HorizontalListview not scrolling

Question

my horizontallistview not scroll help me please i get solution of my previous post How to load dynamic images in custom ListView this HorizontalListView class will display image but problem is is not scrolling if i add 3 images only 1 &half display how do i add scrol view in this code help me please. every thing is work fine only Horizontal Listview not scroll

import android.content.Context;
import android.database.DataSetObserver;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.util.Log;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.Scroller;


public class HorizontalListView extends AdapterView {

  public boolean mAlwaysOverrideTouch = true;
  protected ListAdapter mAdapter;
  private int mLeftViewIndex = -1;
  private int mRightViewIndex = 0;
  protected int mCurrentX;
  protected int mNextX;
  private int mMaxX = Integer.MAX_VALUE;
  private int mDisplayOffset = 0;
  protected Scroller mScroller;
  private GestureDetector mGesture;
  private Queue mRemovedViewQueue = new LinkedList();
  private OnItemSelectedListener mOnItemSelected;
  private OnItemClickListener mOnItemClicked;
  private OnItemLongClickListener mOnItemLongClicked;
  private boolean mDataChanged = false;
  private boolean mMeasureHeightForVisibleOnly = true;


  public HorizontalListView(Context context, AttributeSet attrs) {
    super(context, attrs);
    initView();
  }

  private synchronized void initView() {
    mLeftViewIndex = -1;
    mRightViewIndex = 0;
    mDisplayOffset = 0;
    mCurrentX = 0;
    mNextX = 0;
    mMaxX = Integer.MAX_VALUE;
    mScroller = new Scroller(getContext());
    mGesture = new GestureDetector(getContext(), mOnGesture);
  }

  @Override
    public void setOnItemSelectedListener(AdapterView.OnItemSelectedListener listener) {
      mOnItemSelected = listener;
    }

  @Override
    public void setOnItemClickListener(AdapterView.OnItemClickListener listener){
      mOnItemClicked = listener;
    }

  @Override
    public void setOnItemLongClickListener(AdapterView.OnItemLongClickListener listener) {
      mOnItemLongClicked = listener;
    }

  private DataSetObserver mDataObserver = new DataSetObserver() {

    @Override
      public void onChanged() {
        synchronized(HorizontalListView.this){
          mDataChanged = true;
        }
        invalidate();
        requestLayout();
      }

    @Override
      public void onInvalidated() {
        reset();
        invalidate();
        requestLayout();
      }

  };

  @Override
    public ListAdapter getAdapter() {
      return mAdapter;
    }

  @Override
    public View getSelectedView() {
      //TODO: implement
      return null;
    }

  @Override
    public void setAdapter(ListAdapter adapter) {
      if(mAdapter != null) {
        mAdapter.unregisterDataSetObserver(mDataObserver);
      }
      mAdapter = adapter;
      mAdapter.registerDataSetObserver(mDataObserver);
      reset();
    }

  /**
   * @param visibleOnly - If set to true, then height is calculated
   * only using visible views. If set to false then height is
   * calculated using _all_ views in adapter. Default is true.
   * Be very careful when passing false, as this may result in
   * significant performance hit for larger number of views.
   */
  public void setHeightMeasureMode(boolean visibleOnly) {
    if(mMeasureHeightForVisibleOnly != visibleOnly) {
      mMeasureHeightForVisibleOnly = visibleOnly;
      requestLayout();
    }
  }

  private synchronized void reset(){
    initView();
    removeAllViewsInLayout();
    requestLayout();
  }

  @Override
    public void setSelection(int position) {
      //TODO: implement
    }

  private void addAndMeasureChild(final View child, int viewPos) {
    LayoutParams params = child.getLayoutParams();
    if(params == null) {
      params = new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);
    }

    addViewInLayout(child, viewPos, params, true);
    child.measure(MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.AT_MOST),
        MeasureSpec.makeMeasureSpec(getHeight(), MeasureSpec.AT_MOST));
  }

  @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
      super.onMeasure(widthMeasureSpec, heightMeasureSpec);

      if(MeasureSpec.getMode(heightMeasureSpec) != MeasureSpec.EXACTLY) {
        int height = 0;

        if(mMeasureHeightForVisibleOnly) {
          int childCount = getChildCount();
          for(int i = 0; i < childCount; i++) {
            View v = getChildAt(i);
            v.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
            if(v.getMeasuredHeight() > height) {
              height = v.getMeasuredHeight();
            }
          }
        } else {

          /* Traverses _all_ views! Bypasses view recycler! */

          HashMap mRecycler = new HashMap();
          int childCount = getAdapter().getCount();
          for(int i = 0; i < childCount; i++) {
            int type = getAdapter().getItemViewType(i);
            View convertView = mRecycler.get(type);
            View v = getAdapter().getView(i, convertView, this);
            mRecycler.put(type, v);

            v.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
            if(v.getMeasuredHeight() > height) {
              height = v.getMeasuredHeight();
            }
          }
        }

        if(MeasureSpec.getMode(heightMeasureSpec) == MeasureSpec.AT_MOST) {
          int maxHeight = MeasureSpec.getSize(heightMeasureSpec);
          if(maxHeight < height) {
            height = maxHeight;
          }
        }

        setMeasuredDimension(getMeasuredWidth(), height);
      }
    }

  @Override
    protected synchronized void onLayout(boolean changed, int left, int top,
        int right, int bottom) {
      super.onLayout(changed, left, top, right, bottom);

      if(mAdapter == null){
        return;
      }

      if(mDataChanged){
        int oldCurrentX = mCurrentX;
        initView();
        removeAllViewsInLayout();
        mNextX = oldCurrentX;
        mDataChanged = false;
      }

      if(mScroller.computeScrollOffset()){
        int scrollx = mScroller.getCurrX();
        mNextX = scrollx;
      }

      if(mNextX <= 0){
        mNextX = 0;
        mScroller.forceFinished(true);
      }
      if(mNextX >= mMaxX) {
        mNextX = mMaxX;
        mScroller.forceFinished(true);
      }

      int dx = mCurrentX - mNextX;

      removeNonVisibleItems(dx);
      fillList(dx);
      positionItems(dx);

      mCurrentX = mNextX;

      if(!mScroller.isFinished()){
        post(new Runnable(){
            public void run() {
            requestLayout();
            }
            });

      }
    }

  private void fillList(final int dx) {
    int edge = 0;
    View child = getChildAt(getChildCount()-1);
    if(child != null) {
      edge = child.getRight();
    }
    fillListRight(edge, dx);

    edge = 0;
    child = getChildAt(0);
    if(child != null) {
      edge = child.getLeft();
    }
    fillListLeft(edge, dx);


  }

  private void fillListRight(int rightEdge, final int dx) {
    while(rightEdge + dx < getWidth() && mRightViewIndex < mAdapter.getCount()) {

      View child = mAdapter.getView(mRightViewIndex, mRemovedViewQueue.poll(), this);
      addAndMeasureChild(child, -1);
      rightEdge += child.getMeasuredWidth();

      if(mRightViewIndex == mAdapter.getCount()-1) {
        mMaxX = mCurrentX + rightEdge - getWidth();
      }

      if (mMaxX < 0) {
        mMaxX = 0;
      }
      mRightViewIndex++;
    }

  }

  private void fillListLeft(int leftEdge, final int dx) {
    while(leftEdge + dx > 0 && mLeftViewIndex >= 0) {
      View child = mAdapter.getView(mLeftViewIndex, mRemovedViewQueue.poll(), this);
      addAndMeasureChild(child, 0);
      leftEdge -= child.getMeasuredWidth();
      mLeftViewIndex--;
      mDisplayOffset -= child.getMeasuredWidth();
    }
  }

  private void removeNonVisibleItems(final int dx) {
    View child = getChildAt(0);
    while(child != null && child.getRight() + dx <= 0) {
      mDisplayOffset += child.getMeasuredWidth();
      mRemovedViewQueue.offer(child);
      removeViewInLayout(child);
      mLeftViewIndex++;
      child = getChildAt(0);

    }

    child = getChildAt(getChildCount()-1);
    while(child != null && child.getLeft() + dx >= getWidth()) {
      mRemovedViewQueue.offer(child);
      removeViewInLayout(child);
      mRightViewIndex--;
      child = getChildAt(getChildCount()-1);
    }
  }

  private void positionItems(final int dx) {
    if(getChildCount() > 0){
      mDisplayOffset += dx;
      int left = mDisplayOffset;
      for(int i=0;i

Diljeet · Accepted Answer

@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
    boolean handled = super.dispatchTouchEvent(ev);
    handled |= mGesture.onTouchEvent(ev); //this is always true during scrolling
    return handled; //returning true will stop the listview functions to scroll it
}

@Override
  public boolean onScroll(MotionEvent e1, MotionEvent e2,
      float distanceX, float distanceY) {

    synchronized(HorizontalListView.this){
      mNextX += (int)distanceX;
    }
    requestLayout();

    return true;
  }

This above code is the problem

According to me the listview won't scroll if you return true in the dispatchTouchEvent function, which is always true while scrolling in your case. the onScroll gesture always returns true and the listview never scrolls.

You are trying to perform the scrolling manually. try returning false and don't handle the scrolling manually.

I can't read your complete code because its too long, but i have spotted the problem for you, now you can handle it any way you want.

HorizontalListview not scrolling

Answers (1)

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