Hello I have a RecyclerView, and I use HorizontalScrollView in children of theRecyclerView`. I need to scroll all of them when I scrolling one. Anyone can tell me How to make that,thanks!
I'm going to assume you're doing something similar to what I did where you have some sort of tabular view and the HorizontalScrollViews are all the same width.
This is how I did it:
First I made a customization to the HorizontalScrollView so I could get event notifications when the view was swiped:
public class HorizontalScrollView extends android.widget.HorizontalScrollView {
private OnScrollListener mListener;
public HorizontalScrollView(Context context) {
super(context);
}
public HorizontalScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public void setOnScrollListener(OnScrollListener listener) {
mListener = listener;
}
#Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
if (mListener != null) {
mListener.onScrollChanged(this, l);
}
}
public interface OnScrollListener {
public void onScrollChanged(View view, int scrollX);
}
}
Then when I create the ViewHolders I add a listener that will set all the views to the same scrollX:
view.setOnScrollListener(new OnScrollListener() {
#Override
public void onScrollChanged(View scrollView, int scrollX) {
for (int i = 0; i < recyclerView.getChildCount(); i++) {
View child = recyclerView.getChildAt(i);
if (child instanceof HorizontalScrollView && child != scrollView) {
HorizontalScrollView scrollView2 = (HorizontalScrollView) child;
if (scrollView2.getScrollX() != scrollX) {
scrollView2.setScrollX(scrollX);
}
}
}
}
});
This code is just for illustration purposes; don't expect to copy/paste this and have it work.
I'm assuming that your ViewHolder can get a reference to your RecyclerView to access all the current list items.
This code had some problems, when you swiped one view then swiped another view while everything was still moving from the first swipe, things could get out of sync. But this is a basic idea to get you started in a positive direction.
After doing a lot of research on stackoverflow and looking for answers I found that I needed to create a subclass of WebView and then do an override on OnScrollChanged etc.. I have the following code...
SearchResultsWebView.setOnScrollChangedCallback(
new Sub_WebView_Results.OnScrollChangedCallback() {
#Override
public void onScroll(int l, int t) {
int tek = (int) Math.floor(SearchResultsWebView.getContentHeight() * SearchResultsWebView.getScale());
if (tek - SearchResultsWebView.getScrollY() == SearchResultsWebView.getHeight())
Toast.makeText(getActivity(), "End", Toast.LENGTH_SHORT).show();
}
});
HOWEVER the problem is that .getScale has been depreciated. I haven't found another way that works.
I tried using ..
SearchResultsWebView.setWebViewClient(new WebViewClient() {
#Override
public void onScaleChanged(WebView view, float oldScale, float newScale) {
super.onScaleChanged(view, oldScale, newScale);
currentScale = newScale;
}
});
And then just passing the [currentScale] but it seems this never gets called so I'm at a loss on how to do this.
Content height for web view is returned dp and thus we need to multiply with the devices density multiplier to get the actual height of the content
with the actual height i deduct the webview's height to calculate when the webview will be visible and compare with scroll y every time user picks up their finger.
This is what i did, working perfectly for me.
webView.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View view, MotionEvent motionEvent) {
if (motionEvent.getAction() == MotionEvent.ACTION_UP) {
if (Math.floor((webView.getContentHeight() * getResources().getDisplayMetrics().density) - webView.getHeight()) == webView.getScrollY()) {
// Bottom Reached , it is necessary to calculate content height because
// it changes showAgreeButton();
return true;
}
return false;
}
});
}
In order to tell if the user has scrolled to the bottom of a web view, I extended the web view and had an interface callback when the user has got to the bottom of the view onScrollChanged. Here is the code:
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.webkit.WebView;
public class EULAWebView extends WebView {
//declare needed constants
private final String TAG = getClass().getSimpleName();
//declare needed variables
private EULAWebInterface eulaWebInteface;
private int paddingOffset = 200;
private boolean bottomReached;
public EULAWebView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public EULAWebView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public EULAWebView(Context context) {
super(context);
}
public void setEULAScrollListener(Context context) {
try {
eulaWebInteface = (EULAWebInterface)context;
} catch (ClassCastException ex) {
Log.e(TAG, "UNABLE TO CAST CONTEXT TO EULAWebInterface");
ex.printStackTrace();
throw new ClassCastException();
}
}
#Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
if(this.computeVerticalScrollRange() <= (this.computeVerticalScrollOffset() +
this.computeVerticalScrollExtent() + this.paddingOffset)) {
if(!bottomReached) {
bottomReached = true;
if(eulaWebInteface != null)
eulaWebInteface.atBottomOfScrollView(true);
}
} else {
if(bottomReached) {
bottomReached = false;
if(eulaWebInteface != null)
eulaWebInteface.atBottomOfScrollView(false);
}
}
super.onScrollChanged(l, t, oldl, oldt);
}
}
Here is the interface that is used to let the activity know that the bottom of the scroll view has changed:
public interface EULAWebInterface {
void atBottomOfScrollView(boolean atBottom);
}
And here is the interface implementation in the activity:
#Override
public void atBottomOfScrollView(boolean atBottom) {
findViewById(R.id.eula_action_layout).setVisibility(atBottom ? View.VISIBLE : View.GONE);
findViewById(R.id.eula_instruction_textview).setVisibility(atBottom ? View.GONE : View.VISIBLE);
}
Apparently I found the answer from: How can i get the current scale of a webView(android)
Instead of WebView.getScale()
You can use: getResources().getDisplayMetrics().density
Try this:
#Override
protected void onScrollChanged(int x, int y, int oldx, int oldy) {
View view = (View) getChildAt(getChildCount()-1);
int diff = (view.getBottom()-(getHeight()+getScrollY()));// Calculate the difference in scrolling
if( diff == 0 ){ // The bottom has been reached if the difference is 0
Log.d(ScrollTest.LOG_TAG, "WebView: Bottom has been reached" );
// DO SOMETHING HERE WHEN THE WEBVIEW HAS REACHED THE BOTTOM!
}
super.onScrollChanged(x, y, oldx, oldy);
}
Btw, why use the scaling method when the above method may work better (it's easier to implement I think)
I want to implement an activity which have search functionality that searches contents of a list view.The search bar should be on top of list view and it should hide from user when he scroll down the list view. And when he is searching for something , it should always be on top of list view!!! How can I implement it.
Best Regards!
I assume you know how to create XML layout with SearchView on top of a ListView, it could be placed inside vertical LinearLayout. The tricky part is how to manipulate SearchView, right?
You can register a listener on your ListView like this:
listView.setOnScrollListener(new AbsListView.OnScrollListener() {
#Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
switch (scrollState) {
case SCROLL_STATE_IDLE:
//scroll was stopped, let's show search bar again
break;
case SCROLL_STATE_TOUCH_SCROLL:
//user is scrolling, let's hide search bar
break;
}
}
#Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
if (firstVisibleItem > 0) {
//user scrolled down, first element is hidden
}
}
});
As you can see, you will be informed about state changes and you can use it if you want hide searchview during touch events. Or, you can listen for changing visible elements. This simple if statement checking firstVisibleItem > 0 will tell you when user scrolled down. You can also track disappearing list items and react whenever any item is shown or hidden.
Another way to listen for scroll changes is extending ListView and override onScrollChanged() method e.g.
class MyListView extends ListView {
public MyListView(Context context) {
super(context);
}
public MyListView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public MyListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
#Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
for (Callbacks c : mCallbacks) {
c.onScrollChanged(l - oldl, t - oldt);
}
}
#Override
public int computeVerticalScrollRange() {
return super.computeVerticalScrollRange();
}
public void addCallbacks(Callbacks listener) {
if (!mCallbacks.contains(listener)) {
mCallbacks.add(listener);
}
}
public static interface Callbacks {
public void onScrollChanged(int deltaX, int deltaY);
}
}
Google folks did something like it in IOSched app.
I have a webview which shows an html file. When the user scrolls to the bottom of this file in webview, I want a button that was previously hidden to show up, which the user can then press to do some activity
I did something similar in iOS, where I just set the delegate to the ViewController and just set the button as visible. How do I do something similar on Android? I noticed there isn't a callback method like in iOS.
Edit: Right now, I have an activity with 2 objects: a webview containing my text, and a button which is currently invisible. I want my activity to receive a message when the webview text scrolls to the bottom, and make the button visible
I had to do this myself, in order to display an "I Agree" button once the user has scrolled to the bottom of a EULA. Lawyers, huh?
In fact when you override the WebView (rather than the ScrollView as in the answer from #JackTurky) you can call computeVerticalScrollRange() to get the height of the content, rather than getBottom() which returns the visible bottom and is not useful.
This is my comprehensive solution. As far as I can see this is all API Level 1 stuff, so it should work anywhere.
public class EulaWebView extends WebView {
public EulaWebView(Context context)
{
this(context, null);
}
public EulaWebView(Context context, AttributeSet attrs)
{
this(context, attrs, 0);
}
public EulaWebView(Context context, AttributeSet attrs, int defStyle)
{
super(context, attrs, defStyle);
}
public OnBottomReachedListener mOnBottomReachedListener = null;
private int mMinDistance = 0;
/**
* Set the listener which will be called when the WebView is scrolled to within some
* margin of the bottom.
* #param bottomReachedListener
* #param allowedDifference
*/
public void setOnBottomReachedListener(OnBottomReachedListener bottomReachedListener, int allowedDifference ) {
mOnBottomReachedListener = bottomReachedListener;
mMinDistance = allowedDifference;
}
/**
* Implement this interface if you want to be notified when the WebView has scrolled to the bottom.
*/
public interface OnBottomReachedListener {
void onBottomReached(View v);
}
#Override
protected void onScrollChanged(int left, int top, int oldLeft, int oldTop) {
if ( mOnBottomReachedListener != null ) {
if ( (computeVerticalScrollRange() - (top + getHeight())) <= mMinDistance )
mOnBottomReachedListener.onBottomReached(this);
}
super.onScrollChanged(left, top, oldLeft, oldTop);
}
}
I use this to display an "I Agree" button once the user has scrolled to the bottom of the WebView, where I call it like this (in a class which "implements OnBottomReachedListener":
EulaWebView mEulaContent;
Button mEulaAgreed;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.eula);
mEulaContent = (EulaWebView) findViewById(R.id.eula_content);
StaticHelpers.loadWebView(this, mEulaContent, R.raw.stylesheet, StaticHelpers.readRawTextFile(this, R.raw.eula), null);
mEulaContent.setVerticalScrollBarEnabled(true);
mEulaContent.setOnBottomReachedListener(this, 50);
mEulaAgreed = (Button) findViewById(R.id.eula_agreed);
mEulaAgreed.setOnClickListener(this);
mEulaAgreed.setVisibility(View.GONE);
}
#Override
public void onBottomReached(View v) {
mEulaAgreed.setVisibility(View.VISIBLE);
}
So when the bottom is reached (or in this case, when they get within 50 pixels of it) the "I Agree" button appears.
[I can't comment on an answer, so leaving my comment here as a new answer]
karora's answer (the first) works very well, except that in the
protected void onScrollChanged(int left, int top, int oldLeft, int oldTop)
method, calling
getContentHeight()
was wildly inaccurate for me. It reported a value much too small, so my listener was called when the user had only scrolled maybe a third of the way down the WebView. I used
computeVerticalScrollRange()
instead, and that is perfect. Thanks to this post for that helpful hint.
try this:
#Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
View view = (View) getChildAt(getChildCount()-1);
int diff = (view.getBottom()-(getHeight()+getScrollY()));// Calculate the scrolldiff
if( diff == 0 ){ // if diff is zero, then the bottom has been reached
Log.d(ScrollTest.LOG_TAG, "MyScrollView: Bottom has been reached" );
yourButton.setVisible(true);
}
super.onScrollChanged(l, t, oldl, oldt);
}
To implement this, extend ScrollView and then override the onScrollChanged method (inherited from View).
Loading / Visible button only when webview reached / scrolled to bottom.
Create JavaScript class :
public class JavaScriptInterface {
#android.webkit.JavascriptInterface
public void didScrollToBottom() {
Log.d(TAG, "Scroll to Bottom");
myHandler.post(new Runnable() {
#Override
public void run() {
btnAccept.setVisibility(View.VISIBLE);
}
});
}
}
In onCreate() :
final JavaScriptInterface jsInterface = new JavaScriptInterface();
myWebView.addJavascriptInterface(jsInterface, "AndroidFunction");
Solutions above didn't fully work for me for the similar issue (hide button while webView is being scrolled, show after scrolling is over). The reason I wanted it to hide while scrolling is because button I want to hide is for jumping to the very bottom of webview, and when it only worked for me when webview is static, but didn't jump to bottom while view is still being scrolled.
So I did the following:
added a onScrollChanged callback to overridden webView, like suggested nearby:
private OnScrollChangedCallback mOnScrollChangedCallback;
public OnScrollChangedCallback getOnScrollChangedCallback() {
return mOnScrollChangedCallback;
}
public void setOnScrollChangedCallback(
final OnScrollChangedCallback onScrollChangedCallback) {
mOnScrollChangedCallback = onScrollChangedCallback;
}
#Override
protected void onScrollChanged(final int l, final int t, final int oldl,
final int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
if (mOnScrollChangedCallback != null){
mOnScrollChangedCallback.onScrollChanged(l, t);
}
}
/**
* Implement in the activity/fragment/view that you want to listen to the
* webview
*/
public static interface OnScrollChangedCallback {
public void onScrollChanged(int l, int t);
}
and in my activity class which implements OnScrollChangedCallback
UPDATED:
Timer timer2showJumpButton;
private long lastScrollEventTimestamp;
public final static int HIDING_JUMP_BUTTON_ON_SCROLL_DELAY = 500;
public void onScrollChanged(int l, int t) {
// showing button when scrolling starts
if (btnJumpToBottom != null) {
btnJumpToBottom.setVisibility(View.VISIBLE);
}
if (btnJumpToTop!= null) {
btnJumpToTop.setVisibility(View.VISIBLE);
}
if (timer2showJumpButton == null) {
final Runnable r2 = new Runnable() {
#Override
public void run() {
if (btnJumpToBottom != null) {
btnJumpToBottom.setVisibility(View.GONE);
}
if (btnJumpToTop!= null) {
btnJumpToTop.setVisibility(View.GONE);
}
}
};
TimerTask timerTask = new TimerTask() {
#Override
public void run() {
if (btnJumpToTop.getVisibility() == View.VISIBLE || btnJumpToBottom.getVisibility() == View.VISIBLE){
long currentTimestamp = System.currentTimeMillis();
if (currentTimestamp - lastScrollEventTimestamp > HIDING_JUMP_BUTTON_ON_SCROLL_DELAY1 ){
webView.postDelayed(r2, HIDING_JUMP_BUTTON_ON_SCROLL_DELAY);
}else{
//too soon
}
}
}
};
try {
timer2showJumpButton = new Timer();
timer2showJumpButton.schedule(timerTask, 500, 500);
} catch (IllegalStateException e) {
logger.warn(TAG + "/onScrollChanged/" + e.getMessage());
}
}
// adding runnable which will hide button back
long currentTimestamp = System.currentTimeMillis();
lastScrollEventTimestamp = currentTimestamp;
}
I'm using a ScrollView in Android and where the visible portion of the ScrollView is the same size as one of the cells inside the Scrollview. Every "cell" is the same height. So what I am trying to do is snap into position after the ScrollView has been scrolled.
Currently I am detecting when the user has touched the ScrollView and when they've started scrolling and working it out from there, but it is quite buggy. It also needs to work when the user just flicks it and it scrolls and then decelerates.
On iPhone there is a function that is something like didDecelerate and there I can do any code I want when the ScrollView has finished scrolling. Is there such a thing with Android? Or is there some code I could look at to figure out a better way of doing it?
I've looked over the Android docs and could not find anything like that.
I recently had to implement the function you described. What i did was to have a Runnable checking out if the ScrollView had stopped scrolling by comparing the value returned by getScrollY() when the onTouchEvent is first triggered with the value returned after a time defined by the variable newCheck.
See code below (working solution):
public class MyScrollView extends ScrollView{
private Runnable scrollerTask;
private int initialPosition;
private int newCheck = 100;
private static final String TAG = "MyScrollView";
public interface OnScrollStoppedListener{
void onScrollStopped();
}
private OnScrollStoppedListener onScrollStoppedListener;
public MyScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
scrollerTask = new Runnable() {
public void run() {
int newPosition = getScrollY();
if(initialPosition - newPosition == 0){//has stopped
if(onScrollStoppedListener!=null){
onScrollStoppedListener.onScrollStopped();
}
}else{
initialPosition = getScrollY();
MyScrollView.this.postDelayed(scrollerTask, newCheck);
}
}
};
}
public void setOnScrollStoppedListener(MyScrollView.OnScrollStoppedListener listener){
onScrollStoppedListener = listener;
}
public void startScrollerTask(){
initialPosition = getScrollY();
MyScrollView.this.postDelayed(scrollerTask, newCheck);
}
}
Then i have:
scroll.setOnTouchListener(new OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_UP) {
scroll.startScrollerTask();
}
return false;
}
});
scroll.setOnScrollStoppedListener(new OnScrollStoppedListener() {
public void onScrollStopped() {
Log.i(TAG, "stopped");
}
});
Here is yet another fix to the, IMHO, missing OnEndScroll event bug in the ScrollView.
Its inspired by hambonious answer.
Simply drop this class into your project (change package to match your own) and use the below xml
package com.thecrag.components.ui;
import android.content.Context;
import android.util.AttributeSet;
import android.widget.ScrollView;
public class ResponsiveScrollView extends ScrollView {
public interface OnEndScrollListener {
public void onEndScroll();
}
private boolean mIsFling;
private OnEndScrollListener mOnEndScrollListener;
public ResponsiveScrollView(Context context) {
this(context, null, 0);
}
public ResponsiveScrollView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public ResponsiveScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
#Override
public void fling(int velocityY) {
super.fling(velocityY);
mIsFling = true;
}
#Override
protected void onScrollChanged(int x, int y, int oldX, int oldY) {
super.onScrollChanged(x, y, oldX, oldY);
if (mIsFling) {
if (Math.abs(y - oldY) < 2 || y >= getMeasuredHeight() || y == 0) {
if (mOnEndScrollListener != null) {
mOnEndScrollListener.onEndScroll();
}
mIsFling = false;
}
}
}
public OnEndScrollListener getOnEndScrollListener() {
return mOnEndScrollListener;
}
public void setOnEndScrollListener(OnEndScrollListener mOnEndScrollListener) {
this.mOnEndScrollListener = mOnEndScrollListener;
}
}
again changing the package name to match your project
<com.thecrag.components.ui.ResponsiveScrollView
android:id="#+id/welcome_scroller"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/welcome_scroll_command_help_container"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_below="#+id/welcome_header_text_thecrag"
android:layout_margin="6dp">
....
</com.thecrag.components.ui.ResponsiveScrollView>
I subclassed (Horizontal)ScrollView and did something like this:
#Override
protected void onScrollChanged(int x, int y, int oldX, int oldY) {
if (Math.abs(x - oldX) > SlowDownThreshold) {
currentlyScrolling = true;
} else {
currentlyScrolling = false;
if (!currentlyTouching) {
//scrolling stopped...handle here
}
}
super.onScrollChanged(x, y, oldX, oldY);
}
I used a value of 1 for the SlowDownThreshold since it always seems to be the difference of the last onScrollChanged event.
In order to make this behave correctly when dragging slowly, I had to do this:
#Override
public boolean onInterceptTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
currentlyTouching = true;
}
return super.onInterceptTouchEvent(event);
}
#Override
public boolean onTouch(View view, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
currentlyTouching = false;
if (!currentlyScrolling) {
//I handle the release from a drag here
return true;
}
}
return false;
}
My approach is determine scrolling state by a timestamp changed each time the onScrollChanged() is called.
It's very easy to determine when is start and end of scrolling.
You can also change threshold ( I use 100ms ) to fix sensitivity.
public class CustomScrollView extends ScrollView {
private long lastScrollUpdate = -1;
private class ScrollStateHandler implements Runnable {
#Override
public void run() {
long currentTime = System.currentTimeMillis();
if ((currentTime - lastScrollUpdate) > 100) {
lastScrollUpdate = -1;
onScrollEnd();
} else {
postDelayed(this, 100);
}
}
}
#Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
if (lastScrollUpdate == -1) {
onScrollStart();
postDelayed(new ScrollStateHandler(), 100);
}
lastScrollUpdate = System.currentTimeMillis();
}
private void onScrollStart() {
// do something
}
private void onScrollEnd() {
// do something
}
}
Here is yet another solution, quite simple and clean in my opinion, naturally inspired by answers above. Basically once user ended gesture check if getScrollY() is still changing, after a brief delay (here 50ms).
public class ScrollViewWithOnStopListener extends ScrollView {
OnScrollStopListener listener;
public interface OnScrollStopListener {
void onScrollStopped(int y);
}
public ScrollViewWithOnStopListener(Context context) {
super(context);
}
public ScrollViewWithOnStopListener(Context context, AttributeSet attrs) {
super(context, attrs);
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_UP:
checkIfScrollStopped();
}
return super.onTouchEvent(ev);
}
int initialY = 0;
private void checkIfScrollStopped() {
initialY = getScrollY();
this.postDelayed(new Runnable() {
#Override
public void run() {
int updatedY = getScrollY();
if (updatedY == initialY) {
//we've stopped
if (listener != null) {
listener.onScrollStopped(getScrollY());
}
} else {
initialY = updatedY;
checkIfScrollStopped();
}
}
}, 50);
}
public void setOnScrollStoppedListener(OnScrollStopListener yListener) {
listener = yListener;
}
}
My approach for this question is to use a timer to check for the following 2 "events".
1) onScrollChanged() stopped being called
2) User's finger is lift from the scrollview
public class CustomScrollView extends HorizontalScrollView {
public CustomScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
Timer ntimer = new Timer();
MotionEvent event;
#Override
protected void onScrollChanged(int l, int t, int oldl, int oldt)
{
checkAgain();
super.onScrollChanged(l, t, oldl, oldt);
}
public void checkAgain(){
try{
ntimer.cancel();
ntimer.purge();
}
catch(Exception e){}
ntimer = new Timer();
ntimer.schedule(new TimerTask() {
#Override
public void run() {
if(event.getAction() == MotionEvent.ACTION_UP){
// ScrollView Stopped Scrolling and Finger is not on the ScrollView
}
else{
// ScrollView Stopped Scrolling But Finger is still on the ScrollView
checkAgain();
}
}
},100);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
this.event = event;
return super.onTouchEvent(event);
}
}
For a simple case like you described, you can probably get away with overriding fling method in your custom scroll view. Fling method gets called to perform "deceleration" every time user raises his finger from the screen.
So what you should do is something like this:
Subclass ScrollView.
public class MyScrollView extends ScrollView {
private Scroller scroller;
private Runnable scrollerTask;
//...
public MyScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
scroller = new Scroller(getContext()); //or OverScroller for 3.0+
scrollerTask = new Runnable() {
#Override
public void run() {
scroller.computeScrollOffset();
scrollTo(0, scroller.getCurrY());
if (!scroller.isFinished()) {
MyScrollView.this.post(this);
} else {
//deceleration ends here, do your code
}
}
};
//...
}
}
Subclass fling method and DO NOT call superclass implementation.
#Override
public void fling(int velocityY) {
scroller.fling(getScrollX(), getScrollY(), 0, velocityY, 0, 0, 0, container.getHeight());
post(scrollerTask);
//add any extra functions you need from android source code:
//show scroll bars
//change focus
//etc.
}
Fling will not trigger if the user stops scrolling before raising up his finger (velocityY == 0). In case you want to intercept this sort of events aswell, override onTouchEvent.
#Override
public boolean onTouchEvent(MotionEvent ev) {
boolean eventConsumed = super.onTouchEvent(ev);
if (eventConsumed && ev.getAction() == MotionEvent.ACTION_UP) {
if (scroller.isFinished()) {
//do your code
}
}
return eventConsumed;
}
NOTE Although this works, overriding fling method might be a bad idea. It is public, but its barely designed for subclassing. Right now it does 3 things - it initiates fling for private mScroller, handles possible focus changes and shows scroll bars. This might change in future android release. For instance, private mScroller instance changed its class from Scroller to OvershootScroller between 2.3 and 3.0. You have to keep in mind all this small differences. In any case, be ready for unforeseen consequences in the future.
My solution is a variation of Lin Yu Cheng's great solution and also detects when scrolling has started and stopped.
Step 1. Define a HorizontalScrollView and OnScrollChangedListener:
CustomHorizontalScrollView scrollView = (CustomHorizontalScrollView) findViewById(R.id.horizontalScrollView);
horizontalScrollListener = new CustomHorizontalScrollView.OnScrollChangedListener() {
#Override
public void onScrollStart() {
// Scrolling has started. Insert your code here...
}
#Override
public void onScrollEnd() {
// Scrolling has stopped. Insert your code here...
}
};
scrollView.setOnScrollChangedListener(horizontalScrollListener);
Step 2. Add the CustomHorizontalScrollView class:
public class CustomHorizontalScrollView extends HorizontalScrollView {
public interface OnScrollChangedListener {
// Developer must implement these methods.
void onScrollStart();
void onScrollEnd();
}
private long lastScrollUpdate = -1;
private int scrollTaskInterval = 100;
private Runnable mScrollingRunnable;
public OnScrollChangedListener mOnScrollListener;
public CustomHorizontalScrollView(Context context) {
this(context, null, 0);
init(context);
}
public CustomHorizontalScrollView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
init(context);
}
public CustomHorizontalScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
private void init(Context context) {
// Check for scrolling every scrollTaskInterval milliseconds
mScrollingRunnable = new Runnable() {
public void run() {
if ((System.currentTimeMillis() - lastScrollUpdate) > scrollTaskInterval) {
// Scrolling has stopped.
lastScrollUpdate = -1;
//CustomHorizontalScrollView.this.onScrollEnd();
mOnScrollListener.onScrollEnd();
} else {
// Still scrolling - Check again in scrollTaskInterval milliseconds...
postDelayed(this, scrollTaskInterval);
}
}
};
}
public void setOnScrollChangedListener(OnScrollChangedListener onScrollChangedListener) {
this.mOnScrollListener = onScrollChangedListener;
}
public void setScrollTaskInterval(int scrollTaskInterval) {
this.scrollTaskInterval = scrollTaskInterval;
}
//void onScrollStart() {
// System.out.println("Scroll started...");
//}
//void onScrollEnd() {
// System.out.println("Scroll ended...");
//}
#Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
if (mOnScrollListener != null) {
if (lastScrollUpdate == -1) {
//CustomHorizontalScrollView.this.onScrollStart();
mOnScrollListener.onScrollStart();
postDelayed(mScrollingRunnable, scrollTaskInterval);
}
lastScrollUpdate = System.currentTimeMillis();
}
}
}
Try taking a look at this question here on StackOverflow - it's not exactly the same as your question, but it gives an idea on how you can manage the scroll event of a ScrollView.
Basicly you need to create your own CustomScrollView by extending ScrollView and override onScrollChanged(int x, int y, int oldx, int oldy). Then you need to reference this in your layout file instead of the standard ScrollView like com.mypackage.CustomScrollView.
There are some great answers here, but my code can detect when scrolling stops without having to extend ScrollView class.
every view instance can call getViewTreeObserver(). when Holding this instance of ViewTreeObserver you can add a OnScrollChangedListener using the function addOnScrollChangedListener().
declare the following:
private ScrollView scrollListener;
private volatile long milesec;
private Handler scrollStopDetector;
private Thread scrollcalled = new Thread() {
#Override
public void run() {
if (System.currentTimeMillis() - milesec > 200) {
//scroll stopped - put your code here
}
}
};
and in your onCreate (or another place) add:
scrollListener = (ScrollView) findViewById(R.id.scroll);
scrollListener.getViewTreeObserver().addOnScrollChangedListener(new OnScrollChangedListener() {
#Override
public void onScrollChanged() {
milesec = System.currentTimeMillis();
scrollStopDetector.postDelayed(scrollcalled, 200);
}
});
you might want to take longer or slower time between this checks, but when scrolling this listner gets called really fast so it will work very fast.
Here's my solution which includes scroll tracking and scroll ending:
public class ObservableHorizontalScrollView extends HorizontalScrollView {
public interface OnScrollListener {
public void onScrollChanged(ObservableHorizontalScrollView scrollView, int x, int y, int oldX, int oldY);
public void onEndScroll(ObservableHorizontalScrollView scrollView);
}
private boolean mIsScrolling;
private boolean mIsTouching;
private Runnable mScrollingRunnable;
private OnScrollListener mOnScrollListener;
public ObservableHorizontalScrollView(Context context) {
this(context, null, 0);
}
public ObservableHorizontalScrollView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public ObservableHorizontalScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
int action = ev.getAction();
if (action == MotionEvent.ACTION_MOVE) {
mIsTouching = true;
mIsScrolling = true;
} else if (action == MotionEvent.ACTION_UP) {
if (mIsTouching && !mIsScrolling) {
if (mOnScrollListener != null) {
mOnScrollListener.onEndScroll(this);
}
}
mIsTouching = false;
}
return super.onTouchEvent(ev);
}
#Override
protected void onScrollChanged(int x, int y, int oldX, int oldY) {
super.onScrollChanged(x, y, oldX, oldY);
if (Math.abs(oldX - x) > 0) {
if (mScrollingRunnable != null) {
removeCallbacks(mScrollingRunnable);
}
mScrollingRunnable = new Runnable() {
public void run() {
if (mIsScrolling && !mIsTouching) {
if (mOnScrollListener != null) {
mOnScrollListener.onEndScroll(ObservableHorizontalScrollView.this);
}
}
mIsScrolling = false;
mScrollingRunnable = null;
}
};
postDelayed(mScrollingRunnable, 200);
}
if (mOnScrollListener != null) {
mOnScrollListener.onScrollChanged(this, x, y, oldX, oldY);
}
}
public OnScrollListener getOnScrollListener() {
return mOnScrollListener;
}
public void setOnScrollListener(OnScrollListener mOnEndScrollListener) {
this.mOnScrollListener = mOnEndScrollListener;
}
}
I think this has come up in the past. AFAIK, you can't easily detect that. My suggestion is that you take a look at ScrollView.java (that's how we do things in Android land :)) and figure out how you can extend the class to provide the functionality you are looking for. This is what I would try first:
#Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
if (mScroller.isFinished()) {
// do something, for example call a listener
}
}
this is an old thread but I'd like to add a shorter solution I came up with:
buttonsScrollView.setOnScrollChangeListener { v, scrollX, scrollY, oldScrollX, oldScrollY ->
handler.removeCallbacksAndMessages(null)
handler.postDelayed({
//YOUR CODE TO BE EXECUTED HERE
},1000)
}
Naturally there's a 1000 milliseconds delay. Adjust that if you need to.
I've made some improvements to ZeroG's answer. Mainly cancellation of excess task calls and implementing the whole thing as a private OnTouchListener, so all the scroll detection code would be in one place.
Paste the following code into your own ScrollView implementation:
private class ScrollFinishHandler implements OnTouchListener
{
private static final int SCROLL_TASK_INTERVAL = 100;
private Runnable mScrollerTask;
private int mInitialPosition = 0;
public ScrollFinishHandler()
{
mScrollerTask = new Runnable() {
public void run() {
int newPosition = getScrollY();
if(mInitialPosition - newPosition == 0)
{//has stopped
onScrollStopped(); // Implement this on your main ScrollView class
}else{
mInitialPosition = getScrollY();
ExpandingLinearLayout.this.postDelayed(mScrollerTask, SCROLL_TASK_INTERVAL);
}
}
};
}
#Override
public boolean onTouch(View v, MotionEvent event)
{
if (event.getAction() == MotionEvent.ACTION_UP)
{
startScrollerTask();
}
else
{
stopScrollerTask();
}
return false;
}
}
And then in your ScrollView implementation:
setOnTouchListener( new ScrollFinishHandler() );
this.getListView().setOnScrollListener(new OnScrollListener(){
#Override
public void onScrollStateChanged(AbsListView view, int scrollState) {}
#Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
if( firstVisibleItem + visibleItemCount >= totalItemCount )
// Last item is shown...
}
Hope the snippet help :)