I have a LinearLayout containing both a ListView and an EditText. When the On-Screen keyboard is launched by touching the EditText, the ListView resizes so that only the top few elements remain visible.
The context that the ListView is being used in has the bottom few elements being more visually relevant than the top, and so I'd like for it to resize so that the bottom remains visible, rather than the top. Any pointers?
(Incidentally, the current fix I'm using involves using smoothScrollToPosition, but the laggy scroll behaviour makes this undesirable)
I just solved a similar issue this morning, and thought I'd post my result here for the benefit of future searchers. My issue was that scrolling to the bottom wasn't helping since I was calling it before the view actually changed size. The solution? Wait until it does change size by using a GlobalLayoutListener
Steps:
1) implement the following method in the activity holding the listview
public void scrollToBottom(){
//I think this is supposed to run on the UI thread
listView.setSelection(mAdapter.getCount() - 1);
}
2) create the following class
public class OnGlobalLayoutListenerWithScrollToBottom implements OnGlobalLayoutListener{
private boolean scroll;
private OnScrollToBottomListener listener;
public interface OnScrollToBottomListener{
public void scrollToBottom();
}
public OnGlobalLayoutListenerWithScrollToBottom(OnScrollToBottomListener listener){
this.listener = listener;
}
#Override
public void onGlobalLayout() {
if(scroll){
listener.scrollToBottom();
scroll = false;
}
}
/**
* Lets the listener know to request a scroll to bottom the next time it is layed out
*/
public void scrollToBottomAtNextOpportunity(){
scroll = true;
}
};
3) In your activity, implement the interface from this class. Then, in your activity, create an instance of this OnGlobalLayoutListener and set it as the listener for your listView
//make sure your class implements OnGlobalLayoutListenerWithScrollToBottom.OnScrollToBottomListener
listViewLayoutListener = new OnGlobalLayoutListenerWithScrollToBottom(this);
listView.getViewTreeObserver().addOnGlobalLayoutListener(listViewLayoutListener);
4) In your activity, before you make changes that will affect the size of list view, such as showing and hiding other views or adding stuff to the listview, simply let the layout listener know to scroll at the next opportunity
listViewLayoutListener.scrollToBottomAtNextOpportunity();
You might achieve this with setSelectionFromTop() and by overriding onSizeChanged() in a custom listview. In your layout, you should have a RelativeLayout has a parent container and place the listview above the edittext.
By creating your own listview and overriding onSizeChange(), you will be able to get the last visible item's position before the listview resizing and get its new height, in order to finally set the "previous" position of the list with an offset of its height.
How it works: Your list will place the previous last visible item at its top and you will add the pixels to scroll it at its bottom, just above your edittext.
To override the method and display it with an offset, do as follows:
#Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
// get last visible item's position before resizing
int lastPosition = super.getLastVisiblePosition();
// call the super method to resize the listview
super.onSizeChanged(w, h, oldw, oldh);
// after resizing, show the last visible item at the bottom of new listview's height
super.setSelectionFromTop(lastPosition, (h - lastItemHeight));
}
lastItemHeight is a little workaround, because I didn't find how to get the last item's height before that onSizeChanged is called. Then, in the case of your listview contains many types of items (without the same height), I prefer to get the selected height when an event occurs, just before the SoftKeyboard opens up.
So in the custom listview, you have this global variable:
int lastItemHeight = 0;
And in the activity (or fragment, whatever), you update this value in OnClickListener:
edittext.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// set a new Thread
listview.post(new Runnable() {
#Override
public void run() {
// get last visible position of items
int lastPosition = listview.getLastVisiblePosition() - 1;
// if the view's last child can be retrieved
if ( listview.getChildAt(lastPosition) != null ) {
// update the height of the last child in custom listview
listview.lastItemHeight = listview.getChildAt(lastPosition).getHeight();
}
}
});
}
});
Note: there is another possible solution but you have to set android:stackFromBottom="true" on the listview, which stackes its content from the bottom. Instead, this solution here can display a specific item without forcing the content to start from the bottom, with the default listview's behaviour.
Second note: (just in case) don't forget to add android:windowSoftInputMode="adjustResize" in the manifest.
You should add this attribute in the manifest for your activity and pick the correct value for it (probably you will pick "adjustResize"):
<activity android:name="package.yourActivity" android:windowSoftInputMode="adjustResize"/>
Related
I want to make a RecyclerView that scrolls infinitely while also being able to scroll to an item programmatically.
At the moment I've made the RecyclerView loop infinitely using this hacky method: https://stackoverflow.com/a/31254146/7443375
i.e. Overriding my adapter
#Override
public int getCount() {
return Integer.MAX_VALUE;
}
Getting position of item in my adapter like so:
int positionInList = position % fragmentList.size();
And then initializing my RecyclerView's scroll position like so:
recyclerView.getLayoutManager().scrollToPosition(Integer.MAX_VALUE / 2);
However, in my Fragment that has the RecyclerView, I want to be able to scroll to a specific item in my list (i.e. item 3 out of a list of 10 items). When I call
recyclerView.getLayoutManager().scrollToPosition(2);
The list goes into an infinite scroll. I can't figure out how to go to the specific item itself.
Furthermore, how can I make sure that the specific item is centered in the screen? I am using LinearSnapHelper to snap the items in the center of the screen as I scroll, but LinearSnapHelper does not seem to work when setting positions programmatically.
Try this way..
recyclerView.post(new Runnable() {
#Override
public void run() {
new CountDownTimer(Integer.MAX_VALUE, 20 ) {
public void onTick(long millis) {
recyclerView.scrollBy(0, 20);
}
public void onFinish() {
}
}.start();
}
});
I have a ListView Object and use:
Timer timer=new Timer();
timer.schedule(new TimerTask() {
#Override
public void run() {
runOnUiThread(new Runnable() {
#SuppressLint("NewApi")
#Override
public void run() {
lv1.scrollBy(0, counter_automatic);
counter_automatic++;
}
});
}
}, 0, 100);
code work correctly and don't get any Error! But I want Scrolling to go till end of listView!
My listView has 286 item! but it goes only for 3 items and after 3 items scrolling continue but items don't appear!
What's the problem?
The scrollBy() method is a member of the View class, and isn't going to work as you're expecting for a ListView because of how it handles its child Views. Depending on what exactly the desired behavior is, you probably want to use smoothScrollToPosition(int position) or smoothScrollBy(int distance, int duration).
The scrollBy method takes pixels as parameters. I suppose you mix up of number of items with amount of pixels.
If you want to smooth scroll to a certain item use smoothScrollToPosition instead. See http://developer.android.com/reference/android/widget/AbsListView.html#smoothScrollToPosition(int)
scrollBy() scrolls by an amount of pixel, and not from item to item. The documentation of scrollBy() says:
public void scrollBy (int x, int y)
Move the scrolled position of your view. This will cause a call to onScrollChanged(int, int, int,
int) and the view will be invalidated.
Parameters
x - the amount of pixels to scroll by horizontally
y - the amount of pixels to scroll by vertically
So what you want to do is something like this:
listView.scrollTo(0, listView.getHeight());
Using scrollTo() instead of scrollBy() should be more reliable for your use-case.
But I guess the method you are actually looking for is smoothScrollToPosition()! Try something like this:
listView.smoothScrollToPosition(adapter.getCount() - 1);
Instead of using scrollBy, try using setSelectionFromTop(int position, int pixelsFromTop). In your case, use counter_automatic as position and let the pixelsFromTop variable not change.
I have a form within a ScrollView. When I tap into an EditText the soft keyboard appears and the ScrollView scrolls the now focused EditText so that it just comes into view.
However, I have hint information just below the EditText that I also would like to show, so the scrolling should go just a bit further up, like this:
The EditText is embedded in a form element and actually I'd like to scroll to the bottom of that. I've checked the source code of ScrollView and it will just scroll to the bottom of the currently focused view. Maybe there's a way to tell the ScrollView that the form element is the currently focused element?
Of course I could write my own ScrollView sub class and override the scroll behavior, but I wonder if there's a more elegant way of doing this.
Any other suggestions (with adjust scrolling with a fixed offset or so) are also appreciated.
I have not really found any way to configure the scrolling behavior of the ScrollView from the outside. So I ended up to define my own sub class of ScrollView:`
/**
* {#link ScrollView} extension that allows to configure scroll offset.
*/
public class ConfigurableScrollView extends ScrollView {
private int scrollOffset = 0;
public ConfigurableScrollView (final Context context, final AttributeSet attrs) {
super(context, attrs);
}
public void setScrollOffset (final int scrollOffset) {
this.scrollOffset = scrollOffset;
}
#Override
protected int computeScrollDeltaToGetChildRectOnScreen (final Rect rect) {
// adjust by scroll offset
int scrollDelta = super.computeScrollDeltaToGetChildRectOnScreen(rect);
int newScrollDelta = (int) Math.signum(scrollDelta) * (scrollDelta + this.scrollOffset);
return newScrollDelta;
}
}
computeScrollDelta(...) is the only protected method that can be targeted for overriding, apart from onSizeChanged(...).
The signum function in the example above ensures that scrolling is only increased, if the ScrollView really thinks that scrolling is necessary (e.g. when keyboard pops up).
I can now set the extra scroll offset once from the outside, as calculated from the height of the hint.
It's not hard to use the extended ConfigurableScrollView instead of the standard ScrollView, I only had to replace the ScrollView XML tag with the FQN of the new class.
Considering that you are using ScrollView you have the possibility to use the method ScrollTo as follow:
scrollView.post(new Runnable() {
#Override
public void run() {
sv.scrollTo(x-value, y-value);
}
});
where the first argument is the scroll value for X, while the second argument is the scroll value for Y. So you just have to set your scrollView offset when the keyboard is displayed.
Hope it helps;)
I'm using
<ExpandableListView
android:id="#+id/listView"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</ExpandableListView>
i want add animation slide for child when onclick parent . So How can i do ?
Final Update
It's been quite a while since I wrote this answer. Since then a lot has changed. The biggest change is with the introduction of RecyclerView that makes animating a list or grid easy. I highly recommend switching over to RecyclerViews if you can. For those who can't I will see what I can do regarding fixing the bugs for my library.
Original answer
I actually do not like the popular implementation of an animated ExpandableListView that simply uses a ListView with an expand animation because in my use case, each of my groups had a lot of children, therefore it was not feasible to use a normal ListView as the child views will not be recycled and the memory usage will be huge with poor performance. Instead, I went with a much more difficult but more scalable and flexible approach.
I extended the ExpandableListView class and overrode the onCollapse and onExpand functions, I also created a subclass of a BaseExpandableListAdapter called AnimatedExpandableListAdapter. Inside the adapter, I overrode the getChildView function and made the function final so that the function cannot be overrode again. Instead I provided another function called getRealChildView for subclasses to override to provide a real child view. I then added an animation flag to the class and made getChildView return a dummy view if the animation flag was set and the real view if the flag was not set. Now with the stage set I do the following for onExpand:
Set the animation flag in the adapter and tell the adapter which group is expanding.
Call notifyDataSetChanged() (forces the adapter to call getChildView() for all views on screen).
The adapter (in animation mode) will then create a dummy view for the expanding group that has initial height 0. The adapter will then get the real child views and pass these views to the dummy view.
The dummy view will then start to draw the real child views within it's own onDraw() function.
The adapter will kick off an animation loop that will expand the dummy view until it is of the right size. It will also set an animation listener so that it can clear the animation flag once the animation completes and will call notifyDataSetChanged() as well.
Finally with all of this done, I was able to not only get the desired animation effect but also the desired performance as this method will work with group with over 100 children.
For the collapsing animation, a little more work needs to be done to get this all setup and running. In particular, when you override onCollapse, you do not want to call the parent's function as it will collapse the group immediately leaving you no chance to play an animation. Instead you want to call super.onCollapse at the end of the collapse animation.
UPDATE:
I spent some time this weekend to rewrite my implementation of this AnimatedExpandableListView and I'm releasing the source with an example usage here:
https://github.com/idunnololz/AnimatedExpandableListView/
animateLayoutChanges adds auto-animation
<ExpandableListView
android:animateLayoutChanges="true"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
#idunnololz solution works great. however i would like to add some code to collapse previously expanded group.
private int previousGroup=-1;
listView.setOnGroupClickListener(new OnGroupClickListener() {
#Override
public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
// We call collapseGroupWithAnimation(int) and
// expandGroupWithAnimation(int) to animate group
// expansion/collapse.
if (listView.isGroupExpanded(groupPosition)) {
listView.collapseGroupWithAnimation(groupPosition);
previousGroup=-1;
} else {
listView.expandGroupWithAnimation(groupPosition);
if(previousGroup!=-1){
listView.collapseGroupWithAnimation(previousGroup);
}
previousGroup=groupPosition;
}
return true;
}
});
#idunnololz solution is working great, but I experienced weird behavior with my custom layout for group. The expand operation was not executed properly, the collapse however worked perfect. I imported his test project and it worked just fine, so I realized the problem is with my custom layout. However when I was not able to locate the problem after some investigation, I decided to uncomment these lines of code in his AnimatedExpandListView:
if (lastGroup && Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
return expandGroup(groupPos, true);
}
which caused the problem (my app is aimed for Android 4.0+).
Found this snnipet not remebering where here in Stack Overflow. Have two basic static methods: expand(View v) and collapse(View v).
You only have to pass the view you want to hide show.
Note: I Don't recomend pass a view having wrap_content as height. May not work fine.
public class expand {
public static void expand(View view) {
view.setVisibility(View.VISIBLE);
final int widthSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
final int heightSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
view.measure(widthSpec, heightSpec);
ValueAnimator mAnimator = slideAnimator(view, 0, view.getMeasuredHeight());
mAnimator.start();
}
public static void collapse(final View view) {
int finalHeight = view.getHeight();
ValueAnimator mAnimator = slideAnimator(view, finalHeight, 0);
mAnimator.addListener(new Animator.AnimatorListener() {
#Override
public void onAnimationEnd(Animator animator) {
view.setVisibility(View.GONE);
}
#Override
public void onAnimationStart(Animator animation) {
}
#Override
public void onAnimationCancel(Animator animation) {
}
#Override
public void onAnimationRepeat(Animator animation) {
}
});
mAnimator.start();
}
private static ValueAnimator slideAnimator(final View v, int start, int end) {
ValueAnimator animator = ValueAnimator.ofInt(start, end);
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
#Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
int value = (Integer) valueAnimator.getAnimatedValue();
ViewGroup.LayoutParams layoutParams = v.getLayoutParams();
layoutParams.height = value;
v.setLayoutParams(layoutParams);
}
});
return animator;
}
}
I am using it, but it always returns 0, even though I have scrolled till the end of the list.
getScrollY() is actually a method on View, not ListView. It is referring to the scroll amount of the entire view, so it will almost always be 0.
If you want to know how far the ListView's contents are scrolled, you can use listView.getFirstVisiblePosition();
It does work, it returns the top part of the scrolled portion of the view in pixels from the top of the visible view. See the getScrollY() documentation. Basically if your list is taking up the full view then you will always get 0, because the top of the scrolled portion of the list is always at the top of the screen.
What you want to do to see if you are at the end of a list is something like this:
public void onCreate(final Bundle bundle) {
super.onCreate(bundle);
setContentView(R.layout.main);
// The list defined as field elswhere
this.view = (ListView) findViewById(R.id.searchResults);
this.view.setOnScrollListener(new OnScrollListener() {
private int priorFirst = -1;
#Override
public void onScroll(final AbsListView view, final int first, final int visible, final int total) {
// detect if last item is visible
if (visible < total && (first + visible == total)) {
// see if we have more results
if (first != priorFirst) {
priorFirst = first;
//Do stuff here, last item is displayed, end of list reached
}
}
}
});
}
The reason for the priorFirst counter is that sometimes scroll events can be generated multiple times, so you only need to react to the first time the end of the list is reached.
If you are trying to do an auto-growing list, I'd suggest this tutorial.
You need two things to precisely define the scroll position of a listView:
To get current position:
int firstVisiblePosition = listView.getFirstVisiblePosition();
int topEdge=listView.getChildAt(0).getTop(); //This gives how much the top view has been scrolled.
To set the position:
listView.setSelectionFromTop(firstVisiblePosition,0);
// Note the '-' sign for scrollTo..
listView.scrollTo(0,-topEdge);