简介
cameraX已经出来有一段时间了，现在已经从alpha版本到现在的beta3版本。其中内部的代码版本跨度特别大，而且资料相对来说只有官方的demo比较可以参考，所以最近完成了项目的开发之后，把经验分享一下提供给各位。
仓库地址
究极花里胡哨camreaX二维码扫描
二维码扫描小优化
去除zxing额外支持的格式（有争议的点，其实并没有特别大的差距）
MultiFormatReader的decodeWithState()是使用方的入口方法，内部调用了decodeInternal()，输入是相机的一帧数据，如果抛了NotFoundException，则表示没找到二维码；如果返回了Result，则表示找到了二维码，并解析完成。 其中，readers变量是一个数组，数组的大小表示支持的条码格式个数，zxing原本因为支持很多格式，因此这个数组长度比较长。当拿到相机的一帧数据后，需要去检测是否是所有支持格式的某一个格式，每一种格式的检测都需要花费一些时间，因此这个遍历对于我们是不必要的。如果将zxing内部定制成只支持QR Code格式，那么就免去了额外的格式检测。
扫描区域放大到全局
去除项目中的扫描区域，将图像识别区域放大到整张区域，这样增加了二维码的边界情况，不需要特意的对准屏幕的扫描区域。
将相机升级到jetpack的CameraX
谷歌已经在官方提供了对于camera2的整合包，集成在CamreaX，而且CameraX内部有对于图片分析的接口，所以我们在这个接口中会对原来的二维码扫描进行一次转移，然后构建一个线程池专门去处理二维码扫描的分析器。
代码语言：javascript复制class CameraXModule(private val view: AutoZoomScanView) {
private var lensFacing: Int = CameraSelector.LENS_FACING_BACK
private var preview: Preview? = null
private var imageAnalyzer: ImageAnalysis? = null
private lateinit var cameraExecutor: ExecutorService
private var camera: Camera? = null
private lateinit var qrCodeAnalyzer: QRCodeAnalyzer
private lateinit var mLifecycleOwner: LifecycleOwner
fun bindWithCameraX(function: (Result) -> Unit, lifecycleOwner: LifecycleOwner) {
mLifecycleOwner = lifecycleOwner
val metrics = DisplayMetrics().also { view.display.getRealMetrics(it) }
Log.d(TAG, "Screen metrics: ${metrics.widthPixels} x ${metrics.heightPixels}")
val screenAspectRatio = aspectRatio(metrics.widthPixels, metrics.heightPixels)
Log.i(TAG, "Preview aspect ratio: $screenAspectRatio")
val cameraSelector = CameraSelector.Builder().requireLensFacing(lensFacing).build()
val cameraProviderFuture = ProcessCameraProvider.getInstance(view.context)
cameraProviderFuture.addListener(
Runnable {
val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()
// Preview
val width = (view.measuredWidth * 1.5F).toInt()
val height = (width * screenAspectRatio).toInt()
preview = Preview.Builder()
// We request aspect ratio but no resolution
.setTargetResolution(Size(width, height))
// Set initial target rotation
.build()
preview?.setSurfaceProvider(view.preView.createSurfaceProvider(null))
cameraExecutor = Executors.newSingleThreadExecutor()
qrCodeAnalyzer = QRCodeAnalyzer(this) { function(it) }
// ImageAnalysis
imageAnalyzer = ImageAnalysis.Builder()
// We request aspect ratio but no resolution
.setTargetResolution(Size(width, height))
// Set initial target rotation, we will have to call this again if rotation changes
// during the lifecycle of this use case
.build()
// The analyzer can then be assigned to the instance
.also {
it.setAnalyzer(cameraExecutor, qrCodeAnalyzer)
}
// Must unbind the use-cases before rebinding them
cameraProvider.unbindAll()
try {
// A variable number of use-cases can be passed here -
// camera provides access to CameraControl & CameraInfo
camera = cameraProvider.bindToLifecycle(
mLifecycleOwner, cameraSelector, preview, imageAnalyzer
)
qrCodeAnalyzer.camera = camera
qrCodeAnalyzer.preview = preview
setFocus(view.width.toFloat() / 2, view.height.toFloat() / 2)
// camera?.cameraControl?.startFocusAndMetering(FocusMeteringAction.FLAG_AF)
// Attach the viewfinder's surface provider to preview use case
} catch (exc: Exception) {
Log.e(TAG, "Use case binding failed", exc)
}
}, ContextCompat.getMainExecutor(view.context)
)
}
fun setFocus(x: Float, y: Float) {
val factory: MeteringPointFactory = SurfaceOrientedMeteringPointFactory(
view.width.toFloat(), view.height.toFloat()
)
//create a point on the center of the view
val autoFocusPoint = factory.createPoint(x, y)
camera?.cameraControl?.startFocusAndMetering(
FocusMeteringAction.Builder(
autoFocusPoint,
FocusMeteringAction.FLAG_AF
).apply {
//auto-focus every 1 seconds
setAutoCancelDuration(1, TimeUnit.SECONDS)
}.build()
)
}
private fun aspectRatio(width: Int, height: Int): Double {
val previewRatio = max(width, height).toDouble() / min(width, height)
if (abs(previewRatio - RATIO_4_3_VALUE) <= abs(previewRatio - RATIO_16_9_VALUE)) {
return RATIO_4_3_VALUE
}
return RATIO_16_9_VALUE
}
@SuppressLint("RestrictedApi")
fun setZoomRatio(zoomRatio: Float) {
if (zoomRatio > getMaxZoomRatio()) {
return
}
val future: ListenableFuture<Void>? = camera?.cameraControl?.setZoomRatio(
zoomRatio
)
future?.apply {
Futures.addCallback(future, object : FutureCallback<Void?> {
override fun onSuccess(result: Void?) {}
override fun onFailure(t: Throwable) {}
}, CameraXExecutors.directExecutor())
}
}
fun getZoomRatio(): Float {
return camera?.cameraInfo?.zoomState?.value?.zoomRatio ?: 0F
}
fun getMaxZoomRatio(): Float {
return camera?.cameraInfo?.zoomState?.value?.maxZoomRatio ?: 0F
}
fun stopCamera() {
// camera?.cameraControl?.
}
internal fun resetAnalyzer() {
qrCodeAnalyzer.resetAnalyzer()
}
companion object {
private const val TAG = "CameraXImp"
private const val RATIO_4_3_VALUE = 4.0 / 3.0
private const val RATIO_16_9_VALUE = 16.0 / 9.0
}
}上述代码基于的是CameraX内的CameraView，其中的构建的宽高必须基于4:3或者16:9的格式。
自动放大
当二维码很小很远时，自动放大能大大加快检测二维码的速度。QRCodeReader的decode()是二维码检测的主方法，分为两步：
（1）大致判断是否存在二维码；
代码语言：javascript复制 val source = PlanarYUVLuminanceSource(data, width, height, 0, 0, width, height, false)
val binarizer = HybridBinarizer(source)
val bitmap = BinaryBitmap(binarizer)
val detectorResult = Detector(bitmap.blackMatrix).detect(map) private fun calculateDistance(resultPoint: Array<ResultPoint>): Int {
val point1X = resultPoint[0].x.toInt()
val point1Y = resultPoint[0].y.toInt()
val point2X = resultPoint[1].x.toInt()
val point2Y = resultPoint[1].y.toInt()
return sqrt(
(point1X - point2X.toDouble()).pow(2.0) (point1Y - point2Y.toDouble()).pow(2.0)
).toInt()
}先要获取到当前区域内是否存在二维码，其次计算二维码的距离。
（2）所以我们需要做的就是先检测该图像区域内是否有一个二维码，同时计算二维码的大小，和图像比例进行一次大小换算，如果发现二维码过小的情况下，自动放大图片区域。
代码语言：javascript复制 private fun zoomCamera(points: Array<ResultPoint>, image: BinaryBitmap): Boolean {
val qrWidth = calculateDistance(points) * 2
val imageWidth = image.blackMatrix.width.toFloat()
val zoomInfo = camera?.cameraInfo?.zoomState?.value
zoomInfo?.apply {
if (qrWidth < imageWidth / 8) {
Log.i("BarcodeAnalyzer", "resolved!!! = $qrWidth imageWidth:${imageWidth}")
val maxScale = zoomInfo.maxZoomRatio
val curValue = zoomInfo.zoomRatio
val gap = maxScale - curValue
val upgradeRatio = if (gap / 4F * 3 > 3F) 3F else maxScale / 4F * 3
module.setZoomRatio(curValue upgradeRatio)
return true
}
}
return false
}双击放大
当前二维码扫描中没有调整焦距的功能，所以我们在这次调整中对其进行了一次双击放大的开发。
通过监控双击事件实现对应监听。
代码语言：javascript复制 private val gestureDetector =
GestureDetector(context, object : GestureDetector.SimpleOnGestureListener() {
override fun onDoubleTap(e: MotionEvent?): Boolean {
cameraXModule.setZoomRatio(cameraXModule.getZoomRatio() 1)
return super.onDoubleTap(e)
}
override fun onSingleTapUp(e: MotionEvent?): Boolean {
e?.apply {
cameraXModule.setFocus(x, y)
}
return super.onSingleTapUp(e)
}
})单击对焦
当前的对焦模式采取的是自动对焦，我们对对焦进行了一次增强，单击制定位置之后会对该区域进行一次对焦。
参考上面代码
简单使用
- 引入依赖
implementation 'com.github.leifzhang:QrCodeLibrary:0.0.1'- 在布局xml中加入AutoZoomScanView
<com.kronos.camerax.qrcode.AutoZoomScanView
android:id="@ id/scanView"
android:layout_width="match_parent"
android:layout_height="match_parent" />- 先申请camera权限并绑定lifecycle
AndPermission.with(this)
.runtime()
.permission(Permission.Group.CAMERA)
.onGranted { permissions: List<String?>? ->
scanView.bindWithLifeCycle(this@MainActivity)
}
.onDenied { permissions: List<String?>? -> }
.start()- 二维码结果回调，之后重新打开分析逻辑
scanView.setOnQrResultListener { view: View, s: String ->
Toast.makeText(
this@MainActivity, s,
Toast.LENGTH_LONG
).show()
scanView.reStart()
}
