android GridView 选中后 图片变大 图片放大不会被掩住

package com.video.browse;import java.io.File;import java.util.ArrayList;import java.util.Iterator;import java.util.List;import com.video.browse.adapter.VideoAdapter;import com.video.browse.ui.VideoGridView;import com.video.browse.util.Constant;import com.video.browse.util.FileFind;import com.video.browse.util.FileVoideInfo;import com.video.browse.util.MediaFormat;import android.R.bool;import android.os.Bundle;import android.util.Log;import android.view.View;import android.widget.AdapterView;import android.widget.GridView;import android.widget.Toast;import android.widget.AdapterView.OnItemClickListener;import android.widget.AdapterView.OnItemSelectedListener;import android.app.Activity;public class MainActivity extends Activity {	private static final String TAG = "MainActivity";	List<FileVoideInfo> list = new ArrayList<FileVoideInfo>();	@Override	protected void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		setContentView(R.layout.activity_main);		if (FileFind.isFileName(Constant.MOVIE_PATH_SD)) {			File filePath = new File(Constant.FILE_PATH);			list = FileFind.getFileList(filePath, true);			Log.i(TAG, "list size:"+list.size());		}				final VideoGridView gridview = (VideoGridView) findViewById(R.id.gridview);		VideoAdapter mImageAdapter = new VideoAdapter(this,list);		gridview.setAdapter(mImageAdapter);		gridview.setOnItemClickListener(new OnItemClickListener() {						public void onItemClick(AdapterView<?> parent, View view,					int position, long id) {				Toast.makeText(MainActivity.this, "" + position,Toast.LENGTH_SHORT).show();// 显示信息;				 			}					});		gridview.setOnItemSelectedListener(new OnItemSelectedListener() {  		    public void onItemSelected(AdapterView<?> arg0, View arg1,  		    	    int arg2, long arg3) {  		    	    Log.d("zonesView", "onItemSelected");		    	    gridview.setCurrentPosition(arg2);		    	    VideoAdapter zonesImageAdapter = (VideoAdapter) gridview.getAdapter();  		    	    zonesImageAdapter.notifyDataSetChanged(arg2);  		    	    }    		    	   public void onNothingSelected(AdapterView<?> arg0) {  		    	        // TODO Auto-generated method stub  		    	           		    	    }           		    	});			}	@Override	protected void onStart() {		super.onStart();		// new Thread(downloadInfoRun).start();	}}

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package com.video.browse.adapter;import java.util.ArrayList;import java.util.List;import com.video.browse.R;import com.video.browse.util.FileVoideInfo;import android.content.Context;import android.util.Log;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.view.animation.Animation;import android.view.animation.AnimationUtils;import android.widget.BaseAdapter;import android.widget.GridView;import android.widget.ImageView;import android.widget.TextView;import android.widget.ImageView.ScaleType;public class VideoAdapter extends BaseAdapter {	int mGalleryItemBackground;	private Context mContext;	private static final String TAG = "VideoAdapter";	List<FileVoideInfo> list = new ArrayList<FileVoideInfo>();	private int selected = -1;		public VideoAdapter(Context context,List<FileVoideInfo> list) {		this.mContext = context;		this.list = list;			}		@Override	public int getCount() { 		Log.i(TAG,"adapter list size: "+list.size());		return list.size();	}	@Override	public Object getItem(int position) {		// TODO Auto-generated method stub		return list.get(position);	}	@Override	public long getItemId(int position) {		// TODO Auto-generated method stub		return position;	}		public void notifyDataSetChanged(int id) {		selected = id;		super.notifyDataSetChanged();	}		@Override	public View getView(int position, View convertView, ViewGroup parent) {		ImageView imgView = new ImageView(mContext);		imgView.setLayoutParams(new GridView.LayoutParams(285, 185));		imgView.setPadding(228, 228, 228, 228);		imgView.setBackgroundResource(R.drawable.nba_4);		if (selected == position) {			imgView.setScaleType(ImageView.ScaleType.CENTER_CROP);			Animation testAnim = AnimationUtils.loadAnimation(mContext,R.anim.anim);			imgView.startAnimation(testAnim);		} else {			imgView.setScaleType(ImageView.ScaleType.CENTER);		}		return imgView;	}}

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package com.video.browse.ui;import android.annotation.SuppressLint;import android.content.Context;import android.util.AttributeSet;import android.widget.GridView;public class VideoGridView extends GridView {	private int position = 0;	public VideoGridView(Context context) {		super(context);	}	public VideoGridView(Context context, AttributeSet attrs) {		super(context, attrs);		setChildrenDrawingOrderEnabled(true);	}	public void setCurrentPosition(int pos) {// 刷新adapter前，在activity中调用这句传入当前选中的item在屏幕中的次序		this.position = pos;	}	@SuppressLint("NewApi")	@Override	protected void setChildrenDrawingOrderEnabled(boolean enabled) {		// TODO Auto-generated method stub		super.setChildrenDrawingOrderEnabled(enabled);	}	@Override	protected int getChildDrawingOrder(int childCount, int i) {		if (i == childCount - 1) {// 这是最后一个需要刷新的item			return position;		}		if (i == position) {// 这是原本要在最后一个刷新的item			return childCount - 1;		}		return i;// 正常次序的item	}}

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<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context=".MainActivity" >    <!--         android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"         -->   <com.video.browse.ui.VideoGridView        android:id="@+id/gridview"        android:layout_width="fill_parent"        android:layout_height="fill_parent"        android:columnWidth="210dp"        android:gravity="center"        android:horizontalSpacing="1dp"        android:numColumns="auto_fit"        android:verticalSpacing="1dp" /></RelativeLayout>

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