fix some issues with camera stucking at focus stage

app/src/main/kotlin/com/simplemobiletools/camera/PhotoProcessor.kt

@@ -8,9 +8,9 @@ import android.net.Uri
 import android.os.AsyncTask
 import android.os.Environment
 import android.util.Log
-import com.simplemobiletools.camera.Preview.Companion.config
 import com.simplemobiletools.camera.activities.MainActivity
 import com.simplemobiletools.camera.extensions.compensateDeviceRotation
+import com.simplemobiletools.camera.extensions.config
 import com.simplemobiletools.camera.extensions.getOutputMediaFile
 import com.simplemobiletools.camera.extensions.getPreviewRotation
 import com.simplemobiletools.commons.extensions.getFileDocument
@@ -49,11 +49,11 @@ class PhotoProcessor(val activity: MainActivity, val uri: Uri?, val currCameraId
             val data = params[0]
             val photoFile = File(path)
             if (activity.needsStupidWritePermissions(path)) {
-                if (config.treeUri.isEmpty()) {
+                if (activity.config.treeUri.isEmpty()) {
                     activity.runOnUiThread {
                         activity.toast(R.string.save_error_internal_storage)
                     }
-                    config.savePhotosFolder = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).toString()
+                    activity.config.savePhotosFolder = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).toString()
                     return ""
                 }
                 var document = activity.getFileDocument(path)

app/src/main/kotlin/com/simplemobiletools/camera/Preview.kt

@@ -23,11 +23,11 @@ import java.io.IOException
 import java.util.*
 
 class Preview : ViewGroup, SurfaceHolder.Callback, MediaScannerConnection.OnScanCompletedListener {
-    companion object {
     var mCamera: Camera? = null
     private val TAG = Preview::class.java.simpleName
     private val FOCUS_AREA_SIZE = 100
     private val PHOTO_PREVIEW_LENGTH = 500L
+    private val REFOCUS_PERIOD = 3000L
 
     lateinit var mSurfaceHolder: SurfaceHolder
     lateinit var mSurfaceView: SurfaceView
@@ -58,7 +58,8 @@ class Preview : ViewGroup, SurfaceHolder.Callback, MediaScannerConnection.OnScan
     private var mCurrCameraId = 0
     private var mMaxZoom = 0
     private var mRotationAtCapture = 0
-    }
+    private var mIsFocusing = false
+    private var autoFocusHandler = Handler()
 
     constructor(context: Context) : super(context)
 
@@ -292,6 +293,7 @@ class Preview : ViewGroup, SurfaceHolder.Callback, MediaScannerConnection.OnScan
             mCamera!!.takePicture(null, null, takePictureCallback)
         }
         mCanTakePicture = false
+        mIsFocusing = false
     }
 
     private val takePictureCallback = Camera.PictureCallback { data, cam ->
@@ -315,12 +317,16 @@ class Preview : ViewGroup, SurfaceHolder.Callback, MediaScannerConnection.OnScan
         mActivity.toggleBottomButtons(false)
         mCamera?.startPreview()
         mCanTakePicture = true
+        focusArea(false, false)
     }
 
     private fun focusArea(takePictureAfter: Boolean, showFocusRect: Boolean = true) {
-        if (mCamera == null)
+        if (mCamera == null || (mIsFocusing && !takePictureAfter))
             return
 
+        if (takePictureAfter)
+            mIsFocusing = true
+
         mCamera!!.cancelAutoFocus()
         if (mParameters!!.maxNumFocusAreas > 0) {
             if (mLastClickX == 0 && mLastClickY == 0) {
@@ -344,12 +350,14 @@ class Preview : ViewGroup, SurfaceHolder.Callback, MediaScannerConnection.OnScan
                 mParameters!!.focusMode = Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE
 
             camera.parameters = mParameters
+
             if (takePictureAfter) {
                 takePicture()
             } else if (!mIsVideoMode || !mIsRecording) {
-                Handler().postDelayed({
+                autoFocusHandler.removeCallbacksAndMessages(null)
+                autoFocusHandler.postDelayed({
                     focusArea(false, false)
-                }, 3000)
+                }, REFOCUS_PERIOD)
             }
         }
     }

app/src/main/kotlin/com/simplemobiletools/camera/dialogs/ChangeResolutionDialog.kt

@@ -5,9 +5,9 @@ import android.support.v7.app.AlertDialog
 import android.view.LayoutInflater
 import android.view.View
 import com.simplemobiletools.camera.Config
-import com.simplemobiletools.camera.Preview
 import com.simplemobiletools.camera.R
 import com.simplemobiletools.camera.activities.SimpleActivity
+import com.simplemobiletools.camera.extensions.config
 import com.simplemobiletools.camera.extensions.getAspectRatio
 import com.simplemobiletools.commons.dialogs.RadioGroupDialog
 import com.simplemobiletools.commons.extensions.setupDialogStuff
@@ -16,7 +16,7 @@ import kotlinx.android.synthetic.main.dialog_change_resolution.view.*
 
 class ChangeResolutionDialog(val activity: SimpleActivity, val config: Config, val camera: Camera, val callback: () -> Unit) {
     var dialog: AlertDialog
-    val isBackCamera = Preview.config.lastUsedCamera == Camera.CameraInfo.CAMERA_FACING_BACK
+    val isBackCamera = activity.config.lastUsedCamera == Camera.CameraInfo.CAMERA_FACING_BACK
 
     init {
         val view = LayoutInflater.from(activity).inflate(R.layout.dialog_change_resolution, null).apply {