Implement Gallery-like HorizontalScrollView

As mentioned in the post "Implement Android Gallery widget" - android.widget.Gallery is no longer supported. Other horizontally scrolling widgets include HorizontalScrollView and ViewPager from the support library.

It's a example to implement Gallery-like view using HorizontalScrollView. Please note that in this example, the bitmaps in HorizontalScrollView will not be removed even not in screen. So if too much bitmaps loaded, error of java.lang.OutOfMemoryError will be thrown!

Add HorizontalScrollView in layout:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    android:orientation="vertical">

    <HorizontalScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >
        <LinearLayout
            android:id="@+id/mygallery"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            />
    </HorizontalScrollView>

</LinearLayout>

Main Java code:

package com.example.androidhorizontalscrollviewgallery;

import java.io.File;

import android.os.Bundle;
import android.os.Environment;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.Toast;

public class MainActivity extends Activity {

 LinearLayout myGallery;
 
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        myGallery = (LinearLayout)findViewById(R.id.mygallery);
        
        String ExternalStorageDirectoryPath = Environment
          .getExternalStorageDirectory()
          .getAbsolutePath();
        
        String targetPath = ExternalStorageDirectoryPath + "/test/";
        
        Toast.makeText(getApplicationContext(), targetPath, Toast.LENGTH_LONG).show();
        File targetDirector = new File(targetPath);
                 
        File[] files = targetDirector.listFiles();
        for (File file : files){
         myGallery.addView(insertPhoto(file.getAbsolutePath()));
        }    
    }

    View insertPhoto(String path){
     Bitmap bm = decodeSampledBitmapFromUri(path, 220, 220);
     
     LinearLayout layout = new LinearLayout(getApplicationContext());
     layout.setLayoutParams(new LayoutParams(250, 250));
     layout.setGravity(Gravity.CENTER);
     
     ImageView imageView = new ImageView(getApplicationContext());
     imageView.setLayoutParams(new LayoutParams(220, 220));
     imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
     imageView.setImageBitmap(bm);
     
     layout.addView(imageView);
     return layout;
    }
    
    public Bitmap decodeSampledBitmapFromUri(String path, int reqWidth, int reqHeight) {
     Bitmap bm = null;
     
     // First decode with inJustDecodeBounds=true to check dimensions
     final BitmapFactory.Options options = new BitmapFactory.Options();
     options.inJustDecodeBounds = true;
     BitmapFactory.decodeFile(path, options);
     
     // Calculate inSampleSize
     options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
     
     // Decode bitmap with inSampleSize set
     options.inJustDecodeBounds = false;
     bm = BitmapFactory.decodeFile(path, options); 
     
     return bm;  
    }
    
    public int calculateInSampleSize(
      
     BitmapFactory.Options options, int reqWidth, int reqHeight) {
     // Raw height and width of image
     final int height = options.outHeight;
     final int width = options.outWidth;
     int inSampleSize = 1;
        
     if (height > reqHeight || width > reqWidth) {
      if (width > height) {
       inSampleSize = Math.round((float)height / (float)reqHeight);   
      } else {
       inSampleSize = Math.round((float)width / (float)reqWidth);   
      }   
     }
     
     return inSampleSize;   
    }
    
}

Download the files.

Next:
- Implement custom LinearLayout for Gallery-like HorizontalScrollView
- Handle onClick for our custom LinearLayout for Gallery-like HorizontalScrollView

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Remark@2015-11-13:
It's a old example. With current Material Design on Android, it's suggested to consider using " RecyclerView + CardView".

Coresponding "Gallery-like RecyclerView + CardView example".