Android - how to detect a touch on screen is a “scroll” touch?

Question

I am creating an android app in Java in which I have a lot of <TextView> around the screen, all of them with onTouchListeners defined. They are wrapped in a <ScrollView> because they occupy more space than available in the screen.

My problem is: when I scroll the app, up/down, by touching at the screen and moving my finger up/down, the scroll works as expected but the onTouchListener of the touched <TextView> is also fired (which is probably expected as well) - I don't want that to happen though. I want the onTouchListener to be ignored when I'm touching the screen to scroll it.

How can I accomplish this? I don't want my function to run when the user is scrolling and "accidentally" fires the onTouchListener on a certain <TextView>.

Answer 1

After searching more, I found this solution by Stimsoni. The idea is to check if the time between the ACTION_DOWN and ACTION_UP events is lower or higher than the value given by ViewConfiguration.getTapTimeout().

From the documentation:

[Returns] the duration in milliseconds we will wait to see if a touch event is a tap or a scroll. If the user does not move within this interval, it is considered to be a tap.

Code:

view.setOnTouchListener(new OnTouchListener() {

    private long startClickTime;

    @Override
    public boolean onTouch(View view, MotionEvent event) {

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

            startClickTime = System.currentTimeMillis();

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

            if (System.currentTimeMillis() - startClickTime < ViewConfiguration.getTapTimeout()) {

                // Touch was a simple tap. Do whatever.

            } else {

                // Touch was a not a simple tap.

            }

        }

        return true;
    }

});

Answer 2

I had the same problem as you, and I solved it with ACTION_CANCEL.

motionEvent.getActionMasked() is equal to ACTION_CANCEL when an action perceived previously (like ACTION_DOWN in your case) is "canceled" now by other gestures like scrolling, etc. your code may be like this:

view.setOnTouchListener(new View.OnTouchListener() {
    @Override
    public boolean onTouch(View view, MotionEvent e) {
        if (e.getActionMasked() == MotionEvent.ACTION_DOWN) {
            // perceive a touch action.
        } else if(e.getActionMasked() == MotionEvent.ACTION_UP ||
                e.getActionMasked() == MotionEvent.ACTION_CANCEL) {
            // ignore the perceived action.      
        }
    }

I hope this helps.

Answer 3

I had a similar problem but with one TextView, search led me here. The text-content potentially takes up more space than available on screen. Simple working example: bpmcounter-android (Kotlin)

class MainActivity : AppCompatActivity() {

    inner class GestureTap : GestureDetector.SimpleOnGestureListener() {
        override fun onSingleTapUp(e: MotionEvent?): Boolean {
            // Do your buttonClick stuff here. Any scrolling action will be ignored
            return true
        }
    }

    @SuppressLint("ClickableViewAccessibility")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val textView = findViewById<TextView>(R.id.textView)
        textView.movementMethod = ScrollingMovementMethod()
        val gestureDetector = GestureDetector(this, GestureTap())
        textView.setOnTouchListener { _, event -> gestureDetector.onTouchEvent(event) }
    }
}

Answer 4

You can identify moving action like this:

view.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {

            if(event.getAction() == MotionEvent.ACTION_MOVE)
            {

            }

            return false;
        }
    });