Develop Reference

How to avoid OOM to load large images from android resource

I have developed 20+ android apps, apps have a tutorial activity that are composed of large image slide (ex; 4 images in the size of 750 x 1334) and would be shown to users at the first launch.
I cannot reduce the sizes anymore, because of image quality.
My code snippet is following;
public class GalleryImageActivity extends BaseActivity implements OnGestureListener, OnTouchListener {
ViewPager imagePager;
GalleryImageAdapter galleryImageAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.gallery_image);
imagePager = (ViewPager) findViewById(R.id.image_pager);
galleryImageAdapter = new GalleryImageAdapter(this);
imagePager.setAdapter(galleryImageAdapter);
imagePager.setOnTouchListener(this);
}
}
public class GalleryImageAdapter extends PagerAdapter {
public static int SCREEN_CNT = 4;
Bitmap[] bmp = new Bitmap[SCREEN_CNT];
#Override
public int getCount() {
return SCREEN_CNT;
}
#Override
public Object instantiateItem(ViewGroup view, int position) {
View view = inflater.inflate(R.layout.gallery_image_item, null);
ImageView imv = (ImageView) view.findViewById(R.id.imgView);
bmp[position] = readBitMap(context, R.drawable.tutorial_img_0 + position, position);
if (bmp[position] != null)
imv.setImageBitmap(bmp[position]);
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
if (bmp[position] != null && !bmp[position].isRecycled())
{
bmp[position].recycle();
System.gc();
bmp[position] = null;
}
}
public Bitmap readBitMap(Context context, int resId, int position) {
BitmapFactory.Options opt = new BitmapFactory.Options();
opt.inJustDecodeBounds = true;
InputStream is = context.getResources().openRawResource(resId);
BitmapFactory.decodeStream(is,null, opt);
opt.inPreferredConfig = Bitmap.Config.RGB_565;
opt.inPurgeable = true;
opt.inInputShareable = true;
opt.inJustDecodeBounds = false;
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
is = context.getResources().openRawResource(resId);
Bitmap bitmap = BitmapFactory.decodeStream(is,null, opt);
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
return bitmap;
}
}
sometimes it works well, but when repeat 5~6 times, BitmapFactory.decodeStream throws "Out of memory".
How can i decide scale size or resolve this problem?
the example images are following;

You can modify readBitMap function as the following;
public Bitmap readBitMap(Context context, int resId, int position){
if (bmp[position] == null || bmp[position].isRecycled())
{
BitmapFactory.Options opt = new BitmapFactory.Options();
opt.inPreferredConfig = Bitmap.Config.RGB_565;
opt.inPurgeable = true;
opt.inInputShareable = true;
DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
opt.inScaled = true;
opt.inDensity = DisplayMetrics.DENSITY_DEFAULT; // !important
InputStream is = context.getResources().openRawResource(resId);
try {
bmp[position] = BitmapFactory.decodeStream(is,null,opt);
} catch (Exception e){
bmp[position] = null;
}
}
return bmp[position];
}
Some type of mobile phone, especially SAMSUNG, is not well-designed about memory leak.
opt.inDensity = DisplayMetrics.DENSITY_DEFAULT is very important.
If inDensity is 0, BitmapFactory.decodeStream will fill in the density associated with the resource. more...
And you should set the imageview's bitmap to null, when your activity (or page) gets destroyed.

A bitmap of size 750x1334 in RGB_565 config requires around 2MB memory. 3 of them can be stored in 6 MB, which should not create OutOfMemoryError if handled with care.
Here are some tips that you can follow.
Use android:largeHeap="true" in application tag of your manifest.
Use FragmentStatePagerAdapter for your ViewPager.
Don't forget to recycle bitmaps as soon as they are no longer needed.
Use Runtime.getRuntime().gc(); after you recycle your bitmaps.
If you are storing images in drawable, move them to drawable-nodpi.
Use Glide or Picasso library.

Try using some image loading library like Picasso or Glide. That will simplify things a lot.
But in your case, I think the issue is not in decoding the image, but rather you are holding on the bitmap already created in memory. Ensure that you only have one Bitmap in memory at all times. Just open your Profiler in studio, and confirm if you are not storing references to multiple bitmaps.

How to build a layout of photos like facebook shows in android app

I want to build a layout of photos same like facebook uses in it's android app. I want to achieve a layout like below:
I have tried the below using recyclerview to show the photos:
rv = (RecyclerView) findViewById(R.id.rv);
final MyAdapter adapter = new MyAdapter();
rv.setAdapter(adapter);
GridLayoutManager mLayoutManager = new GridLayoutManager(this, 2);
rv.setLayoutManager(mLayoutManager);
mLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
#Override
public int getSpanSize(int position) {
if (adapter.getItemCount() == 1) {
return 2;
} else if (adapter.getItemCount() == 2) {
return 1;
} else if (adapter.getItemCount() == 3) {
if (position == 0) {
return 2;
} else {
return 1;
}
} else {
return 1;
}
}
});
Now I do not have width and height of images, I am having url only of that image.
So, in the case if I upload 2 images, I want to check if the images are portrait (height is greater the width) or landscape and need to show the images accordingly.
I have used the below code to get the height and width of image:
new AsyncTask<Void, Void, Void>() {
#Override
protected Void doInBackground(Void... params) {
if (Looper.myLooper()==null)
Looper.prepare();
try { listItemHolder.imageBitmap = Glide.with(mContext).
load(mainImage). asBitmap(). into(-1,-1).
get();
} catch (final ExecutionException e) {
Log.e(TAG, e.getMessage());
} catch (final InterruptedException e) {
Log.e(TAG, e.getMessage());
}
return null;
}
#Override
protected void onPostExecute(Void dummy) {
}
}.execute();
But the code makes my application too slow.
Can anyone have any idea here, how can I achieve this.

You have to use StaggeredGridLayoutManager
StaggeredGridLayoutManager mLayoutManager = new StaggeredGridLayoutManager(this, 2);
rv.setLayoutManager(mLayoutManager);
for that

To get image's width and height:
Your code are using glide to load full picture that makes slow.
If you just want to get dimensions, you could use bitmap option.
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(getResources(), R.id.myimage, options);
int imageHeight = options.outHeight;
int imageWidth = options.outWidth;
String imageType = options.outMimeType;
Just decode it from stream.
Check this Loading Large Bitmaps Efficiently

Android: Scanning a directory and displaying pictures (thumbnails) (pictures are not stored in the mediastore)

I have recently done some tests with display pictures using a custom gallery that i designed using the media queries and mediastore... It worked great but i really need to do something custom.
I don't wish the pictures to be scanned or available in the mediastore hence i would like to have my app scan a directory and create thumbnails and display these thumbnails.
I am finding it really thin on the ground to find any good quality examples to do this.
Can anyone help with a small example.
Here is what i am looking to do.
Pictures are stored in a directory of the sdcard.
Using my custom gallery it would scan this directory but "NOT" using the mediastore
I need to display the contents of the directory but as thumbnails i presume i would need to create this thumbnails first?
Clicking on a thumnail would should the full screen image from my custom gallery.
I suppose i just need a little help in getting the pictures from the the directory considering there are not stored int eh mediastore so i can't use a query. THe other thing that concerns me is that i would need to create the thumbnails for each of the these images (on the fly??) because display the images but at a reduced size i would suspect would be pretty bad for the performance.
Can anyone lend a helping hand?
Thanks in advance

I did exactly the same a while ago. You have to pass a folder name where your images are to setBaseFolder. This method in turn invokes refresh() which - using a FilenameFilter (code not included but is very easy to implement) gets all images named orig_....jpg from that folder and holds it in mFileList. Then we call notifyDataSetChanged() which in turn will trigger getView() for every cell.
Now, in getView() we either fetch a thumbnail bitmap from a cache if we already have it there, otherwise we make a gray placeholder and start a ThumbnailBuilder to create thumbnail resp. get a bitmap from it.
I think you'll have to change the ThumbnailBuilder a bit, because I create quite large "thumbnails" (500x500) as I need the resized images for other purposes too. Also, as I work with photos taken by the camera there is some stuff there, rotating the image according to the exif information. But basicly, ThumbnailBuilder just checks if there already is a thumbnail image (my thumbnail images are placed the same folder but have prefix small_ instead of orig_) - if the thumbnail picture already exists, we get it as a Bitmap and are done, otherwise the image is generated. Finally, in onPostExecute() the bitmap is set to the ImageView.
public class PhotoAdapter extends BaseAdapter {
private Context mContext;
private int mCellSize;
private File mFolder;
private File[] mFileList;
private Map<Object, Bitmap> mThumbnails = new HashMap<Object, Bitmap>();
private Set<Object> mCreatingTriggered = new HashSet<Object>(); // flag that creating already triggered
public PhotoAdapter(Context context, int cellSize) {
mContext = context;
mCellSize = cellSize;
}
#Override
public int getCount() {
if (mFolder == null) {
return 0; // don't do this
} else {
return mFileList.length;
}
}
#Override
public Object getItem(int position) {
return mFileList[position];
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ImageView view = (ImageView)convertView;
if (view == null) {
view = new ImageView(mContext);
view.setLayoutParams(new GridView.LayoutParams(mCellSize, mCellSize));
view.setScaleType(ImageView.ScaleType.CENTER_CROP);
view.setPadding(8, 8, 8, 8);
view.setBackgroundColor(0xFFC6CCD3);
}
Object item = getItem(position);
Bitmap bm = mThumbnails.get(item);
if (bm == null) {
view.setImageBitmap(null);
if (!mCreatingTriggered.contains(item)) {
mCreatingTriggered.add(item);
new ThumbnailBuilder(view, (File)item).execute();
}
} else {
view.setImageBitmap(bm);
}
return view;
}
public void setBaseFolder(File baseFolder) {
if (baseFolder == null) return;
if (!baseFolder.equals(mFolder)) {
releaseThumbnails();
mFolder = baseFolder;
}
refresh();
}
public void refresh() {
if (mFolder == null) {
return;
}
mFileList = mFolder.listFiles(EtbApplication.origImageFilenameFilter);
if (mFileList == null) mFileList = new File[0];
notifyDataSetChanged();
}
public void releaseThumbnails() {
for (Bitmap bm : mThumbnails.values()) {
bm.recycle();
}
mThumbnails.clear();
}
// ------------------------------------------------------------------------------------ Asynchronous Thumbnail builder
private class ThumbnailBuilder extends AsyncTask<Void, Integer, Bitmap> {
private ImageView mView;
private File mFile;
public ThumbnailBuilder(ImageView view, File file) {
mView = view;
mFile = file;
}
#Override
protected Bitmap doInBackground(Void... params) {
Log.d("adapter", "make small image and thumbnail");
try {
return createThumbnail(mFile.getAbsolutePath());
} catch (Exception e) {
return null;
}
}
#Override
protected void onPostExecute(Bitmap result) {
if (result != null) {
mView.setImageBitmap(result);
mThumbnails.put(mFile, result);
} else {
mView.setImageResource(R.drawable.ic_launcher);
}
}
/**
* Creates Thumbnail (also rotates according to exif-info)
* #param file
* #return
* #throws IOException
*/
private Bitmap createThumbnail(String file) throws IOException {
File thumbnailFile = new File(file.replace("orig_", "small_"));
// If a small image version already exists, just load it and be done.
if (thumbnailFile.exists()) {
return BitmapFactory.decodeFile(thumbnailFile.getAbsolutePath());
}
// Decode image size
BitmapFactory.Options bounds = new BitmapFactory.Options();
bounds.inJustDecodeBounds = true;
BitmapFactory.decodeFile(file, bounds);
if ((bounds.outWidth == -1) || (bounds.outHeight == -1))
return null;
int w, h;
if (bounds.outWidth > bounds.outHeight) { // Querformat
w = 500;
h = 500 * bounds.outHeight / bounds.outWidth;
} else { // Hochformat
h = 500;
w = 500 * bounds.outWidth / bounds.outHeight;
}
BitmapFactory.Options opts = new BitmapFactory.Options();
opts.inSampleSize = 4; // resample -- kleiner aber noch nicht die 500 Pixel, die kommen dann unten
Bitmap resizedBitmap = BitmapFactory.decodeFile(file, opts);
resizedBitmap = Bitmap.createScaledBitmap(resizedBitmap, w, h, true);
ExifInterface exif = new ExifInterface(file);
String orientString = exif.getAttribute(ExifInterface.TAG_ORIENTATION);
int orientation = orientString != null ? Integer.parseInt(orientString) : ExifInterface.ORIENTATION_NORMAL;
int rotationAngle = 0;
if (orientation == ExifInterface.ORIENTATION_ROTATE_90) rotationAngle = 90;
if (orientation == ExifInterface.ORIENTATION_ROTATE_180) rotationAngle = 180;
if (orientation == ExifInterface.ORIENTATION_ROTATE_270) rotationAngle = 270;
Matrix matrix = new Matrix();
matrix.setRotate(rotationAngle, (float) resizedBitmap.getWidth() / 2, (float) resizedBitmap.getHeight() / 2);
Bitmap rotatedBitmap = Bitmap.createBitmap(resizedBitmap, 0, 0, w, h, matrix, true);
resizedBitmap.recycle();
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
rotatedBitmap.compress(Bitmap.CompressFormat.JPEG, 90, bytes);
thumbnailFile.createNewFile();
FileOutputStream fo = new FileOutputStream(thumbnailFile);
fo.write(bytes.toByteArray());
fo.close();
//new File(file).delete(); // Originalbild löschen
return rotatedBitmap;
}
}
}

Get the LinearLayout inside a ListView from an Async Task onRetainNonConfigurationInstance()

I hope the title is not mis-leading. I am trying to implement onRetainNonConfigurationInstance() of an AsyncTask of loading images and am getting this error "Java.lang.RuntimeException:Unable to retain Activity". Here is my code for onRetainNonConfigurationInstance():
public Object onRetainNonConfigurationInstance(){
//final ListView listview = list;
final int count = list.getChildCount();
final LoadedImage[] mylist = new LoadedImage[count];
for(int i = 0; i < count; i++){
final ImageView v = (ImageView)list.getChildAt(i); // getting error here
mylist[i] = new LoadedImage(((BitmapDrawable) v.getDrawable()).getBitmap());
}
return mylist;
}
Here is the Logcat:
05-18 08:43:15.385: E/AndroidRuntime(28130): java.lang.RuntimeException: Unable to retain activity {com.MyApps.ImageGen/com.MyApps.ImageGen.Wallpapers}: java.lang.ClassCastException: android.widget.LinearLayout
05-18 08:43:15.385: E/AndroidRuntime(28130): at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:2989)
05-18 08:43:15.385: E/AndroidRuntime(28130): at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:3100)
05-18 08:43:15.385: E/AndroidRuntime(28130): at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3216)
05-18 08:43:15.385: E/AndroidRuntime(28130): at android.app.ActivityThread.access$1600(ActivityThread.java:132)
Here is my layout with the ListView:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<ListView
android:id="#android:id/list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:cacheColorHint="#00000000"
android:listSelector="#android:color/transparent" >
</ListView>
</LinearLayout>
Here is how I setup the ListView:
private void setupViews() {
list = (ListView)findViewById(android.R.id.list);
list.setDivider(null);
list.setDividerHeight(0);
imageAdapter = new ImageAdapter(getApplicationContext());
list.setAdapter(imageAdapter);
list.setOnItemClickListener(this);
}
my async task and Item Adapter:
class LoadImagesFromSDCard extends AsyncTask<Object, LoadedImage, Object> {
#Override
protected Object doInBackground(Object... params) {
Bitmap bitmap = null;
Bitmap newbitmap = null;
Uri uri = null;
String [] img = {MediaStore.Images.Media._ID};
String state = Environment.getExternalStorageState();
if(Environment.MEDIA_MOUNTED.equals(state)){
cursor = getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, img, null, null, null);
} else {
// cursor = getContentResolver().query(MediaStore.Images.Media.INTERNAL_CONTENT_URI, img, null, null, null);
inInternalStorage = true;
}
int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media._ID);
int size = cursor.getCount();
if(size == 0){
//Toast.makeText(getApplicationContext(), "There are no Images on the sdcard", Toast.LENGTH_SHORT).show();
//System.out.println("size equals zero");
Wallpaper.this.runOnUiThread(new Runnable() {
public void run() {
Toast.makeText(getApplicationContext(), "There are no Images on the sdcard", Toast.LENGTH_SHORT).show();
}
});
return params;
}else {
}
for(int i = 0; i < size; i++){
cursor.moveToPosition(i);
int ImageId = cursor.getInt(column_index);
if(inInternalStorage == true){
uri = Uri.withAppendedPath(MediaStore.Images.Media.INTERNAL_CONTENT_URI, "" + ImageId);
}else {
uri = Uri.withAppendedPath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, "" + ImageId);
}
try {
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeStream(getContentResolver().openInputStream(uri), null, options);
int imageHeight = options.outHeight;
int imageWidth = options.outWidth;
String imageType = options.outMimeType;
Log.i(TAG, "imageheight = " + imageHeight);
Log.i(TAG, "imagewidth = " + imageWidth);
Log.i(TAG, "imageType = " + imageType);
//options.inSampleSize=4;
options.inSampleSize = calculateInSampleSize(options, imageWidth, imageHeight);
options.inJustDecodeBounds = false;
//bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri));
bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri), null, options);
if(bitmap != null){
newbitmap = Bitmap.createScaledBitmap(bitmap, 180, 180, true);
bitmap.recycle();
}
if(newbitmap != null){
publishProgress(new LoadedImage(newbitmap));
}
}catch(IOException e){
}
//cursor.close();
}
cursor.close();
return null;
}
#Override
public void onProgressUpdate(LoadedImage... value){
addImage(value);
}
#Override
protected void onPostExecute(Object result) {
setProgressBarIndeterminateVisibility(false);
}
}
private static class LoadedImage {
Bitmap mBitmap;
LoadedImage(Bitmap bitmap) {
mBitmap = bitmap;
}
public Bitmap getBitmap() {
return mBitmap;
}
}
/*Image Adapter to populate grid view of images*/
public class ImageAdapter extends BaseAdapter {
private Context mContext;
private ArrayList<LoadedImage> photos = new ArrayList<LoadedImage>();
public ImageAdapter(Context context){
this.mContext = context;
}
public void addPhotos(LoadedImage photo){
photos.add(photo);
}
#Override
public int getCount() {
return photos.size();
}
#Override
public Object getItem(int position) {
return position;
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ImageView image;
ViewHolder holder;
if(convertView == null){
LayoutInflater inflater = (LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
//convertView = inflater.inflate(R.layout.image_list,null);
convertView = inflater.inflate(R.layout.media_view, null);
holder = new ViewHolder();
holder.image = (ImageView)convertView.findViewById(R.id.media_image_id);
//holder.item_name = (TextView)convertView.findViewById(R.id.media_image_id);
convertView.setTag(holder);
} else{
holder = (ViewHolder)convertView.getTag();
}
//holder.image.setLayoutParams(new GridView.LayoutParams(100, 100));
//String item_name = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DISPLAY_NAME));
holder.image.setImageBitmap(photos.get(position).getBitmap());
//holder.item_name.setText(item_name);
return convertView;
}
}
static class ViewHolder {
ImageView image;
TextView item_name;
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Cursor cursor = null;
int image_column_index = 0;
String[] proj = {MediaStore.Images.Media.DATA};
String state = Environment.getExternalStorageState();
if(Environment.MEDIA_MOUNTED.equals(state)){
cursor = managedQuery(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,proj,null, null,null);
}else{
cursor = managedQuery(MediaStore.Images.Media.INTERNAL_CONTENT_URI,proj,null, null,null);
}
cursor.moveToPosition(position);
image_column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
String info = cursor.getString(image_column_index);
Intent imageviewer = new Intent(getApplicationContext(), ViewImage.class);
imageviewer.putExtra("pic_name", info);
startActivity(imageviewer);
cursor.close();
}
public static 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 = 2;
if (height > reqHeight || width > reqWidth) {
if (width > height) {
inSampleSize = Math.round((float)height / (float)reqHeight);
} else {
inSampleSize = Math.round((float)width / (float)reqWidth);
}
}
/*final int REQUIRED_SIZE = 180;
int scale = 1;
if(reqWidth > REQUIRED_SIZE || reqHeight > REQUIRED_SIZE){
scale = (int)Math.pow(2, (int)Math.round(Math.log(REQUIRED_SIZE/(double)Math.max(reqHeight, reqWidth)) / Math.log(0.5)));
}*/
return inSampleSize;
}
other Methods within Async Task:
private void loadImages() {
final Object data = getLastNonConfigurationInstance();
if(data == null){
new LoadImagesFromSDCard().execute();
}else {
final LoadedImage[] photos = (LoadedImage[])data;
if(photos.length == 0){
new LoadImagesFromSDCard().execute();
}
for(LoadedImage photo:photos){
addImage(photo);
}
}
}
private void addImage(LoadedImage... value) {
for(LoadedImage photo: value){
imageAdapter.addPhotos(photo);
imageAdapter.notifyDataSetChanged();
}
}
I am assuming I should first get the root element before I get the ListView from the logcat error, but I don't know how, I can't seem to find a suitable method from the documentation.
P.S: I am using an Activity and not a ListActivity.

The exception tells you that you try to do an invalid cast. My guess is that your row layout isn't a simple ImageView like you assume with the cast in the onRetainNonConfigurationInstance(), instead your row layout probably has a parent Linearlayout that wraps the ImageView(and other views?!). When you call the method getChildAt you get that parent Linearlayout which you try to cast to a ImageView. Instead you should do this:
//...
for(int i = 0; i < count; i++){
LinearLayout parent = (LinearLayout)list.getChildAt(i);
final ImageView v = (ImageView) parent.findViewById(R.id.the_id_of_the_imageview_from_theRow_layout);
mylist[i] = new LoadedImage(((BitmapDrawable) v.getDrawable()).getBitmap());
}
Note: The getChildAt method returns the rows views for the visible rows only so if you try to access the View for a row that isn't currently visible you'll most likely end up with a NullPointerException(you should get the drawables directly from the adapter and not from parsing all the rows Views).
Edit based on the comments:
If I understood your problem, the behavior you see it's normal. You didn't say how you ended up getting the bitmaps in the onRetainNonConfigurationInstance but my guess is that you just save the images from the ListView rows that are currently visible to the user. When it's time to restore the adapter with the images from getLastNonConfigurationInstance() you end up getting only those images which were previously visible. This will get worse if you rotate the phone again as, most likely, there are fewer images visible in landscape orientation then in the portrait orientation.
I don't know if this will work but you could try to modify the LoadedImage class to store the id of the image from MediaStore.Images.Media. When it's time to save the configuration, stop the LoadImagesFromSDCard task and nullify all the images(remove the Bitmap to which LoadedImage points)from the LoadedImages ArrayList(in the adapter) except the ones that are currently visible to the user. Send the photos ArrayList from your adapter through
onRetainNonConfigurationInstance.
When it's time to restore the adapter set the photos ArrayList of your new adapter to the one you got back and put the ListView to the position of the visible images(so the user sees the sent images). In the getView method of your adapter you'll put a default image(like loading...) when you have a null value for the Bitmap in the associated LoadedImage class. Start a new LoadImagesFromSDCard task to get the images and parse them again. When you get the id from MediaStore.Images.Media you'll check if a LoadedImage with this id exists in the adapter and if it has a Bitmap set to it. If it doesn't exist(or it doesn't have a Bitmap associated) then load the image and put it in the adapter, if not the image already exists and move to the next one.
I don't know if the solution above will work or if it's efficient. I would recommend you to modify the code and load images on demand instead of loading all up in a big task.

Android List view update

I am struggling to update a list view with data from a database, this works nicely by using a SimpleCursorAdapter. But the image view on the rows is not updated on the activity start, I have to scroll through the list a few times and only then the images are loaded in the image view.
This is the binder i am using for the SimpleCursorAdapter:
private class PromotionViewBinder implements SimpleCursorAdapter.ViewBinder {
private int done;
public boolean setViewValue(View view, Cursor cursor, int index) {
Log.e(""+cursor.getCount(),"");
View tmpview = view;
if (index == cursor.getColumnIndex(PromotionsTable.SEEN_COL)) {
boolean read = cursor.getInt(index) > 0 ? true : false;
TextView title = (TextView) tmpview;
if (!read) {
title.setTypeface(Typeface.DEFAULT_BOLD, 0);
} else {
title.setTypeface(Typeface.DEFAULT);
}
return true;
} else if (tmpview.getId() == R.id.promotions_list_row_image){
String imageURL = cursor.getString(index);
Log.e("",imageURL);
imageRetriever.displayImage(imageURL, (ImageView)tmpview);
return true;
} else {
return false;
}
}
}
The image retriever class is the LazyList example from here. As you will see this is using a runnable to retrieve the images and once the task is done is automatically updating the given imageView...Do you think that the reference to the imageView is lost somewhere on the way?
Thanx in advance,
Nick
package com.tipgain.promotions;
The image retriever class:
/**
* This class is used for retrieving images from a given web link. it uses local
* storage and memory to store the images. Once a image is downloaded
* successfully the UI gets updated automatically.
*
*
*/
public class ImageRetriever {
private final String TAG = ImageRetriever.class.getName();
private MemoryImageCache memoryImgCache = new MemoryImageCache();
private LocalStorageImageCache localFileCache;
private Map<ImageView, String> imageViewHolders = Collections
.synchronizedMap(new WeakHashMap<ImageView, String>());
private ExecutorService execService;
final int defaultImageID = R.drawable.photo_not_available;
public ImageRetriever(Context context) {
localFileCache = new LocalStorageImageCache(context);
execService = Executors.newFixedThreadPool(5);
}
public void displayImage(String url, ImageView imageView) {
imageViewHolders.put(imageView, url);
Bitmap bmp = memoryImgCache.retrieve(url);
if (bmp != null) {
Log.e("case 1", " " + (bmp != null));
imageView.setImageBitmap(bmp);
} else {
Log.e("case 2", " " + (bmp == null));
addImageToQueue(url, imageView);
imageView.setImageResource(defaultImageID);
}
}
private void addImageToQueue(String url, ImageView imageView) {
NextImageToLoad img = new NextImageToLoad(url, imageView);
execService.submit(new ImagesRetriever(img));
}
/**
* This method is used for retrieving the Bitmap Image.
*
* #param url
* String representing the url pointing to the image.
* #return Bitmap representing the image
*/
private Bitmap getBitmap(String url) {
File imageFile = localFileCache.getFile(url);
// trying to get the bitmap from the local storage first
Bitmap bmp = decodeImageFile(imageFile);
if (bmp != null)
return bmp;
// if the file was not found locally we retrieve it from the web
try {
URL imageUrl = new URL(url);
HttpURLConnection conn = (HttpURLConnection) imageUrl
.openConnection();
conn.setConnectTimeout(30000);
conn.setReadTimeout(30000);
conn.setInstanceFollowRedirects(true);
InputStream is = conn.getInputStream();
OutputStream os = new FileOutputStream(imageFile);
Utils.CopyStream(is, os);
os.close();
bmp = decodeImageFile(imageFile);
return bmp;
} catch (MalformedURLException e) {
Log.e(TAG, e.getMessage());
} catch (FileNotFoundException e) {
Log.e(TAG, e.getMessage());
} catch (IOException e) {
Log.e(TAG, e.getMessage());
}
return null;
}
/**
* This method is used for decoding a given image file. Also, to reduce
* memory, the image is also scaled.
*
* #param imageFile
* #return
*/
private Bitmap decodeImageFile(File imageFile) {
try {
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeStream(new FileInputStream(imageFile), null,
options);
// Find the correct scale value. It should be the power of 2.
// Deciding the perfect scaling value. (^2).
final int REQUIRED_SIZE = 100;
int tmpWidth = options.outWidth, tmpHeight = options.outHeight;
int scale = 1;
while (true) {
if (tmpWidth / 2 < REQUIRED_SIZE
|| tmpHeight / 2 < REQUIRED_SIZE)
break;
tmpWidth /= 2;
tmpHeight /= 2;
scale *= 2;
}
// decoding using inSampleSize
BitmapFactory.Options option2 = new BitmapFactory.Options();
option2.inSampleSize = scale;
return BitmapFactory.decodeStream(new FileInputStream(imageFile),
null, option2);
} catch (FileNotFoundException e) {
Log.e(TAG, e.getLocalizedMessage());
}
return null;
}
private boolean reusedImage(NextImageToLoad image) {
Context c = image.imageView.getContext();
c.getContentResolver().notifyChange(PromotionsProvider.CONTENT_URI, null);
String tag = imageViewHolders.get(image.imageView);
if ((tag == null) || (!tag.equals(image.url)))
return true;
return false;
}
/**
* Clears the Memory and Local cache
*/
public void clearCache() {
memoryImgCache.clear();
localFileCache.clear();
}
/**
* This class implements a runnable that is used for updating the promotions
* images on the UI
*
*
*/
class UIupdater implements Runnable {
Bitmap bmp;
NextImageToLoad image;
public UIupdater(Bitmap bmp, NextImageToLoad image) {
this.bmp = bmp;
this.image = image;
Log.e("", "ui updater");
}
public void run() {
Log.e("ui updater", "ui updater");
if (reusedImage(image))
return;
Log.e("nick", "" + (bmp == null) + " chberugv");
if (bmp != null){
image.imageView.setImageBitmap(bmp);
Context c = image.imageView.getContext();
c.getContentResolver().notifyChange(PromotionsProvider.CONTENT_URI, null);
}else
image.imageView.setImageResource(defaultImageID);
}
}
private class ImagesRetriever implements Runnable {
NextImageToLoad image;
ImagesRetriever(NextImageToLoad image) {
this.image = image;
}
public void run() {
Log.e("images retirever", " images retriever");
if (reusedImage(image))
return;
Bitmap bmp = getBitmap(image.url);
memoryImgCache.insert(image.url, bmp);
if (reusedImage(image))
return;
UIupdater uiUpdater = new UIupdater(bmp, image);
Activity activity = (Activity) image.imageView.getContext();
activity.runOnUiThread(uiUpdater);
//Context c = image.imageView.getContext();
//c.getContentResolver().notifyChange(PromotionsProvider.CONTENT_URI, null);
}
}
/**
* This class encapsulates the image being downloaded.
*
* #author Nicolae Anca
*
*/
private class NextImageToLoad {
public String url;
public ImageView imageView;
public NextImageToLoad(String u, ImageView i) {
url = u;
imageView = i;
}
}
}
Modified Runnable:
class UIupdater implements Runnable {
Bitmap bmp;
NextImageToLoad image;
public UIupdater(Bitmap bmp, NextImageToLoad image) {
this.bmp = bmp;
this.image = image;
}
public void run() {
if (reusedImage(image))
return;
if (bmp != null){
image.imageView.setImageBitmap(bmp);
Context c = image.imageView.getContext();
c.getContentResolver().notifyChange(PromotionsProvider.CONTENT_URI, null);
}else
image.imageView.setImageResource(defaultImageID);
}
}

Thats an interesting way to do what you are doing. Have you tried extending the Simple Cursor Adapter?
What you do is implement a ViewHolder and put your imageview in it.
Then in your ImageRetriever, write a Listener which will be called once the image is ready and retrieved.
Implement this listener in the Viewholder.
You create the view in getView() and request for the image in BindView().
Once the image gets loaded, the list will be refreshed automatically.

one way to do it is by calling notifyDataSetChenged on listview, and another was is to have adapter as member variable and when something changes on listview you call a function that assigns new listadapter to member adapter. That way your list will be redraw on change.

I guess, you have to use some handler, calling after image load, which will call notifyDataSetChanged for list adapter