Develop Reference

GestureDetector not registering double taps

I am having trouble implementing a touchListener to my recyclerview items that listens for Single taps and double taps.
Here is my code:
val gDetector = GestureDetector(root.context, object : SimpleOnGestureListener() {
override fun onDoubleTap(e: MotionEvent?): Boolean {
Log.i(TAG,"Double tapped")
return super.onDoubleTap(e)
}
override fun onShowPress(e: MotionEvent?) {
Log.i(TAG,"Show Press")
super.onShowPress(e)
}
override fun onSingleTapUp(e: MotionEvent?): Boolean {
Log.i(TAG,"Single tap up")
return super.onSingleTapUp(e)
}
override fun onDoubleTapEvent(e: MotionEvent?): Boolean {
Log.i(TAG,"Double tapped event")
return super.onDoubleTapEvent(e)
}
override fun onSingleTapConfirmed(e: MotionEvent?): Boolean {
Log.i(TAG,"single tap confirmed")
return super.onSingleTapConfirmed(e)
}
override fun onLongPress(e: MotionEvent?) {
Log.i(TAG,"Long press")
super.onLongPress(e)
}
})
root.setOnTouchListener { view, event ->
gDetector.onTouchEvent(event)
}
I am using GestureDetector with onTouchListener but only onShowPress and onLongPress get called when I test it out. onLongPress gets called even when I do a quick tap on an item... onShowPress gets called everytime I tap no matter what.
I was unable to find examples online that combine both GestureDetector with onTouchListener on a view with Kotlin.
any ideas on how to get onDoubleTap and onSingleTapConfirmed to work?
tried removing supers and returning true (this does not work)
I am trying to implement 'GestureDetector.onDoubleTapListener' but I am getting this error:

Try delete super methods. And return false where you don't need to register event.
Return true only where you need to register that event happened.

Disable 2 finger taps on button

I want to prevent a button from intercepting 2 finger taps. I have a standard Android Activity with onTouchEvent and a standard button which occupies more or less the entire screen.
private const val DEBUG_TAG = "Gestures"
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val button = this.findViewById<Button>(R.id.button2)
button.setOnClickListener { Log.d(DEBUG_TAG, "Button tapped")
}
}
override fun onTouchEvent(event: MotionEvent): Boolean {
Log.d(DEBUG_TAG, "onTouchEvent")
val action: Int = MotionEventCompat.getActionMasked(event)
val pointerCount = event.pointerCount;
if (pointerCount > 1) {
Log.d(DEBUG_TAG, "Multi-touch")
}
return super.onTouchEvent(event)
}
}
I want the button to intercept 1 finger taps but ignore 2 finger taps and propagate them to the onTouchEvent of the activity. Currently it intercepts even 2 finger taps.
I tried this in styles.xml but no luck.
<item name="android:windowEnableSplitTouch">false</item>
<item name="android:splitMotionEvents">false</item>
Ideally I would like to do that app-wide but still having onTouchEvent being able to detect 2 finger taps.

You need to block events you don't want to propagate:
override fun onTouchEvent(event: MotionEvent): Boolean {
val action: Int = MotionEventCompat.getActionMasked(event)
val pointerCount = event.pointerCount;
return when (pointerCount) {
1 -> {
// your logic
true //true means you consumed the event (stop propagation)
}
else -> super.onTouchEvent(event)
}
}

How to Stop Event's While Animation is in process?

I am working on Animating my view where i animate the translation and scaling of View.
Problem:
If my animation duration is for 2000 ms (2 Sec) i don't want any user event's to interfere in between animation.
Example if Double Tap on View Trigger's the Scaling Animation and scrolling trigger's Translation Animation.Both animation duration is 2 seconds,But if i double tap and scroll one after another it create's weird result.
So i want to stop event's when animation is going on.
Is there any easy solution without maintaining the state of OnGoing animation and overriding the onTouchEvent to disable events?

Lock UI from events:
private void lockUI() {
getWindow().setFlags(WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE,
WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE);
}
Unlock UI:
private void unlockUI() {
getWindow().clearFlags(WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE);
}

Solution that i used:
Created a State of Animation
private var isAnimationOnGoing: Boolean = false
Setting the State in Animation Listener
translationAnimation.setAnimationListener(object : Animation.AnimationListener {
override fun onAnimationRepeat(animation: Animation?) {
}
override fun onAnimationEnd(animation: Animation?) {
isAnimationOnGoing = false
}
override fun onAnimationStart(animation: Animation?) {
isAnimationOnGoing = true
}
})
Use dispatchTouchEvent(ev: MotionEvent?) . to prevent event's to be received by the ViewGroup or by children's of ViewGroup
override fun dispatchTouchEvent(ev: MotionEvent?): Boolean {
val dispatchTouchEvent = super.dispatchTouchEvent(ev)
if (isAnimationOnGoing) {
return false
}
return dispatchTouchEvent
}

Android VIewGroup handle touch, child handle click

I have i custom ViewPager that detects taps, long press and long press up events with a GestureDetector. It also allows to wipe ViewPager.
Gesture listener is simple:
private inner class GestureListener : GestureDetector.SimpleOnGestureListener() {
override fun onDown(e: MotionEvent?) = true
override fun onLongPress(e: MotionEvent?) {
mTouchListener.invoke(TAPEVENT.LONGTAP)
mWasLongTap = true
}
override fun onSingleTapConfirmed(e: MotionEvent?): Boolean {
mTouchListener.invoke(TAPEVENT.TAP)
return true
}
override fun onSingleTapUp(e: MotionEvent?): Boolean {
if (mWasLongTap) {
mWasLongTap = false
mTouchListener.invoke(TAPEVENT.LONGTAPUP)
}
return true
}
}
//override view group methods
override fun onTouchEvent(ev: MotionEvent?): Boolean {
super.onTouchEvent(ev)
return mDetector.onTouchEvent(ev)
}
override fun dispatchTouchEvent(ev: MotionEvent): Boolean {
mDetector.onTouchEvent(ev)
return super.dispatchTouchEvent(ev)
}
And i have fragments inside a ViewPager. In my fragments i have, lets say, a Button view.
When my button is clicked onSingleTapConfirmed event is fired too.
Cannot figure out what to do to force ViewPager do not process event if there was a click on a child view of a fragment.
Fragment view looks something like this:
<CoordinatorLayout>
<View>
</View>
<Button>
</Button>
</CoordinatorLayout>

I ended up with such a solution.
GestureListener is the same, but onTouchEvent is overridden the other way.
override fun onTouchEvent(ev: MotionEvent): Boolean {
if (ev.action == MotionEvent.ACTION_UP && mWasLongTap) {
mWasLongTap = false
mTouchListener.invoke(TAPEVENT.LONGTAPUP)
}
return mDetector.onTouchEvent(ev) || super.onTouchEvent(ev)
}

Android Kotlin child onClick blocks parent OnTouch

I have this layout hierarchy:
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/parent"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.xxxxxx.Widget
android:id="#+id/widget1"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<com.xxxxxx.Widget
android:id="#+id/widget2"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
</LinearLayout>
I have touch Events for the Parent LinearLayout like this:
parent.setOnTouchListener(myCustomTouchParent)
class MyCustomTouchParent(ctx: Context): View.OnTouchListener {
private var isScrollingDown = false
private var isScrollingUp = false
private val myGestureDetected = GestureDetector(ctx, MyGestureListener())
var onRecyclerViewMovingDown: (() -> Unit)? = null
override fun onTouch(p0: View?, e: MotionEvent): Boolean {
myGestureDetected.onTouchEvent(e)
when(e.action){
MotionEvent.ACTION_UP -> {
if (isScrollingDown) {
onRecyclerViewMovingDown?.invoke()
}
}
MotionEvent.ACTION_DOWN -> {
Log.i("TAg", "Action Down")
isScrollingDown = false
isScrollingUp = false
}
}
return true
}
inner class MyGestureListener: GestureDetector.SimpleOnGestureListener() {
override fun onScroll(e1: MotionEvent, e2: MotionEvent, distanceX: Float, distanceY: Float): Boolean {
if(e2.y - e1.y > 0){
isScrollingUp = true
} else if(e2.y - e1.y < 0){
isScrollingDown = true
}
return super.onScroll(e1, e2, distanceX, distanceY)
}
}
}
Basically, this will detect a 'Scroll Up' event on the parent, and will perform some animations. The problem is, as soon as I set a click listener for widget1 and widget2, the touch event of the parent is no longer working. Is there any workaround for this?

The only thing that worked for me: In the parent LinearLayout, intercept the touch, call onTouchEvent and return false:
override fun onInterceptTouchEvent(ev: MotionEvent): Boolean {
onTouchEvent(ev)
return false
}
Move the TouchInterceptor with the Gesture Detector class to the parent onTouchEvent:
override fun onTouchEvent(e: MotionEvent): Boolean {
myGestureDetected.onTouchEvent(e)
when(e.action){
MotionEvent.ACTION_UP -> {
if (isScrollingDown) {
onRecyclerViewMovingDown?.invoke()
}
}
MotionEvent.ACTION_DOWN -> {
isScrollingDown = false
isScrollingUp = false
}
}
return super.onTouchEvent(e)
}
I don't know if there is a better solution, but this one let me handle touch event on the parent first, then it passed the touch to the childs. There you can set your click listeners.
Also, if you don't set click listeners, the area of touch that contains the clickable item won't trigger touch. so, better set
clickable=true
in all the items, and then only set listeners when you need.

You have to override both onTouchListeners on your children views and return false, that will make them not override their parent ontouch.
widget1.onTouch { view, motionEvent -> return#onTouch false }
widget2.onTouch { view, motionEvent -> return#onTouch false }