I'm trying to detect a onFling event on the entire area of my activity. To do this I:
1) set the GestureDetectorCompat:
private GestureDetectorCompat gDetect;
2) in OnCreate initialize the detector:
gDetect = new GestureDetectorCompat(this, new GestureListener());
3) override the onTouchEvent:
#Override
public boolean onTouchEvent(MotionEvent event) {
gDetect.onTouchEvent(event);
return super.onTouchEvent(event);
}
4) create the GestureListener class:
class GestureListener extends GestureDetector.SimpleOnGestureListener {
#Override
public boolean onDown(MotionEvent event) {
return true;
}
#Override
public boolean onFling(MotionEvent event1, MotionEvent event2,
float velocityX, float velocityY) {
Log.e(null, "onFling: " + event1.toString() + event2.toString());
return super.onFling(event1, event2, velocityX, velocityY);
}
}
It works, but it detects onFling gesture ONLY in the part of my UI where there is not any other view. So, if I swipe in a blank area it works, if I swipe in a part of the activity where is another view (for example a ScrollView or a LinearLayout) the detection isn't triggered.
I hope I've explained my problem: how I can detect gesture on the entire surface of the Activity, to accomplish a simple swipe gesture?
Many tanks.
You can use GestureOverlayView. Here is a great starter resource for GestureOverlayView . Also you can have a look at this SO question.
Basically to use this your application must use the view "GestureOverlayView" and you place your other views in this view. Your activity must implement the interface "OnGesturePerformedListener" and if a gesture is detected then "onGesturePerformedListener" method is called.
Hope this helps. Goodluck!
I am trying to make a simple 2D game using Opengl es 2. I am using GLSurfaceView. I am trying to detect fling gesture on the view but it does not detect anything. Why is this? Following is the code :-
Tried to declare the gesture detecter inside and outside the glsurfaceview.
#SuppressWarnings("deprecation")
final GestureDetector gestureDetector = new GestureDetector(new GestureDetector.SimpleOnGestureListener() {
public void onLongPress(MotionEvent e) {
Log.d("", "Longpress detected");
}
#Override
public boolean onFling(MotionEvent e1, MotionEvent e2,
float velocityX, float velocityY) {
Log.d("", "OnFling detected");
return super.onFling(e1, e2, velocityX, velocityY);
}
});
Inside the GLSurfaceView
#Override
public boolean onTouchEvent(MotionEvent event) {
return gestureDetector.onTouchEvent(event);
}
When i fling on the surface, it detects the long press and prints the debug message for long press rather than fling. Whatever i do on screen, it just detects longpress.. what is wrong?
Include this override for onDown in your listener:
#Override
public boolean onDown(MotionEvent event) {
return true;
}
From the documentation:
This is because all gestures begin with an onDown() message. If you return false from onDown(), as GestureDetector.SimpleOnGestureListener does by default, the system assumes that you want to ignore the rest of the gesture, and the other methods of GestureDetector.OnGestureListener never get called. This has the potential to cause unexpected problems in your app."
I appreciate that this does not explain why you are still managing to get a longpress detected. If the above resolves your issue, perhaps that is a puzzle that doesn't need solving...
I am working in android. I have some functionality which is to be done on these following methods:-
1. MotionEvent.ACTION_DOWN
2. MotionEvent.ACTION_UP
3. MotionEvent.ACTION_MOVE
and i also want to do fling() on that image.
For above requirement i implemented onGestureListener and onTouchListener in my application, but these are not working properly. onTouchListener is working but onGestureListener is not working. When i remove onTouchListner code then onGestureListener is working correctly.
So please suggest me what should i do for this. I want to implement these four methods in my application.
1. MotionEvent.ACTION_DOWN
2. MotionEvent.ACTION_UP
3. MotionEvent.ACTION_MOVE
4. onFling
You can acheive this by implementing the OnGestureListener from your activity overriding the below methods
// For touch
public boolean onSingleTapUp(MotionEvent event) { return false; }
// For Fling
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
return false;
}
Hope this helps.
EDIT 1: Detailed explanation:
1> implement the OnGestureListener from your activity
public class MyActivity implements OnGestureListener
2> create an instance of GestureDetector:
private GestureDetector gestureScanner;
And at onCreate:
// Avoid a deprecated constructor
// (http://developer.android.com/reference/android/view/GestureDetector.html)
gestureScanner = new GestureDetector(this, this);
3> Override the below methods:
#Override
public boolean onTouchEvent(MotionEvent event) {
return gestureScanner.onTouchEvent(event);
}
#Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
/* on scroll to the next page in story */
if (e2.getX() - e1.getX() > SWIPE_MIN_DISTANCE
&& Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
// ...
}
/* on scroll to the previous page in story */
else if (e1.getX() - e2.getX() > SWIPE_MIN_DISTANCE
&& Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
// ...
}
return false;
}
#Override
public boolean onSingleTapUp(MotionEvent event) {
return false;
}
EDIT 2: For handling Move
Override the onScroll method have a look at the details here
Just as a word of advice coming from a fellow Android developer who has chased down the primrose path of the swipe or fling event... When writing a listener or trying to implement the OnGestureListener class be sure to have import android.view.GestureDetector.OnGestureListener in your imports.
Otherwise the OnGesturListener will be using a GestureOverlayView's imports and that's not what it seems you are looking for. Those are helpful especially when trying to implement gesture captures using the Gestures application and importing the saved gestures and creating a Gestures Library for your application during run time to then "predict" what the user is doing by running some fancy algorithm in the background and seeing who deviates the least from the user's input. Which turns out to be an array of locations that came in from the OS as the dragged their little stubby fingers across the flat screen... It's a different approach than just trying to capture a fling, or long press. Which seems as what the users are looking for above and not some fancy multi-press gesture capture, which this approach makes very simple. This technique is also very helpful in video games and giving possibly a "backdoor" to any people out there who like to develop games. Or in the 9-5 world, to put a Support or Admin backdoor into your mobile application to hide some settings or logs from everyday users. In which one can also use the above intended techniques but then you have to get an array of points, or locations across the screen and it gets tedious for any non-math people or self taught developers. Hope I contributed or helped anyone. No one mentioned this to me when I was learning this and I never found it in any of the several books I have read about Android also.
OK, I know this questions sounds weird at first, as GALLERY is designed to be user interactive, but, I like the Gallery functionality, as it suits a lot of my needs. i.e. I can give it a number of pictures, move the whole of them from right to left, or left to right and get them an animate (in my case, zoom) when one of them is selected. So all good.
I just need to do the selection programatically, which I currently have working. I just don't want the user to be able to fling, scroll, select, longpress, etc. by themselves. So no user interaction is required.
So, how can I prevent a user from doing theses things, without writting a gallery function myself (and without chopping a users fingers off!).
Thanks.
Try setting the clickable and focusable properties of your Gallery View to false.
Following worked for me:
Gallery gallery = new Gallery( ctx ) {
#Override
public boolean onTouchEvent(MotionEvent event) {
return true;
}
};
If some interaction is still left you can also try:
Gallery dotList = new Gallery( ctx ) {
#Override
public boolean onTouchEvent(MotionEvent event) {
return true;
}
#Override
public boolean onSingleTapUp(MotionEvent e) {
return true;
}
#Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
return true;
}
};
I am using the onScroll method of GestureDetector.SimpleOnGestureListener to scroll a large bitmap on a canvas. When the scroll has ended I want to redraw the bitmap in case the user wants to scroll further ... off the edge of the bitmap, but I can't see how to detect when the scroll has ended (the user has lifted his finger from the screen).
e2.getAction() always seems to return the value 2 so that is no help.
e2.getPressure seems to return fairly constant values (around 0.25) until the final onScroll call when the pressure seems to fall to about 0.13. I suppose I could detect this reduction in pressure, but this will be far from foolproof.
There must be a better way: can anyone help, please?
Here is how I solved the problem. Hope this helps.
// declare class member variables
private GestureDetector mGestureDetector;
private OnTouchListener mGestureListener;
private boolean mIsScrolling = false;
public void initGestureDetection() {
// Gesture detection
mGestureDetector = new GestureDetector(new SimpleOnGestureListener() {
#Override
public boolean onDoubleTap(MotionEvent e) {
handleDoubleTap(e);
return true;
}
#Override
public boolean onSingleTapConfirmed(MotionEvent e) {
handleSingleTap(e);
return true;
}
#Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
// i'm only scrolling along the X axis
mIsScrolling = true;
handleScroll(Math.round((e2.getX() - e1.getX())));
return true;
}
#Override
/**
* Don't know why but we need to intercept this guy and return true so that the other gestures are handled.
* https://code.google.com/p/android/issues/detail?id=8233
*/
public boolean onDown(MotionEvent e) {
Log.d("GestureDetector --> onDown");
return true;
}
});
mGestureListener = new View.OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
if (mGestureDetector.onTouchEvent(event)) {
return true;
}
if(event.getAction() == MotionEvent.ACTION_UP) {
if(mIsScrolling ) {
Log.d("OnTouchListener --> onTouch ACTION_UP");
mIsScrolling = false;
handleScrollFinished();
};
}
return false;
}
};
// attach the OnTouchListener to the image view
mImageView.setOnTouchListener(mGestureListener);
}
You should take a look at http://developer.android.com/reference/android/widget/Scroller.html.
Especially this could be of help (sorted by relevance):
isFinished();
computeScrollOffset();
getFinalY(); getFinalX(); and getCurrY() getCurrX()
getDuration()
This implies that you have to create a Scroller.
If you want to use touching you could also use GestureDetector and define your own canvas scrolling. The following sample is creating a ScrollableImageView and in order to use it, you have to define the measurements of your image. You can define your own scrolling range and after finishing your scrolling the image gets redrawn.
http://www.anddev.org/viewtopic.php?p=31487#31487
Depending on your code you should consider invalidating (int l, int t, int r, int b); for the invalidation.
SimpleOnGestureListener.onFling()
It seems to take place when a scroll ends (i.e. the user lets the finger go), that's what I am using and it works great for me.
Coming back to this after a few months I've now followed a different tack: using a Handler (as in the Android Snake sample) to send a message to the app every 125 milliseconds which prompts it to check whether a Scroll has been started and whether more than 100 milliseconds has elapsed since the last scroll event.
This seems to work pretty well, but if anyone can see any drawbacks or possible improvements I should be grateful to hear of them.
The relevant the code is in the MyView class:
public class MyView extends android.view.View {
...
private long timeCheckInterval = 125; // milliseconds
private long scrollEndInterval = 100;
public long latestScrollEventTime;
public boolean scrollInProgress = false;
public MyView(Context context) {
super(context);
}
private timeCheckHandler mTimeCheckHandler = new timeCheckHandler();
class timeCheckHandler extends Handler{
#Override
public void handleMessage(Message msg) {
long now = System.currentTimeMillis();
if (scrollInProgress && (now>latestScrollEventTime+scrollEndInterval)) {
scrollInProgress = false;
// Scroll has ended, so insert code here
// which calls doDrawing() method
// to redraw bitmap re-centred where scroll ended
[ layout or view ].invalidate();
}
this.sleep(timeCheckInterval);
}
public void sleep(long delayMillis) {
this.removeMessages(0);
sendMessageDelayed(obtainMessage(0), delayMillis);
}
}
}
#Override protected void onDraw(Canvas canvas){
super.onDraw(canvas);
// code to draw large buffer bitmap onto the view's canvas
// positioned to take account of any scroll that is in progress
}
public void doDrawing() {
// code to do detailed (and time-consuming) drawing
// onto large buffer bitmap
// the following instruction resets the Time Check clock
// the clock is first started when
// the main activity calls this method when the app starts
mTimeCheckHandler.sleep(timeCheckInterval);
}
// rest of MyView class
}
and in the MyGestureDetector class
public class MyGestureDetector extends SimpleOnGestureListener {
#Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
float distanceY) {
[MyView].scrollInProgress = true;
long now = System.currentTimeMillis();
[MyView].latestScrollEventTime =now;
[MyView].scrollX += (int) distanceX;
[MyView].scrollY += (int) distanceY;
// the next instruction causes the View's onDraw method to be called
// which plots the buffer bitmap onto the screen
// shifted to take account of the scroll
[MyView].invalidate();
}
// rest of MyGestureDetector class
}
This is what worked for me.
I've enriched the existing GestureDetector.OnGestureListener with onFingerUp() method. This listener does everything as the built-in GestureDetector and it can also listen to the finger up event (it's not onFling() as this is called only when the finger is lifted up along with a quick swipe action).
import android.content.Context;
import android.os.Handler;
import android.view.GestureDetector;
import android.view.MotionEvent;
public class FingerUpGestureDetector extends GestureDetector {
FingerUpGestureDetector.OnGestureListener fListener;
public FingerUpGestureDetector(Context context, OnGestureListener listener) {
super(context, listener);
fListener = listener;
}
public FingerUpGestureDetector(Context context, GestureDetector.OnGestureListener listener, OnGestureListener fListener) {
super(context, listener);
this.fListener = fListener;
}
public FingerUpGestureDetector(Context context, GestureDetector.OnGestureListener listener, Handler handler, OnGestureListener fListener) {
super(context, listener, handler);
this.fListener = fListener;
}
public FingerUpGestureDetector(Context context, GestureDetector.OnGestureListener listener, Handler handler, boolean unused, OnGestureListener fListener) {
super(context, listener, handler, unused);
this.fListener = fListener;
}
public interface OnGestureListener extends GestureDetector.OnGestureListener {
boolean onFingerUp(MotionEvent e);
}
public static class SimpleOnGestureListener extends GestureDetector.SimpleOnGestureListener implements FingerUpGestureDetector.OnGestureListener {
#Override
public boolean onFingerUp(MotionEvent e) {
return false;
}
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
if (super.onTouchEvent(ev)) return true;
if (ev.getAction() == MotionEvent.ACTION_UP) {
return fListener.onFingerUp(ev);
}
return false;
}
}
I think this will work as you need
protected class SnappingGestureDetectorListener extends SimpleOnGestureListener{
#Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY){
boolean result = super.onScroll(e1, e2, distanceX, distanceY);
if(!result){
//Do what you need to do when the scrolling stop here
}
return result;
}
}
I am sure it is too late for you, however, it seems I have found the right solution to your original question and not necessarily the intention.
If you are using Scroller/OverScroller Object for scrolling you should check the return value from the following function.
public boolean computeScrollOffset()
I was looking into this same issue. I saw Akos Cz's answer to your question. I created something similar, but with my version, I noticed that it only worked for a regular scroll - meaning one that doesn't generate a fling. But if a fling did get generated - regardless if I processed a fling or not, then it did NOT detect the "ACTION_UP" in "onTouchEvent". Now maybe this was just something with my implementation, but if it was I couldn't figure out why.
After further investigation, I noticed that during a fling, the "ACTION_UP" was passed into "onFling" in "e2" every time. So I figured that must be why it wasn't being handled in "onTouchEvent" in those instances.
To make it work for me I only had to call a method to handle the "ACTION_UP" in "onFling" and then it worked for both types of scrolling. Below are the exact steps I took to implement my app:
-initialized a "gestureScrolling" boolean to "false" in a constructor.
-I set it to "true" in "onScroll"
-created a method to handle the "ACTION_UP" event. Inside that event, I reset "gestureSCrolling" to false and then did the rest of the processing I needed to do.
-in "onTouchEvent", if an "ACTION_UP" was detected and "gestureScrolling" = true, then I called my method to handle "ACTION_UP"
-And the part that I did that was different was: I also called my method to handle "ACTION_UP" inside of "onFling".
I haven't done this myself but looking at onTouch() you always get a sequence 0<2>1, so the end has to be a 1 for finger lift.
I don't know Android, but looking at the documentation it seems Rob is right: Android ACTION_UP constant Try checking for ACTION_UP from getAction()?
Edit: What does e1.getAction() show? Does it ever return ACTION_UP? The documentation says it holds the initial down event, so maybe it'll also notify when the pointer is up
Edit: Only two more things I can think of. Are you returning false at any point? That may prevent ACTION_UP
The only other thing I'd try is to have a seperate event, maybe onDown, and set a flag within onScroll such as isScrolling. When ACTION_UP is given to onDown and isScrolling is set then you could do whatever you want and reset isScrolling to false. That is, assuming onDown gets called along with onScroll, and getAction will return ACTION_UP during onDown
i have not tried / used this but an idea for an approach:
stop / interrupt redrawing canvas on EVERY scroll event wait 1s and then start redrawing canvas on EVERY scroll.
this will lead to performing the redraw only at scroll end as only the last scroll will actually be uninterrupted for the redraw to complete.
hope this idea helps you :)
Extract from the onScroll event from GestureListener API: link text
public abstract boolean onScroll
(MotionEvent e1, MotionEvent e2, float
distanceX, float distanceY) Since: API
Level 1
Returns
* true if the event is consumed, else false
Perhaps once the event has been consumed, the action is finished and the user has taken their finger off the screen or at the least finished this onScroll action
You can then use this in an IF statement to scan for == true and then commence with the next action.
If you're using SimpleGestureDetector to handle your scroll events, you can do this
fun handleTouchEvents(event: MotionEvent): Boolean {
if(event.action == ACTION_UP) yourListener.onScrollEnd()
return gestureDetector.onTouchEvent(event)
}
My attempt at adding additional functionality to the gesture detector. Hope it helps someone put his time to better use... gist