Android开发 CameraX开发

东智哥 發表於 2021-8-12 15:24:00

<h1>前言</h1>
　　google推出Camera后,发现Camera功能简单,难以满足需求调用Camera各种效果,所以又推出了Camera2. Camera2功能强大但是使用十分麻烦,回调与冗余代码太多,而且特别容易在释放Camera上犯错导致activty的内存泄露. 所以google推出了更简单易用,但是功能也强大的CameraX.
　　因为CameraX的简单可以帮助我们高效率开发,所以也是有学习的必要性.(Camera2了解就行,没必要死磕浪费太多时间),CameraX有以下优势:
<ol>
<li>CameraX与Liftcycle结合,与Activity或者Fragment的生命周期捆绑,不要考虑摄像头的释放问题,减少了代码的复杂度.</li>
<li>CameraX兼容至 Android L (API 21)</li>
<li>依然支持Camera2的丰富摄像头功能</li>
</ol>
<h1>添加依赖</h1>
<div class="cnblogs_code">
<pre> // CameraX 核心库使用 camera2 实现
implementation "androidx.camera:camera-camera2:1.0.0-beta03"
// 可以使用CameraView
implementation "androidx.camera:camera-view:1.0.0-alpha10"
// 可以使用供应商扩展
implementation "androidx.camera:camera-extensions:1.0.0-alpha10"
//camerax的生命周期库
implementation "androidx.camera:camera-lifecycle:1.0.0-beta03"</pre>
</div>
<h1>获取权限</h1>
跟以前一样,需要动态授权一些必要权限
<div class="cnblogs_code">
<pre> 
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /></pre>
</div>
<h1>预览摄像头画面</h1>
从最简单的预览摄像头图像开始,我们逐步了解使用方式,代码如下:
布局要求使用PreviewView,作为SurfaceProvider
<div class="cnblogs_code">
<pre> <androidx.camera.view.PreviewView
 android:id="@+id/previewView"
 android:layout_width="match_parent"
 android:layout_height="match_parent"/></pre>
</div>
代码:
<div class="cnblogs_code">
<pre>class CameraXActivity : AppCompatActivity() {
private val TAG = CameraXActivity::class.java.simpleName
private lateinit var mPreviewView: PreviewView 
override fun onCreate(savedInstanceState: Bundle?) {
 super.onCreate(savedInstanceState)
 setContentView(R.layout.activity_camera_x2)
 mPreviewView = findViewById(R.id.previewView)
 startCameraPreview()
}

/**
* 开始相机预览
*/
private fun startCameraPreview() {
 val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
 cameraProviderFuture.addListener(Runnable {
 //用于将相机的生命周期绑定到生命周期所有者
 val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()
 //创建预览
 val preview = Preview.Builder().build()
 //选择后置摄像头
 val cameraSelector = CameraSelector.Builder().requireLensFacing(CameraSelector.LENS_FACING_BACK).build()
 try {
 //在重新绑定之前取消绑定
 cameraProvider.unbindAll()
 //将生命周期,选择摄像头,预览,绑定到相机
 val camera = cameraProvider.bindToLifecycle(this, cameraSelector, preview)
 //设置预览的View
 preview.setSurfaceProvider(mPreviewView.createSurfaceProvider(camera.cameraInfo))
 } catch (exc: Exception) {
 Log.e(TAG, "Use case binding failed", exc)
 }
 }, ContextCompat.getMainExecutor(this))
}
}</pre>
</div>
特别简单就完成了,而且无需考虑摄像头的释放
<h1>实现拍照</h1>
<div class="cnblogs_code">
<pre>class CameraXActivity : AppCompatActivity() {
private val TAG = CameraXActivity::class.java.simpleName
private lateinit var mImageCapture: ImageCapture
private lateinit var mImageAnalysis: ImageAnalysis
private lateinit var mPreviewView: PreviewView
override fun onCreate(savedInstanceState: Bundle?) {
 super.onCreate(savedInstanceState)
 setContentView(R.layout.activity_camera_x2)
 mPreviewView = findViewById(R.id.previewView)
 startCameraPreview()
 takePhoto.setOnClickListener {
 //点击后拍照
 takePhoto()
 }
}

/**
* 开始相机预览
*/
private fun startCameraPreview() {
 val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
 cameraProviderFuture.addListener(Runnable {
 val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()
 val preview = Preview.Builder().build()
 //创建图像捕捉
 mImageCapture = ImageCapture.Builder().build()
 val cameraSelector = CameraSelector.Builder().requireLensFacing(CameraSelector.LENS_FACING_BACK).build()
 try {
 cameraProvider.unbindAll()
 //请注意,这里新增了一个ImageCapture
 val camera = cameraProvider.bindToLifecycle(this, cameraSelector, preview, mImageCapture)
 preview.setSurfaceProvider(mPreviewView.createSurfaceProvider(camera.cameraInfo))
 } catch (exc: Exception) {
 Log.e(TAG, "Use case binding failed", exc)
 }
 }, ContextCompat.getMainExecutor(this))
}

/**
* 拍照
*/
private fun takePhoto() {
 //图像的保存路径与名称
 val photoFile = File(applicationContext.externalCacheDir?.path
 , SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.getDefault()).format(System.currentTimeMillis()) + ".jpg")

 // 创建图像文件输出选项
 val outputOptions = ImageCapture.OutputFileOptions.Builder(photoFile).build()

 //拍照,并且注册拍照后的结果监听
 mImageCapture.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 savedUri = Uri.fromFile(photoFile)
 val msg = "Photo capture succeeded: $savedUri"
 Toast.makeText(baseContext, msg, Toast.LENGTH_SHORT).show()
 Log.d(TAG, msg)
 }
 })
}
}</pre>
</div>
<h2>拍照图像旋转</h2>
代码的其他部分与上面的示例代码一致, 我们只需要关注ImageCapture的创建与添加setTargetRotation
<div class="cnblogs_code">
<pre> private fun createImageCapture():ImageCapture{
 //创建图像捕捉
 mImageCapture = ImageCapture.Builder()
 .setTargetRotation(Surface.ROTATION_90)//设置旋转角度,并且只能有4个旋转方向属性ROTATION_0/ROTATION_90/ROTATION_180/ROTATION_270
 .build()
 return mImageCapture
}</pre>
</div>
<h2>设置执行IO线程</h2>
<div class="cnblogs_code">
<pre> private fun createImageCapture():ImageCapture{
 //创建图像捕捉
 mImageCapture = ImageCapture.Builder()
 .setIoExecutor(Executors.newSingleThreadExecutor())//设置执行IO线程
 .build()
 return mImageCapture
}</pre>
</div>
<h2>设置捕捉模式</h2>
<div class="cnblogs_code">
<pre> private fun createImageCapture():ImageCapture{
 //创建图像捕捉
 mImageCapture = ImageCapture.Builder()
 //CAPTURE_MODE_MAXIMIZE_QUALITY 高画质
 //CAPTURE_MODE_MINIMIZE_LATENCY 低延迟
 .setCaptureMode(ImageCapture.CAPTURE_MODE_MAXIMIZE_QUALITY)
 .build()
 return mImageCapture
}</pre>
</div>
<h2>设置闪光灯</h2>
<div class="cnblogs_code">
<pre> private fun createImageCapture():ImageCapture{
 //创建图像捕捉
 mImageCapture = ImageCapture.Builder()
 //FLASH_MODE_ON 闪光灯开启
 //FLASH_MODE_OFF 闪光灯关闭
 //FLASH_MODE_AUTO 闪光灯自动
 .setFlashMode(ImageCapture.FLASH_MODE_ON)
 .build()
 return mImageCapture
}</pre>
</div>
<h2>设置宽高比</h2>
<div class="cnblogs_code">
<pre> private fun createImageCapture():ImageCapture{
 mImageCapture = ImageCapture.Builder()
 //RATIO_4_3 4比3
 //RATIO_16_916比9
 .setTargetAspectRatio(AspectRatio.RATIO_16_9)
 .build()
 return mImageCapture
}</pre>
</div>
<h2>设置分辨率</h2>
下面还帖了一些注释,这注释的意思是,你可以随便设置分辨率大小,但是真正的分辨率并不一定是你设置的数值,而是在摄像头里获取的分辨率列表中去取最近似值.
为什么会有这种说明? 我这里给没有接触过摄像头开发的朋友说明一下:
手机的摄像头的分辨率并不是可以随便设置的,这需要取决于你开发的设备的摄像头驱动的分辨率列表. 在以往开发Camera1和Camera2的时候我们需要自己获取这份列表,从中选择我们需要的分辨率. 在使用CameraX的时候他们帮我们简化了这个筛选过程,你只需要设置目标分辨率,代码会自动选择近似分辨率
<div class="cnblogs_code">
<pre> private fun createImageCapture(): ImageCapture {
 mImageCapture = ImageCapture.Builder()
 /*
 目标分辨率尝试建立图像分辨率的最小界限。实际图像分辨率将是尺寸上最接近的可用分辨率，该分辨率不小于由相机实现确定的目标分辨率。
 但是，如果不存在等于或大于目标分辨率的分辨率，则将选择最接近的小于目标分辨率的可用分辨率。
 与提供的 {@link Size} 具有相同纵横比的分辨率将在不同纵横比的分辨率之前优先考虑。
 */
 .setTargetResolution(Size(1280, 720))
 .build()
 return mImageCapture
}</pre>
</div>
<h1>控制对焦</h1>
<div class="cnblogs_code">
<pre>val factory = SurfaceOrientedMeteringPointFactory(width, height)
val point = factory.createPoint(x, y)
val action = FocusMeteringAction.Builder(point, FocusMeteringAction.FLAG_AF)
.addPoint(point2, FocusMeteringAction.FLAG_AE) // could have many
// auto calling cancelFocusAndMetering in 5 seconds
.setAutoCancelDuration(5, TimeUnit.SECONDS)
.build()

val future = cameraControl.startFocusAndMetering(action)
future.addListener( Runnable {
val result = future.get()
// process the result
} , executor)</pre>
</div>
<h1>实现录像</h1>
<div class="cnblogs_code">
<pre> private void takeVideo() {
 VideoCapture videoCapture = new VideoCaptureConfig.Builder()
 //设置宽高
 .setTargetAspectRatio(aspectRatio(width, height))
 //设置旋转角度
 .setTargetRotation(previewView.getDisplay().getRotation())
 .build();
 //录像前必须解绑
 cameraProvider.unbindAll();
 //开启相机预览
 preview.setSurfaceProvider(previewView.createSurfaceProvider());
 //绑定生命周期，这里如果没有参数preview，则只录像，不显示画面
 cameraProvider.bindToLifecycle(this, cameraSelector,preview, videoCapture);
 //视频路径
 File file = getFile(".mp4");
 //开始录像
 videoCapture.startRecording(file, ContextCompat.getMainExecutor(MainActivity.this), new VideoCapture.OnVideoSavedCallback() {
 @Override
 public void onVideoSaved(@NonNull File file) {
 Toast.makeText(MainActivity.this, file.getAbsolutePath(), Toast.LENGTH_SHORT).show();
 }

 @Override
 public void onError(int videoCaptureError, @NonNull String message, @Nullable Throwable cause) {
 Log.d(TAG, "onError: " + message);
 }
 });
 //停止录像，并且回调OnVideoSavedCallback
 btn4.setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View v) {
 videoCapture.stopRecording();
 preview.clear();
 }
 });
</pre>
</div>
<h1>分析图像</h1>
 
<div class="cnblogs_code">
<pre>val imageAnalysis = ImageAnalysis.Builder()
.setTargetResolution(Size(1280, 720))
.setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
.build()

imageAnalysis.setAnalyzer(Executors.newSingleThreadExecutor(), ImageAnalysis.Analyzer { image ->
val rotationDegrees = image.imageInfo.rotationDegrees //旋转角度
val format = image.format //格式
val width = image.width //宽
val height = image.height //高
val plane = image.planes //PlaneProxy数据
val buffer = plane.buffer
Log.e("ytzn", "rotationDegrees = $rotationDegrees")
Log.e("ytzn", "format = $format")
Log.e("ytzn", "width = $width")
Log.e("ytzn", "height = $height")

// insert your code here.
})
cameraProvider.bindToLifecycle(this as LifecycleOwner, cameraSelector, imageAnalysis, preview)</pre>
</div>
CameraX 会生成 <code dir="ltr">YUV_420_888</code> 格式的图片在ImageFormat类里可以看到此格式
<h1>拓展功能</h1>
<div class="cnblogs_code">
<pre> private fun setPreviewExtender(builder: Preview.Builder, cameraSelector: CameraSelector) {
 val extender = AutoPreviewExtender.create(builder)
 //自动模式
 if (extender.isExtensionAvailable(cameraSelector)) {
 extender.enableExtension(cameraSelector)
 }
 //散景扩展
 val bokehPreviewExtender = BokehPreviewExtender.create(builder)
 if (bokehPreviewExtender.isExtensionAvailable(cameraSelector)) {
 bokehPreviewExtender.enableExtension(cameraSelector)
 }
 //hdr扩展
 val hdrPreviewExtender = HdrPreviewExtender.create(builder)
 if (hdrPreviewExtender.isExtensionAvailable(cameraSelector)) {
 hdrPreviewExtender.enableExtension(cameraSelector)
 }
 //美颜模式
 val beautyPreviewExtender = BeautyPreviewExtender.create(builder)
 if (beautyPreviewExtender.isExtensionAvailable(cameraSelector)) {
 beautyPreviewExtender.enableExtension(cameraSelector)
 }
 //夜晚模式
 val nightPreviewExtender = NightPreviewExtender.create(builder)
 if (nightPreviewExtender.isExtensionAvailable(cameraSelector)) {
 nightPreviewExtender.enableExtension(cameraSelector)
 }

}</pre>
</div>
<h1>CameraX的一些问题</h1>
个人在开发过程中发现了一些问题,如下:
1.CameraX不支持外置摄像头
2.一直没找到跟Camera2一样配置摄像头拍照参数的方式
 
End

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本文来自博客园，作者：观心静，转载请注明原文链接：https://www.cnblogs.com/guanxinjing/p/15132909.html 
<div style="color:orange;font-size:16px;">本文版权归作者和博客园共有，欢迎转载，但必须给出原文链接，并保留此段声明，否则保留追究法律责任的权利。 </div>
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来源：https://www.cnblogs.com/guanxinjing/p/15132909.html

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Android开发 CameraX开发