本篇blog实现了GridView的拖拽功能。方法和上一篇自定义ListView实现拖拽ListItem项交换位置一个原理。只是在交换位置上记录了X轴的相关坐标，计算了X轴的相关变量。
实现效果图如下
说明：
本篇给出实现代码，但是不做任何说明。如需了解请看上一篇blog：自定义ListView实现拖拽ListItem项交换位置
文件代码：
1、MainActivity.java
代码如下:
package com.jay.draggridview;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
public class MainActivity extends Activity {
private static List list = null;
//自定义适配器
private DragGridAdapter adapter = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//初始化数据
initData();
//后面用到的自定义GridView
DragGridView dragGridView = (DragGridView)findViewById(R.id.drag_grid);
adapter = new DragGridAdapter(this, list);
dragGridView.setAdapter(adapter);
}
public void initData(){
list = new ArrayList();
for(int i= 0 ; i < 12 ; i++){
list.add("grid_"+i%12);
}
}
public static class DragGridAdapter extends ArrayAdapter{
public DragGridAdapter(Context context, List objects) {
super(context, 0, objects);
}
public List getList(){
return list;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = convertView;
if(view==null){
view = LayoutInflater.from(getContext()).inflate(R.layout.drag_grid_item, null);
}
try {
Log.v("item", "------"+getItem(position));
//根据文件名获取资源文件夹中的图片资源
Field f= (Field)R.drawable.class.getDeclaredField(getItem(position));
int i=f.getInt(R.drawable.class);
ImageView imageview= (ImageView)view.findViewById(R.id.drag_grid_item_image);
imageview.setImageResource(i);
} catch (SecurityException e) {
e.printStackTrace();
} catch (NoSuchFieldException e) {
e.printStackTrace();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
return view;
}
}
}
2、DragGridView.java
代码如下:
package com.jay.draggridview;
import com.jay.draggridview.MainActivity.DragGridAdapter;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.PixelFormat;
import android.util.AttributeSet;
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.GridView;
import android.widget.ImageView;
import android.widget.Toast;
public class DragGridView extends GridView{
//定义基本的成员变量
private ImageView dragImageView;
private int dragSrcPosition;
private int dragPosition;
//x,y坐标的计算
private int dragPointX;
private int dragPointY;
private int dragOffsetX;
private int dragOffsetY;
private WindowManager windowManager;
private WindowManager.LayoutParams windowParams;
private int scaledTouchSlop;
private int upScrollBounce;
private int downScrollBounce;
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();
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_drag);
//如果选中拖动图标
if(dragger!=null&&dragPointX>dragger.getLeft()&&dragPointXdragger.getTop()&&dragPointYgetChildAt(getChildCount()-1).getTop()&&x>getChildAt(getChildCount()-1).getRight())){
//超出下边界
dragPosition = getAdapter().getCount()-1;
}
//数据交换
if(dragPosition!=dragSrcPosition&&dragPosition>-1&&dragPosition