package com.jj.draggrid;

import java.util.logging.Handler;

import com.jj.draggrid.MainActivity.DragGridAdapter;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.PixelFormat;
import android.util.AttributeSet;
import android.util.Log;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.Toast;

/***
* 自定义拖拽GridView
*
* @author zhangjia
*
*/

public class DragGridView extends GridView {

private WindowManager windowManager;// windows窗口控制类
private WindowManager.LayoutParams windowParams;// 用于控制拖拽项的显示的参数

private int scaledTouchSlop;// 判断滑动的一个距离,scroll的时候会用到(24)

private ImageView dragImageView;// 被拖拽的项(item)，其实就是一个ImageView
private int dragSrcPosition;// 手指拖动项原始在列表中的位置
private int dragPosition;// 手指点击准备拖动的时候,当前拖动项在列表中的位置.

private int dragPointX;// 在当前数据项中的位置
private int dragPointY;// 在当前数据项中的位置
private int dragOffsetX;// 当前视图和屏幕的距离(这里只使用了x方向上)
private int dragOffsetY;// 当前视图和屏幕的距离(这里只使用了y方向上)

private int upScrollBounce;// 拖动的时候，开始向上滚动的边界
private int downScrollBounce;// 拖动的时候，开始向下滚动的边界

private int temChangId;// 临时交换id

private boolean isDoTouch = false;// touch是否可用

private boolean isHide = false;// 是否隐藏

private Handler handler;

public void setDoTouch(boolean isDoTouch) {
this.isDoTouch = isDoTouch;
}

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

@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {

if (ev.getAction() == MotionEvent.ACTION_DOWN) {
int x = (int) ev.getX();
int y = (int) ev.getY();

temChangId = dragSrcPosition = dragPosition = pointToPosition(x, y);

if (dragPosition == AdapterView.INVALID_POSITION) {
return super.onInterceptTouchEvent(ev);
}

ViewGroup itemView = (ViewGroup) getChildAt(dragPosition
- getFirstVisiblePosition());

dragPointX = x - itemView.getLeft();
dragPointY = y - itemView.getTop();
dragOffsetX = (int) (ev.getRawX() - x);
dragOffsetY = (int) (ev.getRawY() - y);

View dragger = itemView.findViewById(R.id.drag_grid_item);

/***
* 判断是否选中拖动图标
*/
if (dragger != null && dragPointX > dragger.getLeft()
&& dragPointX < dragger.getRight()
&& dragPointY > dragger.getTop()
&& dragPointY < dragger.getBottom() + 20) {

upScrollBounce = getHeight() / 4;
downScrollBounce = getHeight() * 3 / 4;

itemView.setDrawingCacheEnabled(true);
Bitmap bm = Bitmap.createBitmap(itemView.getDrawingCache());
startDrag(bm, x, y);// 初始话映像

dragger.setVisibility(View.INVISIBLE);// 隐藏该项.
}
}

return super.onInterceptTouchEvent(ev);
}

@Override
public boolean onTouchEvent(MotionEvent ev) {

if (dragImageView != null && dragPosition != INVALID_POSITION
&& isDoTouch) {
int action = ev.getAction();
switch (action) {
/***
*
*/
case MotionEvent.ACTION_UP:
int upX = (int) ev.getX();
int upY = (int) ev.getY();
stopDrag();// 删除映像
onDrop(upX, upY);// 松开
// isDoTouch = false;
break;
/***
* 拖拽item
*
*/
case MotionEvent.ACTION_MOVE:
int moveX = (int) ev.getX();
int moveY = (int) ev.getY();
onDrag(moveX, moveY);// 拖拽
break;
case MotionEvent.ACTION_DOWN:
int downX = (int) ev.getX();
int downY = (int) ev.getY();
onHide(downX, downY);// 隐藏该项
break;
default:
break;
}
return true;
}

return super.onTouchEvent(ev);
}

/**
* 准备拖动，初始化拖动项的图像
*
* @param bm
* @param y
*/
public void startDrag(Bitmap bm, int x, int y) {

windowParams = new WindowManager.LayoutParams();
windowParams.gravity = Gravity.TOP | Gravity.LEFT;
windowParams.x = x - dragPointX + dragOffsetX;
windowParams.y = y - dragPointY + dragOffsetY;
windowParams.width = WindowManager.LayoutParams.WRAP_CONTENT;
windowParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
windowParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
| WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE
| WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
| WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN;

windowParams.windowAnimations = 0;

ImageView imageView = new ImageView(getContext());
imageView.setImageBitmap(bm);
windowManager = (WindowManager) getContext().getSystemService("window");
windowManager.addView(imageView, windowParams);
dragImageView = imageView;

}

/***
* 拖动时时change
*/
private void onChange(int x, int y) {
// 获取适配器
DragGridAdapter adapter = (DragGridAdapter) getAdapter();
// 数据交换
if (dragPosition < getAdapter().getCount()) {
// 不相等的情况下要进行换位,相等的情况下说明正在移动
if (dragPosition != temChangId) {
adapter.update(temChangId, dragPosition);// 进行换位
temChangId = dragPosition;// 将点击最初所在位置position付给临时的，用于判断是否换位.
}

}

// 为了避免滑动到分割线的时候，返回-1的问题
int tempPosition = pointToPosition(x, y);
if (tempPosition != INVALID_POSITION) {
dragPosition = tempPosition;
}

}

/***
* 拖动执行，在Move方法中执行
*
* @param x
* @param y
*/
public void onDrag(int x, int y) {
// 移动
if (dragImageView != null) {
windowParams.alpha = 0.8f;
windowParams.x = x - dragPointX + dragOffsetX;
windowParams.y = y - dragPointY + dragOffsetY;
windowManager.updateViewLayout(dragImageView, windowParams);
}

onChange(x, y);// 时时交换

// 滚动
if (y < upScrollBounce || y > downScrollBounce) {
// 使用setSelection来实现滚动
setSelection(dragPosition);
}

}

/***
* 隐藏该选项
*/
private void onHide(int x, int y) {
// 获取适配器
DragGridAdapter adapter = (DragGridAdapter) getAdapter();
// 为了避免滑动到分割线的时候，返回-1的问题
int tempPosition = pointToPosition(x, y);
if (tempPosition != INVALID_POSITION) {
dragPosition = tempPosition;
}
adapter.setIsHidePosition(dragPosition);

}

/**
* 停止拖动，删除影像
*/
public void stopDrag() {
if (dragImageView != null) {
windowManager.removeView(dragImageView);
dragImageView = null;
}
}

/***
* 拖动放下的时候
*
* @param x
* @param y
*/
public void onDrop(int x, int y) {

DragGridAdapter adapter = (DragGridAdapter) getAdapter();
adapter.setIsHidePosition(-1);// 不进行隐藏

}

}