/* * Copyright (C) 2013 The Android Open Source Project * https://android.googlesource.com/platform/development/+/master/samples/devbytes/animation/ListViewDraggingAnimation/src/com/example/android/listviewdragginganimation/DynamicListView.java * Modified by Ziver Koc * * 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.zepchat.app.util;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ObjectAnimator;
import android.animation.TypeEvaluator;
import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewTreeObserver;
import android.widget.AbsListView;
import android.widget.ListAdapter;
import android.widget.ListView;

/**
 * The dynamic listview is an extension of listview that supports cell dragging
 * and swapping.
 * <p/>
 * This layout is in charge of positioning the hover cell in the correct location
 * on the screen in response to user touch events. It uses the position of the
 * hover cell to determine when two cells should be swapped. If two cells should
 * be swapped, all the corresponding data set and layout changes are handled here.
 * <p/>
 * If no cell is selected, all the touch events are passed down to the listview
 * and behave normally. If one of the items in the listview experiences a
 * long press event, the contents of its current visible state are captured as
 * a bitmap and its visibility is set to INVISIBLE. A hover cell is then created and
 * added to this layout as an overlaying BitmapDrawable above the listview. Once the
 * hover cell is translated some distance to signify an item swap, a data set change
 * accompanied by animation takes place. When the user releases the hover cell,
 * it animates into its corresponding position in the listview.
 * <p/>
 * When the hover cell is either above or below the bounds of the listview, this
 * listview also scrolls on its own so as to reveal additional content.
 */
public class DynamicListView extends ListView {
    private static final int INVALID_POINTER_ID = -1;
    private static final int INVALID_ID = -1;
    private static final int SMOOTH_SCROLL_AMOUNT_AT_EDGE = 15;
    private static final int MOVE_DURATION = 150;
    private static final int LINE_THICKNESS = 15;
    private static final int REMOVE_OFFSET = 150;
    private static final int SWAP_OFFSET = 130;

    private static enum TouchMode {UNKNOWN, REMOVE, SWAP}

    ;
    private int mDownY = -1;
    private int mDownX = -1;
    private int mLastEventX = -1;
    private int mLastEventY = -1;
    private int mTotalOffset = 0;
    private boolean mCellIsMobile = false;
    private boolean mIsMobileScrolling = false;
    private int mSmoothScrollAmountAtEdge = 0;
    private long mAboveItemId = INVALID_ID;
    private long mMobileItemId = INVALID_ID;
    private long mBelowItemId = INVALID_ID;
    private BitmapDrawable mHoverCell;
    private TouchMode mMode;
    private Rect mHoverCellCurrentBounds;
    private Rect mHoverCellOriginalBounds;
    private int mActivePointerId = INVALID_POINTER_ID;
    private boolean mIsWaitingForScrollFinish = false;
    private int mScrollState = OnScrollListener.SCROLL_STATE_IDLE;
    private DynamicListActionListener listener;

    public DynamicListView(Context context) {
        super(context);
        init(context);
    }

    public DynamicListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public DynamicListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context);
    }

    public void init(Context context) {
        setOnScrollListener(mScrollListener);
        DisplayMetrics metrics = context.getResources().getDisplayMetrics();
        mSmoothScrollAmountAtEdge = (int) (SMOOTH_SCROLL_AMOUNT_AT_EDGE / metrics.density);
    }

    public void setActionListener(DynamicListActionListener l) {
        listener = l;
    }

    /**
     * Creates the hover cell with the appropriate bitmap and of appropriate * size. The hover cell's BitmapDrawable is drawn on top of the bitmap every * single time an invalidate call is made.
     */
    private BitmapDrawable getAndAddHoverView(View v) {
        int w = v.getWidth();
        int h = v.getHeight();
        int top = v.getTop();
        int left = v.getLeft();
        mHoverCellOriginalBounds = new Rect(left, top, left + w, top + h);
        mHoverCellCurrentBounds = new Rect(mHoverCellOriginalBounds);
        BitmapDrawable drawable = new BitmapDrawable(getResources(), getBitmapWithBorder(v));
        drawable.setBounds(mHoverCellCurrentBounds);
        return drawable;
    }

    /**
     * Draws a black border over the screenshot of the view passed in.
     */
    private Bitmap getBitmapWithBorder(View v) {
        Bitmap bitmap = Bitmap.createBitmap(v.getWidth(), v.getHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        v.draw(canvas);
        addBorder(bitmap, Color.BLACK);
        return bitmap;
    }

    private void addBorder(Bitmap b, int color) {
        Paint paint = new Paint();
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(LINE_THICKNESS);
        paint.setColor(color);
        Canvas canvas = new Canvas(b);
        canvas.drawRect(new Rect(0, 0, b.getWidth(), b.getHeight()), paint);
    }

    /**
     * Stores a reference to the views above and below the item currently * corresponding to the hover cell. It is important to note that if this * item is either at the top or bottom of the list, mAboveItemId or mBelowItemId * may be invalid.
     */
    private void updateNeighborViewsForID(long itemID) {
        int position = getPositionForID(itemID);
        ListAdapter adapter = getAdapter();
        mAboveItemId = adapter.getItemId(position - 1);
        mBelowItemId = adapter.getItemId(position + 1);
    }

    /**
     * Retrieves the view in the list corresponding to itemID
     */
    public View getViewForID(long itemID) {
        int firstVisiblePosition = getFirstVisiblePosition();
        ListAdapter adapter = getAdapter();
        for (int i = 0; i < getChildCount(); i++) {
            View v = getChildAt(i);
            int position = firstVisiblePosition + i;
            long id = adapter.getItemId(position);
            if (id == itemID) {
                return v;
            }
        }
        return null;
    }

    /**
     * Retrieves the position in the list corresponding to itemID
     */
    public int getPositionForID(long itemID) {
        View v = getViewForID(itemID);
        if (v == null) {
            return -1;
        } else {
            return getPositionForView(v);
        }
    }

    /**
     * dispatchDraw gets invoked when all the child views are about to be drawn. * By overriding this method, the hover cell (BitmapDrawable) can be drawn * over the listview's items whenever the listview is redrawn.
     */
    @Override
    protected void dispatchDraw(Canvas canvas) {
        super.dispatchDraw(canvas);
        if (mHoverCell != null) {
            mHoverCell.draw(canvas);
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (listener != null) {
            switch (event.getAction() & MotionEvent.ACTION_MASK) {
                case MotionEvent.ACTION_DOWN:
                    mDownX = (int) event.getX();
                    mDownY = (int) event.getY();
                    mActivePointerId = event.getPointerId(0);
                    mMode = TouchMode.UNKNOWN;
                    break;
                case MotionEvent.ACTION_MOVE:
                    if (mActivePointerId == INVALID_POINTER_ID) {
                        break;
                    }
                    int pointerIndex = event.findPointerIndex(mActivePointerId);
                    mLastEventX = (int) event.getX(pointerIndex);
                    mLastEventY = (int) event.getY(pointerIndex);
                    int deltaX = mLastEventX - mDownX;
                    int deltaY = mLastEventY - mDownY;
                    if (mMode == TouchMode.UNKNOWN) {
                        if (Math.abs(deltaX) > 100 || Math.abs(deltaY) > 50) {
                            if (Math.abs(deltaX) >= Math.abs(deltaY)) mMode = TouchMode.REMOVE;
                            if (Math.abs(deltaX) < Math.abs(deltaY) && mDownX < SWAP_OFFSET) mMode = TouchMode.SWAP;
                            if (mMode != TouchMode.UNKNOWN) startItemHover();
                        }
                    }
                    if (mMode == TouchMode.REMOVE) {
                        mHoverCellCurrentBounds.offsetTo(mHoverCellOriginalBounds.left + deltaX, mHoverCellOriginalBounds.top);
                        mHoverCell.setBounds(mHoverCellCurrentBounds);
                        if (mLastEventX + REMOVE_OFFSET > this.getRight()) addBorder(mHoverCell.getBitmap(), Color.RED);
                        else addBorder(mHoverCell.getBitmap(), Color.BLACK);
                        invalidate();
                        return false;
                    } else if (mMode == TouchMode.SWAP) {
                        if (mCellIsMobile) {
                            mHoverCellCurrentBounds.offsetTo(mHoverCellOriginalBounds.left, mHoverCellOriginalBounds.top + deltaY + mTotalOffset);
                            mHoverCell.setBounds(mHoverCellCurrentBounds);
                            invalidate();
                            handleCellSwitch();
                            mIsMobileScrolling = false;
                            handleMobileCellScroll();
                            return false;
                        }
                    }
                    break;
                case MotionEvent.ACTION_UP:
                    touchEventsEnded();
                    break;
                case MotionEvent.ACTION_CANCEL:
                    touchEventsCancelled();
                    break;
                case MotionEvent.ACTION_POINTER_UP: /* If a multitouch event took place and the original touch dictating * the movement of the hover cell has ended, then the dragging event * ends and the hover cell is animated to its corresponding position * in the listview. */
                    pointerIndex = (event.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
                    final int pointerId = event.getPointerId(pointerIndex);
                    if (pointerId == mActivePointerId) {
                        touchEventsEnded();
                    }
                    break;
                default:
                    break;
            }
        }
        return super.onTouchEvent(event);
    }

    protected void startItemHover() {
        mTotalOffset = 0;
        int position = pointToPosition(mDownX, mDownY);
        int itemNum = position - getFirstVisiblePosition();
        View selectedView = getChildAt(itemNum);
        if (selectedView != null) {
            mMobileItemId = getAdapter().getItemId(position);
            mHoverCell = getAndAddHoverView(selectedView);
            selectedView.setVisibility(INVISIBLE);
            mCellIsMobile = true;
            updateNeighborViewsForID(mMobileItemId);
        } else {
            // Invalid position, reset
            mMode = TouchMode.UNKNOWN;
        }
    }

    /**
     * This method determines whether the hover cell has been shifted far enough
     * to invoke a cell swap. If so, then the respective cell swap candidate is
     * determined and the data set is changed. Upon posting a notification of the
     * data set change, a layout is invoked to place the cells in the right place.
     * Using a ViewTreeObserver and a corresponding OnPreDrawListener, we can
     * offset the cell being swapped to where it previously was and then animate it to
     * its new position.
     */
    private void handleCellSwitch() {
        final int deltaY = mLastEventY - mDownY;
        int deltaYTotal = mHoverCellOriginalBounds.top + mTotalOffset + deltaY;
        View belowView = getViewForID(mBelowItemId);
        View mobileView = getViewForID(mMobileItemId);
        View aboveView = getViewForID(mAboveItemId);
        boolean isBelow = (belowView != null) && (deltaYTotal > belowView.getTop());
        boolean isAbove = (aboveView != null) && (deltaYTotal < aboveView.getTop());
        if (isBelow || isAbove) {
            final long switchItemID = isBelow ? mBelowItemId : mAboveItemId;
            View switchView = isBelow ? belowView : aboveView;
            final int originalItem = getPositionForView(mobileView);
            if (switchView == null) {
                updateNeighborViewsForID(mMobileItemId);
                return;
            }
            listener.swapItems(originalItem, getPositionForView(switchView));
            ((StableArrayAdapter) getAdapter()).notifyDataSetChanged();
            mDownY = mLastEventY;
            mobileView.setVisibility(View.VISIBLE);
            switchView.setVisibility(View.INVISIBLE);
            updateNeighborViewsForID(mMobileItemId);
            final int switchViewStartTop = switchView.getTop();
            final ViewTreeObserver observer = getViewTreeObserver();
            observer.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
                public boolean onPreDraw() {
                    observer.removeOnPreDrawListener(this);
                    View switchView = getViewForID(switchItemID);
                    mTotalOffset += deltaY;
                    int switchViewNewTop = switchView.getTop();
                    int delta = switchViewStartTop - switchViewNewTop;
                    switchView.setTranslationY(delta);
                    ObjectAnimator animator = ObjectAnimator.ofFloat(switchView, View.TRANSLATION_Y, 0);
                    animator.setDuration(MOVE_DURATION);
                    animator.start();
                    return true;
                }
            });
        }
    }

    /**
     * Resets all the appropriate fields to a default state while also animating * the hover cell back to its correct location.
     */
    private void touchEventsEnded() {
        final View mobileView = getViewForID(mMobileItemId);
        if (mCellIsMobile || mIsWaitingForScrollFinish) {
            mCellIsMobile = false;
            mIsWaitingForScrollFinish = false;
            mIsMobileScrolling = false;
            mActivePointerId = INVALID_POINTER_ID;
            // If the autoscroller has not completed scrolling, we need to wait for it to
            //bfinish in order to determine the final location of where the hover cell
            // should be animated to.
            if (mScrollState != OnScrollListener.SCROLL_STATE_IDLE) {
                mIsWaitingForScrollFinish = true;
                return;
            }
            if (mMode == TouchMode.REMOVE) {
                if (mLastEventX + REMOVE_OFFSET > mobileView.getRight()) {
                    listener.removeItem(getPositionForView(mobileView));
                    ((StableArrayAdapter) getAdapter()).notifyDataSetChanged();
                    mHoverCellCurrentBounds.offsetTo(this.getRight(), mHoverCellCurrentBounds.top);
                } else
                    // reset
                    mHoverCellCurrentBounds.offsetTo(mHoverCellOriginalBounds.left, mobileView.getTop());
            } else if (mMode == TouchMode.SWAP) {
                mHoverCellCurrentBounds.offsetTo(mHoverCellOriginalBounds.left, mobileView.getTop());
            } // Animate
            ObjectAnimator hoverViewAnimator = ObjectAnimator.ofObject(mHoverCell, "bounds", sBoundEvaluator, mHoverCellCurrentBounds);
            hoverViewAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator valueAnimator) {
                    invalidate();
                }
            });
            hoverViewAnimator.addListener(new AnimatorListenerAdapter() {
                @Override
                public void onAnimationStart(Animator animation) {
                    setEnabled(false);
                }

                @Override
                public void onAnimationEnd(Animator animation) {
                    mAboveItemId = INVALID_ID;
                    mMobileItemId = INVALID_ID;
                    mBelowItemId = INVALID_ID;
                    mobileView.setVisibility(VISIBLE);
                    mHoverCell = null;
                    setEnabled(true);
                    invalidate();
                }
            });
            hoverViewAnimator.start();
        } else {
            touchEventsCancelled();
        }
    }

    /**
     * Resets all the appropriate fields to a default state.
     */
    private void touchEventsCancelled() {
        View mobileView = getViewForID(mMobileItemId);
        if (mCellIsMobile) {
            mAboveItemId = INVALID_ID;
            mMobileItemId = INVALID_ID;
            mBelowItemId = INVALID_ID;
            mobileView.setVisibility(VISIBLE);
            mHoverCell = null;
            invalidate();
        }
        mCellIsMobile = false;
        mIsMobileScrolling = false;
        mActivePointerId = INVALID_POINTER_ID;
    }

    /**
     * This TypeEvaluator is used to animate the BitmapDrawable back to its * final location when the user lifts his finger by modifying the * BitmapDrawable's bounds.
     */
    private final static TypeEvaluator<Rect> sBoundEvaluator = new TypeEvaluator<Rect>() {
        public Rect evaluate(float fraction, Rect startValue, Rect endValue) {
            return new Rect(interpolate(startValue.left, endValue.left, fraction), interpolate(startValue.top, endValue.top, fraction), interpolate(startValue.right, endValue.right, fraction), interpolate(startValue.bottom, endValue.bottom, fraction));
        }

        public int interpolate(int start, int end, float fraction) {
            return (int) (start + fraction * (end - start));
        }
    };

    /**
     * Determines whether this listview is in a scrolling state invoked * by the fact that the hover cell is out of the bounds of the listview;
     */
    private void handleMobileCellScroll() {
        mIsMobileScrolling = handleMobileCellScroll(mHoverCellCurrentBounds);
    }

    /**
     * This method is in charge of determining if the hover cell is above * or below the bounds of the listview. If so, the listview does an appropriate * upward or downward smooth scroll so as to reveal new items.
     */
    public boolean handleMobileCellScroll(Rect r) {
        int offset = computeVerticalScrollOffset();
        int height = getHeight();
        int extent = computeVerticalScrollExtent();
        int range = computeVerticalScrollRange();
        int hoverViewTop = r.top;
        int hoverHeight = r.height();
        if (hoverViewTop <= 0 && offset > 0) {
            smoothScrollBy(-mSmoothScrollAmountAtEdge, 0);
            return true;
        }
        if (hoverViewTop + hoverHeight >= height && (offset + extent) < range) {
            smoothScrollBy(mSmoothScrollAmountAtEdge, 0);
            return true;
        }
        return false;
    }

    /**
     * This scroll listener is added to the listview in order to handle cell swapping
     * when the cell is either at the top or bottom edge of the listview. If the hover
     * cell is at either edge of the listview, the listview will begin scrolling. As
     * scrolling takes place, the listview continuously checks if new cells became visible
     * and determines whether they are potential candidates for a cell swap.
     */
    private AbsListView.OnScrollListener mScrollListener = new AbsListView.OnScrollListener() {
        private int mPreviousFirstVisibleItem = -1;
        private int mPreviousVisibleItemCount = -1;
        private int mCurrentFirstVisibleItem;
        private int mCurrentVisibleItemCount;
        private int mCurrentScrollState;

        public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
            mCurrentFirstVisibleItem = firstVisibleItem;
            mCurrentVisibleItemCount = visibleItemCount;
            mPreviousFirstVisibleItem = (mPreviousFirstVisibleItem == -1) ? mCurrentFirstVisibleItem : mPreviousFirstVisibleItem;
            mPreviousVisibleItemCount = (mPreviousVisibleItemCount == -1) ? mCurrentVisibleItemCount : mPreviousVisibleItemCount;
            checkAndHandleFirstVisibleCellChange();
            checkAndHandleLastVisibleCellChange();
            mPreviousFirstVisibleItem = mCurrentFirstVisibleItem;
            mPreviousVisibleItemCount = mCurrentVisibleItemCount;
        }

        @Override
        public void onScrollStateChanged(AbsListView view, int scrollState) {
            mCurrentScrollState = scrollState;
            mScrollState = scrollState;
            isScrollCompleted();
        }

        /**
         * This method is in charge of invoking 1 of 2 actions. Firstly, if the listview
         * is in a state of scrolling invoked by the hover cell being outside the bounds
         * of the listview, then this scrolling event is continued. Secondly, if the hover
         * cell has already been released, this invokes the animation for the hover cell
         * to return to its correct position after the listview has entered an idle scroll
         * state.
         */
        private void isScrollCompleted() {
            if (mCurrentVisibleItemCount > 0 && mCurrentScrollState == SCROLL_STATE_IDLE) {
                if (mCellIsMobile && mIsMobileScrolling) {
                    handleMobileCellScroll();
                } else if (mIsWaitingForScrollFinish) {
                    touchEventsEnded();
                }
            }
        }

        /**
         * Determines if the listview scrolled up enough to reveal a new cell at the
         * top of the list. If so, then the appropriate parameters are updated.
         */
        public void checkAndHandleFirstVisibleCellChange() {
            if (mCurrentFirstVisibleItem != mPreviousFirstVisibleItem) {
                if (mCellIsMobile && mMobileItemId != INVALID_ID) {
                    updateNeighborViewsForID(mMobileItemId);
                    handleCellSwitch();
                }
            }
        }

        /**
         * Determines if the listview scrolled down enough to reveal a new cell at the
         * bottom of the list. If so, then the appropriate parameters are updated.
         */
        public void checkAndHandleLastVisibleCellChange() {
            int currentLastVisibleItem = mCurrentFirstVisibleItem + mCurrentVisibleItemCount;
            int previousLastVisibleItem = mPreviousFirstVisibleItem + mPreviousVisibleItemCount;
            if (currentLastVisibleItem != previousLastVisibleItem) {
                if (mCellIsMobile && mMobileItemId != INVALID_ID) {
                    updateNeighborViewsForID(mMobileItemId);
                    handleCellSwitch();
                }
            }
        }
    };

    public static interface DynamicListActionListener {
        public void swapItems(int from, int to);

        public void removeItem(int which);
    }
}