How to drag and drop an overlay ImageButton?

Question

I have this overlay button that is being activated using a service. So it is a background button. You can see the button even if the other programs are running. However I have problem with adding a feature on the button where when I hold it, I can drag it anywhere I want to the screen. I have checked some drag and drop options here but I could not applied it properly in my program.

On my dragDrop() method, it does not work because of the following cast error:

error(WindowManagerLayoutParams could not be cast on Freamelayout.LayoutParams)..

Here is my service code:

public class MainPowerAndVolumeService extends Service {

    private ViewGroup mView;
    private LayoutInflater inflater;
    private ImageButton mainButton;
    private Button testButton;


    @Override
    public IBinder
    onBind(Intent intent) {
        return null;
    }


    public void onCreate( ) {
        super.onCreate();


        /*This will make your window or layout to be overlay and of course you can click the buttons*/

        WindowManager.LayoutParams params = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.TYPE_PHONE,
                WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH
                        | WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH
                        | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT
        );



        /*This will load the main.xml view through inflate*/
        WindowManager wm = (WindowManager) getSystemService(WINDOW_SERVICE);

        inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        mView = (ViewGroup) inflater.inflate(R.layout.main, null);


        mainButton =(ImageButton) mView.findViewById(R.id.MainButton);


        wm.addView(mView,params);


        buttonListener();





        dragDrop( );

    }


    public void dragDrop(){

        mainButton.setOnTouchListener(new View.OnTouchListener() {
            int prevX,prevY;
            /**this does not work since framelayout could not be cast to the Window Manager**/
            @Override
            public boolean onTouch(final View v, final MotionEvent event) {
                final FrameLayout.LayoutParams par = (FrameLayout.LayoutParams) v.getLayoutParams();
                switch (event.getAction()) {
                    case MotionEvent.ACTION_MOVE: {
                        par.topMargin += (int) event.getRawY() - prevY;
                        prevY = (int) event.getRawY();
                        par.leftMargin += (int) event.getRawX() - prevX;
                        prevX = (int) event.getRawX();
                        v.setLayoutParams(par);
                        return true;
                    }
                    case MotionEvent.ACTION_UP: {
                        par.topMargin += (int) event.getRawY() - prevY;
                        par.leftMargin += (int) event.getRawX() - prevX;
                        v.setLayoutParams(par);
                        return true;
                    }
                    case MotionEvent.ACTION_DOWN: {
                        prevX = (int) event.getRawX();
                        prevY = (int) event.getRawY();
                        par.bottomMargin = -2 * v.getHeight();
                        par.rightMargin = -2 * v.getWidth();
                        v.setLayoutParams(par);
                        return true;
                    }
                }
                return false;
            }
        });

    }

    public void buttonListener(){

        mainButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

              //  Intent intent = Intent.
                Toast.makeText(MainPowerAndVolumeService.this,
                        "ImageButton (selector) is clicked!",
                        Toast.LENGTH_SHORT).show();


            }
        });


    }




    public void onDestroy(){
        super.onDestroy();
        ((WindowManager) getSystemService(WINDOW_SERVICE)).removeView(mView);

    }


}

Answer 1

You have to set params.gravity to Gravity.TOP | Gravity.LEFT. Set that to your params when you first initialize the View and when you update it in the OnTouchListener. Here is the code:

mView.setOnTouchListener(new View.OnTouchListener() {
    @Override
    public boolean onTouch(View v, MotionEvent event)
    {
        if(event.getAction() == MotionEvent.ACTION_MOVE || event.getAction() == MotionEvent.ACTION_DOWN)
        {
           /* You can play around with the offset to set where you want the users finger to be on the view. Currently it should be centered.*/
            xOffset = v.getWidth()/2;
            yOffset = v.getHeight()/2;          
            x = (int) event.getRawX() - xOffset;
            y = (int) event.getRawY() - yOffset;
            WindowManager.LayoutParams params = new WindowManager.LayoutParams(
            WindowManager.LayoutParams.WRAP_CONTENT,
            WindowManager.LayoutParams.WRAP_CONTENT,
            x,y,
            WindowManager.LayoutParams.TYPE_PHONE ,
            WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL |
            WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH |
            WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
            PixelFormat.TRANSLUCENT);
            params.gravity = Gravity.TOP | Gravity. LEFT;
            wm.updateViewLayout(mView, params);
            return true;
        }
        return false;
    }
});

If you want to save it so your button shows up at the same spot when the user reloads your app, just set a SharedPreference for x and y in the OnTouchListener's ACTION_UP. Then recall them and insert them into your params when you first initialize the View.