近期项目遇到需要拖拽的RecyclerView来实现需求，首先考虑了ItemTouchHelper 这个类，但是后续使用发现无法把item视图拖出RecyclerView的视图范围，于是打算自定义RecyclerView来实现长按item可在屏幕内随意拖拽,在此简单记录一下。
实现效果
主要思路
- 继承RecylerView，重写dispatchTouchEvent
- 根据findChildViewUnder和getChildAdapterPosition方法获取到手指所在的View和索引
- 利用WindowManager添加获取到的视图到屏幕窗口
- 根据手指滑动的位置索引改变添加的视图位置，实现滑动
实现代码
package com.pgc.dragrecyclerviewdemo;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.os.Handler;
import android.os.Vibrator;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;
import android.widget.ImageView;
import androidx.recyclerview.widget.RecyclerView;
import java.util.Objects;
/**
* @explain 长按移动的recyclerView
* @author Created by PengGuiChu on 2022/4/11 11:58
*/
public class DragRecyclerView extends RecyclerView {
//拖拽响应的时间 默认为1s
private long mDragResponseMs = 1000;
//是否支持拖拽，默认不支持
private boolean isDrag = false;
//振动器，用于提示替换
private final Vibrator mVibrator;
//拖拽的item的position
private int mDragPosition;
//拖拽的item对应的View
private View mDragView;
//窗口管理器，用于为Activity上添加拖拽的View
private final WindowManager mWindowManager;
//item镜像的布局参数
private WindowManager.LayoutParams mLayoutParams;
//item镜像的 显示镜像，这里用ImageView显示
private ImageView mDragMirrorView;
//item镜像的bitmap
private Bitmap mDragBitmap;
//按下的点到所在item的左边缘距离
private int mPoint2ItemLeft;
private int mPoint2ItemTop;
//DragView到上边缘的距离
private int mOffset2Top;
private int mOffset2Left;
//按下时x,y
private int mDownX;
private int mDownY;
//移动的时x.y
private int mMoveX;
private int mMoveY;
//状态栏高度
private final int mStatusHeight;
//item发生变化的回调接口
private OnItemMoveListener itemMoveListener;
private final Handler mHandler;
/**
* 长按的Runnable
*/
private final Runnable mLongClickRunnable = new Runnable() {
@Override
public void run() {
isDrag = true;
mVibrator.vibrate(200);
//隐藏该item
mDragView.setVisibility(INVISIBLE);
//在点击的地方创建并显示item镜像
createDragView(mDragBitmap, mDownX, mDownY);
}
};
public DragRecyclerView(Context context) {
this(context, null);
}
public DragRecyclerView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public DragRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
mVibrator = (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE);
mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
mHandler = new Handler();
mStatusHeight = getStatusHeight(context);
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
mDownX = (int) ev.getX();
mDownY = (int) ev.getY();
mDragView=findChildViewUnder(mDownX,mDownY);
if (mDragView == null) {
return super.dispatchTouchEvent(ev);
}
//获取按下的position
mDragPosition =getChildAdapterPosition(mDragView);
if (mDragPosition == NO_POSITION) { //无效就返回
return super.dispatchTouchEvent(ev);
}
//延时长按执行mLongClickRunable
mHandler.postDelayed(mLongClickRunnable, mDragResponseMs);
//获取按下的item对应的View 由于存在复用机制，所以需要 处理FirstVisiblePosition
//计算按下的点到所在item的left top 距离
mPoint2ItemLeft = mDownX - mDragView.getLeft();
mPoint2ItemTop = mDownY - mDragView.getTop();
//计算RecyclerView的left top 偏移量：原始距离 - 相对距离就是偏移量
mOffset2Left = (int) ev.getRawX() - mDownX;
mOffset2Top = (int) ev.getRawY() - mDownY;
//开启视图缓存
mDragView.setDrawingCacheEnabled(true);
//获取缓存的中的bitmap镜像 包含了item中的ImageView和TextView
mDragBitmap = Bitmap.createBitmap(mDragView.getDrawingCache());
//释放视图缓存 避免出现重复的镜像
mDragView.destroyDrawingCache();
break;
case MotionEvent.ACTION_MOVE:
mMoveX = (int) ev.getX();
mMoveY = (int) ev.getY();
//如果只在按下的item上移动，未超过边界，就不移除mLongClickRunable
if (!isTouchInItem(mDragView, mMoveX, mMoveY)) {
mHandler.removeCallbacks(mLongClickRunnable);
}
break;
case MotionEvent.ACTION_UP:
mHandler.removeCallbacks(mLongClickRunnable);
//判断是否是点击
if (!isDrag&&mDragMirrorView==null&&itemMoveListener!=null&&Math.abs(mMoveX-mDownX)<20&&Math.abs(mMoveY-mDownY)<20){
itemMoveListener.onItemClick(mDragPosition);
}
break;
default:
break;
}
return super.dispatchTouchEvent(ev);
}
@SuppressLint("ClickableViewAccessibility")
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (isDrag && mDragMirrorView != null) {
switch (ev.getAction()) {
case MotionEvent.ACTION_MOVE:
mMoveX = (int) ev.getX();
mMoveY = (int) ev.getY();
onDragItem(mMoveX, mMoveY);
break;
case MotionEvent.ACTION_UP:
onStopDrag();
isDrag = false;
break;
default:
break;
}
return true;
}
return super.onTouchEvent(ev);
}
/************************对外提供的接口***************************************/
public boolean isDrag() {
return isDrag;
}
public void setDrag(boolean drag) {
isDrag = drag;
}
public long getDragResponseMs() {
return mDragResponseMs;
}
public void setDragResponseMs(long mDragResponseMs) {
this.mDragResponseMs = mDragResponseMs;
}
public void setOnItemMoveListener(OnItemMoveListener itemMoveListener) {
this.itemMoveListener = itemMoveListener;
}
/******************************************************************************/
/**
* 点是否在该View上面
*
* @param view
* @param x
* @param y
* @return
*/
private boolean isTouchInItem(View view, int x, int y) {
if (view == null) {
return false;
}
if (view.getLeft() < x && x < view.getRight()
&& view.getTop() < y && y < view.getBottom()) {
return true;
} else {
return false;
}
}
/**
* 获取状态栏的高度
*
* @param context
* @return
*/
@SuppressLint("PrivateApi")
private static int getStatusHeight(Context context) {
int statusHeight;
Rect localRect = new Rect();
((Activity) context).getWindow().getDecorView().getWindowVisibleDisplayFrame(localRect);
statusHeight = localRect.top;
if (0 == statusHeight) {
Class<?> localClass;
try {
localClass = Class.forName("com.android.internal.R$dimen");
Object localObject = localClass.newInstance();
int height = Integer.parseInt(Objects.requireNonNull(localClass.getField("status_bar_height").get(localObject)).toString());
statusHeight = context.getResources().getDimensionPixelSize(height);
} catch (Exception e) {
e.printStackTrace();
}
}
return statusHeight;
}
/**
* 停止拖动
*/
private void onStopDrag() {
if (mDragView != null) {
mDragView.setVisibility(VISIBLE);
}
removeDragImage();
if (itemMoveListener!=null){
itemMoveListener.onUp(mDragPosition);
}
}
/**
* WindowManager 移除镜像
*/
private void removeDragImage() {
if (mDragMirrorView != null) {
mWindowManager.removeView(mDragMirrorView);
mDragMirrorView = null;
}
}
/**
* 拖动item到指定位置
*
* @param x
* @param y
*/
private void onDragItem(int x, int y) {
mLayoutParams.x = x - mPoint2ItemLeft + mOffset2Left;
mLayoutParams.y = y - mPoint2ItemTop + mOffset2Top - mStatusHeight;
//更新镜像位置
mWindowManager.updateViewLayout(mDragMirrorView, mLayoutParams);
int[] location = new int[2];
getLocationOnScreen(location);
int pY = location[1];
if (itemMoveListener!=null){
itemMoveListener.onMove(x,y+pY);
}
}
/**
* 创建拖动的镜像
*
* @param bitmap
* @param downX
* @param downY
*/
@SuppressLint("RtlHardcoded")
private void createDragView(Bitmap bitmap, int downX, int downY) {
mLayoutParams = new WindowManager.LayoutParams();
mLayoutParams.format = PixelFormat.TRANSLUCENT; //图片之外其他地方透明
mLayoutParams.gravity = Gravity.TOP | Gravity.LEFT; //左 上
//指定位置 其实就是 该 item 对应的 rawX rawY 因为Window 添加View是需要知道 raw x ,y的
mLayoutParams.x = mOffset2Left + (downX - mPoint2ItemLeft);
mLayoutParams.y = mOffset2Top + (downY - mPoint2ItemTop) + mStatusHeight;
//指定布局大小
mLayoutParams.width = WindowManager.LayoutParams.WRAP_CONTENT;
mLayoutParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
//透明度
mLayoutParams.alpha = 0.5f;
//指定标志 不能获取焦点和触摸,允许拖动到窗口外
mLayoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
| WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE|WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS;
mDragMirrorView = new ImageView(getContext());
mDragMirrorView.setImageBitmap(bitmap);
//添加View到窗口中
mWindowManager.addView(mDragMirrorView, mLayoutParams);
}
/**
* item 交换时的回调接口
*/
public interface OnItemMoveListener {
void onMove(int x, int y);
void onUp(int position);
void onItemClick(int position);
}
}使用
<com.pgc.dragrecyclerviewdemo.DragRecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="300dp"
app:layout_constraintBottom_toTopOf="@id/view_5"
/>recyclerView.setOnItemMoveListener(new DragRecyclerView.OnItemMoveListener() {
@Override
public void onMove(int x, int y) {
if (x > viewX1 && x < viewX1 + viewWidth1 && y > viewY1 && y < viewY1 + viewHeight1) {
moveType = 1;
} else if (x > viewX2 && x < viewX2 + viewWidth2 && y > viewY2 && y < viewY2 + viewHeight2) {
moveType = 2;
} else if (x > viewX3 && x < viewX3 + viewWidth3 && y > viewY3 && y < viewY3 + viewHeight3) {
moveType = 3;
} else if (x > viewX4 && x < viewX4 + viewWidth4 && y > viewY4 && y < viewY4 + viewHeight4) {
moveType = 4;
} else if (x > viewX5 && x < viewX5 + viewWidth5 && y > viewY5 && y < viewY5 + viewHeight5) {
moveType = 5;
} else {
moveType = -1;
}
if (moveType != -1)
Toast.makeText(getApplicationContext(), "移动到VIEW" + moveType, Toast.LENGTH_LONG).show();
}
@Override
public void onUp(int position) {
Log.d("哦豁",moveType+"----"+position);
}
@Override
public void onItemClick(int position) {
Log.d("进入","点击了="+position);
}
});
