【Android开发】范例2-实现幻灯片式图片浏览器

  
    android:orientation="vertical"  
    android:layout_width="fill_parent"  
    android:layout_height="fill_parent"  
    android:id="@+id/layout1"
    android:gravity="center_horizontal"
    >  
            android:id="@+id/imageSwitcher"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:paddingTop="30px"
        android:layout_weight="2"/>
            android:id="@+id/gallery1"
        android:spacing="5px"
        android:layout_weight="1"
        android:unselectedAlpha="0.6"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

package com.example.test;  
  
import android.app.Activity;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.ViewSwitcher.ViewFactory;
  
public class MainActivity extends Activity {  
    //定义并初始化保存图片id的数组
      private int[] imageId=new int[]{R.drawable.img1,R.drawable.img2,R.drawable.img3,R.drawable.img4,
              R.drawable.img5,R.drawable.img6,R.drawable.img7,R.drawable.img8,R.drawable.img9};
      //声明一个图像切换器对象
      private ImageSwitcher imageSwitcher;
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  
         
        Gallery gallery=(Gallery)findViewById(R.id.gallery1);//获取gallery组件
        
        imageSwitcher=(ImageSwitcher)findViewById(R.id.imageSwitcher);//获取图像切换器
        //设置动画效果
        imageSwitcher.setInAnimation(AnimationUtils.loadAnimation(this,
                android.R.anim.fade_in));//设置淡入动画
        imageSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this, 
                android.R.anim.fade_out));//设置淡出动画
        imageSwitcher.setFactory(new ViewFactory(){


            @Override
            public View makeView() {
                ImageView imageView=new ImageView(MainActivity.this);//实例化一个imageView类的对象
                imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);//设置保持纵横比居中缩放图像
                imageView.setLayoutParams(new ImageSwitcher.LayoutParams(
                        LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));
                return imageView;//返回imageView对象
            }
        });
        
        BaseAdapter adapter=new BaseAdapter(){


            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                ImageView imageView;//声明ImageView的对象
                if(convertView==null){
                    imageView=new ImageView(MainActivity.this);//实例化ImageView的对象
                    imageView.setScaleType(ImageView.ScaleType.FIT_XY);//设置缩放方式
                    imageView.setLayoutParams(new Gallery.LayoutParams(180,135));
                    //设置gallery每一项图片的背景资源(使用的是attr.xml的自定义样式)
                    TypedArray typedArray=obtainStyledAttributes(R.styleable.Gallery);
                    imageView.setBackgroundResource(typedArray.getResourceId(
                            R.styleable.Gallery_android_galleryItemBackground, 0));
                    
                    imageView.setPadding(5, 0, 5, 0);//设置imageView的内边距
                }else{
                    imageView=(ImageView)convertView;
                }
                imageView.setImageResource(imageId[position]);//为imageView设置要显示的图片
                return imageView;//返回ImageView
            }
            
            //功能:获得当前选项的id
            @Override
            public long getItemId(int position) {
                return position;
            }
            
            //功能：获得当前选项
            @Override
            public Object getItem(int position) {
                return position;
            }
            
            //获得数量
            @Override
            public int getCount() {
                return imageId.length;
            }
        };
        
        gallery.setAdapter(adapter);//将适配器与Gallery关联
        gallery.setSelection(imageId.length/2);//选中中间的图片
        gallery.setOnItemSelectedListener(new OnItemSelectedListener() {


            @Override
            public void onItemSelected(AdapterView> parent, View v,
                    int position, long id) {
                imageSwitcher.setImageResource(imageId[position]);//显示选中的图片
            }


            @Override
            public void onNothingSelected(AdapterView> arg0) {
                // TODO Auto-generated method stub
            }
        });
    }  
}