ImageSwitcher View android exam

You saw in the previous section on how to use the Gallery view together with an ImageView view to display a series of thumbnail images so that when one is selected, the selected image is displayed in the ImageView view. Because this is such a common UI task, Android provides the ImageSwitcher view, which is functionally similar to what you have achieved in the previous section.
Modify the displayview.xml file as follows by adding the ImageSwitcher element:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:background="#ff000000" 
    > 
 
    <ImageSwitcher 
        android:id="@+id/switcher1" 
        android:layout_width="fill_parent" 
        android:layout_height="fill_parent"                 
        android:layout_alignParentLeft="true" 
        android:layout_alignParentRight="true" 
        android:layout_alignParentBottom="true"      
        /> 
    <Gallery
        android:id="@+id/gallery1"
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content"       
        /> 
 
</RelativeLayout>

Modify the DisplayViewsExample.java file as shown below:

package net.learn2develop.AndroidViews;
 
import android.app.Activity;
import android.content.Context;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
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.ViewSwitcher.ViewFactory;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.AdapterView.OnItemClickListener;
 
public class DisplayViewsExample extends Activity 
implements ViewFactory
{    
    //---the images to display---
    Integer[] imageIDs = {
            R.drawable.pic1,
            R.drawable.pic2,
            R.drawable.pic3,
            R.drawable.pic4,
            R.drawable.pic5,
            R.drawable.pic6,
            R.drawable.pic7                    
    };
 
    private ImageSwitcher imageSwitcher;
 
    @Override    
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.displayview);
 
        imageSwitcher = (ImageSwitcher) findViewById(R.id.switcher1);
        imageSwitcher.setFactory(this);
        imageSwitcher.setInAnimation(AnimationUtils.loadAnimation(this,
                android.R.anim.fade_in));
        imageSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this,
                android.R.anim.fade_out));
 
        Gallery gallery = (Gallery) findViewById(R.id.gallery1);
        gallery.setAdapter(new ImageAdapter(this));
        gallery.setOnItemClickListener(new OnItemClickListener() 
        {
            public void onItemClick(AdapterView parent, 
            View v, int position, long id) 
            {                
             imageSwitcher.setImageResource(imageIDs[position]);
            }
        });  
    }
 
    public View makeView() 
    {
        ImageView imageView = new ImageView(this);
        imageView.setBackgroundColor(0xFF000000);
        imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
        imageView.setLayoutParams(new 
                ImageSwitcher.LayoutParams(
                        LayoutParams.FILL_PARENT,
                        LayoutParams.FILL_PARENT));
        return imageView;
    }
 
    public class ImageAdapter extends BaseAdapter 
    {
        private Context context;
        private int itemBackground;
 
        public ImageAdapter(Context c) 
        {
            context = c;
 
            //---setting the style---                
            TypedArray a = obtainStyledAttributes(R.styleable.Gallery1);
            itemBackground = a.getResourceId(
                    R.styleable.Gallery1_android_galleryItemBackground, 0);
            a.recycle();                                                    
        }
 
        //---returns the number of images---
        public int getCount() 
        {
            return imageIDs.length;
        }
 
        //---returns the ID of an item--- 
        public Object getItem(int position) 
        {
            return position;
        }
 
        public long getItemId(int position) 
        {
            return position;
        }
 
        //---returns an ImageView view---
        public View getView(int position, View convertView, ViewGroup parent)
        {
            ImageView imageView = new ImageView(context);
            imageView.setImageResource(imageIDs[position]);
            imageView.setScaleType(ImageView.ScaleType.FIT_XY);
            imageView.setLayoutParams(new Gallery.LayoutParams(150, 120));
            imageView.setBackgroundResource(itemBackground);
            return imageView;
        }
   }    
    }

Observe that the DisplayViewsExample class now implements the ViewFactory class. The ViewFactory class creates the views in a ViewSwitcher view. When your class implements the ViewFactory class, you need to override the makeView() method, which creates a new View to be added in a ViewSwitcher.
Press F11 in Eclipse and observe the ImageSwitcher in action as shown in Figure 13.

Figure 13: The ImageSwitcher in action