Refer to the last exercise "Android 4 Face Detection: setFocusAreas() using face detected faces", it will throw java.lang.RuntimeException: autoFocus failed almost everytime in onFaceDetection() when camera.autoFocus(myAutoFocusCallback) is called after face detected, and setFocusAreas() called.
I delay calling camera.autoFocus(myAutoFocusCallback) for 500ms (using ScheduledExecutorService), it seem that the problem solved.
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.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.SurfaceView;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
public class AndroidCamera extends Activity implements SurfaceHolder.Callback{
Camera camera;
SurfaceView surfaceView;
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);
surfaceView = (SurfaceView)findViewById(R.id.camerapreview);
surfaceHolder = surfaceView.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);
}
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);
if(camera.getParameters().getMaxNumFocusAreas()>0){
camera.getParameters().setFocusAreas(focusList);
}
if(camera.getParameters().getMaxNumMeteringAreas()>0){
camera.getParameters().setMeteringAreas(focusList);
}
buttonTakePicture.setEnabled(false);
//camera.getParameters().setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
//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();
}
}};
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;
public DrawingView(Context context) {
super(context);
haveFace = false;
drawingPaint = new Paint();
drawingPaint.setColor(Color.GREEN);
drawingPaint.setStyle(Paint.Style.STROKE);
drawingPaint.setStrokeWidth(2);
}
public void setHaveFace(boolean h){
haveFace = h;
}
@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);
}
}
}
}
Download the files. Next: - Gets the distances from the camera to the focus point - getFocusDistances()
