1、概述

项目要求一个可拖拽的gridview功能，主要是可以长按图标，然后手指移动到对应位置，松开后图标移动到对应手指松开的位置，后面的图标依次挪移一个position。

2、效果图

拖拽前效果图 拖拽后效果图

3、重写dispatchTouchEvent方法

/** 
 * 长按的Runnable 
 */  
private Runnable mLongClickRunable = 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);  
    }  
};  
/** 
 * 当moveY的值大于向上滚动的边界值，触发GridView自动向上滚动 
 * 当moveY的值小于向下滚动的边界值，触犯GridView自动向下滚动 
 * 否则不进行滚动 
 */  
private Runnable mScrollRunbale = new Runnable() {  
    @Override  
    public void run() {  
        int scrollY = 0;  
        if (mMoveY > mUpScrollBorder){  
            scrollY = mSpeed;  
            mHandler.postDelayed(mScrollRunbale,25);  
        }else if (mMoveY < mDownScrollBorder){  
            scrollY = -mSpeed;  
            mHandler.postDelayed(mScrollRunbale,25);  
        }else {  
            scrollY = 0;  
            mHandler.removeCallbacks(mScrollRunbale);  
        }  
        smoothScrollBy(scrollY,10);  
    }  
};  

5、对外暴露的方法

/************************对外提供的接口***************************************/  
public boolean isDrag() {  
    return isDrag;  
}  
//设置是否可拖拽  
public void setDrag(boolean drag) {  
    isDrag = drag;  
}  
public long getDragResponseMs() {  
    return mDragResponseMs;  
}  
//设置长按响应时长  
public void setDragResponseMs(long mDragResponseMs) {  
    this.mDragResponseMs = mDragResponseMs;  
}  
public void setOnItemChangeListener(OnItemChangeListener changeListener) {  
    this.changeListener = changeListener;  
}  
/******************************************************************************/  

6、如何在页面中调用

DragGridView dragGridView = findViewById(R.id.dgv);  
dragGridView.setNumColumns(NUM_COLUMNS);  
initData();  
mMoreColorTypeAdapter = new MoreColorTypeAdapter(this, true, data, NUM_COLUMNS);  
dragGridView.setAdapter(mMoreColorTypeAdapter);  
dragGridView.setOnItemClickListener(this);  
dragGridView.setOnItemChangeListener(new DragGridView.OnItemChangeListener() {  
    @Override  
    public void onChange(int from, int to) {  
        Data dataBean = data.get(from);  
        //直接交互  
        //Collections.swap(dataSourceList,from,to);  
        //非直接交互 这里的处理需要注意下 排序交换  
        if(from < to){  
            for(int i = from; i < to; i++){  
                Collections.swap(data, i, i + 1);  
            }  
        }else if(from > to){  
            for(int i = from; i > to; i--){  
                Collections.swap(data, i, i - 1);  
            }  
        }  
        data.set(to, dataBean);  
        mMoreColorTypeAdapter.notifyDataSetChanged();  
    }  
    @Override  
    public void onStop() {  
        //拖动停止  
    }  
});  

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