Implement a photo bar using android.widget.Gallery, with custom BaseAdapter, and custom object.

In this example, I will implement a photo bar using android.widget.Gallery.



We will implement MyAdapter extends BaseAdapter, it hold a ArrayList of our custom object ImageItem. In the constructor of MyAdapter, an empty ArrayList of ImageItem will be new. And a method addImageItem is implemented to add new items into the ArrayList.

insertDummyImageItem(3) is a dummy method to add new items into the ArrayList of MyAdapter. As a example, all items have the same bitmap - R.drawable.icon. After items inserted, we have to call notifyDataSetChanged() of the MyAdapter to update the photo bar.

In such a approach, we can add new item on runtime. We will do more on coming post "Update BaseAdapter in backgrond Thread, to insert Gallery items in run-time.".

package com.AndroidPhotoBar;

import java.util.ArrayList;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageView;

public class AndroidPhotoBarActivity extends Activity {

ArrayList<ImageItem> arrayImageItem;
MyAdapter myAdapter;

  public class ImageItem {
 
   Bitmap bitmapImage;
 
   ImageItem(){
    //To simplify, we use a default image here
    bitmapImage = BitmapFactory.decodeResource(
      AndroidPhotoBarActivity.this.getResources(), R.drawable.icon);
   }
 
   public Bitmap getImage(){
    return bitmapImage;
   }
 
}

  Gallery myPhotoBar;

/** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      myPhotoBar = (Gallery)findViewById(R.id.photobar);
    
      myAdapter = new MyAdapter(this); //init myAdapter without ImageItem
    
      //insert dummy ImageItem into myAdapter
      insertDummyImageItem(2);
      myPhotoBar.setAdapter(myAdapter);
    
      //insert dummy ImageItem into myAdapter in Run time
      insertDummyImageItem(3);
      myAdapter.notifyDataSetChanged();

  }

  private void insertDummyImageItem(int cnt){

   //Insert dummy ImageItem into myAdapter
   for(int i = 0; i < cnt; i++){
    myAdapter.addImageItem(new ImageItem());
   }

  }

  public class MyAdapter extends BaseAdapter {
 
   Context context;
   ArrayList<ImageItem> _arrayImageItem;
 
   MyAdapter(Context c){
    context = c;
    _arrayImageItem = new ArrayList<ImageItem>();
   }
 
   public void addImageItem(ImageItem item){
    _arrayImageItem.add(item);
   }

public int getCount() {
 // TODO Auto-generated method stub
 return _arrayImageItem.size();
}

public Object getItem(int position) {
 // TODO Auto-generated method stub
 return _arrayImageItem.get(position);
}

public long getItemId(int position) {
 // TODO Auto-generated method stub
 return position;
}

public View getView(int position, View convertView, ViewGroup parent) {
 // TODO Auto-generated method stub
 ImageView imageView;
 imageView = new ImageView(context);

 imageView.setLayoutParams(new Gallery.LayoutParams(150, 150));
 imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
 imageView.setImageBitmap(_arrayImageItem.get(position).getImage());

 return imageView;
}

}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  >
<TextView
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:text="@string/hello"
  />
<Gallery
android:id="@+id/photobar"
android:layout_width="fill_parent"
android:layout_height="150dp"
/>
</LinearLayout>

next post:
- Update BaseAdapter in backgrond Thread, to insert Gallery items in run-time.

related article:
- Implement Horizontal ListView using android.widget.Gallery, with custom BaseAdapter.