我正在使用带有Firebase MLKit条形码阅读器的CameraX来检测条形码。应用程序识别条形码没有问题。但是我想在CameraX的预览中添加边界框,实时显示条形码的区域。边界框的信息是从条形码检测器功能中获取的。但如下图所示,它既没有正确的位置,也没有正确的大小。
这是我的活动布局。
<?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">
<Button
android:id="@+id/camera_capture_button"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_marginBottom="50dp"
android:scaleType="fitCenter"
android:text="Take Photo"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
android:elevation="2dp" />
<SurfaceView
android:id="@+id/overlayView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<androidx.camera.view.PreviewView
android:id="@+id/previewView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
SurfaceView
是用来绘制这个矩形的。
条码检测发生在 BarcodeAnalyzer
类,它实现了 ImageAnalysis.Analyzer
内侧被覆盖 analyze
函数,我检索条码数据,如下图所示。
@SuppressLint("UnsafeExperimentalUsageError")
override fun analyze(imageProxy: ImageProxy) {
val mediaImage = imageProxy.image
val rotationDegrees = degreesToFirebaseRotation(imageProxy.imageInfo.rotationDegrees)
if (mediaImage != null) {
val analyzedImageHeight = mediaImage.height
val analyzedImageWidth = mediaImage.width
val image = FirebaseVisionImage
.fromMediaImage(mediaImage,rotationDegrees)
detector.detectInImage(image)
.addOnSuccessListener { barcodes ->
for (barcode in barcodes) {
val bounds = barcode.boundingBox
val corners = barcode.cornerPoints
val rawValue = barcode.rawValue
if(::barcodeDetectListener.isInitialized && rawValue != null && bounds != null){
barcodeDetectListener.onBarcodeDetect(
rawValue,
bounds,
analyzedImageWidth,
analyzedImageHeight
)
}
}
imageProxy.close()
}
.addOnFailureListener {
Log.e(tag,"Barcode Reading Exception: ${it.localizedMessage}")
imageProxy.close()
}
.addOnCanceledListener {
Log.e(tag,"Barcode Reading Canceled")
imageProxy.close()
}
}
}
barcodeDetectListener
是对我创建的一个接口的引用,以便将这些数据传回我的活动中。
interface BarcodeDetectListener {
fun onBarcodeDetect(code: String, codeBound: Rect, imageWidth: Int, imageHeight: Int)
}
在我的主活动中,我把这些数据发送到了 OverlaySurfaceHolder
其中实现了 SurfaceHolder.Callback
. 该类负责在叠加的 SurfaceView
.
override fun onBarcodeDetect(code: String, codeBound: Rect, analyzedImageWidth: Int,
analyzedImageHeight: Int) {
Log.i(TAG,"barcode : $code")
overlaySurfaceHolder.repositionBound(codeBound,previewView.width,previewView.height,
analyzedImageWidth,analyzedImageHeight)
overlayView.invalidate()
}
正如你所看到的,我正在发送叠加的。SurfaceView
中计算的宽度和高度。OverlaySurfaceHolder
类。
OverlaySurfaceHolder.kt
class OverlaySurfaceHolder: SurfaceHolder.Callback {
var previewViewWidth: Int = 0
var previewViewHeight: Int = 0
var analyzedImageWidth: Int = 0
var analyzedImageHeight: Int = 0
private lateinit var drawingThread: DrawingThread
private lateinit var barcodeBound :Rect
private val tag = OverlaySurfaceHolder::class.java.simpleName
override fun surfaceChanged(holder: SurfaceHolder?, format: Int, width: Int, height: Int) {
}
override fun surfaceDestroyed(holder: SurfaceHolder?) {
var retry = true
drawingThread.running = false
while (retry){
try {
drawingThread.join()
retry = false
} catch (e: InterruptedException) {
}
}
}
override fun surfaceCreated(holder: SurfaceHolder?) {
drawingThread = DrawingThread(holder)
drawingThread.running = true
drawingThread.start()
}
fun repositionBound(codeBound: Rect, previewViewWidth: Int, previewViewHeight: Int,
analyzedImageWidth: Int, analyzedImageHeight: Int){
this.barcodeBound = codeBound
this.previewViewWidth = previewViewWidth
this.previewViewHeight = previewViewHeight
this.analyzedImageWidth = analyzedImageWidth
this.analyzedImageHeight = analyzedImageHeight
}
inner class DrawingThread(private val holder: SurfaceHolder?): Thread() {
var running = false
private fun adjustXCoordinates(valueX: Int): Float{
return if(previewViewWidth != 0){
(valueX / analyzedImageWidth.toFloat()) * previewViewWidth.toFloat()
}else{
valueX.toFloat()
}
}
private fun adjustYCoordinates(valueY: Int): Float{
return if(previewViewHeight != 0){
(valueY / analyzedImageHeight.toFloat()) * previewViewHeight.toFloat()
}else{
valueY.toFloat()
}
}
override fun run() {
while(running){
if(::barcodeBound.isInitialized){
val canvas = holder!!.lockCanvas()
if (canvas != null) {
synchronized(holder) {
canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR)
val myPaint = Paint()
myPaint.color = Color.rgb(20, 100, 50)
myPaint.strokeWidth = 6f
myPaint.style = Paint.Style.STROKE
val refinedRect = RectF()
refinedRect.left = adjustXCoordinates(barcodeBound.left)
refinedRect.right = adjustXCoordinates(barcodeBound.right)
refinedRect.top = adjustYCoordinates(barcodeBound.top)
refinedRect.bottom = adjustYCoordinates(barcodeBound.bottom)
canvas.drawRect(refinedRect,myPaint)
}
holder.unlockCanvasAndPost(canvas)
}else{
Log.e(tag, "Cannot draw onto the canvas as it's null")
}
try {
sleep(30)
} catch (e: InterruptedException) {
e.printStackTrace()
}
}
}
}
}
}
谁能告诉我,我到底做错了什么?
我没有很清楚的线索,但这里有一些你可以尝试的东西。
当你调整XCoordinates的时候 如果预览宽度为0,你就直接返回valueX.toFloat(). 你能不能增加一些日志,看看它是否真的属于这种情况? 另外增加一些日志打印分析和预览维度也会有帮助。
另一个值得注意的是,你发送给检测器的图像可能与预览View区域的长宽比不同。例如,如果您的相机拍摄了一张4:3的照片,它将把它发送到检测器。但是,如果您的视图区域是1:1,它将裁剪照片的某些部分来显示它。在这种情况下,你在调整坐标时也需要考虑到这一点。根据我的测试,图片会根据CENTER_CROP来适应View区域。如果你想非常小心,可能值得检查一下相机开发网站上是否有这方面的记录。
希望对你有所帮助,或多或少。