Count Screen Pixels Covered by each finger touch

Hello I need to count pixels that are covered by each fingers in multi-touch.When fingers down one by one it should plus pixels in count and finger up it should subtract pixels of that finger.I have did this but it is not getting exact counts i don't know what's wrong with it.please help me i am sucked at it.

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Image img = new Image(getApplicationContext());
setContentView(R.layout.activity_main);

final ImageView MyimageView = (ImageView)findViewById(R.id.imageView);
final TextView LeftPixelView = (TextView)findViewById(R.id.LeftPixelView);
final TextView RightPixelView = (TextView)findViewById(R.id.RightPixelView);
final TextView PressureView = (TextView)findViewById(R.id.PressureView);
final TextView OrientationView = (TextView)findViewById(R.id.OrientationView);
final Display display = getWindowManager().getDefaultDisplay();
final int ScreenWidth = display.getWidth();




if (MyimageView != null) {
    MyimageView.setOnTouchListener(new View.OnTouchListener() {
        @Override

    public boolean onTouch(View arg0, MotionEvent event) {

            // get pointer index from the event object
         //   int pointerIndex = event.getActionIndex();

            mScaleDetector.onTouchEvent(event);

            // get pointer ID
          //  int pointerId = event.getPointerId(pointerIndex);

            // get masked (not specific to a pointer) action


            int maskedAction = event.getActionMasked();

            switch (maskedAction) {

                case MotionEvent.ACTION_DOWN: {

                    final float x = event.getX();
                    final float y = event.getY();

                    mLastTouchX = x;
                    mLastTouchY = y;

                    ///Toast toast = Toast.makeText(getApplicationContext(), "Action down", Toast.LENGTH_SHORT);
                     //toast.show();
                    int pointerIndex = event.getActionIndex();
                    mActivePointerId = event.getPointerId(0);

                    TouchMajor = event.getTouchMajor(pointerIndex);
                    TouchMinor = event.getTouchMinor(pointerIndex);

                    Pressure = event.getPressure(pointerIndex);
                    PressureView.setText("Pressure :"+Float.toString(Pressure));

                    //Orientaation =Double.toString( event.getOrientation(mActivePointerId));
                    //left Side of scren

                    if(event.getX(mActivePointerId) < ScreenWidth/2)
                    {
                        LeftPixChange =  (TouchMajor + TouchMinor) / 2;
                        LeftPixSize = LeftPixChange;
                        LeftPixelView.setText(Float.toString(LeftPixSize));
                        OrientationView.setText("Left Side Clicked");
                    }
                    else if(event.getX(mActivePointerId) > ScreenWidth/2)
                    {
                         RightPixChange =  (TouchMajor + TouchMinor) / 2;
                         RightPixSize = RightPixChange;
                        RightPixelView.setText(Float.toString(RightPixSize));
                        OrientationView.setText("Right Side Clicked");
                    }

                    break;
                }
                case MotionEvent.ACTION_POINTER_DOWN: {
                   final int pointerIndex = (event.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK)
                            >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
                    final int pointerId = event.getPointerId(pointerIndex);

                    if (pointerId == mActivePointerId) {
                        // This was our active pointer going up. Choose a new
                        // active pointer and adjust accordingly.
                        final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
                         mLastTouchX = event.getX(newPointerIndex);
                         mLastTouchY = event.getY(newPointerIndex);
                        mActivePointerId = event.getPointerId(newPointerIndex);
                    }

                    TouchMajor = event.getTouchMajor(pointerIndex);
                    TouchMinor = event.getTouchMinor(pointerIndex);

                    Pressure =Pressure +  event.getPressure(pointerIndex);
                    PressureView.setText("Cummulative pressure :"+Float.toString(Pressure));

                    //Orientaation = Orientaation+","+ event.getOrientation(mActivePointerId);
                   // OrientationView.setText(Orientaation);
                   //we take pointerindex here because pointerId remains same but index will be increased
                    if(event.getX(pointerIndex) < ScreenWidth/2)
                    {
                        LeftPixChange = (TouchMajor + TouchMinor) / 2;
                        LeftPixSize =LeftPixSize + LeftPixChange;
                        LeftPixelView.setText(Float.toString(LeftPixSize));
                        OrientationView.setText("Multi Left side clicked");

                        IsLeftSideActive = true;
                    }
                    else if(event.getX(pointerIndex) > ScreenWidth/2)
                    {
                        RightPixChange = (TouchMajor + TouchMinor) / 2;
                        RightPixSize =RightPixSize + RightPixChange;
                        RightPixelView.setText(Float.toString(RightPixSize));

                        OrientationView.setText("Multi Right side clicked");

                        IsRightSideActive = true;
                    }
                    else
                    {
                        OrientationView.setText("Both Sidse Clicked simultaneously");
                    }
                    break;
                }
                case MotionEvent.ACTION_MOVE: { // a pointer was moved
                    // TODO use data
                    final int pointerIndex = event.findPointerIndex(mActivePointerId);

                    final float x = event.getX(pointerIndex);
                    final float y = event.getY(pointerIndex);

                  if (!mScaleDetector.isInProgress()) {
                        final float dx = x - mLastTouchX;
                        final float dy = y - mLastTouchY;

                        mPosX += dx;
                        mPosY += dy;

                        MyimageView.invalidate();
                    }

                    mLastTouchX = x;
                    mLastTouchY = y;
                    break;
                }


                case MotionEvent.ACTION_UP:{

                    mActivePointerId = INVALID_POINTER_ID;
                    //Toast toast = Toast.makeText(getContext(), "Action UP", Toast.LENGTH_SHORT);
                    //toast.show();
                    RightPixelView.setText(Float.toString(0.0f));
                    LeftPixelView.setText(Float.toString(0.0f));
                    PressureView.setText("Pressure : 0.0");
                    OrientationView.setText("");
                    break;
                }
                case MotionEvent.ACTION_POINTER_UP:{
                    final int pointerIndex = (event.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK)
                            >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
                    final int pointerId = event.getPointerId(pointerIndex);

                    if (pointerId == mActivePointerId) {
                        // This was our active pointer going up. Choose a new
                        // active pointer and adjust accordingly.
                        final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
                         mLastTouchX = event.getX(newPointerIndex);
                         mLastTouchY = event.getY(newPointerIndex);
                        mActivePointerId = event.getPointerId(newPointerIndex);


                    }
                    if(event.getX(pointerIndex) > ScreenWidth/2)
                    {
                        RightPixSize = RightPixSize - RightPixChange;
                        RightPixelView.setText(Double.toString(RightPixSize));
                    }
                    else if(event.getX(pointerIndex) < ScreenWidth/2){
                        LeftPixSize = LeftPixSize - LeftPixChange;
                        LeftPixelView.setText(Double.toString(LeftPixSize));
                        IsRightSideActive = false;
                    }


                    Pressure = Pressure - event.getPressure(event.getActionIndex());

                    PressureView.setText("Pressure :"+ Double.toString(Pressure));





                    break;

                }
                case MotionEvent.ACTION_CANCEL: {
                    // TODO use data

                    mActivePointerId = INVALID_POINTER_ID;



                    MyimageView.invalidate();

                    break;
                }
            }
              MyimageView.invalidate();

            return true;
        }});
}`