Implement Android Gallery widget with scale-down bitmap

In the exercise of "Android Gallery widget", the bitmap are loaded in Gallery widget without re-size. If you load with big picture, error of java.lang.OutOfMemoryError will be thrown.

Last post "Scale bitmap Efficiently" explain how to scale-down bitmap. It will be apply in the Gallery.

package com.example.androidgallery; import java.io.File; import java.util.ArrayList; import android.os.Bundle; import android.os.Environment; import android.app.Activity; import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.view.Gravity; import android.view.Menu; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.Gallery; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.Toast; public class MainActivity extends Activity { public class GalleryBaseAdapter extends BaseAdapter { ArrayList<String> GalleryFileList; Context context; GalleryBaseAdapter(Context cont){ context = cont; GalleryFileList = new ArrayList<String>(); } @Override public int getCount() { return GalleryFileList.size(); } @Override public Object getItem(int position) { return GalleryFileList.get(position); } @Override public long getItemId(int position) { // TODO Auto-generated method stub return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { //Bitmap bm = BitmapFactory.decodeFile(GalleryFileList.get(position)); Bitmap bm = decodeSampledBitmapFromUri(GalleryFileList.get(position), 200, 200); LinearLayout layout = new LinearLayout(context); layout.setLayoutParams(new Gallery.LayoutParams(250, 250)); layout.setGravity(Gravity.CENTER); ImageView imageView = new ImageView(context); imageView.setLayoutParams(new Gallery.LayoutParams(200, 200)); imageView.setScaleType(ImageView.ScaleType.CENTER_CROP); imageView.setImageBitmap(bm); layout.addView(imageView); return layout; } public void add(String newitem){ GalleryFileList.add(newitem); } } GalleryBaseAdapter myGalleryBaseAdapter; Gallery myPhotoGallery; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); myPhotoGallery = (Gallery)findViewById(R.id.photogallery); myGalleryBaseAdapter = new GalleryBaseAdapter(this); 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){ myGalleryBaseAdapter.add(file.getPath()); } myPhotoGallery.setAdapter(myGalleryBaseAdapter); } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.activity_main, menu); return true; } 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; } }

The layout refer "Android Gallery widget".