edu.uark.spARK.SwipeDismissListViewTouchListener.java Source code

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Here is the source code for edu.uark.spARK.SwipeDismissListViewTouchListener.java

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/*
 * Copyright 2013 Google Inc.
 *
 * 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 edu.uark.spARK;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ValueAnimator;
import android.graphics.Rect;
import android.os.SystemClock;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.RelativeLayout;

/**
 * A {@link android.view.View.OnTouchListener} that makes the list items in a {@link ListView}
 * dismissable. {@link ListView} is given special treatment because by default it handles touches
 * for its list items... i.e. it's in charge of drawing the pressed state (the list selector),
 * handling list item clicks, etc.
 *
 * <p>After creating the listener, the caller should also call {@link
 * ListView#setOnScrollListener(android.widget.AbsListView.OnScrollListener)}, passing in the scroll
 * listener returned by {@link #makeScrollListener()}. If a scroll listener is already assigned, the
 * caller should still pass scroll changes through to this listener. This will ensure that this
 * {@link SwipeDismissListViewTouchListener} is paused during list view scrolling.</p>
 *
 * <p>Example usage:</p>
 *
 * <pre>
//         SwipeDismissListViewTouchListener touchListener =
//                                  new SwipeDismissListViewTouchListener(
//                                                  mListView,
//                                          new SwipeDismissListViewTouchListener.DismissCallbacks() {
//                                              public void onDismiss(ListView listView, int[] reverseSortedPositions) {
//                                                  for (int position : reverseSortedPositions) {
//                                                          arrayListContent.remove(arrayListContent.get(position));
//                                                  }
//                                                  mAdapter.notifyDataSetChanged();
//                                              }
//
//                                                                        @Override
//                                                                        public boolean canDismiss(int position) {
//                                                                                // TODO Auto-generated method stub
//                                                                                return true;
//                                                                        }
//                                          });
//                          mListView.setOnTouchListener(touchListener);
//                          mListView.setOnScrollListener(touchListener.makeScrollListener());
 * </pre>
 *
 * <p>This class Requires API level 12 or later due to use of {@link
 * android.view.ViewPropertyAnimator}.</p>
 */
public class SwipeDismissListViewTouchListener implements View.OnTouchListener {

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

    // Fixed properties
    private ListView mListView;
    private DismissCallbacks mCallbacks;
    private int mViewWidth = 1; // 1 and not 0 to prevent dividing by zero

    // Transient properties
    private List<PendingDismissData> mPendingDismisses = new ArrayList<PendingDismissData>();
    private int mDismissAnimationRefCount = 0;
    private float mDownX;
    public boolean mSwiping;
    private VelocityTracker mVelocityTracker;
    private int mDownPosition;
    private View mDownView;
    private boolean mPaused;

    // Custom long press properties
    private static final int MIN_CLICK_DURATION = 1000;
    private boolean longClickActive;
    private long clickDuration;

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

        /**
         * Called when the user has indicated they she would like to dismiss one or more list item
         * positions.
         *
         * @param listView               The originating {@link ListView}.
         * @param reverseSortedPositions An array of positions to dismiss, sorted in descending
         *                               order for convenience.
         */
        void onDismiss(ListView listView, int[] reverseSortedPositions);
    }

    /**
     * Constructs a new swipe-to-dismiss touch listener for the given list view.
     *
     * @param listView  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 SwipeDismissListViewTouchListener(ListView listView, DismissCallbacks callbacks) {
        ViewConfiguration vc = ViewConfiguration.get(listView.getContext());
        mSlop = vc.getScaledTouchSlop();
        mMinFlingVelocity = vc.getScaledMinimumFlingVelocity() * 16;
        mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity();
        mAnimationTime = listView.getContext().getResources().getInteger(android.R.integer.config_shortAnimTime);
        mListView = listView;
        mCallbacks = callbacks;
    }

    /**
     * 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;
    }

    /**
     * Returns an {@link android.widget.AbsListView.OnScrollListener} to be added to the {@link
     * ListView} using {@link 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 SwipeDismissListViewTouchListener} is
     * paused during list view scrolling.</p>
     *
     * @see SwipeDismissListViewTouchListener
     */
    public AbsListView.OnScrollListener makeScrollListener() {
        return new AbsListView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(AbsListView absListView, int scrollState) {
                setEnabled(scrollState != AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL);
            }

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

    /**
     * Manually cause the item at the given position to be dismissed (trigger the dismiss
     * animation).
     */
    public void dismiss(int position) {
        dismiss(getViewForPosition(position), position, true);
    }

    @Override
    public boolean onTouch(View view, MotionEvent motionEvent) {
        if (mViewWidth < 2) {
            mViewWidth = mListView.getWidth();
        }
        switch (motionEvent.getActionMasked()) {
        case MotionEvent.ACTION_DOWN: {
            mPaused = false;
            longClickActive = false;
            //                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 = mListView.getChildCount();
            int[] listViewCoords = new int[2];
            mListView.getLocationOnScreen(listViewCoords);
            int x = (int) motionEvent.getRawX() - listViewCoords[0];
            int y = (int) motionEvent.getRawY() - listViewCoords[1];
            View child;

            //ignore header views
            for (int i = 1; i < childCount; i++) {
                child = mListView.getChildAt(i);
                child.getHitRect(rect);
                if (rect.contains(x, y)) {
                    mDownView = child;
                    break;
                }
            }
            if (mDownView != null) {
                mDownView = mDownView.findViewById(R.id.table);
                mDownX = motionEvent.getRawX();
                //TODO: really need to figure out why npe is happening here
                try {
                    mDownPosition = mListView.getPositionForView(mDownView);
                } catch (NullPointerException npe) {
                    //why does this keep happening?
                    npe.printStackTrace();
                }
                if (mCallbacks.canDismiss(mDownPosition)) {
                    mVelocityTracker = VelocityTracker.obtain();
                    mVelocityTracker.addMovement(motionEvent);
                } else {
                    mDownView = null;
                }
            }
            view.onTouchEvent(motionEvent);
            return true;
        }

        case MotionEvent.ACTION_UP: {
            if (longClickActive) {
                RelativeLayout darkenTop = (RelativeLayout) mListView.getRootView()
                        .findViewById(R.id.darkenScreenTop);
                ImageView darkenBottom = (ImageView) mListView.getRootView().findViewById(R.id.darkenScreenBottom);
                darkenTop.animate().alpha(0).setDuration(mAnimationTime).setListener(null);
                darkenBottom.animate().alpha(0).setDuration(mAnimationTime).setListener(null);
                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) {
                    dismiss = true;
                    dismissRight = deltaX > 0;
                } else if (mMinFlingVelocity <= absVelocityX && absVelocityX <= mMaxFlingVelocity
                        && absVelocityY < absVelocityX) {
                    // dismiss only if flinging in the same direction as dragging
                    dismiss = (velocityX < 0) == (deltaX < 0);
                    dismissRight = mVelocityTracker.getXVelocity() > 0;
                }
                if (dismiss) {
                    // dismiss
                    dismiss(mDownView, mDownPosition, dismissRight);
                } else {
                    // cancel
                    mDownView.animate().translationX(0).alpha(1).setDuration(mAnimationTime).setListener(null);
                }
                mVelocityTracker.recycle();
                mVelocityTracker = null;
                mDownX = 0;
                mDownView = null;
                mDownPosition = ListView.INVALID_POSITION;
                mSwiping = false;
            }
            break;
        }

        case MotionEvent.ACTION_CANCEL: {
            longClickActive = false;
            mPaused = false;
            RelativeLayout darkenTop = (RelativeLayout) mListView.getRootView().findViewById(R.id.darkenScreenTop);
            ImageView darkenBottom = (ImageView) mListView.getRootView().findViewById(R.id.darkenScreenBottom);

            darkenTop.animate().alpha(0).setDuration(mAnimationTime).setListener(null);
            darkenBottom.animate().alpha(0).setDuration(mAnimationTime).setListener(null);

            if (mVelocityTracker == null) {
                break;
            }

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

        case MotionEvent.ACTION_MOVE: {
            if (mVelocityTracker == null || mPaused) {
                break;
            }
            if (longClickActive) {
                mVelocityTracker.addMovement(motionEvent);
                float deltaX = motionEvent.getRawX() - mDownX;
                //the if statement is allowing the listview to scroll until a sufficient deltaX is made, while we want swiping immediately 
                //                        if (Math.abs(deltaX) > mSlop) {
                mSwiping = true;
                mListView.requestDisallowInterceptTouchEvent(true);

                // Cancel ListView's touch (un-highlighting the item) which is not what we want
                MotionEvent cancelEvent = MotionEvent.obtain(motionEvent);
                cancelEvent.setAction(MotionEvent.ACTION_CANCEL
                        | (motionEvent.getActionIndex() << MotionEvent.ACTION_POINTER_INDEX_SHIFT));
                mListView.onTouchEvent(cancelEvent);
                cancelEvent.recycle();
                //                        }
                if (mSwiping) {

                    mDownView.setTranslationX(deltaX);
                    //we don't want the alpha to change
                    //                    mDownView.setAlpha(Math.max(0.15f, Math.min(1f,
                    //                            1f - 2f * Math.abs(deltaX) / mViewWidth)));
                    return true;
                }
            }
            break;
        }
        }
        return false;
    }

    private void dismiss(final View view, final int position, boolean dismissRight) {
        ++mDismissAnimationRefCount;
        if (view == null) {
            // No view, shortcut to calling onDismiss to let it deal with adapter
            // updates and all that.
            mCallbacks.onDismiss(mListView, new int[] { position });
            return;
        }

        view.animate().translationX(dismissRight ? mViewWidth : -mViewWidth).alpha(0).setDuration(mAnimationTime)
                .setListener(new AnimatorListenerAdapter() {
                    @Override
                    public void onAnimationEnd(Animator animation) {
                        performDismiss(view, position);
                    }
                });
    }

    private View getViewForPosition(int position) {

        int index = position - (mListView.getFirstVisiblePosition() - mListView.getHeaderViewsCount());
        return (index >= 0 && index < mListView.getChildCount()) ? mListView.getChildAt(index) : null;
    }

    class PendingDismissData implements Comparable<PendingDismissData> {
        public int position;
        public View view;

        public PendingDismissData(int position, View view) {
            this.position = position;
            this.view = view;
        }

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

    private void performDismiss(final View dismissView, final 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.

        final ViewGroup.LayoutParams lp = dismissView.getLayoutParams();
        final int originalHeight = dismissView.getHeight();

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

        animator.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                --mDismissAnimationRefCount;
                if (mDismissAnimationRefCount == 0) {
                    // No active animations, process all pending dismisses.
                    // Sort by descending position
                    Collections.sort(mPendingDismisses);

                    int[] dismissPositions = new int[mPendingDismisses.size()];
                    for (int i = mPendingDismisses.size() - 1; i >= 0; i--) {
                        dismissPositions[i] = mPendingDismisses.get(i).position;
                    }
                    mCallbacks.onDismiss(mListView, dismissPositions);

                    ViewGroup.LayoutParams lp;
                    for (PendingDismissData pendingDismiss : mPendingDismisses) {
                        // Reset view presentation
                        pendingDismiss.view.setAlpha(1f);
                        pendingDismiss.view.setTranslationX(0);
                        lp = pendingDismiss.view.getLayoutParams();
                        lp.height = originalHeight;
                        pendingDismiss.view.setLayoutParams(lp);
                    }

                    mPendingDismisses.clear();
                }
            }
        });

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

        mPendingDismisses.add(new PendingDismissData(dismissPosition, dismissView));
        animator.start();
    }

    public void setLongClickActive(boolean b) {
        longClickActive = b;
    }

}