How to manage undo after swipe to delete in android ListView?

Library to make the items in a ListView or RecyclerView dismissable with the possibility to undo it, using your own view to provide this functionality like the Gmail app for Android does.

https://github.com/hudomju/android-swipe-to-dismiss-undo

Here's a gist, just in case the page gets changed or link goes invalid:

ListViewActivity:

public class ListViewActivity extends Activity {

private static final int TIME_TO_AUTOMATICALLY_DISMISS_ITEM = 3000;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.list_view_activity);
    init((ListView) findViewById(R.id.list_view));
}

private void init(ListView listView) {
    final MyBaseAdapter adapter = new MyBaseAdapter();
    listView.setAdapter(adapter);
    final SwipeToDismissTouchListener<ListViewAdapter> touchListener =
            new SwipeToDismissTouchListener<>(
                    new ListViewAdapter(listView),
                    new SwipeToDismissTouchListener.DismissCallbacks<ListViewAdapter>() {
                        @Override
                        public boolean canDismiss(int position) {
                            return true;
                        }

                        @Override
                        public void onPendingDismiss(ListViewAdapter recyclerView, int position) {

                        }

                        @Override
                        public void onDismiss(ListViewAdapter view, int position) {
                            adapter.remove(position);
                        }
                    });

    touchListener.setDismissDelay(TIME_TO_AUTOMATICALLY_DISMISS_ITEM);
    listView.setOnTouchListener(touchListener);
    // Setting this scroll listener is required to ensure that during ListView scrolling,
    // we don't look for swipes.
    listView.setOnScrollListener((AbsListView.OnScrollListener) touchListener.makeScrollListener());
    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            if (touchListener.existPendingDismisses()) {
                touchListener.undoPendingDismiss();
            } else {
                Toast.makeText(ListViewActivity.this, "Position " + position, LENGTH_SHORT).show();
            }
        }
    });
}

static class MyBaseAdapter extends BaseAdapter {

    private static final int SIZE = 100;

    private final List<String> mDataSet = new ArrayList<>();

    MyBaseAdapter() {
        for (int i = 0; i < SIZE; i++)
            mDataSet.add(i, "This is row number " + i);
    }

    @Override
    public int getCount() {
        return mDataSet.size();
    }

    @Override
    public String getItem(int position) {
        return mDataSet.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    public void remove(int position) {
        mDataSet.remove(position);
        notifyDataSetChanged();
    }

    static class ViewHolder {
        TextView dataTextView;
        ViewHolder(View view) {
            dataTextView = (TextView) view.findViewById(R.id.txt_data);
            view.setTag(this);
        }
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        ViewHolder viewHolder = convertView == null
                ? new ViewHolder(convertView = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.list_item, parent, false))
                : (ViewHolder) convertView.getTag();

        viewHolder.dataTextView.setText(mDataSet.get(position));
        return convertView;
    }
}

}

SwipeToDismissTouchListener:

public class SwipeToDismissTouchListener<SomeCollectionView extends ViewAdapter> implements
    View.OnTouchListener {

// Cached ViewConfiguration and system-wide constant values
private final int mSlop;
private final int mMinFlingVelocity;
private final int mMaxFlingVelocity;
private final long mAnimationTime;

// Fixed properties
private final SomeCollectionView mRecyclerView;
private final DismissCallbacks<SomeCollectionView> mCallbacks;
private int mViewWidth = 1; // 1 and not 0 to prevent dividing by zero

// Transient properties
private PendingDismissData mPendingDismiss;
private float mDownX;
private float mDownY;
private boolean mSwiping;
private int mSwipingSlop;
private VelocityTracker mVelocityTracker;
private int mDownPosition;
private RowContainer mRowContainer;
private boolean mPaused;

// Handler to dismiss pending items after a delay
private final Handler mHandler;
private final Runnable mDismissRunnable = new Runnable() {
    @Override
    public void run() {
        processPendingDismisses();
    }
};
private long mDismissDelayMillis = -1; // negative to disable automatic dismissing

public class RowContainer {

    final View container;
    final View dataContainer;
    final View undoContainer;
    boolean dataContainerHasBeenDismissed;

    public RowContainer(ViewGroup container) {
        this.container = container;
        dataContainer = container.getChildAt(0);
        undoContainer = container.getChildAt(1);
        dataContainerHasBeenDismissed = false;
    }

    View getCurrentSwipingView() {
        return dataContainerHasBeenDismissed ? undoContainer: dataContainer;
    }

}

/**
 * The callback interface used by {@link SwipeToDismissTouchListener} to inform its client
 * about a successful dismissal of one or more list item positions.
 */
public interface DismissCallbacks<SomeCollectionView extends ViewAdapter> {
    /**
     * Called to determine whether the given position can be dismissed.
     */
    boolean canDismiss(int position);

    /**
     * Called when an item is swiped away by the user and the undo layout is completely visible.
     * Do NOT remove the list item yet, that should be done in {@link #onDismiss(com.hudomju.swipe.adapter.ViewAdapter, int)}
     * This may also be called immediately before and item is completely dismissed.
     *
     * @param recyclerView The originating {@link android.support.v7.widget.RecyclerView}.
     * @param position The position of the dismissed item.
     */
    void onPendingDismiss(SomeCollectionView recyclerView, int position);

    /**
     * Called when the item is completely dismissed and removed from the list, after the undo layout is hidden.
     *
     * @param recyclerView The originating {@link android.support.v7.widget.RecyclerView}.
     * @param position The position of the dismissed item.
     */
    void onDismiss(SomeCollectionView recyclerView, int position);
}

/**
 * Constructs a new swipe-to-dismiss touch listener for the given list view.
 *
 * @param recyclerView  The list view whose items should be dismissable.
 * @param callbacks The callback to trigger when the user has indicated that she would like to
 *                  dismiss one or more list items.
 */
public SwipeToDismissTouchListener(SomeCollectionView recyclerView,
                                   DismissCallbacks<SomeCollectionView> callbacks) {
    ViewConfiguration vc = ViewConfiguration.get(recyclerView.getContext());
    mSlop = vc.getScaledTouchSlop();
    mMinFlingVelocity = vc.getScaledMinimumFlingVelocity() * 16;
    mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity();
    mAnimationTime = recyclerView.getContext().getResources().getInteger(
            android.R.integer.config_shortAnimTime);
    mRecyclerView = recyclerView;
    mCallbacks = callbacks;
    mHandler = new Handler();
}

/**
 * Enables or disables (pauses or resumes) watching for swipe-to-dismiss gestures.
 *
 * @param enabled Whether or not to watch for gestures.
 */
public void setEnabled(boolean enabled) {
    mPaused = !enabled;
}

/**
 * Set the delay after which the pending items will be dismissed when there was no user action.
 * Set to a negative value to disable automatic dismissing items.
 * @param dismissDelayMillis The delay between onPendingDismiss and onDismiss calls, in milliseconds.
 */
public void setDismissDelay(long dismissDelayMillis) {
    this.mDismissDelayMillis = dismissDelayMillis;
}

/**
 * Returns an {@link android.widget.AbsListView.OnScrollListener} to be added to the {@link
 * android.widget.ListView} using {@link android.widget.ListView#setOnScrollListener(android.widget.AbsListView.OnScrollListener)}.
 * If a scroll listener is already assigned, the caller should still pass scroll changes through
 * to this listener. This will ensure that this {@link SwipeToDismissTouchListener} is
 * paused during list view scrolling.</p>
 *
 * @see SwipeToDismissTouchListener
 */
public Object makeScrollListener() {
    return mRecyclerView.makeScrollListener(new AbsListView.OnScrollListener() {
        @Override
        public void onScrollStateChanged(AbsListView absListView, int scrollState) {
            processPendingDismisses();
            setEnabled(scrollState != AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL);
        }

        @Override
        public void onScroll(AbsListView absListView, int i, int i1, int i2) {
        }
    });
}

@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
    if (mViewWidth < 2) {
        mViewWidth = mRecyclerView.getWidth();
    }

    switch (motionEvent.getActionMasked()) {
        case MotionEvent.ACTION_DOWN: {
            if (mPaused) {
                return false;
            }

            // TODO: ensure this is a finger, and set a flag

            // Find the child view that was touched (perform a hit test)
            Rect rect = new Rect();
            int childCount = mRecyclerView.getChildCount();
            int[] listViewCoords = new int[2];
            mRecyclerView.getLocationOnScreen(listViewCoords);
            int x = (int) motionEvent.getRawX() - listViewCoords[0];
            int y = (int) motionEvent.getRawY() - listViewCoords[1];
            View child;
            for (int i = 0; i < childCount; i++) {
                child = mRecyclerView.getChildAt(i);
                child.getHitRect(rect);
                if (rect.contains(x, y)) {
                    assert child instanceof ViewGroup &&
                            ((ViewGroup) child).getChildCount() == 2 :
                            "Each child needs to extend from ViewGroup and have two children";

                    boolean dataContainerHasBeenDismissed = mPendingDismiss != null &&
                            mPendingDismiss.position == mRecyclerView.getChildPosition(child) &&
                            mPendingDismiss.rowContainer.dataContainerHasBeenDismissed;
                    mRowContainer = new RowContainer((ViewGroup) child);
                    mRowContainer.dataContainerHasBeenDismissed = dataContainerHasBeenDismissed;
                    break;
                }
            }

            if (mRowContainer != null) {
                mDownX = motionEvent.getRawX();
                mDownY = motionEvent.getRawY();
                mDownPosition = mRecyclerView.getChildPosition(mRowContainer.container);
                if (mCallbacks.canDismiss(mDownPosition)) {
                    mVelocityTracker = VelocityTracker.obtain();
                    mVelocityTracker.addMovement(motionEvent);
                } else {
                    mRowContainer = null;
                }
            }
            return false;
        }

        case MotionEvent.ACTION_CANCEL: {
            if (mVelocityTracker == null) {
                break;
            }

            if (mRowContainer != null && mSwiping) {
                // cancel
                mRowContainer.getCurrentSwipingView()
                        .animate()
                        .translationX(0)
                        .alpha(1)
                        .setDuration(mAnimationTime)
                        .setListener(null);
            }
            mVelocityTracker.recycle();
            mVelocityTracker = null;
            mDownX = 0;
            mDownY = 0;
            mRowContainer = null;
            mDownPosition = ListView.INVALID_POSITION;
            mSwiping = false;
            break;
        }

        case MotionEvent.ACTION_UP: {
            if (mVelocityTracker == null) {
                break;
            }

            float deltaX = motionEvent.getRawX() - mDownX;
            mVelocityTracker.addMovement(motionEvent);
            mVelocityTracker.computeCurrentVelocity(1000);
            float velocityX = mVelocityTracker.getXVelocity();
            float absVelocityX = Math.abs(velocityX);
            float absVelocityY = Math.abs(mVelocityTracker.getYVelocity());
            boolean dismiss = false;
            boolean dismissRight = false;
            if (Math.abs(deltaX) > mViewWidth / 2 && mSwiping) {
                dismiss = true;
                dismissRight = deltaX > 0;
            } else if (mMinFlingVelocity <= absVelocityX && absVelocityX <= mMaxFlingVelocity
                    && absVelocityY < absVelocityX && mSwiping) {
                // dismiss only if flinging in the same direction as dragging
                dismiss = (velocityX < 0) == (deltaX < 0);
                dismissRight = mVelocityTracker.getXVelocity() > 0;
            }
            if (dismiss && mDownPosition != ListView.INVALID_POSITION) {
                // dismiss
                final RowContainer downView = mRowContainer; // mDownView gets null'd before animation ends
                final int downPosition = mDownPosition;
                mRowContainer.getCurrentSwipingView()
                        .animate()
                        .translationX(dismissRight ? mViewWidth : -mViewWidth)
                        .alpha(0)
                        .setDuration(mAnimationTime)
                        .setListener(new AnimatorListenerAdapter() {
                            @Override
                            public void onAnimationEnd(Animator animation) {
                                performDismiss(downView, downPosition);
                            }
                        });
            } else {
                // cancel
                mRowContainer.getCurrentSwipingView()
                        .animate()
                        .translationX(0)
                        .alpha(1)
                        .setDuration(mAnimationTime)
                        .setListener(null);
            }
            mVelocityTracker.recycle();
            mVelocityTracker = null;
            mDownX = 0;
            mDownY = 0;
            mRowContainer = null;
            mDownPosition = ListView.INVALID_POSITION;
            mSwiping = false;
            break;
        }

        case MotionEvent.ACTION_MOVE: {
            if (mVelocityTracker == null || mPaused) {
                break;
            }

            mVelocityTracker.addMovement(motionEvent);
            float deltaX = motionEvent.getRawX() - mDownX;
            float deltaY = motionEvent.getRawY() - mDownY;
            if (Math.abs(deltaX) > mSlop && Math.abs(deltaY) < Math.abs(deltaX) / 2) {
                mSwiping = true;
                mSwipingSlop = deltaX > 0 ? mSlop : -mSlop;
                mRecyclerView.requestDisallowInterceptTouchEvent(true);

                // Cancel ListView's touch (un-highlighting the item)
                MotionEvent cancelEvent = MotionEvent.obtain(motionEvent);
                cancelEvent.setAction(MotionEvent.ACTION_CANCEL |
                        (motionEvent.getActionIndex()
                                << MotionEvent.ACTION_POINTER_INDEX_SHIFT));
                mRecyclerView.onTouchEvent(cancelEvent);
                cancelEvent.recycle();
            }

            if (mSwiping) {
                mRowContainer.getCurrentSwipingView().setTranslationX(deltaX - mSwipingSlop);
                mRowContainer.getCurrentSwipingView().setAlpha(Math.max(0f, Math.min(1f,
                        1f - 2f * Math.abs(deltaX) / mViewWidth)));
                return true;
            }
            break;
        }
    }
    return false;
}

class PendingDismissData implements Comparable<PendingDismissData> {
    public int position;
    public RowContainer rowContainer;

    public PendingDismissData(int position, RowContainer rowContainer) {
        this.position = position;
        this.rowContainer= rowContainer;
    }

    @Override
    public int compareTo(@NonNull PendingDismissData other) {
        // Sort by descending position
        return other.position - position;
    }
}

private void performDismiss(RowContainer dismissView, int dismissPosition) {
    // Animate the dismissed list item to zero-height and fire the dismiss callback when
    // all dismissed list item animations have completed. This triggers layout on each animation
    // frame; in the future we may want to do something smarter and more performant.
    if (mPendingDismiss != null) {
        boolean dismissingDifferentRow = mPendingDismiss.position != dismissPosition;
        int newPosition = mPendingDismiss.position < dismissPosition ? dismissPosition-1 : dismissPosition;
        processPendingDismisses();
        if (dismissingDifferentRow) {
            addPendingDismiss(dismissView, newPosition);
        }
    } else {
        addPendingDismiss(dismissView, dismissPosition);
    }
}

private void addPendingDismiss(RowContainer dismissView, int dismissPosition) {
    dismissView.dataContainerHasBeenDismissed = true;
    dismissView.undoContainer.setVisibility(View.VISIBLE);
    mPendingDismiss = new PendingDismissData(dismissPosition, dismissView);
    // Notify the callbacks
    mCallbacks.onPendingDismiss(mRecyclerView, dismissPosition);
    // Automatically dismiss the item after a certain delay
    if(mDismissDelayMillis >= 0)
        mHandler.removeCallbacks(mDismissRunnable);
        mHandler.postDelayed(mDismissRunnable, mDismissDelayMillis);
}

/**
 * If a view was dismissed and the undo container is showing it will proceed with the final
 * dismiss of the item.
 * @return whether there were any pending rows to be dismissed.
 */
public boolean processPendingDismisses() {
    boolean existPendingDismisses = existPendingDismisses();
    if (existPendingDismisses) processPendingDismisses(mPendingDismiss);
    return existPendingDismisses;
}

/**
 * Whether a row has been dismissed and is waiting for confirmation
 * @return whether there are any pending rows to be dismissed.
 */
public boolean existPendingDismisses() {
    return mPendingDismiss != null && mPendingDismiss.rowContainer.dataContainerHasBeenDismissed;
}

/**
 * If a view was dismissed and the undo container is showing it will undo and make the data
 * container reappear.
 * @return whether there were any pending rows to be dismissed.
 */
public boolean undoPendingDismiss() {
    boolean existPendingDismisses = existPendingDismisses();
    if (existPendingDismisses) {
        mPendingDismiss.rowContainer.undoContainer.setVisibility(View.GONE);
        mPendingDismiss.rowContainer.dataContainer
                .animate()
                .translationX(0)
                .alpha(1)
                .setDuration(mAnimationTime)
                .setListener(null);
        mPendingDismiss = null;
    }
    return existPendingDismisses;
}

private void processPendingDismisses(final PendingDismissData pendingDismissData) {
    mPendingDismiss = null;
    final ViewGroup.LayoutParams lp = pendingDismissData.rowContainer.container.getLayoutParams();
    final int originalHeight = pendingDismissData.rowContainer.container.getHeight();

    ValueAnimator animator = ValueAnimator.ofInt(originalHeight, 1).setDuration(mAnimationTime);

    animator.addListener(new AnimatorListenerAdapter() {
        @Override
        public void onAnimationEnd(Animator animation) {
            if (mCallbacks.canDismiss(pendingDismissData.position))
                mCallbacks.onDismiss(mRecyclerView, pendingDismissData.position);
            pendingDismissData.rowContainer.dataContainer.post(new Runnable() {
                @Override
                public void run() {
                    pendingDismissData.rowContainer.dataContainer.setTranslationX(0);
                    pendingDismissData.rowContainer.dataContainer.setAlpha(1);
                    pendingDismissData.rowContainer.undoContainer.setVisibility(View.GONE);
                    pendingDismissData.rowContainer.undoContainer.setTranslationX(0);
                    pendingDismissData.rowContainer.undoContainer.setAlpha(1);

                    lp.height = originalHeight;
                    pendingDismissData.rowContainer.container.setLayoutParams(lp);
                }
            });
        }
    });

    animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator valueAnimator) {
            lp.height = (Integer) valueAnimator.getAnimatedValue();
            pendingDismissData.rowContainer.container.setLayoutParams(lp);
        }
    });

    animator.start();
}

}

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