در این مقاله می خواهیم در مورد تشخیص چهره در دوربین صحبت نماییم اینکه با زدن یک دکمه دوربین اجرا شود و تصویر را تشخیص دهد این نمونه با # C نوشته شده است.

در مرحله ی اول ما داخل Main layout خود یک دکمه قرار می دهیم و داخل آن یک رویداد برای گرفتن عکس می گذاریم.

کد Main  به صورت زیر است:

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:orientation="vertical"  
    android:layout_width="fill_parent"  
    android:layout_height="match_parent"  
    android:padding="10dip">  
    <TextView  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        android:text="Click Take a Picture button"  
        android:gravity="center_horizontal"  
        android:layout_weight="1.0" />  
    <Button  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:id="@+id/take_picture"  
        android:layout_margin="5dip"  
        android:text="Take Picture"  
        android:layout_gravity="center_horizontal" />  
</LinearLayout> 

در مرحله ی بعدی از یک دکمه و یک ImageView استفاده می کنیم، برای نمایش عکس که زمانی که دوربین فعال شد بتواند صورت فرد مورد نظر را تشخیص دهد در زیر کد Layout دوم را می نویسیم:

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:orientation="vertical"  
    android:layout_width="fill_parent"  
    android:layout_height="fill_parent">  
    <ImageView  
        android:layout_width="fill_parent"  
        android:layout_height="fill_parent"  
        android:id="@+id/image_view"  
        android:layout_weight="1.0"  
        android:src="@android:drawable/ic_menu_report_image" />  
    <Button  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:id="@+id/detect_face"  
        android:text="Detect Face"  
        android:layout_gravity="center_horizontal" />  
</LinearLayout>  

حالا مر حله ی کد نویسی در کلاس را شروع می نماییم:

یک Activity برای گرفتن عکس باز می کنیم:

private void openCamera()  
{  
   Intent intent = new Intent (Android.Provider.MediaStore.ActionImageCapture);  
   StartActivityForResult (intent, TAKE_PICTURE_CODE);  
}  

حالا به مرحله ی گرفتن عکس و نمایش آن در لایه ی detectlayout.axml  می رویم:

private void processCameraImage(Intent intent)  
{  
    //Change layout to main Layout  
    SetContentView(Resource.Layout.detectlayout);  
  
    Button detect_face = FindViewById<Button> (Resource.Id.detect_face);  
  
    detect_face.Click += detect_face_Clicked;  
  
    ImageView image_view = FindViewById<ImageView> (Resource.Id.image_view);  
  
    //Set image   
    image_view.SetImageBitmap(cameraBitmap);  
} 

حالا کدهای تشخیص چهره و کشیدن یک مربع به دور چهره ی یک شخص:

    private void detectFaces(){  
        //first check if picture has been taken  
        if(null != cameraBitmap){  
            //get width of a picture  
            int width = cameraBitmap.Width;  
            //get height of a picture  
            int height = cameraBitmap.Height;  
            //Initialize a facedetector with the picture dimensions and the max number of faces to check  
            FaceDetector detector = new FaceDetector(width, height, MainActivity.MAX_FACES);  
            //Create an array of faces with the number of max faces to check  
            FaceDetector.Face[] faces = new FaceDetector.Face[MainActivity.MAX_FACES];  
      
            //create a main bitmap  
            Bitmap bitmap565 = Bitmap.CreateBitmap(width, height, Bitmap.Config.Rgb565);  
            //create a dither paint  
            Paint ditherPaint = new Paint();  
            //create a draw paint  
            Paint drawPaint = new Paint();  
      
            //set true dither to dither paint variable  
            ditherPaint.Dither = true;  
            //set color red for the square  
            drawPaint.Color = Color.Green;  
            //set stroke to style  
            drawPaint.SetStyle(Paint.Style.Stroke);  
            //set stroke width  
            drawPaint.StrokeWidth = 2;  
      
            //Create a canvas  
            Canvas canvas = new Canvas();  
            //set bitmap to canvas  
            canvas.SetBitmap(bitmap565);  
            //draw bitmap to canvas  
            canvas.DrawBitmap(cameraBitmap, 0, 0, ditherPaint);  
      
            //get a number of faces detected  
            int facesFound = detector.FindFaces(bitmap565, faces);  
            //mid face point  
            PointF midPoint = new PointF();  
            //eye distance variable  
            float eyeDistance = 0.0f;  
            //confidence variable  
            float confidence = 0.0f;  
            //print numbre of faces found  
            System.Console.WriteLine ("Number of faces found: " + facesFound);  
      
            //check if found at least one face  
            if(facesFound > 0)  
            {  
                //for each face draw a red squeare  
                for(int index=0; index<facesFound; ++index){  
                    // get midpoint of a face  
                    faces[index].GetMidPoint(midPoint);  
                    //get eye distance  
                    eyeDistance = faces[index].EyesDistance();  
                    //get confidence  
                    confidence = faces [index].Confidence ();  
                    //print all parameters  
                    System.Console.WriteLine ("Confidence: " + confidence +   
                        ", Eye distance: " + eyeDistance +   
                        ", Mid Point: (" + midPoint.X + ", " + midPoint.Y + ")");  
                    //draw a square in the picture  
                    canvas.DrawRect((int)midPoint.X - eyeDistance ,   
                        (int)midPoint.Y- eyeDistance ,   
                        (int)midPoint.X + eyeDistance,   
                        (int)midPoint.Y + eyeDistance, drawPaint);  
                }  
            }  
      
            //get imageview from layout  
            ImageView imageView = (ImageView)FindViewById(Resource.Id.image_view);  
            //set image with the red squares to imageview  
            imageView.SetImageBitmap(bitmap565);  
        }  
    }   

کل کدها به صورت زیر خواهد بود:

  public class MainActivity : Activity
    {
        //Intent code for camera activity
        private static int TAKE_PICTURE_CODE = 100;

        //Max Faces to detect in a picture
        private static int MAX_FACES = 5;

        //Bitmap of a picture taken
        private Bitmap cameraBitmap = null;

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.Main);

            Button take_picture = FindViewById<Button>(Resource.Id.take_picture);

            take_picture.Click += take_picture_Clicked;

        }

        void take_picture_Clicked(object sender, EventArgs args)
        {
            //call OpenCamera() Event
            openCamera();
        }



        //OnActivityResult
        protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
        {
            base.OnActivityResult(requestCode, resultCode, data);
            //check if method return takepicturecode
            if (TAKE_PICTURE_CODE == requestCode)
            {
                //Call a method to process image data
                processCameraImage(data);
            }
        }


        /// <summary>
        /// Open an activity for take a picture
        /// </summary>
        private void openCamera()
        {
            Intent intent = new Intent(Android.Provider.MediaStore.ActionImageCapture);
            StartActivityForResult(intent, TAKE_PICTURE_CODE);
        }

        /// <summary>
        /// Process picture taken an change UI to detect face
        /// </summary>
        /// <param name="intent">Intent.</param>
        private void processCameraImage(Intent intent)
        {
            //Change layout to main Layout
            SetContentView(Resource.Layout.detectlayout);

            Button detect_face = FindViewById<Button>(Resource.Id.detect_face);

            detect_face.Click += detect_face_Clicked;

            ImageView image_view = FindViewById<ImageView>(Resource.Id.image_view);

            //Set image 
            image_view.SetImageBitmap(cameraBitmap);
        }

        void detect_face_Clicked(object sender, EventArgs args)
        {
            //Detect Face
            detectFaces();
        }

        /// <summary>
        /// detect faces on a picture and draw a square in each face
        /// </summary<
        private void detectFaces()
        {
            //first check if picture has been taken
            if (null != cameraBitmap)
            {
                //get width of a picture
                int width = cameraBitmap.Width;
                //get height of a picture
                int height = cameraBitmap.Height;
                //Initialize a facedetector with the picture dimensions and the max number of faces to check
                FaceDetector detector = new FaceDetector(width, height, MainActivity.MAX_FACES);
                //Create an array of faces with the number of max faces to check
                Android.Media.FaceDetector.Face[] faces = new Android.Media.FaceDetector.Face[MainActivity.MAX_FACES];

                //create a main bitmap
                Bitmap bitmap565 = Bitmap.CreateBitmap(width, height, Bitmap.Config.Rgb565);
                //create a dither paint
                Paint ditherPaint = new Paint();
                //create a draw paint
                Paint drawPaint = new Paint();

                //set true dither to dither paint variable
                ditherPaint.Dither = true;
                //set color red for the square
                drawPaint.Color = Color.Green;
                //set stroke to style
                drawPaint.SetStyle(Paint.Style.Stroke);
                //set stroke width
                drawPaint.StrokeWidth = 2;

                //Create a canvas
                Canvas canvas = new Canvas();
                //set bitmap to canvas
                canvas.SetBitmap(bitmap565);
                //draw bitmap to canvas
                canvas.DrawBitmap(cameraBitmap, 0, 0, ditherPaint);

                //get a number of faces detected
                int facesFound = detector.FindFaces(bitmap565, faces);
                //mid face point
                PointF midPoint = new PointF();
                //eye distance variable
                float eyeDistance = 0.0f;
                //confidence variable
                float confidence = 0.0f;
                //print numbre of faces found
                System.Console.WriteLine("Number of faces found: " + facesFound);

                //check if found at least one face
                if (facesFound > 0)
                {
                    //for each face draw a red squeare
                    for (int index = 0; index < facesFound; ++index)
                    {
                        // get midpoint of a face
                        faces[index].GetMidPoint(midPoint);
                        //get eye distance
                        eyeDistance = faces[index].EyesDistance();
                        //get confidence
                        confidence = faces[index].Confidence();
                        //print all parameters
                        System.Console.WriteLine("Confidence: " + confidence +
                            ", Eye distance: " + eyeDistance +
                            ", Mid Point: (" + midPoint.X + ", " + midPoint.Y + ")");
                        //draw a square in the picture
                        canvas.DrawRect((int)midPoint.X - eyeDistance,
                            (int)midPoint.Y - eyeDistance,
                            (int)midPoint.X + eyeDistance,
                            (int)midPoint.Y + eyeDistance, drawPaint);
                    }
                }

                //get imageview from layout
                ImageView imageView = (ImageView)FindViewById(Resource.Id.image_view);
                //set image with the red squares to imageview
                imageView.SetImageBitmap(bitmap565);
            }
        }
    }

خروجی به صورت زیر خواهد بود:

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