Impostare l'area di messa a fuoco della fotocamera in Android

Question

seguendo diversi tutorial ed esempi Sono arrivato al prossimo algoritmo per impostare la messa a fuoco della telecamera su un punto specifico, il problema è che la fotocamera ignora completamente il punto ed esegue una normale messa a fuoco generale invece di l'area rect che ho specificato. C'è qualcos'altro che mi manca nell'algoritmo? Questo è stato testato su diversi telefoni tutti con Android 4.0 e versioni successive, quindi l'API dell'area di messa a fuoco è supportata su questi dispositivi. Nota, l'app che sto scrivendo funziona solo in modalità orizzontale.

@Override 
public boolean onTouchEvent(final MotionEvent event) 
{ 
    if (event.getAction() == MotionEvent.ACTION_UP) 
    { 
     float x = event.getX(); 
     float y = event.getY(); 
     float touchMajor = event.getTouchMajor(); 
     float touchMinor = event.getTouchMinor(); 

     Rect touchRect = new Rect((int)(x - touchMajor/2), (int)(y - touchMinor/2), (int)(x + touchMajor/2), (int)(y + touchMinor/2)); 

     this.submitFocusAreaRect(touchRect); 
    } 
} 

private void submitFocusAreaRect(final Rect touchRect) 
{ 
    Camera.Parameters cameraParameters = camera.getParameters(); 

    if (cameraParameters.getMaxNumFocusAreas() == 0) 
    { 
     return; 
    } 

    // Convert from View's width and height to +/- 1000 

    Rect focusArea = new Rect(); 

    focusArea.set(touchRect.left * 2000/cameraSurfaceView.getWidth() - 1000, 
         touchRect.top * 2000/cameraSurfaceView.getHeight() - 1000, 
         touchRect.right * 2000/cameraSurfaceView.getWidth() - 1000, 
         touchRect.bottom * 2000/cameraSurfaceView.getHeight() - 1000); 

    // Submit focus area to camera 

    ArrayList<Camera.Area> focusAreas = new ArrayList<Camera.Area>(); 
    focusAreas.add(new Camera.Area(focusArea, 1000)); 

    cameraParameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO); 
    cameraParameters.setFocusAreas(focusAreas); 
    camera.setParameters(cameraParameters); 

    // Start the autofocus operation 

    camera.autoFocus(this); 
} 

Answer 1

prima cameraParameters.setFocusAreas (focusAreas) ;, si dovrebbe aggiungere questo:

cameraParameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO); 

Answer 2

questo non è il mio codice, ma si può provare. Tutti i crediti vanno al ragazzo/i che ha fatto l'esempio qui Touch to select focus and metering area

Inoltre ho contribuito a quel codice con una piccola riga perché quando stavo facendo clic per la seconda volta in Surface View l'app si stava schiacciando. Quindi plese essere libero di utilizzare la classe ("AndroidCamera") sotto:

import java.io.FileNotFoundException; 
import java.io.IOException; 
import java.io.OutputStream; 
import java.util.ArrayList; 
import java.util.List; 
import java.util.concurrent.Executors; 
import java.util.concurrent.ScheduledExecutorService; 
import java.util.concurrent.TimeUnit; 

import android.app.Activity; 
import android.content.ContentValues; 
import android.content.Context; 
import android.content.pm.ActivityInfo; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.graphics.PixelFormat; 
import android.graphics.Rect; 
import android.hardware.Camera; 
import android.hardware.Camera.AutoFocusCallback; 
import android.hardware.Camera.Face; 
import android.hardware.Camera.FaceDetectionListener; 
import android.hardware.Camera.Parameters; 
import android.hardware.Camera.PictureCallback; 
import android.hardware.Camera.ShutterCallback; 
import android.net.Uri; 
import android.os.Bundle; 
import android.provider.MediaStore.Images.Media; 
import android.view.LayoutInflater; 
import android.view.SurfaceHolder; 
import android.view.View; 
import android.view.ViewGroup.LayoutParams; 
import android.widget.Button; 
import android.widget.TextView; 

public class AndroidCamera extends Activity implements SurfaceHolder.Callback{ 

    Camera camera; 
    CameraSurfaceView cameraSurfaceView; 
    SurfaceHolder surfaceHolder; 
    boolean previewing = false; 
    LayoutInflater controlInflater = null; 

    Button buttonTakePicture; 
    TextView prompt; 

    DrawingView drawingView; 
    Face[] detectedFaces; 

    final int RESULT_SAVEIMAGE = 0; 

    private ScheduledExecutorService myScheduledExecutorService; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 
     setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE); 

     getWindow().setFormat(PixelFormat.UNKNOWN); 
     cameraSurfaceView = (CameraSurfaceView)findViewById(R.id.camerapreview); 
     surfaceHolder = cameraSurfaceView.getHolder(); 
     surfaceHolder.addCallback(this); 
     surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); 

     drawingView = new DrawingView(this); 
     LayoutParams layoutParamsDrawing 
       = new LayoutParams(LayoutParams.FILL_PARENT, 
       LayoutParams.FILL_PARENT); 
     this.addContentView(drawingView, layoutParamsDrawing); 

     controlInflater = LayoutInflater.from(getBaseContext()); 
     View viewControl = controlInflater.inflate(R.layout.control, null); 
     LayoutParams layoutParamsControl 
       = new LayoutParams(LayoutParams.FILL_PARENT, 
       LayoutParams.FILL_PARENT); 
     this.addContentView(viewControl, layoutParamsControl); 

     buttonTakePicture = (Button)findViewById(R.id.takepicture); 
     buttonTakePicture.setOnClickListener(new Button.OnClickListener(){ 

      @Override 
      public void onClick(View arg0) { 
       // TODO Auto-generated method stub 
       camera.takePicture(myShutterCallback, 
         myPictureCallback_RAW, myPictureCallback_JPG); 
      }}); 

     /* 
     LinearLayout layoutBackground = (LinearLayout)findViewById(R.id.background); 
     layoutBackground.setOnClickListener(new LinearLayout.OnClickListener(){ 

    @Override 
    public void onClick(View arg0) { 
    // TODO Auto-generated method stub 

    buttonTakePicture.setEnabled(false); 
    camera.autoFocus(myAutoFocusCallback); 
    }}); 
    */ 

     prompt = (TextView)findViewById(R.id.prompt); 
    } 

    public void touchFocus(final Rect tfocusRect){ 

     buttonTakePicture.setEnabled(false); 
     camera.stopFaceDetection(); 

     //Convert from View's width and height to +/- 1000 
     final Rect targetFocusRect = new Rect(
       tfocusRect.left * 2000/drawingView.getWidth() - 1000, 
       tfocusRect.top * 2000/drawingView.getHeight() - 1000, 
       tfocusRect.right * 2000/drawingView.getWidth() - 1000, 
       tfocusRect.bottom * 2000/drawingView.getHeight() - 1000); 

     final List<Camera.Area> focusList = new ArrayList<Camera.Area>(); 
     Camera.Area focusArea = new Camera.Area(targetFocusRect, 1000); 
     focusList.add(focusArea); 

     Parameters para = camera.getParameters(); 
     para.setFocusAreas(focusList); 
     para.setMeteringAreas(focusList); 
     camera.setParameters(para); 

     camera.autoFocus(myAutoFocusCallback); 

     drawingView.setHaveTouch(true, tfocusRect); 
     drawingView.invalidate(); 
     camera.startFaceDetection(); 
    } 

    FaceDetectionListener faceDetectionListener 
      = new FaceDetectionListener(){ 

     @Override 
     public void onFaceDetection(Face[] faces, Camera tcamera) { 

      if (faces.length == 0){ 
       //prompt.setText(" No Face Detected! "); 
       drawingView.setHaveFace(false); 
      }else{ 
       //prompt.setText(String.valueOf(faces.length) + " Face Detected :) "); 
       drawingView.setHaveFace(true); 
       detectedFaces = faces; 

       //Set the FocusAreas using the first detected face 
       List<Camera.Area> focusList = new ArrayList<Camera.Area>(); 
       Camera.Area firstFace = new Camera.Area(faces[0].rect, 1000); 
       focusList.add(firstFace); 

       Parameters para = camera.getParameters(); 

       if(para.getMaxNumFocusAreas()>0){ 
        para.setFocusAreas(focusList); 
       } 

       if(para.getMaxNumMeteringAreas()>0){ 
        para.setMeteringAreas(focusList); 
       } 

       camera.setParameters(para); 

       buttonTakePicture.setEnabled(false); 

       //Stop further Face Detection 
       camera.stopFaceDetection(); 

       buttonTakePicture.setEnabled(false); 

    /* 
    * Allways throw java.lang.RuntimeException: autoFocus failed 
    * if I call autoFocus(myAutoFocusCallback) here! 
    * 
    camera.autoFocus(myAutoFocusCallback); 
    */ 

       //Delay call autoFocus(myAutoFocusCallback) 
       myScheduledExecutorService = Executors.newScheduledThreadPool(1); 
       myScheduledExecutorService.schedule(new Runnable(){ 
        public void run() { 
         camera.autoFocus(myAutoFocusCallback); 
        } 
       }, 500, TimeUnit.MILLISECONDS); 

      } 

      drawingView.invalidate(); 

     }}; 

    AutoFocusCallback myAutoFocusCallback = new AutoFocusCallback(){ 

     @Override 
     public void onAutoFocus(boolean arg0, Camera arg1) { 
      // TODO Auto-generated method stub 
      if (arg0){ 
       buttonTakePicture.setEnabled(true); 
       camera.cancelAutoFocus(); 
      } 

      float focusDistances[] = new float[3]; 
      arg1.getParameters().getFocusDistances(focusDistances); 
      prompt.setText("Optimal Focus Distance(meters): " 
        + focusDistances[Camera.Parameters.FOCUS_DISTANCE_OPTIMAL_INDEX]); 

     }}; 

    ShutterCallback myShutterCallback = new ShutterCallback(){ 

     @Override 
     public void onShutter() { 
      // TODO Auto-generated method stub 

     }}; 

    PictureCallback myPictureCallback_RAW = new PictureCallback(){ 

     @Override 
     public void onPictureTaken(byte[] arg0, Camera arg1) { 
      // TODO Auto-generated method stub 

     }}; 

    PictureCallback myPictureCallback_JPG = new PictureCallback(){ 

     @Override 
     public void onPictureTaken(byte[] arg0, Camera arg1) { 
      // TODO Auto-generated method stub 
    /*Bitmap bitmapPicture 
    = BitmapFactory.decodeByteArray(arg0, 0, arg0.length); */ 

      Uri uriTarget = getContentResolver().insert(Media.EXTERNAL_CONTENT_URI, new ContentValues()); 

      OutputStream imageFileOS; 
      try { 
       imageFileOS = getContentResolver().openOutputStream(uriTarget); 
       imageFileOS.write(arg0); 
       imageFileOS.flush(); 
       imageFileOS.close(); 

       prompt.setText("Image saved: " + uriTarget.toString()); 

      } catch (FileNotFoundException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 

      camera.startPreview(); 
      camera.startFaceDetection(); 
     }}; 

    @Override 
    public void surfaceChanged(SurfaceHolder holder, int format, int width, 
           int height) { 
     // TODO Auto-generated method stub 
     if(previewing){ 
      camera.stopFaceDetection(); 
      camera.stopPreview(); 
      previewing = false; 
     } 

     if (camera != null){ 
      try { 
       camera.setPreviewDisplay(surfaceHolder); 
       camera.startPreview(); 

       prompt.setText(String.valueOf(
         "Max Face: " + camera.getParameters().getMaxNumDetectedFaces())); 
       camera.startFaceDetection(); 
       previewing = true; 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
     } 
    } 

    @Override 
    public void surfaceCreated(SurfaceHolder holder) { 
     // TODO Auto-generated method stub 
     camera = Camera.open(); 
     camera.setFaceDetectionListener(faceDetectionListener); 
    } 

    @Override 
    public void surfaceDestroyed(SurfaceHolder holder) { 
     // TODO Auto-generated method stub 
     camera.stopFaceDetection(); 
     camera.stopPreview(); 
     camera.release(); 
     camera = null; 
     previewing = false; 
    } 

    private class DrawingView extends View{ 

     boolean haveFace; 
     Paint drawingPaint; 

     boolean haveTouch; 
     Rect touchArea; 

     public DrawingView(Context context) { 
      super(context); 
      haveFace = false; 
      drawingPaint = new Paint(); 
      drawingPaint.setColor(Color.GREEN); 
      drawingPaint.setStyle(Paint.Style.STROKE); 
      drawingPaint.setStrokeWidth(2); 

      haveTouch = false; 
     } 

     public void setHaveFace(boolean h){ 
      haveFace = h; 
     } 

     public void setHaveTouch(boolean t, Rect tArea){ 
      haveTouch = t; 
      touchArea = tArea; 
     } 

     @Override 
     protected void onDraw(Canvas canvas) { 
      // TODO Auto-generated method stub 
      if(haveFace){ 

       // Camera driver coordinates range from (-1000, -1000) to (1000, 1000). 
       // UI coordinates range from (0, 0) to (width, height). 

       int vWidth = getWidth(); 
       int vHeight = getHeight(); 

       for(int i=0; i<detectedFaces.length; i++){ 

        if(i == 0){ 
         drawingPaint.setColor(Color.GREEN); 
        }else{ 
         drawingPaint.setColor(Color.RED); 
        } 

        int l = detectedFaces[i].rect.left; 
        int t = detectedFaces[i].rect.top; 
        int r = detectedFaces[i].rect.right; 
        int b = detectedFaces[i].rect.bottom; 
        int left = (l+1000) * vWidth/2000; 
        int top = (t+1000) * vHeight/2000; 
        int right = (r+1000) * vWidth/2000; 
        int bottom = (b+1000) * vHeight/2000; 
        canvas.drawRect(
          left, top, right, bottom, 
          drawingPaint); 
       } 
      }else{ 
       canvas.drawColor(Color.TRANSPARENT); 
      } 

      if(haveTouch){ 
       drawingPaint.setColor(Color.BLUE); 
       canvas.drawRect(
         touchArea.left, touchArea.top, touchArea.right, touchArea.bottom, 
         drawingPaint); 
      } 
     } 

    } 
} 

Tutto quello che ho fatto è stato di aggiungere camera.startFaceDetection(); dopo drawingView.invalidate();

P.S. Su quel sito c'è un link per scaricare l'intero progetto!