Develop Reference

2 ViewPager not scrolling in Android 2.3

I am using Navigation Drawer in my app, that contains some Fragments just like in the below picture.
Every Fragment Contains another ViewPager that is an ImageSlider, and below that is a Listview and at the top I am using the SwipeRefreshLayout. My problem is the image slider works well on devices that has Android version 3.0 or higher but the swipe left or right doesn't works on devices 2.3 and lower, instead it invokes the Parent ViewPager's swipe that is it navigates the fragment. I am using support Version 4 library for this purpose to support devices lower than 3.0. All functions works quite well on 2.3 devices except that one. I have googled it but I haven't found any help anywhere. So to make it scroll what should I do for this, any idea/help will be highly appreciated.

You can use this ViewPager as your parent ViewPager. This allows the child ViewPager to scroll.
public class CustomViewPager extends ViewPager {
public CustomViewPager(Context context) {
super(context);
}
public CustomViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
}
#Override
protected boolean canScroll(View v, boolean checkV, int dx, int x, int y) {
try {
//Handle the issue only in lower versions of android
if (v != this && v instanceof ViewPager && CJRAppCommonUtility.getOSVersion() < android.os.Build.VERSION_CODES.HONEYCOMB) {
ViewPager viewPager = (ViewPager) v;
int currentPage = viewPager.getCurrentItem();
int size = viewPager.getAdapter().getCount();
//if ViewPager has reached its end and if user tries to swipe left allow the parent to scroll
if (currentPage == (size - 1) && dx < 0) {
return false;
}
//if ViewPager has reached its start and if user tries to swipe right allow the parent to scroll
else if (currentPage == 0 && dx > 0) {
return false;
}
//Allow the child to scroll hence blocking parent scroll
else {
return true;
}
}
return super.canScroll(v, checkV, dx, x, y);
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
}
Android developers site has a nice explanation about handling touch events in a Viewgroup. You can refer it here: http://developer.android.com/training/gestures/viewgroup.html
Hope it helps!!

In older version of Android requestDisallowInterceptTouchEvent doesn't work that great. The solution here is to extend view pager and override the onInterceptTouchEvent and store a list of children that are scrollable. Then, when onInterceptTouchEvent is called you can iterate through the list of scrollable children, get their hit rect, and see if the touch event is inside the hit rect. If it is, you can just return false to not handle it and let the child take it.
Something like this:
#Override
public boolean onInterceptTouchEvent(MotionEvent ev)
{
for (View view : scrollableChildren)
{
// get the hit rectangle for the view
Rect rect = new Rect();
view.getHitRect(rect);
// check to see if the click was inside this child
if (rect.contains((int) ev.getX(), (int) ev.getY()))
{
return false;
}
}
return super.onInterceptTouchEvent(ev);
}

Android / kindle drag drop freezing occasionally

I'm not sure if this is a device issue or an issue with my code but I created a simple draggable sortable list using a relative layout and image views. I have very specific reasons for doing it this way and that is not my question.
The problem I'm having is occasionally it will totally freeze my app. The item will get stuck in the dragging state. If I lift my finger the shadow (dragging) object is still on the screen and if I touch the screen it will move to that spot. This will go on for about a minute and then I will get an error saying the app is non responsive with the option to kill it or wait. The only useful bit in the logcat is as follows:
12-09 14:23:13.157: W/WindowManager(16415): Drag is in progress but there is no drag window handle.
Then when the app times out I get this as an error
12-09 14:59:09.782: E/ActivityManager(16415): ANR in com.appname.appname (com.appname.appname/.MainActivity)
12-09 14:59:09.782: E/ActivityManager(16415): Reason: keyDispatchingTimedOut
I googled this error message and the only info was someone with no drag listener and another person saying it was the device touch sensor not keeping up.
Ideally, I'd love to fix this error and prevent it from happening in the first place. It does seem to happen mostly if I drag quickly, but I can't very well ask my users not to drag quickly... right?
Alternatively, is there a way that I could detect that dragging has frozen the app and interrupt the drag. Like set a timer on the touch listener and if there are no drag_location messages within like a second or two interrupt the drag? The timer stuff I know how to do, but I don't know how I would force the drag to stop while it's frozen. Any ideas?
Here's the code:
setup
//happens once when the app loads
RelativeLayout trackList = (RelativeLayout) findViewById(R.id.nsTrackList1);
trackList.setOnDragListener(new MyTrackDragListener(this));
//happens in a loop for each "track" (image view)
trackButton = new ImageView(this);
trackButton.setImageDrawable(nsPackages[trackId].banner[bannerSizeSelector]);
trackButton.setOnTouchListener(new MyTrackTouchListener());
On touch
public class MyTrackTouchListener implements OnTouchListener {
boolean isDragging=false;
float prevX, prevY;
public boolean onTouch(View view, MotionEvent motionEvent) {
if(motionEvent.getPointerCount() < 2 && !isDragging) return false;
if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
isDragging=false;
prevX=0;
prevY=0;
return true;
} else if (motionEvent.getAction() == MotionEvent.ACTION_MOVE) {
if(isDragging) return true;
boolean wasFirst = (prevX == 0 || prevY == 0);
float theTotalDiff = Math.abs(prevX - motionEvent.getX()) + Math.abs(prevY - motionEvent.getY());
prevX=motionEvent.getX();
prevY=motionEvent.getY();
if(wasFirst) return true;
if(theTotalDiff <3) return true;
ClipData data = ClipData.newPlainText("", "");
DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
view.startDrag(data, shadowBuilder, view, 0);
int thisViewId = view.getId();
//hide view
view.setVisibility(View.GONE);
isDragging=true;
return true;
} else if (motionEvent.getAction() == MotionEvent.ACTION_UP || motionEvent.getAction() == MotionEvent.ACTION_CANCEL) {
isDragging=false;
return true;
}else {
Integer thisAction = motionEvent.getAction();
Log.d("looper","Motion action: "+thisAction.toString());
return false;
}
}
}
On Drag
class MyTrackDragListener implements OnDragListener {
public static boolean isDragging=false;
private MainActivity parent;
public MyTrackDragListener(MainActivity myAct){
parent=myAct;
}
#Override
public boolean onDrag(View v, DragEvent event) {
int action = event.getAction();
switch (event.getAction()) {
case DragEvent.ACTION_DRAG_STARTED:
isDragging=true;
// do nothing
return true;
case DragEvent.ACTION_DROP:
View view = (View) event.getLocalState();
parent.doDropSort(view,(int) event.getY());
return true;
case DragEvent.ACTION_DRAG_ENDED:
if(isDragging && event.getResult()==false){
View view2 = (View) event.getLocalState();
parent.doDropSort(view2,(int) event.getY(),true);
return true;
}
isDragging=false;
break;
case DragEvent.ACTION_DRAG_LOCATION:
parent.doDragHover((int) event.getY());
return true;
default:
Log.d("looper","drag other... "+String.valueOf(event.getAction()));
}
return false;
}
}
A few things I already tried
Removing the drag listener entirely
Always return true from onDrag
Always return false from onDrag
Basically every combination of return true/false in drag and touch
Removing the 2 finger and Action_Move part and triggering drag on Action_down instead
Same results. Drag and drop works perfectly about 70% of the time and then suddenly does the freezing behavior described above. Sometimes it's on the very first drag sometimes it's after several. I've noticed on consistent pattern except possibly drag speed. It seems to USUALLY happen when I'm dragging quickly, but drag direction or where I drag to doesn't seem to matter.

YAY! I Figured it out. Here's the answer incase it helps someone in the future.
I finally narrowed it down to only the top list item (don't know how I missed that) and then started commenting out lines until it didn't break which narrowed it down to this line:
view.setVisibility(View.GONE);
The way my list was set up each item used the Layout Property BELOW in a relative layout (except the top item). Once I removed the top item from the view the 2nd to top item was below an item which was visibility GONE so it didn't know what to do. The solution was to set the parameter of the next item in the view. Luckily I manually set the view IDs of my track buttons (there are other views that scroll too.. labels and such) so they are sequential. So my fix was simply finding the item with id+1 and making it become the top item by setting BELOW to zero like this...
// the top item in my list is ALWAYS view id 1
if(thisViewId == 1){
ImageView nextTrackButton = (ImageView) trackList.findViewById(thisViewId+1);
LayoutParams ntLP = (LayoutParams) nextTrackButton.getLayoutParams();
ntLP.addRule(RelativeLayout.BELOW,0);
nextTrackButton.setLayoutParams(ntLP);
}
//hide view
view.setVisibility(View.GONE);

Custom onInterceptTouchEvent in ListView

How can I implement a custom onInterceptTouchEvent() in a ListView that give the scrolling priority to the child's of the ListView and as soon as they did their scrolling , give it back to the ListView ? I want to give priority to the inner views.

Try overriding onInterceptTouchEvent() of your children like this:
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
if(!isAtTop && !isAtBottom){
getParent().requestDisallowInterceptTouchEvent(true);
}
return super.onInterceptTouchEvent(ev);
}
In onInterceptTouchEvent() calculate if the ListView has scrolled totally to the top or bottom. If it is somewhere in between then ask the parent to not intercept touches.
To check for top or bottom try:
int scrollRange = computeVerticalScrollRange();
int scrollOffset = computeVerticalScrollOffset();
int scrollExtend = computeVerticalScrollExtent();
if(scrollOffset == 0){
//AtTop
}else if(scrollRange == scrollOffset + scrollExtend){
//AtBottom
}

Is it possible to pass an onTouchEvent to multiple views in Android?

I have read a few questions regarding this topic on SO but haven't really found a solid answer to it.
I have a framelayout that I stack multiple custom views on, however the onTouch event only works with the top view. (the custom views are all the same view with the same onTouch event, just multiple of them)
FrameLayout
customView[2] <--- this is the last view added and the only one that receives the event
customView[1]
customView[0]
I'm testing it on Android 2.2 and am wondering if there is any way for the other views below to know where the touch happened?
EDIT (Adding some code)
I'm adding some code to hopefully help explain where I'm running into issues. At first I just automatically had the onTouchEvent return true. This made it so that the last view (in my case customerView[2]) would be the only one generating a value.
However, once I added the method to set the onTouchEvent to return true or false, now the only view returning a generated value is customView[0].
I hope this clears up what I am asking. I'm rather new to this and I appreciate you taking the time to explain it (and of course I appreciate your patience).
Also, I realize that my TextView's don't update with the value on each touchEvent, I'm working on fixing that.
My Activity:
public class MyActivity extend Activity {
CustomView[] customView;
TextView[] textView;
int numViews 3;
//FrameLayout and Params created
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
for(int i = 0; i < numViews; i++) {
customView[i] = new CustomView(this, i);
//Allows the onTouch to be handled by all Views - View[0] is the bottom view
if(i == 0) {
customView[i].setTouchBool(true); //set view's onTouch to return true
} else {
customView[i].setTouchBool(false); //set view's onTouch to return false
}
//Set TextView to display the number generated by the CustomView
textView[i].setText(Double.toString(customView[i].getGeneratedNumber()));
//Add views to main layout
frame.addView(textView[i]);
frame.addView(customView[i]);
}
}
}
My View:
public class CustomView extends View {
boolean onTouchHandler = true;
int xVal = 0, yVal = 0;
int index;
double generatedNum = 0;
public CustomView(Context context) {
this(context, 0);
this.index = 0;
}
public CustomView(Context context, int index) {
super(context);
this.index = index;
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
final int action = ev.getAction();
switch(action) {
case MotionEvent.ACTION_DOWN: {
//do logic
}
case MotionEvent.ACTION_MOVE: {
//do logic
}
case MotionEvent.ACTION_UP: {
xVal = (int) ev.getX();
yVal = (int) ev.getY();
generateNumber(xVal, yVal, index);
break;
}
}
return onTouchHandler;
}
private void generateNumber(int x, int y, int index) {
if(index == 0) {
generatedNum = (x / 2) * (y / 2) + 64;
} else {
generatedNum = (x / 2) * (y / 2) + (index * 128);
}
}
public double getGeneratedNumber() {
return generatedNum;
}
public boolean setTouchBool(boolean b) {
this.onTouchHandler = b;
}
}

Android will cascade down the views calling onTouchEvent on each one until it receives a true from one of them. If you want a touch event to be handled by all of them, then return false until it reaches the last one.
EDIT:
Ok. If I understand correctly, you have a single top view containing a bunch of child views one layer deep. My original answer was assuming that you had three custom views that were on top of each other in the ViewGroup's hierarchy (View3 is a child of View2. View2 is a child of View1. View1 is a child of ParentView). You want the user's touch event on the parent view to get sent to all of it's children.
If that's the case, AFAIK, there is no view in Android's API that allows that. So, you'll have to make a custom view that does it.
OK, I haven't tested this, so please tell me if it works and if it's what you're trying. Create a custom class that extends whatever object frame is, then override the onTouch method like so.
#Override
public boolean onTouchEvent(MotionEvent ev) {
for(int i = 0; i < this.getChildCount(); i++){
this.getChildAt(i).dispatchTouchEvent(ev);
}
return true;
}
Now, keep the same logic that your custom views have, except they should all return false because your parent view will not receive the onTouch event unless they do as stated in my previous answer
note: with this implementation, the child view that the user actually touches will fire twice because the logic will go
fire child touch event -> return false -> fire parent touch event -> fire child touch event again

I know this question is very old, but I had the same problem and solved it by creating my own Layout to determine which child is actually touched.
I therefore iterate over the children of my custom layout and check if the user actually clicked on the view. The collision detection is handled in the custom view's onTouch() method. (Collision detection is done by intersecting a Region() with the event's x,y coordinates. For me this was convennient because I drew the custom view with a Path())
Here is a kotlin code snippet from my custom layout for better understanding:
class CustomLayout(context: Context, attrs: AttributeSet) :
RelativeLayout(context, attrs){
override fun dispatchTouchEvent(ev: MotionEvent): Boolean {
if(ev.action != MotionEvent.ACTION_UP){
return true
}
//Iterate over child view and search for the right child that should handle this touch event
for (i in childCount - 1 downTo 0) {
val child = getChildAt(i)
if (!viewTouched(child, ev)) {
continue
}
//Do something
Timber.d("Touched view: ${child.id}")
}
return true
}
private fun viewTouched(child: View, ev: MotionEvent) : Boolean {
child as OnTouchListener
//onTouch() does the collision detection
return child.onTouch(child, ev)
}

Overriding onTouchEvent competing with ScrollView

From a simplistic overview I have a custom View that contains some bitmaps the user can drag around and resize.
The way I do this is fairly standard as in I override onTouchEvent in my CustomView and check if the user is touching within an image, etc.
My problem comes when I want to place this CustomView in a ScrollView. This works, but the ScrollView and the CustomView seem to compete for MotionEvents, i.e. when I try to drag an image it either moves sluggishly or the view scrolls.
I'm thinking I may have to extend a ScrollView so I can override onInterceptTouchEvent and let it know if the user is within the bounds of an image not to try and scroll. But then because the ScrollView is higher up in the hierarchy how would I get access to the CustomView's current state?
Is there a better way?

Normally Android uses a long press to begin a drag in cases like these since it helps disambiguate when the user intends to drag an item vs. scroll the item's container. But if you have an unambiguous signal when the user begins dragging an item, try getParent().requestDisallowInterceptTouchEvent(true) from the custom view when you know the user is beginning a drag. (Docs for this method here.) This will prevent the ScrollView from intercepting touch events until the end of the current gesture.

None of the solutions found worked "out of the box" for me, probably because my custom view extends View, not ViewGroup, and thus I can't implement onInterceptTouchEvent.
Also calling getParent().requestDisallowInterceptTouchEvent(true) was throwing NPE, or doing nothing at all.
Finally this is how I solved the problem:
Inside your custom onTouchEvent call requestDisallow... when your view will take care of the event. For example:
#Override
public boolean onTouchEvent(MotionEvent event) {
Point pt = new Point( (int)event.getX(), (int)event.getY() );
if (event.getAction() == MotionEvent.ACTION_DOWN) {
if (/*this is an interesting event my View will handle*/) {
// here is the fix! now without NPE
if (getParent() != null) {
getParent().requestDisallowInterceptTouchEvent(true);
}
clicked_on_image = true;
}
} else if (event.getAction() == MotionEvent.ACTION_MOVE) {
if (clicked_on_image) {
//do stuff, drag the image or whatever
}
} else if (event.getAction() == MotionEvent.ACTION_UP) {
clicked_on_image = false;
}
return true;
}
Now my custom view works fine, handling some events and letting scrollView catch the ones we don't care about. Found the solution here: http://android-devblog.blogspot.com.es/2011/01/scrolling-inside-scrollview.html
Hope it helps.

There is an Android event called MotionEvent.ACTION_CANCEL (value = 3). All I do is override my custom control's onTouchEvent method and capture this value. If I detect this condition then I respond accordingly.
Here is some code:
#Override
public boolean onTouchEvent(MotionEvent event) {
if(isTouchable) {
int maskedAction = event.getActionMasked();
if (maskedAction == MotionEvent.ACTION_DOWN) {
this.setTextColor(resources.getColor(R.color.octane_orange));
initialClick = event.getX();
} else if (maskedAction == MotionEvent.ACTION_UP) {
this.setTextColor(defaultTextColor);
endingClick = event.getX();
checkIfSwipeOrClick(initialClick, endingClick, range);
} else if(maskedAction == MotionEvent.ACTION_CANCEL)
this.setTextColor(defaultTextColor);
}
return true;
}