CameraX的官方介绍
CameraX 是一个 Jetpack 支持库，旨在帮助您简化相机应用的开发工作。它提供一致且易用的 API 接口，适用于大多数 Android 设备，并可向后兼容至 Android 5.0（API 级别 21）。
上一篇文章介绍了自定义相机，但是需要写的代码很多。
上一篇文章传送门：https://www.jianshu.com/p/c1955529dd4c
其实Google的Android大神们已经为我们封装好了CameraController，如果想快速实现相机的开发，直接使用即可，本篇就是介绍CameraController的使用方法，并写了拍照，录像和扫描二维码的功能。
扫描二维码在Android端原先一直都是用zxing的开源库，但是Google开源的MLKit库现在也可以支持扫描二维码等图像处理了，这个demo就是引入的MLKit库。
想直接下载Demo的同学可以直接点击：
https://github.com/cgztzero/KotlinCameraXDemo
1.引入CameraX项目配置
// The following line is optional, as the core library is included indirectly by camera-camera2
implementation "androidx.camera:camera-core:${camerax_version}"
implementation "androidx.camera:camera-camera2:${camerax_version}"
// If you want to additionally use the CameraX Lifecycle library
implementation "androidx.camera:camera-lifecycle:${camerax_version}"
// If you want to additionally use the CameraX View class
implementation "androidx.camera:camera-view:1.0.0-alpha24"
2.准备CameraController实例
//可以看到CameraController是一个抽象类
public abstract class CameraController {
CameraController的唯一实现类是LifecycleCameraController ，从名字就可以猜出来是可以跟Lifcycle进行绑定的
public final class LifecycleCameraController extends CameraController {
private static final String TAG = "CamLifecycleController";
@Nullable
private LifecycleOwner mLifecycleOwner;
public LifecycleCameraController(@NonNull Context context) {
super(context);
}
初始化CameraController
class CameraControllerActivity : BaseActivity() {
private lateinit var binding: ActivityPictureBinding
private lateinit var lifecycleCameraController: LifecycleCameraController//声明一个CameraController
private lateinit var cameraExecutor: ExecutorService //相机需要执行任务的线程池 后续会用到
private fun initController() {
cameraExecutor = Executors.newSingleThreadExecutor()//因为只能同时执行一个任务
//这样就初始化完成了
lifecycleCameraController = LifecycleCameraController(this)
lifecycleCameraController.bindToLifecycle(this)
}
3.在xml布局文件中需要加入一个CameraX的预览view,PreviewView本质就是一个Framelayout，里面封装了相机相关的字段以及预览用的SurfaceHolder等等
4.CameraController和PreviewView进行绑定就可以预览了
private fun initController() {
cameraExecutor = Executors.newSingleThreadExecutor()
lifecycleCameraController = LifecycleCameraController(this)
lifecycleCameraController.bindToLifecycle(this)
lifecycleCameraController.imageCaptureFlashMode = ImageCapture.FLASH_MODE_AUTO
binding.previewView.controller = lifecycleCameraController
//点击屏幕手动对焦的动画
binding.previewView.setOnTouchListener { _, event ->
if (event.action == MotionEvent.ACTION_DOWN) {
startFocusAnim(event.x.toInt(), event.y.toInt())
}
false
}
}
注意，因为PrewviewView中已经封装好了点击会自动调用CameraController的对焦方法， 所有我们只需要增加一个动画就好了，瞬间觉得少写好多代码~~~
5.实现拍照方法
@SuppressLint("UnsafeOptInUsageError")
private fun takePicture() {
val photoFile = createPhotoFile()
val metadata = ImageCapture.Metadata().apply {
//水平翻转
isReversedHorizontal = lensFacing == CameraSelector.LENS_FACING_FRONT
}
val outputOptions = ImageCapture.OutputFileOptions.Builder(photoFile)
.setMetadata(metadata)
.build()
lifecycleCameraController.setEnabledUseCases(CameraController.IMAGE_CAPTURE or CameraController.IMAGE_ANALYSIS)
lifecycleCameraController.takePicture(
outputOptions,
cameraExecutor,
object : ImageCapture.OnImageSavedCallback {
override fun onError(exc: ImageCaptureException) {
Log.d("OnImageSavedCallback", "Photo capture failed: ${exc.message}", exc)
}
override fun onImageSaved(output: ImageCapture.OutputFileResults) {
val savedUri = output.savedUri ?: Uri.fromFile(photoFile)
Log.d("OnImageSavedCallback", "Photo capture succeeded: $savedUri")
}
})
}
拍照方法只需要这么几行代码就可以了，瞬间又觉得少写好多代码。
不过这里需要注意的是这行代码：
lifecycleCameraController.setEnabledUseCases(CameraController.IMAGE_CAPTURE or CameraController.IMAGE_ANALYSIS)
意思就是要设置CameraController支持拍照和图片解析。要进行相应的操作，要设置CameraController支持相应的UseCase。如下图所示：图片分析，拍照，预览和录像都是UseCase的具体实现类
6.实现录像
private fun startRecord() {
if (isRecording()) {
Toast.makeText(this, "正在录像", Toast.LENGTH_SHORT).show()
return
}
val videoFile = createVideoFile()
val outputOptions = OutputFileOptions.builder(videoFile).build()
lifecycleCameraController.setEnabledUseCases(CameraController.VIDEO_CAPTURE)
lifecycleCameraController.startRecording(
outputOptions,
cameraExecutor,
object : OnVideoSavedCallback {
override fun onVideoSaved(output: OutputFileResults) {
val savedUri = output.savedUri ?: Uri.fromFile(videoFile)
Log.e("ztzt", "onVideoSaved：${savedUri.path}")
//这里注意 是在视频录制的线程的回调
runOnUiThread {
Toast.makeText(
this@CameraControllerActivity,
"录像完成：${savedUri.path}",
Toast.LENGTH_SHORT
).show()
}
}
override fun onError(videoCaptureError: Int, message: String, cause: Throwable?) {
Log.e("ztzt", "onError：${message}")
}
})
}
停止录像需要调用
lifecycleCameraController.stopRecording()
同样要注意的是要设置支持录像
lifecycleCameraController.setEnabledUseCases(CameraController.VIDEO_CAPTURE)
这样拍照和录像的代码就基本实现了，我们还可以完善一些细节
切换Android手机的前置和后置摄像头
private fun switchCamera() {
lensFacing = if (lensFacing == CameraSelector.LENS_FACING_BACK) {
CameraSelector.LENS_FACING_FRONT
} else {
CameraSelector.LENS_FACING_BACK
}
lifecycleCameraController.cameraSelector =
CameraSelector.Builder().requireLensFacing(lensFacing).build()
}
设置闪光灯模式
三种闪光灯模式
ImageCapture.FLASH_MODE_AUTO
ImageCapture.FLASH_MODE_ON
ImageCapture.FLASH_MODE_OFF
private fun setFlashMode(mode: Int) {
if (lifecycleCameraController.imageCaptureFlashMode == mode) {
return
}
lifecycleCameraController.imageCaptureFlashMode = mode
when (mode) {
ImageCapture.FLASH_MODE_AUTO -> Toast.makeText(this, "闪光灯自动", Toast.LENGTH_SHORT).show()
ImageCapture.FLASH_MODE_ON -> Toast.makeText(this, "闪光灯打开", Toast.LENGTH_SHORT).show()
ImageCapture.FLASH_MODE_OFF -> Toast.makeText(this, "闪光灯关闭", Toast.LENGTH_SHORT).show()
}
}
Demo的传送门：
https://github.com/cgztzero/KotlinCameraXDemo
写的不好，欢迎各位多多交流~
下一篇介绍如何使用二维码扫描
二维码扫描文章的传送门：
https://www.jianshu.com/p/2defccdd14b4