I have scrollview with child LinearLayout . I am adding data programmaticaly to it. When i add some data to top of linearlayout it automatically scrolls to top element. But i want something like , user reaches top -> scrolls upside to load previous data ->add data to linearlayout top but should not get focus, after addition complete , if user scrolls then and then only it should display .
How to achieve this?
Well I thought of a way and it works almost perfectly.
I have a LinearLayout (llCommunicationsLayout) inside a ScrollView (svCommunications) .
I inflate a new LinearLayout, I'm going to add views to the top of this new LinearLayout and then add this new layout to the LinearLayout inside the ScrollView.
This is the new layout:
final LinearLayout wrapperLayout = (LinearLayout) mInflater.inflate(R.layout.empty_layout, null);
I add my views to the 0'th position of this layout.
wrapperLayout.addView(view, 0);
After all the views are added into the wrapperLayout, I add the wrapperLayout into the llCommunicationsLayout (the one inside my ScrollView)
llCommunicationsLayout.addView(wrapperLayout, 0);
After this, I calculate their heights after the wrapperLayout is on screen (has a measurable height)
wrapperLayout.post(new Runnable() {
#Override
public void run() {
int wrapperHeight = wrapperLayout.getHeight();
int svHeight = svCommunications.getHeight();
int scrollHeight = Math.abs(svHeight - wrapperHeight);
DisplayMetrics displaymetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
int displayHeight = displaymetrics.heightPixels / 4;
svCommunications.scrollTo(0, (scrollHeight + displayHeight));
}
});
Here, I get both the newly added layout's and the ScrollView's heights.
I calculate their difference, add the 1/4 of the height of the screen of my device and scroll it, voila!
It's not perfect, but after the layouts are added, it no longer scrolls to the top of the screen. Experiment with the displayHeight for different results.
Hope this helps someone out.
You can grab the current view which is on top of your LinearLayout then add new content to your LinearLayout and then scroll back to view which was previously on top. The code would be something like:
public void addViewsOnTop(List<View> views) {
final View currentViewOnTop = (linearLayout.getChildCount() > 0) ? linearLayout.getChildAt(0) : null;
// Add Views. Note that views will appear in reverse order
for(View view : views) {
linearLayout.addView(view, 0);
}
// Scroll back to view which was on top
if(currentViewOnTop != null) {
new Handler().post(new Runnable() {
#Override
public void run() {
scrollView.scrollTo(0, currentViewOnTop.getBottom());
}
});
}
}
Solved....
Try this, worked for me ,
lv_chat.setAdapter(adapter);
lv_chat.setSelection(somePreviousPosition);
Related
I have a fragment at the bottom of my Activity which can be filled with words(views). This is a image of the fragment:
Between the blue buttons you can inflate views by clicking on a item in an GridView that is above this fragment. Everytime I click an item a view with text: "Test" is being added. It starts left with inflating views untill it doesn't fit in the LinearLayout anymore.
When the LinearLayout is full, it looks like this:
When the layout looks full, you still can inflate views but you don't see them being added anymore.
The most right purple view you can see on the image above has a bigger height then the rest because it doesn't fit anymore.
I want to check if there is enough space in the LinearLayout to inflate a new view.
This is the code that inflates the views in the LinearLayout:
public void inflateAllViews(){
LayoutInflater inflaterr = (LayoutInflater) MainApplication.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
linearLayout.removeAllViews();
ArrayList<WordTile> wordsToInflate = WordManager.getWordsToInflate();
for(WordTile WordTile : wordsToInflate){
View word = inflaterr.inflate(R.layout.word, null);
final TextView textView = (TextView)word.findViewById(R.id.text_word);
textView.setText(WordTile.getTitle());
linearLayout.addView(word);
}
}
But I need to check whether the view can be added or not because there is no space left. Because in the background you can add unlimited views to the LinearLayout.
I tried to find a way to calculate the widths of the inflated views. The only thing I found was this:
ViewTreeObserver vto = word.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
Log.d("TEST", "Height = " + word.getHeight() + " Width = " + word.getWidth());
widthOfChildren += word.getWidth();
System.out.println("widthofchildren:" + widthOfChildren);
ViewTreeObserver obs = word.getViewTreeObserver();
obs.removeGlobalOnLayoutListener(this);
}
});
The code works and prints the width I need for every view. But I can't use the width outside of the OnGlobalLayoutListener....
Does anyone have a solution to my problem?
EDIT:
The problem is not the width of the LinearLayout because I know that width, it is the widths of the views that are in the LinearLayout. The LinearLayout has a standard width which doesn't change.
I have a LinearLayout (vertical) with two child views in it. The 1st one is a ScrollView and the 2nd one is another layout with Visibility.GONE, its size is not fixed (determined by its children).
<LinearLayout vertical>
<ScrollView> ... </ScrollView>
<AnotherLayout visibility=GONE height=wrap_content> ... </AnotherLayout>
</LinearLayout>
At some point of time I want to show AnotherLayout. But, once it pops up, I also want to adjust the scrolling of my ScollView one. For this, I need to know the size of this AnotherLayout.
I'm doing something like that:
int oldHeight = scrollArea.getHeight();
linearLayout.setVisibility(VISIBLE);
int newHeight = scrollArea.getHeight();
But oldHeight and newHeight are still the same.
How can I calculate the new height?
The two dimensions are the same because visibility change took time and the line of code was run before that so it returns the same.
You can use a visibility listener to calculate the dimension after visibility change , You may use that
linearLayout.setTag(linearLayout.getVisibility());
linearLayout.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
int newVis = linearLayout.getVisibility();
if((int)linearLayout.getTag() != newVis)
{
linearLayout.setTag(linearLayout.getVisibility());
//visibility has changed
int newHeight = scrollArea.getHeight();
}
}
});
In scrollview, if I add any view in middle, normally all the views below the added view scrolls downside. But I want to scroll the top views of added view to upside without disturbing the bottom views. Is it possible in scrollview , please help me ?
In the figure , If view 4 was added , then view 1 has to be scrolled upwards , without changing the positions of view 2 and view 3.
You can probably get the height of the view you are adding with and then scroll the scrollview manually that many pixels
scrollView.scrollBy(0, viewAdded.getHeight())
I've been wanting to try this question for quite some time, I finally got the chance today. The method is pretty simple (in fact, #dweebo already mentioned it earlier) - we move the ScrollView up as we add the view. For getting precise (and valid) dimensions when adding, we use a ViewTreeObserver. Here's the code you can get hints from:
// Getting reference to ScrollView
final ScrollView scrollView = (ScrollView) findViewById(R.id.scrollView);
// Assuming a LinearLayout container within ScrollView
final LinearLayout parent = (LinearLayout) findViewById(R.id.parent);
// The child we are adding
final View view = new View(ScaleActivity.this);
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, 100);
view.setLayoutParams(params);
// Finally, adding the child
parent.addView(view, 2); // at index 2
// This is what we need for the dimensions when adding
ViewTreeObserver viewTreeObserver = parent.getViewTreeObserver();
viewTreeObserver.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
#Override
public boolean onPreDraw() {
parent.getViewTreeObserver().removeOnPreDrawListener(this);
scrollView.scrollBy(0, view.getHeight());
// For smooth scrolling, run below line instead
// scrollView.smoothScrollBy(0, view.getHeight())
return false;
}
});
I would like to set the Height of my ScrollView per Code dynamically cause my ScrollView is actually higher then it shall be (empty space at bottom).
My thoughts were, that I could get the Heights of all Controls within the the ScrollView, sum-up them and then I could set that Height to my ScrollView.
What I tried is following code:
protected override void OnStart()
{
base.OnStart();
SetScrollViewSize();
}
private void SetScrollViewSize()
{
var root = FindViewById<ScrollView>(Resource.Id.root);
if (root != null)
{
var controls = GetSelfAndChildrenRecursive(root); //Gives me all Controls in the root (The ScrollView)
int heightOfAllControlsTogether = 0;
foreach (ViewGroup control in controls)
{
heightOfAllControlsTogether += control.Height;
}
ViewGroup.LayoutParams parameters = new ViewGroup.LayoutParams(root.Width, heightOfAllControlsTogether);
root.LayoutParameters = parameters;
}
}
The Heights and MeasuredHeights are always 0 (zero) - (I know it needs to be rendered first, but what would be the right place then?) and I'm not even sure if my approach would work.
Any Help would be appreciated!
Well I found out why.
The Background-Graphic was too high. That was creating the empty space at the bottom.
THis is an example to set scrollview height based on total height of Children:
private void setScrollViewHeightBasedOnChildren() {
int size = layoutRoot.getChildCount();
LinearLayout item = (LinearLayout) layoutRoot.getChildAt(0);
item.measure(0, 0);
int height = item.getMeasuredHeight();
//Reset size of ScrollView
scroll.setMinimumHeight(height / size);
scroll.invalidate();
}
See details: Set the height of ScrollView equal total height of children
I have a number of elements in a ListView that scroll off the screen.
I would like there to be blank space at the end of the View. That is, the user should be able to scroll past the last element such that the last element is in the middle of the viewport.
I could use an OverScroller, but I think that would only enable the View to have a bouncy effect like one often sees on the iPhone.
Is there something I might have overlooked?
The scrolled-to-the-botton screen should look something like this:
The accepted answer is too complicated, and addFooterView is not for this kind of thing. The proper and simpler way is to set the paddingTop and paddingBottom, and you need to set clipToPadding to "false". In your list view or grid view, add the following:
android:paddingTop="100dp"
android:paddingBottom="100dp"
android:clipToPadding="false"
You'll get blank space at the top and the bottom that moves with your finger scroll.
Inflate any layout of your choice (this could be an XML of and ImageView with no drawable and with set height and width of your choice)
Measure the screen height and create new LayoutParams and set the height of it to 1/2 of the screen height
Set the new layout params on your inflated view
Use the ListView's addFooterView() method to add that view to the bottom of your list (there is also an addHeaderView())
Code to measure screen height
WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
int screenHeight = display.getHeight();
Code to set half screen height:
View layout = inflater.inflate(R.layout.mylistviewfooter, container, false);
ViewGroup.LayoutParams lp = layout.getLayoutParams();
lp.height = screenHeight/2;
layout.setLayoutParams(lp);
myListView.addFooterView(layout);
An Aside:
When you add a footer or header view to any listview, it has to be done before adding the adapter. Also, if you need to get your adapter class after doing this you will need to know calling the listview's adapter by getAdapter() will return an instance of HeaderViewListAdapter in which you will need to call its getWrappedAdapter method
Something like this :
MyAdapterClassInstance myAdapter = (MyAdapterClassInstance) ((HeaderViewListAdapter) myListView.getAdapter()).getWrappedAdapter();
this 100% works.
in adapter set your code like this
//in getCount
#Override
public int getCount() {
return ArrayList.size()+1;
}
//in getview make your code like this
public View getView(final int i, View view, ViewGroup viewGroup) {
view = inflter.inflate(R.layout.yourlayout, null);
if(i<getCount()-1) {
//your code
}
else{
ViewGroup itemContainer =(ViewGroup) view.findViewById(R.id.container);
itemContainer.setVisibility(View.INVISIBLE);
}
Return view;
}
if you have multiple listviews in your app, create an xml of a footer, something like this:
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:minHeight="200dp"
android:layout_width="match_parent"
android:layout_height="200dp"></LinearLayout>
and then in the code, use this:
listView.addFooterView(LayoutInflater.from(getActivity()).inflate(R.layout.empty200, null));
This do the job in a simple way
android:paddingBottom="100dp"
android:clipToPadding="false"
Try the followings:
View footer = new View(getActivity());
footer.setLayoutParams( new AbsListView.LayoutParams( LayoutParams.FILL_PARENT, 100 ));
// 100 is the height, you can change it.
mListView.addFooterView(footer, null, false);