AndroidはGridViewをターゲットViewにドラッグ&ドロップすることを実現

package cn.com.weather.serviceDemo.view;

import cn.com.weather.serviceDemo.interfaces.OnDropListener;
import cn.com.weather.serviceDemo.util.DeviceUtil;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Matrix;
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;

public class MyGridView extends GridView{
	
	private ImageView dragImageView;
	private WindowManager windowManager;
	private WindowManager.LayoutParams windowParams;
	
	private int dragSrcPosition;//     
	private int dragPosition;
	
	//     
    private int dragPointX;
    private int dragPointY;
    //           
    private int dragOffsetX;
    private int dragOffsetY;
    
    private View myView;//  view
    private int dropPosition = -1;//   
    
    private OnDropListener onDropListener;

	public MyGridView(Context context, AttributeSet attrs) {
		super(context, attrs);
	}
	
	public void setView(View view){
		myView = view;
	}
	
	public void setOnDropListener(OnDropListener onDropListener){
		this.onDropListener = onDropListener;
	}
	
	private boolean setOnItemLongClickListener(final MotionEvent ev){
		this.setOnItemLongClickListener(new OnItemLongClickListener() {

			@Override
			public boolean onItemLongClick(AdapterView<?> parent, View view,
					int position, long id) {
				final int x = (int)ev.getX();//      GridView    
				final int y = (int)ev.getY();
				
				dragSrcPosition = dragPosition = position;
				
				if(dragPosition == AdapterView.INVALID_POSITION ){
					return false;
				}
				
				final ViewGroup item = (ViewGroup)getChildAt(dragPosition - getFirstVisiblePosition());
				
				dragPointX = x - item.getLeft();
				dragPointY = y - item.getTop();
				dragOffsetX = (int)ev.getRawX() - x;
				dragOffsetY = (int)ev.getRawY() - y;
				
				item.destroyDrawingCache();//  cache
				item.setDrawingCacheEnabled(true);
				Bitmap bitmap = Bitmap.createBitmap(item.getDrawingCache());
				startDrag(getScaleBitmap(bitmap), x, y);
				DeviceUtil.Vibrate(getContext(), 100);
				return false;
			}
		});
		
		return super.onInterceptTouchEvent(ev);
	}

	@Override
	public boolean onInterceptTouchEvent(MotionEvent ev) {
		if(ev.getAction() == MotionEvent.ACTION_DOWN){
			return setOnItemLongClickListener(ev);
		}
		return super.onInterceptTouchEvent(ev);
	}
	
	@Override
	public boolean onTouchEvent(MotionEvent ev) {
		if(dragImageView != null && dragPosition != AdapterView.INVALID_POSITION){
			int x = (int)ev.getX();
			int y = (int)ev.getY();
			switch (ev.getAction()) {
			case MotionEvent.ACTION_UP:
				stopDrag();
				onDrop((int)ev.getRawX(), (int)ev.getRawY());
				break;

			case MotionEvent.ACTION_MOVE:
				onDrag(x, y);
				break;
			}
			
			
		}
		return super.onTouchEvent(ev);
	}

	private void startDrag(Bitmap bm, int x, int y){
		stopDrag();
		
		windowParams = new WindowManager.LayoutParams();
		windowParams.gravity = Gravity.TOP|Gravity.LEFT;
		//           
		windowParams.x = x - dragPointX + dragOffsetX;
		windowParams.y = y - dragPointY + dragOffsetY;
		
		windowParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
		windowParams.width = 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.format = PixelFormat.TRANSLUCENT;
		windowParams.windowAnimations = 0;
		
		ImageView imageView = new ImageView(this.getContext());
		imageView.setImageBitmap(bm);
		
		windowManager = (WindowManager)this.getContext().getSystemService(Context.WINDOW_SERVICE);
		windowManager.addView(imageView, windowParams);
		dragImageView = imageView;
	}
	
	private void stopDrag(){
		if (dragImageView != null) {
			windowManager.removeView(dragImageView);
			dragImageView = null;
		}
	}
	
	private void onDrag(int x, int y){
		if(dragImageView != null){
			windowParams.alpha = 0.8f;
			windowParams.x = x - dragPointX + dragOffsetX;
			windowParams.y = y - dragPointY + dragOffsetY;
			windowManager.updateViewLayout(dragImageView, windowParams);
		}
		
	}
	
	private void onDrop(int x, int y){
		boolean inView = isInView(x, y, myView);
		if(inView){
			if(onDropListener!=null){
				onDropListener.onDrop(dragSrcPosition);
			}
		}
	}
	
	private Bitmap getScaleBitmap(Bitmap bitmap){
		Matrix matrix = new Matrix();
		matrix.postScale(1.1f, 1.1f);
		return Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
	}
	
	private boolean isInView(int x, int y, View view){
		if(view == null) return false;
		
		int[] location = new int[2];
		view.getLocationInWindow(location);
		int _x = location[0];
		int _y = location[1];
		int width = view.getWidth();
		int height = view.getHeight();
		
		if(_x <x && x <_x+width && _y<y && y<_y+height){
			return true;
		}
		return false;
	}
	
	

}