  90.             cameraProvider!!.unbind(previewUseCase)
  91.         }
  92.  
  93.         val builder = Preview.Builder()
  94.         builder.setTargetAspectRatio(AspectRatio.RATIO_16_9).build()
  95.         previewUseCase = builder.build()
  96.         previewUseCase!!.setSurfaceProvider(previewView.surfaceProvider)
  97.         cameraProvider!!.bindToLifecycle(
  98.             this,
  99.             cameraSelector!!,
  100.             previewUseCase
  101.         )
  102.     }
  103.  
  104.     private var lastTime = 0L
  105.     private var lastShowTime = 0L
  106.     private var count = 0
  107.     private var maxFrameMs = 0L
  108.     private var minFrameMs = Long.MAX_VALUE
  109.  
  110.  
  111.     private fun bindAnalysisUseCase() {
  112.         if (analysisUseCase != null) {
  113.             cameraProvider!!.unbind(analysisUseCase)
  114.         }
  115.         val builder = ImageAnalysis.Builder().setTargetAspectRatio(AspectRatio.RATIO_16_9)
  116.         analysisUseCase = builder.build()
  117.         analysisUseCase?.setAnalyzer(
  118.             ContextCompat.getMainExecutor(this)
  119.         ) { imageProxy: ImageProxy ->
  120.             count += 1
  121.             val currentTime = SystemClock.elapsedRealtime()
  122.             val d = currentTime - lastShowTime
  123.             maxFrameMs = maxFrameMs.coerceAtLeast(d)
  124.             minFrameMs = minFrameMs.coerceAtMost(d)
  125.             if ((currentTime - lastTime) >= 1000){
  126.                 tvFps.text = "fps: ${count}, 两帧最大：${maxFrameMs}, 最小：${minFrameMs}"
  127.                 lastTime = currentTime
  128.                 count = 0
  129.                 maxFrameMs = 0
  130.                 minFrameMs = Long.MAX_VALUE
  131.             }
  132.             lastShowTime = currentTime
  133.             Log.d(TAG,"ImageProxy: 宽高： ${imageProxy.width} * ${imageProxy.height}")
  134.  
  135.             //必须close,相机才会下发下一帧数据,否则会一直阻塞相机下发数据
  136.             imageProxy.close()
  137.         }
  138.         camera = cameraProvider!!.bindToLifecycle(
  139.             this,
  140.             cameraSelector!!,
  141.             analysisUseCase
  142.         )
  143.     }
  144.  
  145.     private fun switchCamera() {
  146.         if (cameraProvider == null) {
  147.             return
  148.         }
  149.         val newLensFacing =
  150.             if (lensFacing == CameraSelector.LENS_FACING_FRONT) {
  151.                 CameraSelector.LENS_FACING_BACK
  152.             } else {
  153.                 CameraSelector.LENS_FACING_FRONT
  154.             }
  155.         val newCameraSelector = CameraSelector.Builder().requireLensFacing(newLensFacing).build()
  156.         try {
  157.             if (cameraProvider!!.hasCamera(newCameraSelector)) {
  158.                 lensFacing = newLensFacing
  159.                 cameraSelector = newCameraSelector
  160.                 startCamera()
  161.                 return
  162.             }
  163.         } catch (e: CameraInfoUnavailableException) {
  164.             // Falls through
  165.         }
  166.     }
  167. }

添加权限工具类代码

  1. object PermissionsUtil {
  2.  
  3.     private const val TAG = "PermissionsUtil"
  4.     private const val PERMISSION_REQUESTS = 1
  5.  
  6.     fun requestPermission(context: Context) {
  7.         if (!allPermissionsGranted(context)) {
  8.             runtimePermissions(context)
  9.         }
  10.     }
  11.  
  12.     private fun isPermissionGranted(context: Context, permission: String?): Boolean {
  13.         if (ContextCompat.checkSelfPermission(context, permission!!) ==
  14.             PackageManager.PERMISSION_GRANTED
  15.         ) {
  16.             return true
  17.         }
  18.         return false
  19.     }
  20.  
  21.     fun allPermissionsGranted(context: Context): Boolean {
  22.         for (permission in requiredPermissions(context)) {
  23.             if (!isPermissionGranted(context, permission)) {
  24.                 return false
  25.             }
  26.         }
  27.         return true
  28.     }
  29.  
  30.     private fun requiredPermissions(context: Context): Array<String?> {
  31.         val info =
  32.             context.packageManager.getPackageInfo(context.packageName, PackageManager.GET_PERMISSIONS)
  33.         val ps = info.requestedPermissions
  34.         if (ps != null && ps.isNotEmpty()) {
  35.             ps
  36.         } else {
  37.             arrayOfNulls(0)
  38.         }
  39.         return ps
  40.     }
  41.  
  42.     private fun runtimePermissions(context: Context) {
  43.         val allNeededPermissions: MutableList<String?> = ArrayList()
  44.         for (permission in requiredPermissions(context)) {
  45.             if (!isPermissionGranted(context, permission)) {
  46.                 allNeededPermissions.add(permission)
  47.             }
  48.         }
  49.         if (allNeededPermissions.isNotEmpty()) {
  50.             ActivityCompat.requestPermissions(
  51.                 getActivity(context),
  52.                 allNeededPermissions.toTypedArray(),
  53.                 PERMISSION_REQUESTS
  54.             )
  55.         }
  56.     }
  57.  
  58.     @SuppressLint("UseRequireInsteadOfGet")
  59.     private fun getActivity(context: Context) = when (context) {
  60.         is Fragment -> {
  61.             (context as Fragment).activity!!
  62.         }
  63.         is Activity -> {
  64.             context
  65.         }
  66.         else -> {
  67.             throw RuntimeException("context 必须是 Activity 或者 Fragment ")
  68.         }
  69.     }
  70. }

运行起来看下效果

ok，没问题

有问题请留言！

demo地址 https://github.com/LeoLiang23/cameraDemo

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