storing variables from onTouch MotionEvent - Android

Question

I have an imageView & I want to find out in which direction the touch is moving. On DOWN, it stores the X and Y coordinates in variables initX and initY. On move, it stores the current coordinates on finalX and finalY.

I have these variables displayed in textViews, and they're showing the values I'd expect.

On UP, I call another method, whichWayToMove, and pass it initX, initY, finalX and finalY. However, the values passed through are always zero. They shouldn't be. Any idea why?

public void moveTile(){


    ImageView view1 = (ImageView) findViewById(R.id.view1);
    ImageView view2 = (ImageView) findViewById(R.id.view2);

    final TextView tv = (TextView) findViewById(R.id.textView);
    final TextView tv2 = (TextView) findViewById(R.id.textView2);
    final TextView tv3 = (TextView) findViewById(R.id.textView3);



    view1.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {  // half-inched from https://developer.android.com/training/gestures/detector.html

            int initialY =0;
            int finalY = 0;
            int initialX = 0;
            int finalX = 0;

            int action = MotionEventCompat.getActionMasked(event);

            switch(action) {
                case (MotionEvent.ACTION_DOWN):

                    initialX = (int) event.getX();
                    initialY = (int) event.getY();
                    tv.setText(initialX + ", " + initialY);

                    tv3.setText( initialX + ", " + initialY );
                    return true;
                case (MotionEvent.ACTION_MOVE):
                    tv.setText("Action was MOVE");
                    finalX = (int) event.getX();
                    finalY = (int) event.getY();

                    tv2.setText(finalX + ", " + finalY);


                    return true;
                case (MotionEvent.ACTION_UP):

                    whichWayToMove(initialX, finalX, initialY, finalY);


                    tv.setText("Action was UP");
                    return true;
                case (MotionEvent.ACTION_CANCEL):
                    tv.setText("Action was CANCEL");
                    return true;
                case (MotionEvent.ACTION_OUTSIDE):
                    tv.setText("Movement occurred outside bounds " +
                            "of current screen element");
                    return true;
                default:
                    tv.setText("wut?");

            }


                    return false;
        }
    });




}



public void whichWayToMove(int initX, int finalX, int initY, int finalY){

    TextView tv4 = (TextView) findViewById(R.id.textView4);
    TextView tv5 = (TextView) findViewById(R.id.textView5);

    tv5.setText("initX: " + initX + ". finalX: " + finalX + " initY: " + initY + " . finalY: " +
            "" + finalY +
            "" );

    String direction = "";

    int deltaX = initX - finalX;
    int deltaY = initY - finalY;



    if (Math.abs(deltaX)> Math.abs(deltaY)){ // then we're moving on the X axis

        if (deltaX >= 0){direction = "left";}
        else {direction = "right";}

    }

        else { // we're moving on the Y axis

        if (deltaY >= 0){direction = "up";}
        else {direction = "down";}

    }

   // tv4.setText("direction is: " + direction);
    tv4.setText("deltaX is: " + deltaX + ". deltaY is: " + deltaY);

}

that's because on each event you create new variables. You need to have global variables for your X and Y. — Vladyslav Matviienko, Nov 21 '16 at 11:30

StefMa · Answer 1 · 2016-11-22T06:29:36.993

This is because everytime your action got "changed" the listener is called again.

So your finalY and finalX is zero.

When you want to get the current coordinates where the ACTION_UP happens just call event.getX(); like in the other cases

Update

If you want to store your variables "persistent" you have to store it in global variables.

public class MyTouchListener implements View.OnTouchListener {

  private int mOnDownX;

  private int mOnDownY;

  @Override
  public boolean onTouch(View v, MotionEvent event) {
    int action = MotionEventCompat.getActionMasked(event);

    switch(action) {
      case (MotionEvent.ACTION_DOWN):

        mOnDownX = (int) event.getX();
        mOnDownY = (int) event.getY();
        break;

     case (MotionEvent.ACTION_UP):

       int mOnUpX = (int) event.getX();
       int mOnUpY = (int) event.getY();

       Log.v("Finger down at X:", String.valueOf(mOnDownX));
       Log.v("Finger down at Y:", String.valueOf(mOnDownY));

       Log.v("Finger up at X:", String.valueOf(mOnUpX));
       Log.v("Finger up at Y:", String.valueOf(mOnUpY));
       break;
  }
}

That works great for the finalX and finalY. How do I preserve the initX & initY? — Heinz, Nov 21 '16 at 11:56
I've updated my answer. Don't forget to accept these if it answer your question. — StefMa, Nov 22 '16 at 06:30

storing variables from onTouch MotionEvent - Android

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