Develop Reference

Forward touch event to dynamically attached view, without lifting finger

I have a problem I am struggling with a while now.
I have a Layout with a Button and a container in it.
<FrameLayout ... >
<Button
android:id="#+id/button"
...
/>
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/overlayContainer"/>
</FrameLayout>
My goal is that as I long-press the button, I attach a custom view MyCustomViewto the container and keep the finger pressed.
All the following (ACTION_MOVE, ACTION_UP) events should then ideally be dispatched to and evaluated by MyCustomView.
MyCustomView works like a circular flyout menu: it overlays, dims the background, and shows some options. You then slide your pressed finger to the option, lift it up, and it triggers a result.
mButton.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View v) {
// attach custom view to overlayContainer
// simplified code for demonstration
overlayContainer.addView(new MyCustomView());
return true;
}
});
Right now I don't see any option to "steal" the ACTION_DOWN-Event (which is required to start the event flow to a view) from the Button as I'm above it.
Nor does it work to manually generate and dispatch a ACTION_DOWN-Event in MyCustomView as I attach it.
While researching I found this post here, it basically is the same requirement, but for iOS (also does not provide an elegant solution, other that an click capturing overlay view) ): How to preserve touch event after new view is added by long press
Note that I want to avoid some kind of global overlay over the main view, I would like the solution to be as pluggable and portable as possible.
Thanks for any suggestions.

To answer my own question after the hint in the comments:
I solved it using a bare stripped version of TouchDelegate (had to extend it, since it unfortunetaly is no interface - setTouchDelegate only accepts TouchDelegate (sub)classes. Not 100% clean, but works great.
public class CustomTouchDelegate extends TouchDelegate {
private View mDelegateView;
public CustomTouchDelegate(View delegateView) {
super(new Rect(), delegateView);
mDelegateView = delegateView;
}
public boolean onTouchEvent(MotionEvent event) {
return mDelegateView.dispatchTouchEvent(event);
}
}
Then in my onLongClick method:
mButton.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View v) {
// attach custom view to overlayContainer, simplified for demonstration
MyCustomView myMenuView = new MyCustomView()
mButton.setTouchDelegate(new CustomTouchDelegate(myMenuView));
// What's left out here is to mButton.setTouchDelegate = null,
// as soon as the temporary Overlay View is removed
overlayContainer.addView(myMenuView);
return true;
}
});
This way, all my ACTION_MOVE events from the Button are delegated to MyCustomView (and may or may not need some translation of the coordinates) - et voilà.
Thanks to pskink for the hint.

Android Navigation Drawer Doesn't Pass onTouchEvent to Activity

I have an Activity which uses the Android NavigationDrawer.
When using only fragments (as usual), everything works perfect.
But now I want to use this drawer on other activities of my app, and for some of them,
I don't want the main view to be a fragment.
Question
The problem is, the onTouchEvent() of the activity itself (and the onItemClickedListener() of a child ListView for that matter) isn't called, because the drawer consumes it.
Of course, I want it to be called:)
Needless to say, I would hope the answer will be simple (even a XML one), and hopefully not by extending the Drawer class (unless that's what it takes of course).
More Info
The Activity's main layout is very simple, basically a ListView and the DrawerLayout on top of it (below in XML).
The Drawer has one fragment as it's childView (for fragment navigation) and of course, the ListView for the Drawer Items.
I've seen many questions regarding (not exactly) similar issues, and the frequent answer was to use onInterceptTouch(), requestDisallowInterceptTouchEvent() on the DrawerLayout, and on the Parent view (Activity's main content) and even onTouchEvent() (with False returned) on the ListView of the Drawer.
Nothing seems to do the trick.
I read this link
and it does seem like using Intercept methods somewhere could be the answer. But how?
Please let me know if you need any code. But it's a very basic code/layout for this matter.
Thanks!

Apparently the answer is somewhat easy, although it does make you extend the DrawerLayout and do some thinking, and maybe will result in some strange results (using the LAST
example, I haven't seen any, yet).
Anyway, related questions which looking backwards can help understanding the issue (will explain about the first one later on):
1. DrawerLayout prevents call of MainActivity.onTouchEvent()
2. How can I requestDisallowTouchEvents on Android DrawerLayout
3. Set drag margin for Android Navigation Drawer
Answer
First, please note that I put lots of examples here. If you just want the best one (for me), jump to the last one.
Secondly, if someone has enough reputation, please comment on the first link's question and put a link to this answer (it can help that guy).
Example 1
Well, basically, just extend Android's DrawerLayout and replace onTouchEvent() to this:
#Override
public boolean onTouchEvent(MotionEvent arg0) {
super.onTouchEvent(arg0);
return false;
}
This solution will do anything except that it won't open the Drawer on slides, only menu clicks and the like. Besides, it forwards clicks so when the Drawer is open
for instance, touching outside of it will NOT close it, but click on whatever is behind (e.g. a ListView). Le'ts try harder...
Example 2
Now, let's catch the open OR visible cases, to return true (and consume the action at the Drawer).
#Override
public boolean onTouchEvent(MotionEvent arg0) {
super.onTouchEvent(arg0);
if(isDrawerOpen(findViewById(R.id.list_slidermenu)) ||
isDrawerVisible(findViewById(R.id.list_slidermenu))){
return true;
}
return false;
}
This solution is better, as it prevents clicks on behind the Drawer when the drawer is open or even visible (slide starts...). But touch-sliding it still doesn't work.
Example 3
Ok, so let's just split cases. Touches (MotionEvent.ACTION_DOWN) inside the Drawer's margin (area that Google desided to slide Drawer when touched at)
will result in returning True to consume the action, and others will forward the event (return False).
#Override
public boolean onTouchEvent(MotionEvent arg0) {
super.onTouchEvent(arg0);
float edge = 30;//that's for a left drawer obviously. Use <parentWidth - 30> for the right one.
View mDrawerListView = findViewById(R.id.drawer_listview);
if(isDrawerOpen(mDrawerListView) ||
isDrawerVisible(mDrawerListView)){
return true;
} else if(arg0.getAction() == MotionEvent.ACTION_DOWN && arg0.getX() > edge){
return false;
}
return true;
}
Note that I used 30dp. That's what I found to be the margin (although in one of the links it is said to be 20....).
Well, the next example would of course be deciding what is, exactly, that edge (see in code above) value is, according to Android. We don't want to
use a number that could change or whatever.
New Question
So now that first link should come handy. It "hacks" the Drawer code to get that Drawer edge/megin number. BUT, it didn't work for me, as those exact Field names could not be found.
I run mDrawerLayout.getClass().getField() which returns all the fields, but without any luck finding what we want. Anyone?
Last Example - Full Code
Ok, looking on example number 3, after understanding what exactly I did, we can make it faster by extending the onFinishInflate() method and save it as a global variable
for this CustomDrawerLayout for later use. We can also put that first 'if' inside the second one to save some more work. OK here goes:
View mDrawerListView;
...
#Override
protected void onFinishInflate() {
super.onFinishInflate();
mDrawerListView = findViewById(R.id.drawer_listview);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
super.onTouchEvent(event);
if(event.getX() > 30 && event.getAction() == MotionEvent.ACTION_DOWN){
if(isDrawerOpen(mDrawerListView) || isDrawerVisible(mDrawerListView)){
return true;
} else{
return false;
}
}
return true;
}
That's it for now! Hope it'll helps someone in the future beside myself, hehe....

While working on the same problem I was inspired by guy_m's answer and boiled down his proposals to the following solution.
Again it amounts to extending DrawerLayout and overriding onInterceptTouchEvent(). The logic is simple:
Whenever the touch event occurs off the drawer view (the slideable part), we return false. Then our DrawerLayout is out of the game when it comes to handling the event -- the event is handled by whatever view we put into the DrawerLayout at the respective position.
On the other hand, when the event occurs inside the drawer view, we delegate to super.onInterceptTouchEvent() to decide what to do with the event. That way the drawer will slide in and out as before on touch gestures happening on itself.
The following code sample is for a DrawerLayout whose drawer view is located on the right (android:gravity="right"). It should be obvious how to modify it to cover also the case of a left-placed drawer.
public class CustomDrawerLayout extends DrawerLayout
{
#Override
public boolean onInterceptTouchEvent( MotionEvent event )
{
final View drawerView = getChildAt( 1 );
final ViewConfiguration config = ViewConfiguration.get( getContext() );
// Calculate the area on the right border of the screen on which
// the DrawerLayout should *always* intercept touch events.
// In case the drawer is closed, we still want the DrawerLayout
// to respond to touch/drag gestures there and reopen the drawer!
final int rightBoundary = getWidth() - 2 * config.getScaledTouchSlop();
// If the drawer is opened and the event happened
// on its surface, or if the event happened on the
// right border of the layout, then we let DrawerLayout
// decide if it wants to intercept (and properly handle)
// the event.
// Otherwise we disallow DrawerLayout to intercept (return false),
// thereby letting its child views handle the event.
return ( isDrawerOpen( drawerView ) && drawerView.getLeft() <= event.getX()
|| rightBoundary <= event.getX() )
&& super.onInterceptTouchEvent( event );
}
}

With these answers, i still had some trouble. I could get the motionEvent back to the activity but I lost the onClick listener answer by fragment or everything on the screen. So I found another way to have everything work ( get answer when override OntouchEvent from activity, and answer to onClick Listener )
Extend DrawerLayout and Override this methode :
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
if(super.onInterceptTouchEvent(ev)) return true;
else {
Activity activity = AppContext.getCurrentActivity();
return activity.onTouchEvent(ev);
}
}
if the drawer want the motion event, let it handle it. And if not, pass the event to activity yourself. (AppContext.getCurrentActivity is something from you with current activity, you can for instance attach activity as weakreference to the drawerLayout OnCreate)
The good thing with this way, you don't care about the edge and don't care if start or end. And you don't care also if it is open or close. Everything work fine.

I have a solution:
Set OnTouchListener on the screen layout (the first childview of DrawerLayout, normally) and transmit the TouchEvent to a custom GestureDetector.
So, you can do your own things in it. One more important thing: if you want to override onSingleTapUp() or something else, you should return true in onDown() to make sure that you can get the rest MotionEvent to make onSingleTapUp() work.
private class MyGestureListener implements GestureDetector.OnGestureListener{
#Override
public boolean onDown(MotionEvent e) {
return true;
}
#Override
public void onShowPress(MotionEvent e) {
}
#Override
public boolean onSingleTapUp(MotionEvent e) {
// do your own things
return true;
}
#Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
return false;
}
#Override
public void onLongPress(MotionEvent e) {
}
#Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
return false;
}
}
and set it :
mGestureDetector=new GestureDetector(this, new MyGestureListener());
layout_content.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
return mGestureDetector.onTouchEvent(event);
}
});

To add on to guy_m 's answer, here is my implementation for a drawer that opens from the right, includes constructors so that it is viewable in the layout editor and also takes into account when a user swipes from past the edge point:
public class CustomDrawerLayout extends DrawerLayout {
View mDrawerListView;
float edge;
int holddown = 0;
static final String TAG = CustomDrawerLayout.class.getSimpleName();
public CustomDrawerLayout(#NonNull Context context) {
super(context);
setscreendimensionvals(context);
}
public CustomDrawerLayout(#NonNull Context context, #Nullable AttributeSet attrs) {
super(context, attrs);
setscreendimensionvals(context);
}
public CustomDrawerLayout(#NonNull Context context, #Nullable AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
setscreendimensionvals(context);
}
private void setscreendimensionvals(Context context){
DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
/*((Activity) context).getWindowManager()
.getDefaultDisplay()
.getMetrics(displayMetrics); */
int width = displayMetrics.widthPixels;
float density = displayMetrics.density;
edge = width - (30 * density); // 30 is the edge of the screen where the navigation drawer comes out
Log.d(TAG,"edge: " + edge);
Log.d(TAG,"width: " + width);
}
#Override
protected void onFinishInflate() {
super.onFinishInflate();
mDrawerListView = findViewById(R.id.drawerconstraint_overworld);
}
#Override
public boolean onTouchEvent(MotionEvent event){
super.onTouchEvent(event); // need to add action up and a local variable to detect when lifted finger
//Log.d(TAG,"point: " + event.getX());
if(event.getX() >= edge && (event.getAction() == MotionEvent.ACTION_DOWN || event.getAction() == MotionEvent.ACTION_MOVE)){
holddown = 1;
//Log.d(TAG,"hold down");
}
if(event.getAction() == MotionEvent.ACTION_UP){
holddown = 0;
//Log.d(TAG,"hold up");
}
if(holddown == 1){
return true;
}else{
if(isDrawerOpen(mDrawerListView) || isDrawerVisible(mDrawerListView)){
return true;
} else{
return false;
}
}
}
}

For anyone who might have the unfortunate luck of encountering as persistent an issue as this one, I will add onto the others' answers with my own problem case and solution in the hopes that fewer souls will face this nightmare of a headscratcher.
Due notice is that my explanation will most likely work for any swipeable view whose parent is DrawerLayout (e.g. this solution only works for views that are children of DrawerLayout), but I will regale my experience and my toils for the purpose of clarity.
In my case, I needed to have a MaterialCalendarView (3rd-party CalendarView on steroids) in a DrawerLayout with a NavigationView to the right (i.e. with "android:gravity"="end"). It wasn't long after implementing the view hierarchy that I realised there had existed a conflict between the swipe events of my NavigationView and MaterialCalendarView.
In essence, what occured was that whenever I began swiping the MaterialCalendarView to the right in order to swipe back to the next month, I wound up triggering the DrawerLayout's touch event interceptor and closing said DrawerLayout instead of swiping to the previous month.
So, the solution should be easy, shouldn't it? Set a onTouchListeneron the MaterialCalendarView, call requestDisallowInterceptTouchEvent(), and call it a day—akin to this in the view-hosting Activity:
calendar.setOnTouchListener { _, motionEvent ->
when(motionEvent.action) {
MotionEvent.ACTION_DOWN, MotionEvent.ACTION_MOVE -> {
drawerLayout.requestDisallowInterceptTouchEvent(true)
}
}
true
}
...and you should be all set?
Well, the fact that I'm answering here is enough to infer that wasn't the case and that my onTouchListener wasn't, like the rest, being triggered.
After extensively scouring this thread and trying to follow everyone's advice, I came at a point wherein none of the solutions offered were helpful for someone who'd simply wanted to "exclude" a view from being detected by the DrawerLayout's touch event interceptor. Some ideas entirely paralysed my touch event infrastructure, while others simply gave me more of the same behaviour. I had hit a roadblock and I didn't know what to do.
Then, an epiphany.
I realised that due to my inexperience with writing custom views I'd missed the glaringly obvious: what I needed to do was simply find out where the MaterialCalendarView was, get its coordinates, and see if any touch events are inside in order to call the proper implementation (be it the Activity or default DrawerLayout one)! And, of course, since in the former, the onTouchListener disables interception of touch events by the DrawerLayout, that meant only the MaterialCalendarView could handle the swipes! It was so simple!
And fast-forward to learning about MotionEvents, reading up on what the heck a Rect was, and a muddy in-between of crashes, I finally wrote the custom DrawerLayout which responded to my swipes on the MaterialCalendarView only with the Activity implementation and ignored the ones outside, opting for the DrawerLayout touch interceptor:
class EventCalendarDrawerLayout : DrawerLayout {
constructor(context: Context) : super(context)
constructor(context: Context, attrs: AttributeSet, defStyle: Int) : super(context, attrs, defStyle)
constructor(context: Context, attrs: AttributeSet) : this(context, attrs, 0)
lateinit var calendar: MaterialCalendarView
lateinit var drawer: View
override fun onFinishInflate() {
super.onFinishInflate()
drawer = getChildAt(1)
calendar = findViewById(R.id.event_calendar)
}
override fun onInterceptTouchEvent(event: MotionEvent): Boolean {
val rect = Rect()
calendar.getGlobalVisibleRect(rect) // get the calendar rect positions
// respond to proper motions and forward events contained inside the calendar's rect only
if((event.action == MotionEvent.ACTION_MOVE ||
event.action == MotionEvent.ACTION_DOWN) && rect.contains(event.x.roundToInt(), event.y.roundToInt())) {
return (context as Activity).onTouchEvent(event)
}
// otherwise return the default intercept touch event response
return super.onInterceptTouchEvent(event)
}
}
It's not rocket science, truly, but it is something I deemed worth showing, as it was new and unexpected for me (and undoubtedly many others yet to venture here). Nevertheless, I believe that this implementation may work to ignore as many views embedded inside DrawerLayouts as one could possibly wish for.

SeekBar inside a draggable view (SlideHolder)

I use a 3rd party component (AndroidSideMenu) which allows the whole activity to be dragged to the right to expose a side menu.
In the main (non-menu) section of the layout I have a horizontal SeekBar.
The problem is that when I start dragging the SeekBar button, the whole layout drags along with it because the SlideHolder component is also responding to the drag events.
I'm not sure how touch events are managed in Android, but is there a way to stop the events after they are processed by the SeekBar so that they don't reach the parent container?
So when you drag the Seekbar, the whole screen (parent) must stay put, but when you drag outside the SeekBar it must still work as required for the side menu?
Thanks

In the container of the SeekBar, create and apply (to the seekBar) an OnTouchListener like the following:
private final OnTouchListener onTouchListener = new OnTouchListener()
{
public boolean onTouch(View v, MotionEvent event)
{
// If the View in question isn't a child of the seekBar and
// isn't the seekBar itself, then return and don't consume the event.
if ( (seekBar.findViewById(v.getId()) == null) &&
(v.getId() != seekBar.getId()) )
{
return false;
}
// The View is either a child of the seekBar or is the seekBar itself,
// so we pass the event along to the seekBar and return true, signifying
// that the event has been consumed.
seekBar.onTouchEvent(event);
return true;
}
}
Try this out and see if it works; you may need to create a more robust condition for the if statement.

onTouchEvent() will not be triggered if setSystemUiVisibility(View.SYSTEM_UI_FLAG_HIDE_NAVIGATION) is invoked

I call
getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_HIDE_NAVIGATION)
when my app starts to make my app able to display the full screen.
I want my app's UI to pop up when screen is touched, but Activity.onTouchEvent() is not triggered until the screen is touched a second time. At first touch, only the Virtual Keys are shown.
So, I have to trigger my app's UI to pop up on
public void onSystemUiVisibilityChange(int visibility) {
if (visibility == View.SYSTEM_UI_FLAG_VISIBLE) {
// show my APP UI
}
}
but onSystemUiVisibilityChange with View.SYSTEM_UI_FLAG_VISIBLE will be invoked NOT once per touch (3 times on my Galaxy Nexus) by system, especially if the user touches the screen very fast/often.
project lib 4.0 or 4.03.
Samsung galaxy(9250) with 4.03.

Android 4.4 (API Level 19) introduces a new SYSTEM_UI_FLAG_IMMERSIVE flag for setSystemUiVisibility() that lets your app go truly "full screen." This flag, when combined with the SYSTEM_UI_FLAG_HIDE_NAVIGATION and SYSTEM_UI_FLAG_FULLSCREEN flags, hides the navigation and status bars and lets your app capture all touch events on the screen.

This did work for me:
setOnSystemUiVisibilityChangeListener(new OnSystemUiVisibilityChangeListener() {
#Override
public void onSystemUiVisibilityChange(int visibility) {
if ((visibility & SYSTEM_UI_FLAG_HIDE_NAVIGATION) == 0) {
// show my app UI
}
}
});

What I've done is first imported android.view.GestureDetector so I can use it to detect gestures. Android has a number of default gestures that are automatically detected in the GestureDector class. Most of this info is found here, but below is code in a form that I've used in an actual project that works.
First I've made an anonymous class in my Activity (this can be nested wherever, but I tend to make my anonymous classes at the bottom, right before the closing bracket). NOTE: You can also implement OnGestureListener as part of your class, also.
The code below is for using gesture detection to give a simple hide/show.
I've declared and defined my action bar (my UI, which is initially hidden) as an instance variable, so I can access it here, and wherever else, but you can substitute it for a getActionBar().show() and getActionBar().hide() in the case you don't want to declare it as an instance variable. Substitute your UI in the place of the actionBar here:
public class Example extends ActionBarActivity {
// declared in onCreate() method
private android.support.v7.app.ActionBar actionBar;
private GestureDetectorCompat mDetector;
private YourView view1;
private YourView view2;
private YourView view3;
private YourView view4;
// some other code
class GestureListener extends GestureDetector.SimpleOnGestureListener {
private static final String DEBUG_TAG = "Gestures in Example Class";
#Override
public boolean onDoubleTap(MotionEvent event) {
Log.d(DEBUG_TAG, "onDoubleTap: " + event.toString());
// if there is a double tap, show the action bar
actionBar.show();
return true;
}
#Override
public boolean onSingleTapConfirmed(MotionEvent event) {
Log.d(DEBUG_TAG, "onSingleTapConfirmed: " + event.toString());
// if the tap is below the action bar, hide the action bar
if (event.getRawY() > getResources().getDimension(R.dimen.abc_action_bar_default_height)) {
actionBar.hide();
return true;
}
return false;
}
#Override
public boolean onDown(MotionEvent event) {
return true;
}
} // end-of-Example Class
Then in my onCreate() I've declared my GestureDetector and also (optionally) set my GestureListeners:
private GestureDetectorCompat mDetector;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// some code here
mDetector = new GestureDetectorCompat(this, new GestureListener());
// this code is for more advanced view logic not needed for a basic set-up
//setGestureListeners();
} // end-of-method onCreate()
Then in order to actually send gestures to be processed we provide the instructions for doing that, there are two ways I know about, first the simplest:
/**
* This method recognizes a touchEvent and passes it to your custom GestureListener
* class.
*/
#Override
public boolean onTouchEvent(MotionEvent event){
this.mDetector.onTouchEvent(event);
return super.onTouchEvent(event);
}
The second way is more complex, but if you want to only recognize touch events on certain Views in your layout as in the case where you have overlapping views and can only access the top View, you can create a custom class to pass the event around or up:
class MyOnTouchListener implements View.OnTouchListener {
public boolean onTouch(View v, MotionEvent event) {
if (v.equals(view4)) {
return mDetector.onTouchEvent(event);
} else return false;
}
} // end-of-class MyOnTouchListener
and then use it here:
public void setGestureListeners() {
/* when we return false for any of these onTouch methods
* it means that the the touchEvent is passed onto the next View.
* The order in which touchEvents are sent to are in the order they
* are declared.
*/
view1.setOnTouchListener(new MyOnTouchListener());
view2.setOnTouchListener(new MyOnTouchListener());
view3.setOnTouchListener(new MyOnTouchListener());
view4.setOnTouchListener(new MyOnTouchListener());
} // end-of-method setGestureListeners()
In my setGestureListeners method, I gave them all the same set of commands, that essentially only recognizes touchEvents on view4. Otherwise, it just passes the touchEvent to the next view.
This is code using AppCompat, but if you are not building for older versions, you can use the regular GestureDetector and ActionBar.

Have you tried adding code to only show your UI when the state has changed? You have to maintain the last known visibility and only show your UI when you first come into being visible:
int mLastSystemUiVis;
#Override
public void onSystemUiVisibilityChange(int visibility) {
int diff = mLastSystemUiVis ^ visibility;
mLastSystemUiVis = visibility;
if ((diff&SYSTEM_UI_FLAG_VISIBLE) != 0
&& (visibility&SYSTEM_UI_FLAG_VISIBLE) == 0) {
// DISPLAY YOUR UI
}
}
Code sample adopted from the Android docs

The method Activity.onTouchEvent() gets called at the end of the responder chain (meaning after all other views have had a chance to consume the event). If you tap on a view that is interested in touch (i.e. a Button or EditText) there's a good chance your Activity will never see that event.
If you want to have access to touches before they every get dispatched to your view(s), override Activity.dispatchTouchEvent() instead, which is the method called at the beginning of the event chain:
#Override
public boolean dispatchTouchEvent(MotionEvent event) {
//Check the event and do magic here, such as...
if (event.getAction() == MotionEvent.ACTION_DOWN) {
}
//Be careful not to override the return unless necessary
return super.dispatchTouchEvent(event);
}
Beware not to override the return value of this method unless you purposefully want to steal touches from the rest of the views, an unnecessary return true; in this spot will break other touch handling.

I got this problem too, and I found this http://developer.android.com/reference/android/view/View.html#SYSTEM_UI_FLAG_HIDE_NAVIGATION
So, no way to help. Even the android system packaged Gallery app used SYSTEM_UI_FLAG_LOW_PROFILE instead of SYSTEM_UI_FLAG_HIDE_NAVIGATION in photo page view. This is at least what we can do.

I had a very similar issue with trying to update the UI from an onTouchEvent() requiring two touches to work, and I tried a bunch of elaborate stuff before finally getting it to work on the first click.
In my case, I was showing a previously hidden item, then getting its height, then moving a button down by that height. The problem I ran into is that the height was showing as 0 until after the first touch event finished. I was able to solve this by calling show() during ACTION_UP for the onTouchEvent() instead of its ACTION_DOWN. Maybe it'd work if you did something similar?

Try to use:
getWindow().getDecorView().setSystemUiVisibility(View.GONE);
instead:
getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_HIDE_NAVIGATION)
After that you can use normal activity in fullscreen and if you want nav keys you need to swipe from bottom to up. Working for me at Galaxy Tab 2 with android 4.1.2

Change how SlidingDrawer responds to trackball or cursor

(Please note that the behavior described in this question only appeared because of something else seemingly unrelated we were doing. See the accepted answer.)
We have an Android activity with a GridView and a SlidingDrawer inside of a RelativeLayout. The way this activity responds to the trackball (or cursor keys) is rather odd. The focus will move among the items in the GridView, but whenever the cursor moves in a direction "out" of the GridView. (e.g. up when at the top, left when already at the leftmost item) the sliding drawer opens or shut. Notably, the focus stays on the same item in the GridView---it does not move to the sliding drawer.
With a trackball this is particularly horrible, as spinning the trackball past your real destination will cause the sliding drawer to repeatedly open and close.
We've determined that we can turn off the trackball entirely by overriding onTrackballEvent(). We'd prefer to have the trackball and cursor work normally on the GridView but not cause the sliding drawer to open or close. In principle we'd also like the trackball to focus on the various contents of the sliding drawer when it is open.
How?

You may consider creating custom views extending GridView and SlidingDrawer and using custom implementations of onInterceptTouchEvent and onTouchEvent for the GridView and a custom implementation just for onInterceptTouchEvent for the SlidingDrawer. You may not need to implement a custom SlidingDrawer depending on what user interactions may be triggered on the handle
for your custom GridView, give it an interface maybe defined like this:
public interface MyGridViewListener {
public boolean shouldPreventScroll();
}
return if your custom SlidingDrawer is opened. this returned value will be used to determine if actions should be performed(for onInterceptTouchEvent and onTouchEvent methods) on the GridView. So when the SlidingDrawer is opened, actions performed on the GridView will not trigger anything on the SlidingDrawer.
Activity:
MyGridView gridView = (MyGridView) findViewById(R.id.gridView);
gridView.setMyGridViewListener(new MyGridViewListener() {
#Override
public boolean shouldPreventScroll() {
return slidingDrawer.isOpened();
}
});
MyCustomGridView:
shouldIntercept will be called whenever some touch/track event happens on the GridView.
private boolean shouldIntercept() {
boolean shouldIntercept = false;
if(myGridViewListener != null) {
shouldIntercept = myGridViewListener.shouldPreventScroll();
}
return shouldIntercept;
}
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
return shouldIntercept() ? true : super.onInterceptTouchEvent(ev);
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
return shouldIntercept() ? true : super.onTouchEvent(ev);
}
#Override
public boolean onTrackballEvent(MotionEvent event) {
return shouldIntercept() ? true : super.onTrackballEvent(event);
}
public MyGridViewListener getMyGridViewListener() {
return myGridViewListener;
}
public void setMyGridViewListener(
MyGridViewListener myGridViewListener) {
this.myGridViewListener = myGridViewListener;
}
I hope this points you in a right direction or at least helps

While playing around with a custom sliding drawer I set the layout of the handle to some odd value, something like
handle.layout(0, 0,0, 0);
to make the handle disappear but dragging a finger from the side of the screen would still open the sliding drawer, which is what I didn't want, so I set
handle.layout(10000, 10000, 10000, 10000);
which moved it way outside the viewable area and the drawer could no longer be pulled out manually by dragging from the side of the screen. After looking at the source code its teh position of the handle that determines the sliding of the drawer, get rid of the handle and it should solve your problem.
If you need to open/close the drawer call animateOpen()/animateClose()

As it turned out, we caused this problem by an unrelated bit of foolishness. We wanted the MENU key to open and close the SlidingDrawer. We did this by overriding onPrepareOptionsMenu():
public boolean onPrepareOptionsMenu (Menu menu) {
slidingDrawer.animateToggle();
return true;
}
This works fine; but it turns out it can be called when the menu is not about to be opened. In particular, if the Activity uses setDefaultKeyMode(DEFAULT_KEYS_SHORTCUT), then an unhandled key event will end up accessing the menu. This includes trackball motion off the edge of the screen.
The less dumb way to get the desired behavior is
public boolean onKeyUp(int keyCode, KeyEvent event) {
if(keyCode==KeyEvent.KEYCODE_MENU) {
slidingDrawer.animateToggle();
}
return super.onKeyUp(keyCode,event);
}
Meanwhile, we can get the trackball to move within the SlidingDrawer when it is open by setting up a SlidingDrawer.OnDrawerOpenListener which calls
slidingDrawer.getContent().requestFocus();
Finally it seems like a good idea to call
slidingDrawer.getHandle().setFocusable(false);