Android Open Source - ListView-Swipe-to-Delete Item Exp List Gesture Detector

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License

The source code is released under:
Apache License
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Java Source Code

/*
 * Copyright (C) 2013 Steelkiwi Development, Julia Zudikova
 * /*from w  w w.j  a  va 2s  . c o  m*/
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.skd.swipetodelete.explist;

import android.util.DisplayMetrics;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.MotionEvent;
import android.widget.ExpandableListView;

/*
 * Represents a class detecting gestures on an expandable list view item:
 * - single tap -> opens item menu;
 * - swipe from left to right -> marks item as removed;
 * - swipe from right to left -> undoes item's removal.
 */

public class ItemExpListGestureDetector extends SimpleOnGestureListener {
  private int REL_SWIPE_MIN_DISTANCE;
  private int REL_SWIPE_MAX_OFF_PATH;
  private int REL_SWIPE_THRESHOLD_VELOCITY;
  
  private int temp_position = -1;

  private ItemBaseExpListHandler itemListHandler;
  
  public ItemExpListGestureDetector(DisplayMetrics dm, ItemBaseExpListHandler itemListHandler) {
    REL_SWIPE_MIN_DISTANCE = (int) (120.0f * dm.densityDpi / 160.0f + 0.5);
    REL_SWIPE_MAX_OFF_PATH = (int) (250.0f * dm.densityDpi / 160.0f + 0.5);
    REL_SWIPE_THRESHOLD_VELOCITY = (int) (200.0f * dm.densityDpi / 160.0f + 0.5);
    this.itemListHandler = itemListHandler;
  }

  @Override
  public boolean onSingleTapUp(MotionEvent e) {
    int pos = itemListHandler.getListView().pointToPosition((int) e.getX(), (int) e.getY());
    if (pos < 0) { return true; }
    long expPos = itemListHandler.getListView().getExpandableListPosition(pos);
    int groupPos = ExpandableListView.getPackedPositionGroup(expPos);
    int childPos = ExpandableListView.getPackedPositionChild(expPos);
    if (childPos >= 0) {
      itemListHandler.onItemClicked(groupPos, childPos);
    }
    else {
      itemListHandler.onGroupClicked(groupPos);
    }
    return true;
  }

  @Override
  public boolean onDown(MotionEvent e) {
    temp_position = itemListHandler.getListView().pointToPosition((int) e.getX(), (int) e.getY());
    return super.onDown(e);
  }

  @Override
  public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
    if (Math.abs(e1.getY() - e2.getY()) > REL_SWIPE_MAX_OFF_PATH) { return false; }
    if ((e1.getX() - e2.getX() > REL_SWIPE_MIN_DISTANCE) &&
      (Math.abs(velocityX) > REL_SWIPE_THRESHOLD_VELOCITY)) {
      int pos = itemListHandler.getListView().pointToPosition((int) e1.getX(), (int) e2.getY());
      if (pos >= 0 && temp_position == pos) {
        long expPos = itemListHandler.getListView().getExpandableListPosition(pos);
        int groupPos = ExpandableListView.getPackedPositionGroup(expPos);
        int childPos = ExpandableListView.getPackedPositionChild(expPos);
        if (childPos >= 0) {
          itemListHandler.onItemSwiped(false, groupPos, childPos);
        }
      }
    }
    else if ((e2.getX() - e1.getX() > REL_SWIPE_MIN_DISTANCE) && 
         (Math.abs(velocityX) > REL_SWIPE_THRESHOLD_VELOCITY)) {
      int pos = itemListHandler.getListView().pointToPosition((int) e1.getX(), (int) e2.getY());
      if (pos >= 0 && temp_position == pos) {
        long expPos = itemListHandler.getListView().getExpandableListPosition(pos);
        int groupPos = ExpandableListView.getPackedPositionGroup(expPos);
        int childPos = ExpandableListView.getPackedPositionChild(expPos);
        if (childPos >= 0) {
          itemListHandler.onItemSwiped(true, groupPos, childPos);
        }
      }
    }
    return false;
  }
}
Java Source Code List
