Gallery使用示例(二)

main.xml如下:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:gravity="center_horizontal"
   >

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="270dip"
        android:layout_height="350dip"
        android:layout_marginTop="20dip"
        android:scaleType="fitXY"
        android:layout_gravity="center_horizontal"
       />
    <Gallery 
        android:id="@+id/gallery"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:spacing="10dip"
        android:unselectedAlpha="0.6"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="40dip"
        
     />
</LinearLayout>

MainActivity如下:

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;
/**
 * Demo描述:
 * 利用Gallery预览图片.点击其中的某张图片时
 * 将该图片在ImageView中显示
 *
 */
public class MainActivity extends Activity {
    private int imagesID []= null;
    private Gallery mGallery;
    private ImageView mImageView;
    private BaseAdapter mBaseAdapter;
    @Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		init();
		mGallery.setAdapter(mBaseAdapter);
		//mGallery初始时显示的图片
		mGallery.setSelection(imagesID.length/2);
		mGallery.setOnItemClickListener(new OnItemClickListener() {
			@Override
			public void onItemClick(AdapterView<?> parent, View view,int position, long id) {
				Toast.makeText(getApplicationContext(),
			    "点击了第" + (position + 1) + "张图片", Toast.LENGTH_SHORT).show();
				//点击时切换图片
				mImageView.setImageResource(imagesID[position]);
			}
		});
	}
   
	private void init() {
		mGallery=(Gallery) findViewById(R.id.gallery);
		imagesID=new int []{
				R.drawable.a,R.drawable.b,R.drawable.c,R.drawable.d,
				R.drawable.e,R.drawable.f,R.drawable.g,R.drawable.h};
		mImageView=(ImageView) findViewById(R.id.imageView);
		//mImageView初始时显示的图片
		mImageView.setImageResource(imagesID[imagesID.length/2]);
		mBaseAdapter = new BaseAdapter() {
			@Override
			public View getView(int position, View convertView, ViewGroup parent) {
				ImageView imageView = new ImageView(MainActivity.this);
				//设置图片来源
				imageView.setImageResource(imagesID[position]);
				//拉伸图片以填充View的高宽
				imageView.setScaleType(ImageView.ScaleType.FIT_XY);
				//控制显示图片的大小
				imageView.setLayoutParams(new Gallery.LayoutParams(130, 130));
				imageView.setBackgroundColor(0xFF000000);
				return imageView;
			}

			@Override
			public long getItemId(int position) {
				return position;
			}

			@Override
			public Object getItem(int position) {
				return position;
			}

			@Override
			public int getCount() {
				return imagesID.length;
			}
		};
	}

}