package com.freelib.multiitem.helper;
import android.support.annotation.NonNull;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.OrientationHelper;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.helper.ItemTouchHelper;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import com.freelib.multiitem.adapter.holder.BaseViewHolder;
import com.freelib.multiitem.listener.OnItemDragListener;
/**
* Created by free46000 on 2016/8/19.
* 面板拖动辅助类 -跨RecyclerView拖动
* <p>
* <b>计算横向和竖向的RecyclerView滚动</b>{@link #scrollIfNecessary(RecyclerView, int, int)}<br>
* 大量参考了`ItemTouchHelper`的源码，根据用户触摸位置计算是否需要滚动，和滚动的方向与距离 详见ItemDragListener的calcXXXScrollDistance() calcScrollXXXDirect()；
* 采用定时Runnable形式，保证持续的滚动；
* 滚动时调用Item位置计算方法，使得在滚动过程中也可以更换Item位置
* <p>
* <b>Item位置更换计算</b>{@link #moveIfNecessary(float, float)}<br>
* 触摸位置都为相对屏幕位置，方便后续计算
* 根据触摸位置horizontalRecycler.findChildViewUnder(x, y)找到垂直recyclerView的位置，若找到位置继续<br>
* 根据上一次垂直recyclerView所在的位置，判断是否为第一次选中或者是切换recyclerView的操作，此处可通过itemDragListener回调拦截此次操作的结果<br>
* 如果需要切换recyclerView的位置，此时需要对被拖动的Item进行remove，并在新的recyclerView中add进去<br>
* 根据触摸位置recyclerView.findChildViewUnder(itemX, itemY)找到itemView的位置<br>
* 根据上一次itemView所在的位置，判断是否需要移动itemView位置的操作，此处可通过itemDragListener回调拦截此次操作的结果<br>
* 如果需要移动动itemView位置则需要把recyclerView滚动到合适的位置，防recyclerView乱跳<br>
*/
public class ItemDragHelper {
public static final int NONE = -1;
private OnItemDragListener dragListener = new EmptyDragListener();
private RecyclerView horizontalRecycler;
private DragFloatViewHelper floatViewHelper;
private boolean isDrag;
private int lastRecyclerPos = NONE;
private RecyclerView lastRecyclerView;
private int lastItemPos = NONE;
private float lastTouchRawX;
private float lastTouchRawY;
private int itemViewHeight;
/**
* 横向滚动的RecyclerView
*
* @param horizontalRecycler
*/
public ItemDragHelper(@NonNull RecyclerView horizontalRecycler) {
this.horizontalRecycler = horizontalRecycler;
floatViewHelper = new DragFloatViewHelper();
}
/**
* 开始拖拽
*
* @param viewHolder 选中的Item的ViewHolder
*/
public void startDrag(@NonNull BaseViewHolder viewHolder) {
View itemView = viewHolder.itemView;
int itemPosition = viewHolder.getItemPosition();
dragListener.setItemViewHolder(viewHolder);
if (!dragListener.onItemSelected(itemView, itemPosition)) {
return;
}
isDrag = true;
initParams();
lastItemPos = itemPosition;
dragListener.onDragStart();
floatViewHelper.createView(itemView, lastTouchRawX, lastTouchRawY, dragListener.getScale());
dragListener.onDrawFloatView(floatViewHelper.getFloatView());
RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) itemView.getLayoutParams();
itemViewHeight = itemView.getHeight() + params.topMargin + params.bottomMargin;
}
private void initParams() {
lastRecyclerPos = NONE;
lastRecyclerView = null;
}
/**
* 设置拖拽回调Listener
*
* @param onItemDragListener 回调Listener
*/
public void setOnItemDragListener(@NonNull OnItemDragListener onItemDragListener) {
this.dragListener = onItemDragListener;
}
public RecyclerView getHorizontalRecycler() {
return horizontalRecycler;
}
/**
* 必须完整处理Touch事件，可以在Activity或者外层的ViewGroup或可以拦截Touch事件的地方回调都可以
*
* @param event touch的event
* @return true表示消耗掉事件
*/
public boolean onTouch(@NonNull MotionEvent event) {
lastTouchRawX = event.getRawX();
lastTouchRawY = event.getRawY();
if (!isDrag) {
return false;
}
//如果drag过程没有MOVE事件，lastVerticalPos和lastRecyclerView是不能被正确初始化的，这样dragFinish回调就会有问题
// if (event.getActionMasked() == MotionEvent.ACTION_MOVE) {
floatViewHelper.updateView((int) lastTouchRawX, (int) lastTouchRawY);
moveIfNecessary(lastTouchRawX, lastTouchRawY);
scrollRunnableStart();
// }
if (event.getActionMasked() == MotionEvent.ACTION_UP ||
event.getActionMasked() == MotionEvent.ACTION_CANCEL ||
event.getActionMasked() == MotionEvent.ACTION_OUTSIDE) {
stopDrag();
}
return true;
}
private void scrollRunnableStart() {
if (lastRecyclerView != null) {
lastRecyclerView.removeCallbacks(scrollRunnable);
scrollRunnable.run();
lastRecyclerView.invalidate();
}
}
private void stopDrag() {
if (isDrag) {
dragListener.onDragFinish(lastRecyclerView, lastRecyclerPos, lastItemPos);
floatViewHelper.removeView();
}
isDrag = false;
}
/**
* 当用户拖动的时候，计算是否需要移动Item
*
* @param touchRawX float event.getRawX()
* @param touchRawY float event.getRawY()
*/
private boolean moveIfNecessary(float touchRawX, float touchRawY) {
boolean result = true;
//找到当前触摸点下的recyclerView
float[] location = getInsideLocation(horizontalRecycler, touchRawX, touchRawY);
View view = horizontalRecycler.findChildViewUnder(location[0], location[1]);
int recyclerPos = getPositionByChildView(view);
// System.out.println("find_parent_out:lastRecPos:" + lastRecyclerPos + "-recPos:" + recyclerPos + "=loc0:" + location[0] + "=loc1:" + location[1]);
RecyclerView recyclerView = findRecyclerView(view);
//没有找到所属位置或者目标RecyclerView，则不继续
if (recyclerPos == NONE || recyclerView == null) {
return false;
}
//找到当前触摸点下的itemView
location = getInsideLocation(recyclerView, touchRawX, touchRawY);
float itemX = location[0];
float itemY = location[1];
View itemView = recyclerView.findChildViewUnder(itemX, itemY);
int itemPos = getTargetItemPos(itemView, itemY, lastRecyclerPos, recyclerPos);
// System.out.println("find_parent_out:lastItemPos:" + lastItemPos + "==itemPos:" + itemPos + "==childX:" + itemX + "===childY:" + itemY);
if (isSelectedRecyclerView(lastRecyclerPos, recyclerPos)) {
dragListener.onRecyclerSelected(recyclerView, recyclerPos);
lastRecyclerPos = recyclerPos;
lastRecyclerView = recyclerView;
} else if (isChangeRecyclerView(lastRecyclerPos, recyclerPos)) {
itemPos = calcItemPositionWhenChangeRecycler(recyclerView, itemView, itemPos, itemX, itemY);
// System.out.println("find_parent_inside:" + itemPos + "==" + lastRecyclerPos + "-" + recyclerPos + "==" + "childX:" + itemX + "childY:" + itemY);
if (itemPos != NONE) {
//当recycler change的时候，返回Recycler Position
recyclerPos = dragListener.onRecyclerChangedRecyclerPosition(lastRecyclerView, recyclerView,
lastItemPos, itemPos, lastRecyclerPos, recyclerPos);
//当recycler切换的时候，返回Item位置，有的Recycler不管touch在什么位置都要替换指定的item位置
itemPos = dragListener.onRecyclerChangedItemPosition(lastRecyclerView, recyclerView,
lastItemPos, itemPos, lastRecyclerPos, recyclerPos);
boolean isChanged = dragListener.onRecyclerChanged(lastRecyclerView, recyclerView,
lastItemPos, itemPos, lastRecyclerPos, recyclerPos);
if (!isChanged) {
return result;
}
// System.out.println("find_parent:" + lastRecyclerPos + "-" + verticalPos);
//在切换recycle view并且触摸到子recycle view的item的时候才真正去改变值
lastRecyclerPos = recyclerPos;
lastRecyclerView = recyclerView;
//因为切换父控件，所以需要重置为当前itemPos，不然上个的最后位置有可能超过当前的大小抛出错误
lastItemPos = itemPos;
}
}
if (itemPos == NONE) {
return result;
}
if (isItemNeedChange(itemView, lastItemPos, itemPos, itemY)) {
itemPos = dragListener.onItemChangedPosition(recyclerView, lastItemPos, itemPos, lastRecyclerPos);
boolean isChanged = dragListener.onItemChanged(recyclerView, lastItemPos, itemPos, lastRecyclerPos);
if (!isChanged) {
return result;
}
scrollToRightPositionWhenItemChanged(recyclerView, itemView, itemPos);
// System.out.println("find:" + lastRecyclerPos + "-" + recyclerPos + "======" + lastItemPos + "-" + itemPos);
lastItemPos = itemPos;
}
return result;
}
/**
* 当item位置变换，滚动recycler到正确的位置
* TODO: 2017/2/21 0021 整理更优雅的写法 还有scrollToPosition(0)是否必要？
*/
private void scrollToRightPositionWhenItemChanged(RecyclerView recyclerView, View itemView, int itemPos) {
final RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
if (layoutManager instanceof ItemTouchHelper.ViewDropHandler) {
OrientationHelper helper = OrientationHelper.createVerticalHelper(layoutManager);
int start = helper.getDecoratedStart(itemView);
int end = helper.getDecoratedEnd(itemView);
((LinearLayoutManager) layoutManager).scrollToPositionWithOffset(
itemPos, lastItemPos > itemPos ? start : end - itemViewHeight);
// System.out.println(lastItemPos + "-" + childPos + "OrientationHelperOrientationHelper:"
// + height + "==" + itemViewHeight + "=||=" + start + "===" + end + "||||||" + myStart + "===" + itemTargetView.getHeight() );
}
if (lastItemPos == 0 || itemPos == 0) {
recyclerView.scrollToPosition(0);
}
}
/**
* 获取当前点击的位置在RecyclerView内部的坐标 (Y坐标范围0+padding到height-padding)?
*/
private float[] getInsideLocation(RecyclerView recyclerView, float touchRawX, float touchRawY) {
float[] result = new float[2];
int[] location = new int[2];
recyclerView.getLocationOnScreen(location);
result[0] = touchRawX - location[0];
result[1] = touchRawY - location[1];
// System.out.println("getInsideLocation:" + result[0] + "-" + result[1] + "==" + "X:" + touchRawX + "Y:" + touchRawY);
result[0] = result[0] / dragListener.getScale();
result[1] = result[1] / dragListener.getScale();
int minY = recyclerView.getPaddingTop();
int maxY = recyclerView.getHeight() - recyclerView.getPaddingBottom();
result[1] = Math.min(Math.max(result[1], minY), maxY);
return result;
}
/**
* 当在两个RecyclerView中切换时，计算目标RecyclerView中Child位置 (若目标RecyclerView为空返回0)
*/
private int calcItemPositionWhenChangeRecycler(RecyclerView verticalRecycler, View itemView, int itemPos, float childX, float childY) {
//若目标RecyclerView为空返回0
if (itemPos == NONE && verticalRecycler.getAdapter().getItemCount() == 0) {
itemPos = 0;
} else if (itemView != null) {
int top = itemView.getTop();
if ((top + itemView.getHeight() * dragListener.getMoveLimit()) < childY) {
//证明滑动位置在targetView的下部，所以要插入到当前位置+1
itemPos++;
}
}
return itemPos;
}
/**
* 从view中获取需要操作的RecyclerView
*
* @param view View
*/
protected RecyclerView findRecyclerView(View view) {
if (view == null) {
return null;
}
if (view instanceof RecyclerView) {
return (RecyclerView) view;
} else if (view instanceof ViewGroup) {
ViewGroup viewGroup = (ViewGroup) view;
RecyclerView recyclerView;
for (int i = 0, count = viewGroup.getChildCount(); i < count; i++) {
recyclerView = findRecyclerView(viewGroup.getChildAt(i));
if (recyclerView != null) {
return recyclerView;
}
}
}
return null;
}
/**
* 滚动Runnable，为了可持续滚动
*/
private final Runnable scrollRunnable = new Runnable() {
@Override
public void run() {
float[] horLocation = getInsideLocation(horizontalRecycler, lastTouchRawX, lastTouchRawY);
float[] verLocation = getInsideLocation(lastRecyclerView, lastTouchRawX, lastTouchRawY);
boolean isHorizontalScroll = scrollIfNecessary(horizontalRecycler, (int) horLocation[0], (int) horLocation[1]);
boolean isVerticalScroll = scrollIfNecessary(lastRecyclerView, (int) verLocation[0], (int) verLocation[1]);
if (isDrag && (isHorizontalScroll || isVerticalScroll)) {
//it might be lost during scrolling
moveIfNecessary(lastTouchRawX, lastTouchRawY);
lastRecyclerView.removeCallbacks(scrollRunnable);
ViewCompat.postOnAnimation(lastRecyclerView, this);
}
}
};
/**
* 当用户滚动到边缘的时候,计算是否需要滚动
*/
private boolean scrollIfNecessary(RecyclerView recyclerView, int curX, int curY) {
if (!isDrag) {
return false;
}
RecyclerView.LayoutManager lm = recyclerView.getLayoutManager();
int scrollX = 0;
int scrollY = 0;
if (lm.canScrollHorizontally()) {
scrollX = dragListener.calcHorizontalScrollDistance(recyclerView, curX, curY);
}
if (lm.canScrollVertically()) {
scrollY = dragListener.calcVerticalScrollDistance(recyclerView, curX, curY);
}
// System.out.println("scroll:::::" + scrollY + "=" + recyclerView.getScrollY() + "curY::" + curY);
// System.out.println("scroll:::::" + scrollX + "=" + recyclerView.getScrollX() + "curX::" + curX);
if (scrollX != 0 || scrollY != 0) {
recyclerView.scrollBy(scrollX, scrollY);
}
return scrollX != 0 || scrollY != 0;
}
/**
* 获取需要move的目标Position，即toPosition
*
* @return NONE为找不到
*/
private int getTargetItemPos(View itemTargetView, float childY, int lastRecyclerPos, int currRecyclerPos) {
int itemPos = getPositionByChildView(itemTargetView);
if (itemPos == NONE) {
return itemPos;
}
if ((itemPos != lastItemPos || lastRecyclerPos != currRecyclerPos)) {
return itemPos;
}
return NONE;
}
/**
* 两个Item是否需要move
*/
private boolean isItemNeedChange(View itemView, int lastItemPos, int itemPos, float itemY) {
if (itemView == null || lastItemPos == NONE || itemPos == NONE || lastItemPos == itemPos) {
return false;
}
int top = itemView.getTop();
int moveLimit = (int) (top + itemView.getHeight() * dragListener.getMoveLimit());
// System.out.println("isNeedRemove-top:" + top + "==height:" + itemView.getHeight()
// + "==touchY:" + itemY + "moveLimit==" + moveLimit + "lastItemPos > itemPos===" + (lastItemPos > itemPos));
if (lastItemPos > itemPos) {
// return touchY < moveLimit && top >= 0;
return itemY < moveLimit;
} else {
return itemY > moveLimit;
}
}
/**
* touch的位置是否为当前view，防止两个item切换时的抖动问题
*/
private boolean isCurrPosition(float childY, View itemView) {
// System.out.println("isCurrPosition:" + (childY > itemView.getTop() && childY < itemView.getBottom()));
return childY >= itemView.getTop() && childY <= itemView.getBottom();
}
/**
* 查找当前view在RecyclerView中的位置 没有返回NONE
*/
private int getPositionByChildView(View itemView) {
if (itemView == null) {
return NONE;
}
try {
return ((RecyclerView.LayoutParams) itemView.getLayoutParams()).getViewAdapterPosition();
} catch (Exception e) {
e.printStackTrace();
}
return NONE;
}
/**
* 是否真正切换了RecyclerView
* 需要注意这里把没有切换后没有touch到Item当成不是真正切换
*/
private boolean isChangeRecyclerView(int lastRecyclerPos, int currRecyclerPos) {
return lastRecyclerPos != currRecyclerPos && lastRecyclerPos != NONE && currRecyclerPos != NONE;
}
/**
* 是否为初次选中RecycleView
*/
private boolean isSelectedRecyclerView(int lastRecyclerPos, int currRecyclerPos) {
return lastRecyclerPos == NONE && currRecyclerPos != NONE;
}
/**
* 是否为第一次选中子ItemView
*/
private boolean isSelectedChildView(int lastChildPos, int currChildPos) {
return lastChildPos == NONE && currChildPos != NONE;
}
static class EmptyDragListener extends OnItemDragListener {
}
}