Rotate and scale a view based on a single handle on Android

I am trying to rotate and scale a view based on a single "drag" handle in Android. When rotating the layout and resizing the window, the end result should be that the drag handle follows the user's finger wherever they move.

This is based on the combination of these two questions:

• How to scale a view in android using a handle?
• Rotating around two points in android doesn't work

The only thing that seems to be wrong is the rotation code.

Here is my activity code:

public class MainActivity extends Activity {
    ImageView imageView;
    ImageView dragHandle;
    RelativeLayout layout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        imageView = (ImageView) findViewById(R.id.imageView1);
        imageView.setBackgroundColor(Color.MAGENTA);
        dragHandle = (ImageView) findViewById(R.id.imageView2);
        dragHandle.setBackgroundColor(Color.CYAN);
        layout = (RelativeLayout) findViewById(R.id.relativeLayout2);
        layout.setBackgroundColor(Color.YELLOW);
        setUpResize();

    }

    public void setUpResize() {
        dragHandle.setOnTouchListener(new View.OnTouchListener() {

            float centerX, centerY, startR, startScale, startX, startY;

            float startAngle;
            float zeroAngle;
            int firstPointX;
            int firstPointY;

            public boolean onTouch(View v, MotionEvent e) {

                if (e.getAction() == MotionEvent.ACTION_DOWN) {

                    // calculate center of image
                    centerX = (imageView.getLeft() + imageView.getRight()) / 2f;
                    centerY = (imageView.getTop() + imageView.getBottom()) / 2f;

                    // recalculate coordinates of starting point
                    startX = e.getRawX() - dragHandle.getX() + centerX;
                    startY = e.getRawY() - dragHandle.getY() + centerY;

                    // get starting distance and scale
                    startR = (float) Math.hypot(e.getRawX() - startX, e.getRawY() - startY);
                    startScale = imageView.getScaleX();

                    /*
                     * Rotate code
                     */

                    int[] locationOfLayout = new int[2];
                    int[] locationOfDrag = new int[2];

                    layout.getLocationOnScreen(locationOfLayout);
                    dragHandle.getLocationOnScreen(locationOfDrag);

                    firstPointX = locationOfLayout[0];
                    firstPointY = locationOfLayout[1];

                    float secondPointX = e.getRawX();
                    float secondPointY = e.getRawY();

                    zeroAngle = findRotation(firstPointX, firstPointY, secondPointX, secondPointY); // remember
                                                                                                    // "zero"
                                                                                                    // angle
                    startAngle = layout.getRotation(); // remember angle at
                                                        // which layout is
                                                        // rotated at the start

                } else if (e.getAction() == MotionEvent.ACTION_MOVE) {

                    // calculate new distance
                    float newR = (float) Math.hypot(e.getRawX() - startX, e.getRawY() - startY);

                    // set new scale
                    float newScale = newR / startR * startScale;
                    imageView.setScaleX(newScale);
                    imageView.setScaleY(newScale);

                    // move handler image
                    dragHandle.setX(centerX + imageView.getWidth() / 2f * newScale);
                    dragHandle.setY(centerY + imageView.getHeight() / 2f * newScale);

                    /*
                     * Rotate code
                     */

                    layout.setRotation(findRotation(firstPointX, firstPointY, e.getRawX(), e.getRawY()) - zeroAngle
                            + startAngle); // rotate relative to start and zero
                                            // angle

                } else if (e.getAction() == MotionEvent.ACTION_UP) {

                }
                return true;
            }
        });
    }

    private float findRotation(float firstPointX, float firstPointY, float secondPointX, float secondPointY) {
        double delta_x = (secondPointX - firstPointX);
        double delta_y = (secondPointY - firstPointY);
        double radians = Math.atan2(delta_y, delta_x);
        return (float) Math.toDegrees(radians);
    }
}

      

        
        
        
      

    

XML:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <RelativeLayout
        android:id="@+id/relativeLayout2"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_centerInParent="true" >

        <ImageView
            android:id="@+id/imageView1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:layout_centerVertical="true"
            android:src="@drawable/ic_launcher" />

        <ImageView
            android:id="@+id/imageView2"
            android:layout_width="20dp"
            android:layout_height="20dp"
            android:layout_below="@+id/imageView1"
            android:layout_toRightOf="@+id/imageView1"
            android:src="@drawable/meanicons" />

    </RelativeLayout>

</RelativeLayout>