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How to revoke `requestDisallowInterceptTouchEvent(false)` without lifting finger (Action.UP or Cancel)?

I have WebView(s) inside the RecyclerView. In order to get smooth scrolling experience such that when user scrolls, the RecyclerView will be responsible for scrolling (WebView should not scroll) I called getParent().requestDisallowInterceptTouchEvent(false); inside webview#onTouchEvent(event) when there is only one touch point and is moving vertcially (scrolling up and down).
private void handleSingleFingerTouch(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
x1 = ev.getX();
y1 = ev.getY();
break;
case MotionEvent.ACTION_MOVE:
x2 = ev.getX();
y2 = ev.getY();
// -ve param for canScrollHorizontally is to check scroll left. +ve otherwise
if (Math.abs(x1 - x2) >= Math.abs(y1 - y2)
&& canScrollHorizontally((int) (x1 - x2))) {
// scrolling horizontally. Retain the touch inside the webView.
getParent().requestDisallowInterceptTouchEvent(true);
} else {
// scrolling vertically. Share the touch event with the parent.
getParent().requestDisallowInterceptTouchEvent(false);
}
x1 = x2;
y1 = y2;
}
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
boolean multiTouch = ev.getPointerCount() > 1;
if (multiTouch) {
getParent().requestDisallowInterceptTouchEvent(true);
} else {
handleSingleFingerTouch(ev);
}
return super.onTouchEvent(ev);
}
It works as expected with just one bug, I found that while RecyclerView(and webview) scrolling and I touch inside the WebView, then RecyclerView stops scrolling as expected, then if I don't lift up my finger but keep finger on the screen and try to zoom, the webview would not zoom and actually it wouldn't receive touch event at all. I have to lift my fingers and touch again to zoom. I know this is because getParent().requestDisallowInterceptTouchEvent(false); won't cancel unless UI receive CANCEL or UP event. I tried to implement an interface that call getParent().requestDisallowInterceptTouchEvent(true); when multi-touch happen. Though it did get called, but seems it doesn't work. Zoom still not happen and onTouchEvent inside the WebView still not get triggered. Any idea to solve this?

So basically the solution is to override the onInterceptTouchEvent of the recyclerView
override fun onInterceptTouchEvent(e: MotionEvent): Boolean {
// When recyclerview is scrolling this will stop scrolling and allow touch event passed to child views.
if (e.action == MotionEvent.ACTION_DOWN && this.scrollState == RecyclerView.SCROLL_STATE_SETTLING) {
this.stopScroll()
}
return super.onInterceptTouchEvent(e)
}

not Working ScrollView and HorizontalListView

Can some one help my with ScrolView in Android Mobile App.My problem- on my vertical ScrollView i have horizontal "hlistview»,and when i moved "hlistview" up/down/right/left play only one. How they can work together? At time,work only one.
hListView.setOnTouchListener(new HorizontalListView.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
v.getParent().requestDisallowInterceptTouchEvent(true);
break;
case MotionEvent.ACTION_UP:
v.getParent().requestDisallowInterceptTouchEvent(false);
break;
}
v.onTouchEvent(event);
return true;
}
});

On nested scrollviews you must intercept the touch events. However if you just requestDisallowInterceptTouchEvent on ACTION_DOWN you are making the it's parent disable touch events the moment your finger touches the screen. That's not the wanted behavior. You need to set a threshold and only disallow the events the moment your scroll distance has hit that threshold.
On the nested scrollview ACTION_DOWN set a field saving the initial X (for horizontal swipe) like this:
mLastX = event.getX();
Next on ACTION_MOVE compare it with your threshold (50 in this example)
if (Math.abs(event.getX() - mLastX) > 50)
requestDisallowInterceptTouchEvent(true);

Drag and drop in ScrollView

I have some ImageViews inside a HorizontalScrollView.
I would like to be able to drag and drop the ImageViews somewhere else, but still maintain scrolling capability. Dragging should only be activated when the user starts a mostly vertical motion with their finger.
For now, I have drag and drop activate on long-press, but that is not a good solution.
To illustrate:

I had to do exactly this as well. After reading http://techin-android.blogspot.in/2011/11/swipe-event-in-android-scrollview.html I adapted the code as follows:
class MyOnTouchListener implements View.OnTouchListener {
static final int MIN_DISTANCE_Y = 40;
private float downY, upY;
#Override
public boolean onTouch(View view, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN: {
downY = event.getY();
return true;
}
case MotionEvent.ACTION_MOVE: {
upY = event.getY();
float deltaY = downY - upY;
// swipe vertical?
if (Math.abs(deltaY) > MIN_DISTANCE_Y) {
if (deltaY < 0) {
//Start your drag here if appropriate
return true;
}
if (deltaY > 0) {
//Or start your drag here if appropriate
return true;
}
}
}
}
return false;
}
}
And then set the listener on the ImageViews:
imageView.setOnTouchListener(new MyOnTouchListener());
In this version of the code I am only checking for movement in the vertical direction (I also changed the minimum movement to be 40 instead of 100 as in the original code). If a vertical movement is detected, the specific ImageView can begin to drag or do any other actions you want. If a vertical movement is not detected, the ImageView's MyTouchListener returns false which means the ImageView does not consume the touch event. This allows the parent ScrollView to eventually get the touch event and consume it (for scroll detection). The answers here are helpful for understanding touch events: MotionEvent handling in ScrollView in Android.

Floating List view in android?

Is it possible to create a list view in android that is not fixed to a particular position and user can move the list view on a gesture some what floating listview that can be moved anywhere on the screen?I tried finding it but could not find some link.Does any one have some idea about it?

You can achieve this by setting an OnTouchListener on the list view and overriding it's onTouch() method. In the onTouch() method you will have to handle the touch events like(ACTION_DOWN, ACTION_MOVE). Here is how you can handle touch event:
#Override
public boolean onTouch (View v, MotionEvent event)
{
switch(event.getAction() & MotionEvent.ACTION_MASK)
{
case MotionEvent.ACTION_DOWN:
start.set(event.getX(), event.getY()); //saving the initial x and y position
mode = DRAG;
break;
case MotionEvent.ACTION_MOVE:
if(mode == DRAG) {
float scrollByX = event.getX() - start.x; //computing the scroll in X
float scrollByY = event.getY() - start.y; //computing the scroll in Y
v.scrollBy((int)scrollByX/20, 0);
}
break;
}
return false;
}
When the user places the finger down on the screen the ACTION_DOWN event is triggered and when the user drags his finger on the screen ACTION_MOVE event is triggered. Hence a drag event is a combination of ACTION_DOWN and ACTION_MOVE.
Once you have the scrollX and scrollY value the you can move the view on the screen by passing these values to the scrollBy() method of the View class.
Here in the code there are two things to notice:
first is that I have passed 0 as the value of scrollY as it will prevent the list view to be dragged and scrolled simultaneously.
second is that the return value is false as you want the android to handle the scrolling of the list items
Here you can find the complete code for this

I would move the listview using the margins from the layout.
Outline:
Override OnTouch, and based on the event.getX() and event.getY(), update the margins of the listview as follows:
if the parent is a relative layout:
RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams)mListView.getLayoutParams();
lp.leftMargin = event.getX();
lp.topMargin = event.getY();
mListView.setLayoutParams(lp);
Add the dispatchTouchEvent to your activity so that events from the listview get passed up to onTouch:
#Override
public boolean dispatchTouchEvent(MotionEvent ev) {
onTouchEvent(ev);
return super.dispatchTouchEvent(ev);
}
Hope this helps.

Although it's hard to maintain, AbsoluteLayout lets you specify a position in (x,y) coordinates. You would just declare your ListView inside a AbsoluteLayout, get a handle to it in java code where you intercept the clicks and then set new coordinates.

In the Android framework, the word "floating" is usually synonymous with new Window (such as a Dialog). It depends somewhat on what your end goal is, but if you want to create a ListView that floats over the rest of the content in your hierarchy, that you can easily hide and show, you should probably consider wrapping that view inside a PopupWindow, which has methods to allow you to easily show the window with showAsDropdown() and shotAtLocation() and also move it around while visible with update().
This is how the newer versions of the SDK create pop-up lists for Spinner and Menu

Android Gallery Flipping issue

I have a Gallery of views that contain a TextView Label and then a listview below that. It works excellent except that in order to get it to flip from element to element, the user has to touch either above the listview (near the label) and fling or in between gallery objects. Sometimes below the listview works too.But I really want to be able to fling while touching the listview too because it takes up a majority of the screen. How can this be done? What code do you need to see?

I had a similar problem and solved this by overriding the Gallery and implementing the onInterceptTouchEvent to ensure that move events are intercepted by the Gallery, and all other events are handled normally.
Returning true in the onInterceptTouchEvent causes all following touch events in this touch sequence to be sent to this view, false leaves the event for it's children.
TouchSlop is needed as when doing a click there is sometimes a small amount of movement.
Would love to claim this as my own idea, but got the basics of the code from the default Android Launcher code.
public class MyGallery extends Gallery{
private MotionEvent downEvent;
private int touchSlop;
private float lastMotionY;
private float lastMotionX;
public MyGallery(Context context) {
super(context);
initTouchSlop();
}
private void initTouchSlop() {
final ViewConfiguration configuration = ViewConfiguration.get(getContext());
touchSlop = configuration.getScaledTouchSlop();
}
#Override public boolean onInterceptTouchEvent(MotionEvent ev) {
final float x = ev.getX();
final float y = ev.getY();
switch (ev.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_MOVE: {
final int xDiff = (int) Math.abs(x - lastMotionX);
final int yDiff = (int) Math.abs(y - lastMotionY);
// have we moved enough to consider this a scroll
if (xDiff > touchSlop || yDiff > touchSlop) {
// this is the event we want, but we need to resend the Down event as this could have been consumed by a child
Log.d(TAG, "Move event detected: Start intercepting touch events");
if (downEvent != null) this.onTouchEvent(downEvent);
downEvent = null;
return true;
}
return false;
}
case MotionEvent.ACTION_DOWN: {
// need to save the on down event incase this is going to be a scroll
downEvent = MotionEvent.obtain(ev);
lastMotionX = x;
lastMotionY = y;
return false;
}
default: {
// if this is not a down or scroll event then it is not for us
downEvent = null;
return false;
}
}
}

You would want to set the onTouchListener() on the listview, or maybe the entire Linear/Relative layout.
getListView().setOnTouchListener(yourlistener) OR set it on the entire layout. If you post a little code, I could help you further. XML and how you are using in with the Java class would be most helpful.