I had work with the FaceDetection some time ago. When I was working on that the onFaceDetection didn't work for me, so,I found another way for work on it.
I worked with PreviewCallback, this method takes each frame and you can use it to recognize faces. The only problem here is the format, the default format is NV21 , and you can change it by setPreviewFormat(int), but that didn't work for me too, so, I had to make de conversion for get a Bitmap type that recives the FaceDetector. Here is my code:
public PreviewCallback mPreviewCallback = new PreviewCallback(){
@Override
public void onPreviewFrame(byte[] data, Camera camera) {
Camera.Size size = camera.getParameters().getPreviewSize();
Bitmap mfoto_imm = this.getBitmapFromNV21(data, size.width, size.height, true); //here I get the Bitmap from getBitmapFromNV21 that is the conversion method
Bitmap mfoto= mfoto_imm.copy(Bitmap.Config.RGB_565, true);
imagen.setImageBitmap(mfoto);
int alto= mfoto.getHeight();
int ancho= mfoto.getWidth();
int count;
canvas= new Canvas(mfoto);
dibujo.setColor(Color.GREEN);
dibujo.setAntiAlias(true);
dibujo.setStrokeWidth(8);
canvas.drawBitmap(mfoto, matrix, dibujo);
FaceDetector mface= new FaceDetector(ancho,alto,1);
FaceDetector.Face [] face= new FaceDetector.Face[1];
count = mface.findFaces(mfoto, face);
PointF midpoint = new PointF();
int fpx = 0;
int fpy = 0;
if (count > 0) {
face[count-1].getMidPoint(midpoint); // you have to take the last one less 1
fpx= (int)midpoint.x; // middle pint of the face in x.
fpy= (int)midpoint.y; // middle point of the face in y.
}
canvas.drawCircle(fpx, fpy, 10, dibujo); // here I draw a circle on the middle of the face
imagen.invalidate();
}
}
and here are the conversion methods.
public Bitmap getBitmapFromNV21(byte[] data, int width, int height, boolean rotated) {
Bitmap bitmap = null;
int[] pixels = new int[width * height];
// Conver the array
this.yuv2rgb(pixels, data, width, height, rotated);
if(rotated)
{
bitmap = Bitmap.createBitmap(pixels, height, width, Bitmap.Config.RGB_565);
}
else
{
bitmap = Bitmap.createBitmap(pixels, width, height, Bitmap.Config.RGB_565);
}
return bitmap;
}
public void yuv2rgb(int[] out, byte[] in, int width, int height, boolean rotated)
throws NullPointerException, IllegalArgumentException
{
final int size = width * height;
if(out == null) throw new NullPointerException("buffer 'out' == null");
if(out.length < size) throw new IllegalArgumentException("buffer 'out' length < " + size);
if(in == null) throw new NullPointerException("buffer 'in' == null");
if(in.length < (size * 3 / 2)) throw new IllegalArgumentException("buffer 'in' length != " + in.length + " < " + (size * 3/ 2));
// YCrCb
int Y, Cr = 0, Cb = 0;
int Rn = 0, Gn = 0, Bn = 0;
for(int j = 0, pixPtr = 0, cOff0 = size - width; j < height; j++) {
if((j & 0x1) == 0)
cOff0 += width;
int pixPos = height - 1 - j;
for(int i = 0, cOff = cOff0; i < width; i++, cOff++, pixPtr++, pixPos += height) {
// Get Y
Y = 0xff & in[pixPtr]; // 0xff es por el signo
// Get Cr y Cb
if((pixPtr & 0x1) == 0) {
Cr = in[cOff];
if(Cr < 0) Cr += 127; else Cr -= 128;
Cb = in[cOff + 1];
if(Cb < 0) Cb += 127; else Cb -= 128;
Bn = Cb + (Cb >> 1) + (Cb >> 2) + (Cb >> 6);
Gn = - (Cb >> 2) + (Cb >> 4) + (Cb >> 5) - (Cr >> 1) + (Cr >> 3) + (Cr >> 4) + (Cr >> 5);
Rn = Cr + (Cr >> 2) + (Cr >> 3) + (Cr >> 5);
}
int R = Y + Rn;
if(R < 0) R = 0; else if(R > 255) R = 255;
int B = Y + Bn;
if(B < 0) B = 0; else if(B > 255) B = 255;
int G = Y + Gn;
if(G < 0) G = 0; else if(G > 255) G = 255; //At this point the code could apply some filter From the separate components of the image.For example, they could swap 2 components or remove one
int rgb = 0xff000000 | (R << 16) | (G << 8) | B; //Depending on the option the output buffer is filled or not applying the transformation
if(rotated)
out[pixPos] = rgb;
else
out[pixPtr] = rgb;
}
}
}
};
The setPreviewFormat(int) in some devices doesn't work, but maybe you can try and create the Bitmap without use the conversion.
I hope this help you.
