Looks like setting RecyclerView's item layout to clickable="true", consume some touch events completely, particulary MotionEvent.ACTION_DOWN (ACTION_MOVE and ACTION_UP afterwards are working):
item.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/demo_item_container"
android:layout_width="match_parent"
android:layout_height="?android:attr/listPreferredItemHeight"
android:background="?android:attr/selectableItemBackground"
android:clickable="true"> <-- this what breaks touch event ACTION_DOWN
....
</LinearLayout>
Having very basic RecyclerView setup in onCreate():
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.list);
... //Standard recyclerView init stuff
//Please note that this is NOT recyclerView.addOnItemTouchListener()
recyclerView.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View view, MotionEvent motionEvent) {
Log.d("", "TOUCH --- " + motionEvent.getActionMasked());
//Will never get here ACTION_DOWN when item set to android:clickable="true"
return false;
}
});
Is this intended behaviour or bug in RecyclerView cause it is still a preview?
PS. I want this to be clickable as per docs to react on pressed state and have ripple effect on click. When set to false ACTION_DOWN is working fine but pressed state is not triggered and selectableBackground does not have any effect.
This is intended behaviour NOT a bug.
When set item clickable true, ACTION_DOWN will be consumed, recycler view
will NEVER get ACTION_DOWN.
Why are you need ACTION_DOWN in onTouch() of recycler view? Does it necessary?
if you want to set lastY in ACTION_DOWN, why not this
case MotionEvent.ACTION_MOVE:
if (linearLayoutManager.findFirstCompletelyVisibleItemPosition() == 0) {
// initial
if (lastY == -1)
lastY = y;
float dy = y - lastY;
// use dy to do your work
lastY = y;
break;
case:MotionEvent.ACTION_UP:
// reset
lastY = -1;
break;
Does it you want to? if you still want the ACTION_DOWN, try to get it in activity, such as:
public boolean dispatchTouchEvent(MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_DOWN)
lastY = ev.getRawY();
return super.dispatchTouchEvent(ev);
Related
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)
}
How can I limit the scrolling ability of a vertical Recyclerview to only allow scrolling down?
I want to make somehow a "list with no return to the top".
EDIT: It's not a duplicate. I don't want to disable scrolling vertically. I just want to disable scrolling upwards.
I figured out a solution using an OnItemTouchListener.
The scrolling event consists of 3 MotionEvents : ACTION_DOWN , ACTION_MOVE and ACTION_UP.
So on ACTION_DOWN we get the vertical position of the cursor (Y) and the on ACTION_MOVE we compare the new position to the old one.
By returning true, the method onInterceptTouchEvent() makes sure we intercept the scrolling event.
float lastY;
recyclerView.addOnItemTouchListener(new RecyclerView.OnItemTouchListener() {
#Override
public boolean onInterceptTouchEvent(RecyclerView recyclerView, MotionEvent event) {
int action = event.getAction();
if(action == MotionEvent.ACTION_DOWN) {
lastY = event.getY();
}
if (action == MotionEvent.ACTION_MOVE && event.getY() > lastY) {
return true;
}
return false;
}
...
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.
I have a ScrollView on top of another view(with Buttons). The ScrollView is taking the whole screen and is obscuring the view that is beneath it.
At some point in my app I need the ScrollView to be disabled (but still visible) and transfer all the touch events to the Buttons that are beneath the ScrollView. How can I do that? Some views like Buttons are automatically doing that when disabled but a ScrollView is not doing that.
Try to implement your own ScrollView which has a flag to indicate the status(disabled/enabled) and also overrides the onTouchEvent and dispatchTouchEvent to let the touch events get pass the ScrollView. Here is an example:
public class DisabledScrollView extends ScrollView {
private boolean mIsDisable = false;
// if status is true, disable the ScrollView
public void setDisableStatus(boolean status) {
mIsDisable = status;
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
// no more tocuh events for this ScrollView
if (mIsDisable) {
return false;
}
return super.onTouchEvent(ev);
}
public boolean dispatchTouchEvent(MotionEvent ev) {
// although the ScrollView doesn't get touch events , its children will get them so intercept them.
if (mIsDisable) {
return false;
}
return super.dispatchTouchEvent(ev);
}
}
Then all you have to do is change the value of that flag. See if it works.
In my case, I just needed to handle the touch event in View A, which was overlaping View B and then send the event to View B. Both views were child of the same RelativeLayout, but there was no parent-child relation between views A and B. This worked for me:
viewA.setOnTouchListener( new OnTouchListener(){
#Override
public boolean onTouch(View v, MotionEvent event) {
// do my stuff here
viewB.dispatchTouchEvent( event );
}
}
In this case I have a recyclerview under a scrollview. The top of scrollview is in vertical scroll, and the recyclerview is in horizontal scroll. The scrollview have top padding, making the recyclerview is visible through the transparency in the scrollview padding. I have to make it this way because when the scrollview is scrolled the recyclerview will scroll vertically to like parallax effect (this effect is in another code). This code below is working for my case, might help
scrollView.setOnTouchListener(new View.OnTouchListener() {
float mDownX,mDownY;
boolean mIsSwiping,isDown;
#Override
public boolean onTouch(View v, MotionEvent event) {
if(mIsSwiping){
recyclerView.dispatchTouchEvent(event);
}
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
mIsSwiping = false;
isDown = true;
mDownX = event.getX();
mDownY = event.getY();
break;
case MotionEvent.ACTION_MOVE:
if(isDown){
float deltaX = Math.abs(event.getX() - mDownX);
float deltaY = Math.abs(event.getY() - mDownY);
mDownX = event.getX();
mDownY = event.getY();
if(deltaX!=deltaY){
isDown = false;
if(deltaX>deltaY){
mIsSwiping = true;
}
}
}
}
return mIsSwiping;
}
});
This is the layout
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/gray0"
android:clipToPadding="false"
android:clipChildren="false"
android:paddingBottom="70dp">
<android.support.v7.widget.RecyclerView
android:id="#+id/recyclerview"
android:layout_width="match_parent"
android:layout_height="320dp"
android:orientation="horizontal"
app:layoutManager="android.support.v7.widget.LinearLayoutManager"/>
<ScrollView
android:id="#+id/scrollview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingTop="301.75dp"
android:paddingBottom="23.5dp"
android:clipChildren="false"
android:clipToPadding="false">
.
.
.
I have a custom Android view which overrides onTouchEvent(MotionEvent) to handle horizontal scrolling of content within the view. However, when the ScrollView in which this is contained scrolls vertically, the custom view stops receiving touch events. Ideally what I want is for the custom view to continue receiving events so it can handle its own horizontal scrolling, while the containing view hierarchy deals with vertical scrolling.
Is there any way to continue receiving those motion events on scroll? If not, is there any other way to get the touch events I need?
Use requestDisallowInterceptTouchEvent(true) in the childview to prevent from vertical scrolling if you want to continue doing horizontal scrolling and latter reset it when done.
private float downXpos = 0;
private float downYpos = 0;
private boolean touchcaptured = false;
#Override
public boolean onTouchEvent(MotionEvent event) {
switch(event.getAction()) {
case MotionEvent.ACTION_DOWN:
downXpos = event.getX();
downYpos = event.getY();
touchcaptured = false;
break;
case MotionEvent.ACTION_UP:
requestDisallowInterceptTouchEvent(false);
break;
case MotionEvent.ACTION_MOVE:
float xdisplacement = Math.abs(event.getX() - downXpos);
float ydisplacement = Math.abs(event.getY() - downYpos);
if( !touchcaptured && xdisplacement > ydisplacement && xdisplacement > 10) {
requestDisallowInterceptTouchEvent(true);
touchcaptured = true;
}
break;
}
super.onTouchEvent(event);
return true;
}
I'm answering my own question in case anyone else is as bad at Googling for the answer as I apparently was. :P
A workaround for this problem is to extend ScrollView and override the onInterceptTouchEvent method so that it only intercepts touch events where the Y movement is significant (greater than the X movement, according to one suggestion).