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我通过SurfaceView创建一个相机，但是当我按Home并且再次返回到活动时。 SurfaceView不再显示任何东西。它没有调用 surfaceCreated(SurfaceHolder holder)SurfaceView如何重新创建，如果它已被破坏
当我回到活动。我该怎么办？
这里是科特林 ``` 类MyCameraView我的代码写：SurfaceView，SurfaceHolder.Callback，Camera.PreviewCallback，Camera.FaceDetectionListener {
private lateinit var mCamera : Camera
var sizes : List<Camera.Size>? = null
constructor(ctx : Context, attrs : AttributeSet?) : super(ctx,attrs){
holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
holder.addCallback(this)
}
constructor(ctx : Context):this(ctx,null){
}
override fun surfaceChanged(p0: SurfaceHolder?, format: Int, width: Int, height: Int) {
Log.e("MyCameraView","CHANGE ")
val sizes = mCamera.parameters.supportedPreviewSizes
val size = getOptimalSzie(sizes)
val supportWith = size.height
val supportHeight : Int = size.width
val radio : Float = width.toFloat()/supportWith
setMeasuredDimension(width,(supportHeight*radio).toInt())
layout(0, (-(supportHeight*radio)/5).toInt(),width, ((supportHeight*radio).toInt()-(supportHeight*radio)/5).toInt())
}
override fun surfaceDestroyed(p0: SurfaceHolder?) {
Log.e("MyCameraView","DESTORY")
holder.removeCallback(this)
mCamera.setPreviewCallback(null)
mCamera.stopFaceDetection()
mCamera.stopPreview()
mCamera.lock()
mCamera.release()
}
override fun surfaceCreated(p0: SurfaceHolder?) {
Log.e("MyCameraView","OPEN")
mCamera = Camera.open(Camera.CameraInfo.CAMERA_FACING_FRONT)
mCamera.setDisplayOrientation(90)
mCamera.setPreviewCallback(this)
mCamera.setPreviewDisplay(holder)
mCamera.setFaceDetectionListener(this)
mCamera.startPreview();
mCamera.startFaceDetection()
}
private fun getOptimalSzie(sizes: List<Camera.Size>): Camera.Size {
var pos = 0
var ratio = 0
var viewRatio = height/width
sizes.forEachIndexed { index, size ->
val curRatio = size.width/size.height
if(ratio == 0) ratio = curRatio
else if((viewRatio - curRatio) < (viewRatio - ratio) ){
ratio = curRatio
pos = index
}
}
return sizes[pos]
}
override fun onPreviewFrame(data: ByteArray?, camera: Camera) {
if(allowTake) {
val parameters = camera.getParameters()
val width = parameters.previewSize.width
val height = parameters.previewSize.height
val yuv = YuvImage(data, parameters.previewFormat, width, height, null)
val out = ByteArrayOutputStream()
yuv.compressToJpeg(Rect(0, 0, width, height), 50, out)
val bytes = out.toByteArray()
val b = BitmapFactory.decodeByteArray(bytes, 0, bytes.size)
detected?.invoke(bytes)
allowTake = false
hasTake = true
}
}
var hasTake = false
private var allowTake = false
override fun onFaceDetection(faces: Array<out Camera.Face>?, camera: Camera?) {
if(!hasTake) {
allowTake = true
}
}
private var detected: ((bitmap : ByteArray) -> Unit)? = null
fun onFaceDetected(detected : (bitmap : ByteArray)->Unit){
this.detected = detected
}
}