跳到图片放大区域

package com.momo2.momo2.utils;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.graphics.drawable.BitmapDrawable;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.view.ViewGroup;
import android.view.Window;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout.LayoutParams;
import android.widget.TextView;
import android.widget.Toast;

import com.momo2.momo2.MyApplication;
import com.momo2.momo2.R;
//图片放大界面，对应的布局xml文件是max_iv.xml
public class MaxImageViewActivity extends Activity implements
		OnPageChangeListener {
	private List<String> list;// 图片路径的集合

	private ViewPager vp;
	private String img;
	private ArrayList<ImageView> mImageViewCacheList;

	private float startX = 0;
	private float startY = 0;
	private float endX = 0;
	private float endY = 0;
	private TextView total_num_tv;
	private TextView num_tv;
	private Button save_btn;
	private int position = 0;
	Bitmap bitmap = null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.max_iv);
		mImageViewCacheList = new ArrayList<ImageView>();
		list = (List<String>) getIntent().getStringArrayListExtra("list");
		vp = (ViewPager) findViewById(R.id.vp);
		vp.setOnPageChangeListener(this);
		total_num_tv = (TextView) findViewById(R.id.total_num_tv);
		num_tv = (TextView) findViewById(R.id.num_tv);
		save_btn = (Button) findViewById(R.id.save_btn);
		save_btn.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View arg0) {

				bitmap = ((BitmapDrawable) mImageViewCacheList.get(position)
						.getDrawable()).getBitmap();
				saveImageToGallery(MaxImageViewActivity.this, bitmap);

			}
		});

		total_num_tv.setText(list.size() + "");

		img = getIntent().getStringExtra("img");

		vp.setAdapter(new ViewPagerImageAdapter(list));
		vp.setOnTouchListener(new OnTouchListener() {

			@Override
			public boolean onTouch(View arg0, MotionEvent event) {
				switch (event.getAction()) {
				case MotionEvent.ACTION_DOWN:
					startX = event.getX();
					startY = event.getY();
					break;

				case MotionEvent.ACTION_UP:
					endX = event.getX();
					endY = event.getY();

					if (Math.abs(startX - endX) < 5
							|| Math.abs(startY - endY) < 5) {
						finish();
					}

					break;
				}

				return false;
			}
		});
		for (int i = 0; i < list.size(); i++) {
			if (img.equals(list.get(i))) {
				vp.setCurrentItem(i);
				num_tv.setText((i + 1) + "");
				position = i;
			}
		}

	}

	@Override
	public void onPageScrollStateChanged(int arg0) {
		// TODO Auto-generated method stub

	}

	@Override
	public void onPageScrolled(int arg0, float arg1, int arg2) {
		// TODO Auto-generated method stub

	}

	@Override
	public void onPageSelected(int position) {
		num_tv.setText((position + 1) + "");
		this.position = position;
	}

	public void saveImageToGallery(Context context, Bitmap bmp) {
		// 首先保存图片
		File appDir = new File(Environment.getExternalStorageDirectory(),
				"detail");
		if (!appDir.exists()) {
			appDir.mkdir();
		}
		String fileName = System.currentTimeMillis() + ".jpg";
		File file = new File(appDir, fileName);
		try {
			FileOutputStream fos = new FileOutputStream(file);
			bmp.compress(CompressFormat.JPEG, 100, fos);
			fos.flush();
			fos.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		if (!bmp.isRecycled()) {
			// bitmap.recycle(); 当存储大图片时，为避免出现OOM ，及时回收Bitmap
			System.gc(); // 通知系统回收
		}
		// 其次把文件插入到系统图库
		try {
			MediaStore.Images.Media.insertImage(context.getContentResolver(),
					file.getAbsolutePath(), fileName, null);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}
		// 最后通知图库更新
		Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
		Uri uri = Uri.fromFile(file);
		intent.setData(uri);
		context.sendBroadcast(intent);

		Toast.makeText(context, "已保存在图库相册" + file.getAbsolutePath(), 0).show();
	}

	public class ViewPagerImageAdapter extends PagerAdapter {
		private List<String> list;

		public ViewPagerImageAdapter(List<String> list) {
			this.list = list;
			// mImageViewCacheList = new ArrayList<ImageView>();
		}

		@Override
		public int getCount() {

			return list.size();
		}

		@Override
		public boolean isViewFromObject(View arg0, Object arg1) {

			return arg0 == arg1;
		}

		/**
		 * 载入图片进去，用当前的position 除以 图片数组长度取余数是关键
		 */
		@Override
		public Object instantiateItem(ViewGroup container, int position) {
			String imageUrl = list.get(position);
			ImageView imageView = null;
			imageView = new ImageView(MaxImageViewActivity.this);
			mImageViewCacheList.add(imageView);
			imageView.setLayoutParams(new LayoutParams(
					LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));

			MyApplication.getImageLoader().displayImage(
					imageUrl,
					imageView,
					MyApplication.getFadeOptions(R.drawable.empty_photo,
							R.drawable.empty_photo, R.drawable.empty_photo));
			container.addView(imageView);
			return imageView;
		}

		@Override
		public void destroyItem(ViewGroup container, int position, Object object) {
			ImageView view = (ImageView) object;
			((ViewPager) container).removeView(view);
		}
	}

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#000000"
    android:orientation="vertical" >

    <android.support.v4.view.ViewPager
        android:id="@+id/vp"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:layout_weight="1" >
    </android.support.v4.view.ViewPager>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="10dp" >

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerVertical="true"
            android:layout_marginBottom="15dp"
            android:layout_marginLeft="20dp"
            android:orientation="horizontal" >

            <TextView
                android:id="@+id/num_tv"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="3"
                android:textColor="@color/white"
                android:textSize="16sp" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="/"
                android:textColor="@color/white"
                android:textSize="16sp" />

            <TextView
                android:id="@+id/total_num_tv"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="3"
                android:textColor="@color/white"
                android:textSize="16sp" />
        </LinearLayout>

        <Button
            android:id="@+id/save_btn"
            android:layout_width="80dp"
            android:layout_height="30dp"
            android:layout_alignParentRight="true"
            android:layout_centerInParent="true"
            android:layout_marginRight="40dp"
            android:background="@color/diy_red"
            android:text="保存"
            android:textColor="@color/white" />
    </RelativeLayout>

</LinearLayout>