Touch to select focus and metering area

Further work on last exercise "Gets the distances from the camera to the focus point - getFocusDistances()" (and the post "Set Camera.Parameters"), It's modified to implement touching to select focus and metering area.

Modify from the exercise "Gets the distances from the camera to the focus point - getFocusDistances()". In this exercise, a new class CameraSurfaceView.java (extends SurfaceView) is implemented to replace the SurfaceView. And override the onTouchEvent(MotionEvent event) method to get user touch position, and area. The touched area will be passed to main activity, AndroidCamera.java, via touchFocus() method.

package com.exercise.AndroidCamera;

import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.SurfaceView;

public class CameraSurfaceView extends SurfaceView {

 public CameraSurfaceView(Context context) {
  super(context);
  // TODO Auto-generated constructor stub
 }

 public CameraSurfaceView(Context context, AttributeSet attrs) {
  super(context, attrs);
  // TODO Auto-generated constructor stub
 }

 public CameraSurfaceView(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  // TODO Auto-generated constructor stub
 }

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  // TODO Auto-generated method stub
  setMeasuredDimension(
    MeasureSpec.getSize(widthMeasureSpec),
    MeasureSpec.getSize(heightMeasureSpec));
 }

 @Override
 public boolean onTouchEvent(MotionEvent event) {
  
  if(event.getAction() == MotionEvent.ACTION_DOWN){
   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));
      
      ((AndroidCamera)getContext()).touchFocus(touchRect);
  }
  
  
  return true;
 }
 
}

Modify main.xml to place CameraSurfaceView, instead of Surfaceview.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />
    <TextView
        android:id="@+id/prompt"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
    <com.exercise.AndroidCamera.CameraSurfaceView
        android:id="@+id/camerapreview"  
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content" />

</LinearLayout>

Modify the main Java code, To handle touchFocus() method. And also remove the original layoutBackground OnClickListener().

package com.exercise.AndroidCamera;

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();
    }
    
    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);
   }
  }
  
 }
}

Download the files.