Android - move an ImageView on screen (Like dragging)

Question

I\'m trying to create an app that can move an ImageView on your device like dragging and when I put like 75% of the ImageView out of the screen show a

Answer 1

I'm using this method to drag an ImageView , I hope that this can help you : So I defined those attributes of the class :

 private float xCoOrdinate, yCoOrdinate;
 private double screenCenterX, screenCenterY;

Then I implement this code under the OnCreate() method of the activity :

 mRrootLayout.getBackground().setAlpha(255);

    /**
     * Calculate max hypo value and center of screen.
     */
    final DisplayMetrics display = getResources().getDisplayMetrics();
    screenCenterX = display.widthPixels / 2;
    screenCenterY = (display.heightPixels - getStatusBarHeight()) / 2;
    final double maxHypo = Math.hypot(screenCenterX, screenCenterY);

    mImageView.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            /**
             * Calculate hypo value of current imageview position according to center
             */
            double centerYPos = mImageView.getY() + (mImageView.getHeight() / 2);
            double centerXPos = mImageView.getX() + (mImageView.getWidth() / 2);
            double a = screenCenterX - centerXPos;
            double b = screenCenterY - centerYPos;
            double hypo = Math.hypot(a, b);

            /**
             * change alpha of background of layout
             */
            alpha = (int) (hypo * 255) / (int) maxHypo;
            if (alpha < 255)
                mRrootLayout.getBackground().setAlpha(255 - alpha);

            switch (event.getActionMasked()) {
                case MotionEvent.ACTION_DOWN:
                    xCoOrdinate = mImageView.getX() - event.getRawX();
                    yCoOrdinate = mImageView.getY() - event.getRawY();
                    break;
                case MotionEvent.ACTION_MOVE:
                    mImageView.animate().x(event.getRawX() + xCoOrdinate).y(event.getRawY() + yCoOrdinate).setDuration(0).start();
                    break;
                case MotionEvent.ACTION_UP:
                     if (alpha > 50) {
                        Toast.makeText(ImageViewerActivity.this, "Out", Toast.LENGTH_SHORT).show();
                        return false;
                    } else {
                        Toast.makeText(ImageViewerActivity.this, "In", Toast.LENGTH_SHORT).show();
                        mImageView.animate().x(0).y((float) screenCenterY - mImageView.getHeight() / 2).setDuration(100).start();
                        mRrootLayout.getBackground().setAlpha(255);
                    }
                default:
                    return false;
            }
            return true;
        }
    });