在PagerAdapter类上实现浮动按钮

Question

在这段代码中，我想要在每次视图更改时使“关闭”按钮静止（浮动），如下例所示：

http://www.jondev.net/articles/Floating_Views_in_Android_%28Buttons%29

**XML**

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >

    <com.myapplication.helper.TouchImageView
        android:id="@+id/imgDisplay"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:scaleType="fitCenter" />
    </LinearLayout>

  <Button
        android:id="@+id/btnClose"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:layout_marginRight="15dp"
        android:layout_marginTop="15dp"
        android:paddingTop="2dp"
        android:paddingBottom="2dp"
        android:background="@drawable/button_background"
        android:textColor="#ffffff"
        android:text="Close" />

</FrameLayout>

我的PagerFragment：

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.FrameLayout;

import java.util.ArrayList;

import com.myapplication.R;
import com.myapplication.helper.TouchImageView;


public class FullScreenImageAdapter extends PagerAdapter {

    private Activity _activity;
    private ArrayList<String> _imagePaths;
    private LayoutInflater inflater;

    // constructor
    public FullScreenImageAdapter(Activity activity,
                                  ArrayList<String> imagePaths) {
        this._activity = activity;
        this._imagePaths = imagePaths;
    }

    @Override
    public int getCount() {
        return this._imagePaths.size();
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == ((FrameLayout) object);
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        TouchImageView imgDisplay;
        Button btnClose;

        inflater = (LayoutInflater) _activity
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View viewLayout = inflater.inflate(R.layout.layout_fullscreen_image, container,
                false);

        imgDisplay = (TouchImageView) viewLayout.findViewById(R.id.imgDisplay);
        btnClose = (Button) viewLayout.findViewById(R.id.btnClose);

        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inPreferredConfig = Bitmap.Config.ARGB_8888;
        Bitmap bitmap = BitmapFactory.decodeFile(_imagePaths.get(position), options);
        imgDisplay.setImageBitmap(bitmap);

        // close button click event
        btnClose.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                _activity.finish();
            }
        });

        ((ViewPager) container).addView(viewLayout);

        return viewLayout;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        ((ViewPager) container).removeView((FrameLayout) object);

    }


}

谢谢！