图像切换器有什么好处？

我搜索了显示图像的方法，并找到了下一个exampple。我想知道为什么imagewitcher用于imageview？它有什么特别的好处吗？图像切换器有什么好处？

<?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" 
     android:layout_alignParentTop="true" 
     android:layout_alignParentLeft="true" 
    /> 

    <Gallery android:id="@+id/gallery" 
     android:background="#55000000" 
     android:layout_width="match_parent" 
     android:layout_height="60dp" 
     android:layout_alignParentBottom="true" 
     android:layout_alignParentLeft="true" 

     android:gravity="center_vertical" 
     android:spacing="16dp" 
    /> 

</RelativeLayout>

Java代码：

import android.app.Activity; 
import android.content.Context; 
import android.os.Bundle; 
import android.view.View; 
import android.view.ViewGroup; 
import android.view.Window; 
import android.view.animation.AnimationUtils; 
import android.widget.AdapterView; 
import android.widget.BaseAdapter; 
import android.widget.Gallery; 
import android.widget.Gallery.LayoutParams; 
import android.widget.ImageSwitcher; 
import android.widget.ImageView; 
import android.widget.ViewSwitcher; 

public class ImageGalleryExample extends Activity implements 
     AdapterView.OnItemSelectedListener, ViewSwitcher.ViewFactory { 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     requestWindowFeature(Window.FEATURE_NO_TITLE); 

     setContentView(R.layout.main); 

     mSwitcher = (ImageSwitcher) findViewById(R.id.switcher); 
     mSwitcher.setFactory(this); 
     mSwitcher.setInAnimation(AnimationUtils.loadAnimation(this, 
       android.R.anim.fade_in)); 
     mSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this, 
       android.R.anim.fade_out)); 

     Gallery g = (Gallery) findViewById(R.id.gallery); 
     g.setAdapter(new ImageAdapter(this)); 
     g.setOnItemSelectedListener(this); 
    } 

    public void onItemSelected(AdapterView<?> parent, View v, int position, long id) { 
     mSwitcher.setImageResource(mImageIds[position]); 
    } 

    public void onNothingSelected(AdapterView<?> parent) { 
    } 

    public View makeView() { 
     ImageView i = new ImageView(this); 
     i.setBackgroundColor(0xFF000000); 
     i.setScaleType(ImageView.ScaleType.FIT_CENTER); 
     i.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.MATCH_PARENT, 
       LayoutParams.MATCH_PARENT)); 
     return i; 
    } 

    private ImageSwitcher mSwitcher; 

    public class ImageAdapter extends BaseAdapter { 
     public ImageAdapter(Context c) { 
      mContext = c; 
     } 

     public int getCount() { 
      return mThumbIds.length; 
     } 

     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(mThumbIds[position]); 
      i.setAdjustViewBounds(true); 
      i.setLayoutParams(new Gallery.LayoutParams(
        LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); 
      i.setBackgroundResource(R.drawable.picture_frame); 
      return i; 
     } 

     private Context mContext; 

    } 

    private Integer[] mThumbIds = { 
      R.drawable.sample_thumb_0, R.drawable.sample_thumb_1, 
      R.drawable.sample_thumb_2, R.drawable.sample_thumb_3}; 

    private Integer[] mImageIds = { 
      R.drawable.sample_0, R.drawable.sample_1, R.drawable.sample_2, 
      R.drawable.sample_3}; 

}

来源

2014-01-27 Yarh

你是什么意思？'我想知道为什么imagewitcher用于imageview？'？请简要说明你的问题 – GrIsHu