Android入门第十三篇之Gallery + ImageSwitcher

   本文来自http://blog.csdn.net/hellogv/ ，引用必须注明出处！

       上次讲了如何使用Gallery控件，这次就讲Gallery 与ImageSwitcher的结合使用，本文实现一个简单的浏览图片的功能。先贴出程序运行截图：

除了Gallery可以拖拉切换图片，我在ImageSwitcher控件加入了setOnTouchListener事件实现，使得ImageSwitcher也可以在拖拉中切换图片。本例子依然使用JAVA的反射机制来自动读取资源中的图片。

 

main.xml的源码如下:

<?xml version="1.0" encoding="utf-8"?>  
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"   
    android:layout_width="match_parent"   
    android:layout_height="match_parent">   
      
    <ImageSwitcher android:id="@+id/switcher"  
        android:layout_width="match_parent" android:layout_height="match_parent"/>  
      
    <Gallery android:id="@+id/gallery"  
        android:background="#55000000"  
        android:layout_width="match_parent"  
        android:layout_alignParentBottom="true"  
        android:layout_alignParentLeft="true"  
          
        android:gravity="center_vertical"  
        android:spacing="16dp" android:layout_height="100dp"/>  
</RelativeLayout>  

  

程序的源码如下:

package com.testImageView;  
import java.lang.reflect.Field;  
import java.util.ArrayList;  
import android.app.Activity;  
import android.content.Context;  
import android.os.Bundle;  
import android.view.MotionEvent;  
import android.view.View;  
import android.view.View.OnTouchListener;  
import android.view.ViewGroup;  
import android.view.animation.AnimationUtils;  
import android.widget.AdapterView;  
import android.widget.BaseAdapter;  
import android.widget.Gallery;  
import android.widget.ImageSwitcher;  
import android.widget.ImageView;  
import android.widget.AdapterView.OnItemSelectedListener;  
import android.widget.Gallery.LayoutParams;  
import android.widget.ViewSwitcher.ViewFactory;  
public class testImageView extends Activity implements ViewFactory {  
    private ImageSwitcher is;  
    private Gallery gallery;  
    private int downX,upX;  
    private ArrayList<Integer> imgList=new ArrayList<Integer>();//图像ID   
      
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        // TODO Auto-generated method stub   
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  
        //用反射机制来获取资源中的图片ID   
        Field[] fields = R.drawable.class.getDeclaredFields();  
        for (Field field : fields)  
        {  
            if (!"icon".equals(field.getName()))//除了icon之外的图片   
            {     
                int index = 0;  
                try {  
                    index = field.getInt(R.drawable.class);  
                } catch (IllegalArgumentException e) {  
                    // TODO Auto-generated catch block   
                    e.printStackTrace();  
                } catch (IllegalAccessException e) {  
                    // TODO Auto-generated catch block   
                    e.printStackTrace();  
                }  
                //保存图片ID   
                imgList.add(index);  
            }  
        }  
          
        //设置ImageSwitcher控件   
        is = (ImageSwitcher) findViewById(R.id.switcher);  
        is.setFactory(this);  
        is.setInAnimation(AnimationUtils.loadAnimation(this,  
                android.R.anim.fade_in));  
        is.setOutAnimation(AnimationUtils.loadAnimation(this,  
                android.R.anim.fade_out));  
        is.setOnTouchListener(new OnTouchListener(){  
            /* 
             * 在ImageSwitcher控件上滑动可以切换图片 
             */  
            @Override  
            public boolean onTouch(View v, MotionEvent event) {  
                if(event.getAction()==MotionEvent.ACTION_DOWN)  
                {  
                    downX=(int) event.getX();//取得按下时的坐标   
                    return true;  
                }  
                else if(event.getAction()==MotionEvent.ACTION_UP)  
                {  
                    upX=(int) event.getX();//取得松开时的坐标   
                    int index=0;  
                    if(upX-downX>100)//从左拖到右，即看前一张   
                    {  
                        //如果是第一，则去到尾部   
                        if(gallery.getSelectedItemPosition()==0)  
                           index=gallery.getCount()-1;  
                        else  
                            index=gallery.getSelectedItemPosition()-1;  
                    }  
                    else if(downX-upX>100)//从右拖到左，即看后一张   
                    {  
                        //如果是最后，则去到第一   
                        if(gallery.getSelectedItemPosition()==(gallery.getCount()-1))  
                            index=0;  
                        else  
                            index=gallery.getSelectedItemPosition()+1;  
                    }  
                    //改变gallery图片所选，自动触发ImageSwitcher的setOnItemSelectedListener   
                    gallery.setSelection(index, true);  
                    return true;  
                }  
                return false;  
            }  
              
        });  
          
        //设置gallery控件   
        gallery = (Gallery) findViewById(R.id.gallery);  
        gallery.setAdapter(new ImageAdapter(this));  
        gallery.setOnItemSelectedListener(new OnItemSelectedListener(){  
            @Override  
            public void onItemSelected(AdapterView<?> arg0, View arg1,  
                    int position, long arg3) {  
                is.setImageResource(imgList.get(position));  
            }  
            @Override  
            public void onNothingSelected(AdapterView<?> arg0) {  
                // TODO Auto-generated method stub   
            }  
              
        });  
    }  
    //设置ImgaeSwitcher   
    @Override  
    public View makeView() {  
        ImageView i = new ImageView(this);  
        i.setBackgroundColor(0xFF000000);  
        i.setScaleType(ImageView.ScaleType.CENTER);//居中   
        i.setLayoutParams(new ImageSwitcher.LayoutParams(//自适应图片大小   
                LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));  
        return i;  
    }  
    public class ImageAdapter extends BaseAdapter {  
        public ImageAdapter(Context c) {  
            mContext = c;  
        }  
        public int getCount() {  
            return imgList.size();  
        }  
        public Object getItem(int position) {  
            return position;  
        }  
        public long getItemId(int position) {  
            return position;  
        }  
        public View getView(int position, View convertView, ViewGroup parent) {  
            ImageView i = new ImageView(mContext);  
            i.setImageResource(imgList.get(position));  
            i.setAdjustViewBounds(true);  
            i.setLayoutParams(new Gallery.LayoutParams(  
                    LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));  
            return i;  
        }  
        private Context mContext;  
    }  
  
}