Android拖拽排序功能实现

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Android拖拽排序功能实现

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先来看一下效果:

##思路
Android本身就给我们提供了拖拽的实现.

在View身上都有一个startDrag()方法.

想要实现拖拽效果，还需要让拖拽的父View实现一个onDragListener.

##实现概述

首先，我选择继承自GradLayout,然后手动创建child.

然后在每个item身上添加长按事件.

长按时间内容为启动拖拽.

v.startDrag(null, new DragShadowBuilder(v), null, 0);

new DragShadowBuilder(view)是创建一个用于拖拽的虚影,它会自动跟随手势移动.

然后在父容器实现OnDragListener,在开始拖拽的时候实现获取每个View的坐标，放置在集合中.

然后在手势移动的时候，判断当前手势的坐标点是否在某个item上，如果在就移除当前要拖拽的view，然后添加到获取到的坐标点上.

##具体代码实现

package com.qingxiang.ui.view;

import android.animation.LayoutTransition;
import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.DragEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.GridLayout;

import com.bumptech.glide.Glide;
import com.qingxiang.ui.R;
import com.qingxiang.ui.bean.TagGroupBean;
import com.qingxiang.ui.common.CommonViewHolder;
import com.qingxiang.ui.utils.DensityUtils;
import com.qingxiang.ui.utils.L;
import com.qingxiang.ui.utils.QNUtils;
import com.qingxiang.ui.utils.Utils;

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

/**
 * 拖拽排序View
 */
public class DragSortView extends GridLayout {
    private static final String TAG = "DragSortView";
    private static final int COLUMN_COUNT = 4;
    private int itemSize;
    private View dragView;
    private List<Rect> viewRects;
    private int margin;

    public DragSortView(Context context) {
        this(context, null);
    }

    public DragSortView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public DragSortView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        //设置一行多少个条目
        setColumnCount(COLUMN_COUNT);
        //child入场退场动画
        LayoutTransition transition = new LayoutTransition();
        transition.setDuration(150);
        setLayoutTransition(transition);
        //计算item 高度和宽度
        int width = Utils.getScreenWidth();//屏幕高度
        width -= DensityUtils.dp2px(getContext(), 20 + ((COLUMN_COUNT - 1) * 3));//y轴item布局总数
        itemSize = (int) (width * 1.0f / COLUMN_COUNT + 0.5f); //item宽度,高度都是他
        //初始化数据
        viewRects = new ArrayList<>();
        margin = DensityUtils.dp2px(getContext(), 3);
    }

    public void setData(List<TagGroupBean> mDatas) {
        removeAllViews();
        int i = 0;
        for (TagGroupBean mData : mDatas) {
            addView(i, mData);
            i++;
        }
        //实现拖拽
        setOnDragListener(new DragListener());
    }

    private void addView(int pos, TagGroupBean mData) {
        //创建item
        LayoutInflater inflater = LayoutInflater.from(getContext());
        View view = inflater.inflate(R.layout.item_find_edit_sub, this, false);
        CommonViewHolder holder = new CommonViewHolder(view);
        //设置文字
        holder.getTextView(R.id.item_tv).setText(mData.getTag());
        //加载图片
        Glide.with(getContext())
                .load(QNUtils.formatUrl(mData.getIcon(), 1, 400, 400, false))
                .placeholder(R.mipmap.area_img1)
                .into(holder.getIv(R.id.item_iv));
        //长按
        holder.getContentView().setOnLongClickListener(v -> {
            dragView = v;
            v.startDrag(null, new DragShadowBuilder(v), null, 0);
            return true;
        });
        addView(view, getParams(pos));
    }


    private class DragListener implements OnDragListener {
        /**
         * 该值存放的是上一次移动到的位置
         */
        int lastIndex = -1;

        @Override
        public boolean onDrag(View v, DragEvent event) {
            switch (event.getAction()) {
                case DragEvent.ACTION_DRAG_STARTED:
                    initRects();
                    lastIndex = indexOfChild(dragView);
                    if (dragView != null)
                        dragView.setEnabled(false);
                    return true;
                case DragEvent.ACTION_DRAG_ENDED:
                    lastIndex = -1;
                    if (dragView != null) {
                        dragView.setEnabled(true);
                        dragView = null;
                    }
                    return true;
                case DragEvent.ACTION_DRAG_LOCATION:
                    int moveX = (int) event.getX();
                    int moveY = (int) event.getY();
                    L.i(TAG, "location X:" + moveX + " Y:" + moveY);
                    int findIndex = findTouchChildIndex(moveX, moveY);
                    if (findIndex != -1 && findIndex != lastIndex && dragView != null) {
                        removeView(dragView);
                        addView(dragView, findIndex);
                        lastIndex = findIndex;
                    }
                    return true;
            }
            return false;
        }
    }

	/**
	 * 获取当前所有child的坐标区域
	 */
    private void initRects() {
        viewRects.clear();
        for (int i = 0; i < getChildCount(); i++) {
            View child = getChildAt(i);
            Rect object = new Rect(child.getLeft(), child.getTop(), child.getRight(), child.getBottom());
            viewRects.add(object);
        }
    }

	/**
	  找到当前坐标所在的pos点，成功返回pos，失败返回-1*
	 */
    private int findTouchChildIndex(int moveX, int moveY) {
        for (int i = 0; i < viewRects.size(); i++) {
            boolean isFind = viewRects.get(i).contains(moveX, moveY);
            if (isFind) {
                return i;
            }
        }
        return -1;
    }

	/**
	 * 获取布局参数
	 */
    private GridLayout.LayoutParams getParams(int pos) {
        GridLayout.LayoutParams params = new GridLayout.LayoutParams();

        params.height = itemSize;
        params.width = itemSize;
        params.leftMargin = margin;

        if (pos < 4) {
            params.bottomMargin = margin;
        }

        return params;
    }
}