Databases
StackOverflow2013
Postsdbo
POHow to synchronize scrolling distance of two different ListViews each in their own fragment?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHow to synchronize scrolling distance of two different ListViews each in their own fragment?
    primarykey
    data
    text
    <p>I have two fragments each containing a list view. The list view in the left fragment has a very long header view attached to it. The right fragment list view has list elements of varying height (and generally only one element that can be longer than the height of the display). The right fragment's list view is guaranteed to always be much shorter than the length (in pixels) of the left fragment's list view.</p> <p>What I would like to do is, if I touch and drag/fling the left side, the right side moves roughly the same distance in the same direction as the drag/fling operation. If the right fragment's list view reaches the end (or beginning) of the list, it should just stay there. If I manipulate the right list view, it should work as usual.</p> <p>As requested by sabadow, here is some code. First, left fragment:</p> <pre><code>public class LeftFragment extends SherlockFragment { private LeftFragmentListener listener; // The Activity must implement this interface. public interface LeftFragmentListener { public void syncScroll(int diffY); } @Override public void onAttach(Activity activity) { super.onAttach(activity); try { listener = (LeftFragmentListener)activity; } catch (ClassCastException e) { throw new ClassCastException(activity.toString() + " must implement LeftFragment.LeftFragmentListener"); } } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // Inflate the layout for this fragment. final ListView lv = (ListView)inflater.inflate(R.layout.main_left_fragment, container, false); final View header = inflater.inflate(R.layout.main_left_fragment_header, null); lv.addHeaderView(header); ... calls setAdapter, etc. ... lv.setOnScrollListener(new OnScrollListener() { private int lastY; @Override public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) { View c = view.getChildAt(0); if (c != null) { int currY = c.getTop(); int diffY = currY - lastY; lastY = currY; listener.syncScroll(diffY); } } @Override public void onScrollStateChanged(AbsListView view, int scrollState) { if (scrollState != SCROLL_STATE_IDLE) { View c = view.getChildAt(0); if (c != null) lastY = c.getTop(); } } }); return lv; } } </code></pre> <p>Now, Activity:</p> <pre><code>public class MainActivity extends MySlidingActivity implements LeftFragment.LeftFragmentListener { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Two list views. setContentView(R.layout.main_two_frags); } @Override public void syncScroll(int diffY) { RightFragment f = (RightFragment)getSupportFragmentManager().findFragmentById(R.id.main_right_fragment); if (f != null) f.execSyncScroll(diffY); } } </code></pre> <p>And now the right fragment:</p> <pre><code>public class RightFragment extends SherlockFragment { private ListView lv; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // Inflate the layout for this fragment. lv = (ListView)inflater.inflate(R.layout.main_right_fragment, container, false); ... calls setAdapter, etc. ... return lv; } // Event sync across fragments - only used when the two views are showing. public void execSyncScroll(int diffY) { Log.e("setSelection", "lastY + diffY = " + (lastY + diffY)); // lv.setSelectionFromTop(0, lastY + diffY); // lv.scrollBy(0, -diffY); // Nothing I've tried works. } } </code></pre> <p>The comment above where I say "Nothing I've tried works" is where I'm stuck. I have no idea what to do there to get the ListView to scroll.</p> <p>scrollBy() doesn't work properly. It doesn't bound the scrolling to the scrollbar and doesn't show all items in the ListView. setSelectionFromTop() doesn't do anything at all. Using OnTouchListener and passing the MotionEvent (instead of an 'int') causes the application to crash when attempting to call lv.dispatchTouchEvent().</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USPaula Bean
    1. USPaula Bean
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POHow to synchronize scrolling distance of two different ListViews each in their own fragment?
      1. This table or related slice is empty.
      1. VTApproveEditSuggestion
    2. VO
      singulars
      1. POHow to synchronize scrolling distance of two different ListViews each in their own fragment?
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POHow to synchronize scrolling distance of two different ListViews each in their own fragment?
      1. USgh123man
      1. VTFavorite
    1. COplease add some code or stacktrace and reduce the question size ...
      singulars
      1. POHow to synchronize scrolling distance of two different ListViews each in their own fragment?
      1. USsabadow
    2. CO@sabadow - Okay, I've made the changes as you requested. Can you help?
      singulars
      1. POHow to synchronize scrolling distance of two different ListViews each in their own fragment?
      1. USPaula Bean
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload