HelloGallery, read picture files from SD, display in ImageView.

It's a old exercise "HelloGallery, read picture files from SD, using File ArrayList" to demonstrate how to use Gallery. It's modified to add a ImageView to show the large version of the clicked item in Gallery.



Create a file /res/values/attrs.xml.

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <declare-styleable name="Theme">
  <attr name="android:galleryItemBackground" />
 </declare-styleable>
</resources>

Modify /res/layout/main.xml to include a Gallery and 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">
<Gallery
 android:id="@+id/gallery"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"/>
<ImageView
 android:id="@+id/imageview"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"/>
</LinearLayout>

Main code, HelloGallery.java.

package com.exercise.HelloGallery;

import java.io.File;
import java.util.ArrayList;
import java.util.List;

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

public class HelloGallery extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    final ImageView imageView = (ImageView)findViewById(R.id.imageview);
    
    Gallery g = (Gallery) findViewById(R.id.gallery);
    final List<String> SD = ReadSDCard();
    g.setAdapter(new ImageAdapter(this, SD));

    g.setOnItemClickListener(new OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent,
          View v, int position, long id) {
         
         String imageInSD = SD.get(position);
         
         Toast.makeText(HelloGallery.this,
           imageInSD,
              Toast.LENGTH_LONG).show();
         
         Bitmap bitmap = BitmapFactory.decodeFile(imageInSD);
            imageView.setImageBitmap(bitmap);
         
        }
    });
}

private List<String> ReadSDCard()
{
 List<String> tFileList = new ArrayList<String>();

 //It have to be matched with the directory in SDCard
 File f = new File("/sdcard/pictures/");

 File[] files=f.listFiles();

 for(int i=0; i<files.length; i++)
 {
  File file = files[i];
  //add the selected file type only
  String curFile=file.getPath();
  String ext=curFile.substring(curFile.lastIndexOf(".")+1, 
    curFile.length()).toLowerCase();
  if(ext.equals("jpg")||ext.equals("gif")||ext.equals("png"))
  tFileList.add(file.getPath());
 }

 return tFileList;
}

public class ImageAdapter extends BaseAdapter {
    int mGalleryItemBackground;
    private Context mContext;
    private List<String> FileList;

    public ImageAdapter(Context c, List<String> fList) {
        mContext = c;
        FileList = fList;
        TypedArray a = obtainStyledAttributes(R.styleable.Theme);
        mGalleryItemBackground = a.getResourceId(
          R.styleable.Theme_android_galleryItemBackground,
          0);
        a.recycle();
    }

    public int getCount() {
        return FileList.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);

        Bitmap bm = BitmapFactory.decodeFile(
          FileList.get(position).toString());
        i.setImageBitmap(bm);
    
        i.setLayoutParams(new Gallery.LayoutParams(150, 100));
        i.setScaleType(ImageView.ScaleType.FIT_XY);
        i.setBackgroundResource(mGalleryItemBackground);
    
        return i;
    }
}
}

Download the files.