Develop Reference

images in my Grid View disappear as I scroll

I'm using Grid View in order to show images I have stored, but as I scroll down the images disappear in Image View and don't load again.I also use thread for loading images into Image View.
Here is my code(also these codes are in my grid view adapter class) :
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
Log.e("sara" , "this part takes time");
LayoutInflater inflater = getLayoutInflater();
convertView = getLayoutInflater().inflate(R.layout.gallery_gridsq, parent, false);
iv = (ImageView) convertView.findViewById(R.id.icon);
file = new File(Uri.parse(getItem(position).toString()).getPath());
new myTask(iv, file).execute();
return convertView;
}
private class myTask extends AsyncTask <Void , Void ,Bitmap> {
ImageView iv;
File file;
public myTask(ImageView iv, File file) {
this.iv=iv;
this.file= file;
}
#Override
protected Bitmap doInBackground(Void... params) {
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
options.inJustDecodeBounds = false;
options.inSampleSize = 8;
try {
bmp = BitmapFactory.decodeStream(new FileInputStream(file), null, options);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return bmp;
}
#Override
protected void onPostExecute(Bitmap aVoid) {
iv.setImageBitmap(aVoid);
}
}

I can think of the memory issue that caused me the similar trouble.
Check if your getView is still called when you scroll down with your log: Log.e("sara" , "this part takes time");
If that line is called when you scroll down, check the memory from android monitor provided in the android studio.
click android monitor at the bottom > monitors> and observe if memory reaches the cap depending on the set up (probably 128 or 256MB).
If so you are having issues with memory. The very possible reason is that you are not recycling the list and the memory is stacking. At the peak of memory, the images will not be loaded.
It should be implemented in a way that the images that you already loaded be deleted as you scroll down and load new images.
Also, try using glide for it has a good solution with memory issues and generally better in many fields than bitmapfactory.

Android Listview scroll lag with view holder

I have noticed that a ListView in my application has started to stutter quite badly all of a sudden.
I am using Volley to load images for my listview items - downloading and caching the images are fine and scroll smooth as butter.
However I currently have a spinner that sits on top of the NetworkImageView while I wait for the image to load. The lag comes in once the image has successfully loaded - I set the spinner to be invisible and the image to visible. Changing the visibility of these items seems to be the source of the lag.
I am currently using the View Holder pattern, my onResponseLoad looks like the following:
#Override
public void onResponse(ImageLoader.ImageContainer response, boolean isImmediate) {
if (response.getBitmap() != null){ //Check that the image is not null
ProgressBar progress = holder.getProgress(); //Find Spinner - this doesnt cause lag
progress.setVisibility(View.GONE); //Hide spinner (This causes lag)
img.setVisibility(View.VISIBLE); //Image is a network image from the holder (This causes lag)
}
}
(Note that commenting out those two offending lines results in buttery smooth scrolling again)
The other strange thing is that I haven't touched this part of the application in some time and in my current live version, as well as previous commits there is no lag. Comparing my current code base to previous non-lagging versions show that there has been 0 change to the code surrounding this aspect of the application. Furthermore other lists that I have implemented using almost the exact same technique have not experienced this issue.
The only thing I can think of that could be different is that I am now using the latest version of Gradle - although I don't think that should have an impact at run-time.
I am at a total loss as to what is going on, would appreciate any insight on what I should be doing to achieve smooth ListView scrolling (or what may have lead to my implementation's degradation)
EDIT: Posting code of getView() as requested
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View placeSelectorView = convertView;
PlaceViewHolder placeSelectorHolder = null;
if(placeSelectorView == null){ //If we are creating the row for the first time
LayoutInflater inflater = (LayoutInflater) mCtx.getSystemService(Context.LAYOUT_INFLATER_SERVICE); //Inflate the view
placeSelectorView = inflater.inflate(R.layout.place_selector, parent, false); //Get the view
placeSelectorHolder = new PlaceViewHolder(placeSelectorView); //Create holder object
placeSelectorView.setTag(placeSelectorHolder); //Attach reference to the view
}else{
placeSelectorHolder = (PlaceViewHolder) placeSelectorView.getTag(); //Load holder from memory
if(!placeSelectorHolder.isHasImage()){ //Need to optimise this
placeSelectorHolder.getLayout().addView(placeSelectorHolder.getrLayoutThumbnail(), 0);
placeSelectorHolder.setHasImage(true);
}
if(!placeSelectorHolder.isSpinnerVisible()){
placeSelectorHolder.getProgressBar().setVisibility(View.VISIBLE);
placeSelectorHolder.getPlaceImg().setVisibility(View.GONE);
placeSelectorHolder.setSpinnerVisible(true);
}
}
POI place = (values.get(position)); //Get POI object for the place
POI parentPlace = getParent(place); //Get parent POI for place
placeSelectorHolder.getPlaceName().setText(place.getName());
if(parentPlace != null){ //If place has a parent POI
placeSelectorHolder.getParentPlaceName().setText(parentPlace.getName());
}else{ //We don't want the parent text in the view
LinearLayout.LayoutParams layoutParams = (LinearLayout.LayoutParams) placeSelectorHolder.getParentPlaceName().getLayoutParams();
layoutParams.weight = 0; //Setting weight to 0 will remove it from the LinearLayout
placeSelectorHolder.getParentPlaceName().setLayoutParams(layoutParams);
}
final PlaceViewHolder holder = placeSelectorHolder;
loadThumbnail(holder, place);
return placeSelectorView;
}
public void loadThumbnail(final PlaceViewHolder placeSelectorHolder, POI place){
RealmList<poiPhoto> photos = place.getPhotos();
String mUrl;
if(!photos.isEmpty()){
mUrl = photos.get(0).getSmall();
}else{
mUrl = "";
}
final NetworkImageView placeImg = placeSelectorHolder.getPlaceImg();
if(!mUrl.equals("")){ //If there is an Image Available
ImageLoader imageLoader = ServerSingleton.getInstance(getContext()).getImageLoader(); //Get volley imageloader from Singleton
imageLoader.get(mUrl, new ImageLoader.ImageListener() { //Custom get so we can use override onResponse and OnErrorResponse
#Override
public void onResponse(ImageLoader.ImageContainer response, boolean isImmediate) {
if (response.getBitmap() != null){ //Check that the image is not null
ProgressBar progressBar = placeSelectorHolder.getProgressBar(); //Find Spinner
placeImg.setVisibility(View.VISIBLE);
if(progressBar != null) progressBar.setVisibility(View.GONE); //Make the spinner invisible
placeSelectorHolder.setSpinnerVisible(false);
}
}
#Override
public void onErrorResponse(VolleyError error) {
//TO-DO: Get an error image
}
});
placeImg.setImageUrl(mUrl, imageLoader); //Send the request
placeSelectorHolder.setHasImage(true);
}else{ //There is no image
LinearLayout layout = placeSelectorHolder.getLayout(); //Find the horizontal layout
layout.removeView(placeSelectorHolder.getrLayoutThumbnail()); //Remove the Thumbnail layout
placeSelectorHolder.setHasImage(false);
}
}

ImageViews in Android ListView are Showing Previously Loaded Images

I have an android ListView which uses an AsyncTask to download a different image for each ListViewItem. Each image gets added to an ArrayList<Bitmap> the first time it is downloaded and is accessed from the ArrayList<Bitmap> each time after that.
If I slowly scroll through the ListView, each image loads as expected, but if I start scrolling faster, the visible ListViewItems, which have not yet downloaded their images, start to display images from items that have already scrolled off the top of the screen.
Eventually everything syncs up and the images update via the onPostExecution call, but what is going wrong / how can I prevent the images from previous items from appearing in the lower items in the ListView ?
Here's the trimmed down code:
private ArrayList<Bitmap> bitmapArray = new ArrayList<Bitmap>(500);
#Override
public View getItemView(final int position, View convertView, final ViewGroup parent) {
View itemView;
if (convertView == null) {
itemView = getInflater().inflate(ITEM_LAYOUT, parent, false);
} else {
itemView = convertView;
}
final ImageView mImageView = (ImageView) itemView.findViewById(R.id.app_component_joblistitemview_logo);
if (bitmapArray.size()>position && bitmapArray.get(position)!=null) {
// Item exists at bitmapArray[position], use it
Log.i("JobListView","Setting Existing for Position:"+position);
mImageView.setImageBitmap(bitmapArray.get(position));
} else {
// Have not downloaded this ListView[position] logo yet
bitmapArray.add(position,null); // add temporary null value until the image is downloaded
mImageView.setImageBitmap(null);
new DownloadImageTask().execute(logo.getLogoUUID(), mImageView, position);
}
return itemView;
}
// This AsyncTask downloads an image / logo from a specified URL and then updates the specified ImageView
private class DownloadImageTask extends AsyncTask<Object, Void, Bitmap> {
ImageView imageView;
Integer listViewPosition;
#Override
protected Bitmap doInBackground(Object... params) {
String urlString = "http://www.myimages.com/something/"+params[0].toString();
this.imageView = (ImageView)params[1];
this.listViewPosition = (Integer)params[2];
try {
URL url = new URL(urlString);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
Bitmap myBitmap = BitmapFactory.decodeStream(input);
bitmapArray.set(listViewPosition,myBitmap);
return myBitmap;
} catch (Exception e) {
// Log exception
}
}
protected void onPostExecute(Bitmap result) {
imageView.setImageBitmap(result);
}
}

else {
// other methods, then set tag and run task
mImageView.setTag(logo.getLogoUUID());
new DownloadImageTask().execute(logo.getLogoUUID(), mImageView, position);
}
and
int uuid=-1;
protected Bitmap doInBackground(Object... params) {
uuid=params[0];
//other methods
}
protected void onPostExecute(Bitmap result) {
//if tag exists check validity
if(imageView.getTag()==null && imageView.getTag().equals(uuid))
imageView.setImageBitmap(result);
}
lets assume you have 2 pictures - first 10px square, second FHD. when your item needs FHD bitmap Downloader starts downloading, obvius. when you still scrolling and this item is "scrolled out" it apperas (as recycled/convert view) below (or above, depends on scroll direction). then you are setting download 10px bitmap which is ofc much faster. 10 px is set, but previously asynctask downloading fhd picture is still running and still keeps reference to imageView. so when fhd is downloaded it will replace this 10 px. for workaround you might set any identyfying param, your "uuid" is probably perfect for this
how listView and adapter works you may read here and here - check what is convertView in method getView and you might use ViewHolder pattern
PS. I see some null pointers in your code, because of cleaning? example:
View itemView;
final ImageView mImageView = //itemView is just created, findViewById will throw NPE
(ImageView) itemView.findViewById(R.id.app_component_joblistitemview_logo);

Decoding gallery of images in separate thread in android

Guys my program takes really long to open my gallery activity. I have gone through my code and I think I have found whats making the the activity slow down. I think its the part where the image gets decoded. It slows down when there are many images in my gallery and it looks like it takes time to decode them all.
This is my code
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) {
imageView = new ImageView(_activity);
} else {
imageView = (ImageView) convertView;
}
// THIS BELOW IN SEPARATE THREAD
Bitmap image = decodeFile(_filePaths.get(position), imageWidth, imageWidth);
// THIS ABOVE IN SEPARATE THREAD
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setLayoutParams(new GridView.LayoutParams(imageWidth,
imageWidth));
imageView.setImageBitmap(image);
// image view click listener
imageView.setOnClickListener(new OnImageClickListener(position));
return imageView;
}
I think putting the image decoding line in a separate thread might speed up te program. Can anyone tell me how to do it?

You can not use a thread like that. Your whole function will still have to wait for the image to get decoded before returning, because you are returning imageView variable.
First of all, why are you casting convertView to an ImageView, I highly doubt its a good idea to do that. You might have to change your xml and add an imageView, if its missing. Then get a reference to that imageView in this function by using something like
final ImageView listImage = (ImageView) convertView.findViewById(R.id.listImage);
Finally, fire off your thread and set the image into this listImage variable, while returning convertView. Use an ExecuterService.
Here is a simple example.
private final ExecutorService executorService = Executors.newCachedThreadPool();
private final int layoutResourceId; //set this
public View getView(int position, View convertView, ViewGroup parent) {
if(convertView==null){
LayoutInflater inflater = (_activity).getLayoutInflater();
convertView = inflater.inflate(layoutResourceId, parent, false);
}
final ImageView listImage = (ImageView) convertView.findViewById(R.id.listImage);
// THIS BELOW IN SEPARATE THREAD
executorService.submit(new Runnable() {
#Override
public void run() {
Bitmap image = decodeFile(_filePaths.get(position), imageWidth, imageWidth);
listImage.setScaleType(ImageView.ScaleType.CENTER_CROP);
listImage.setLayoutParams(new GridView.LayoutParams(imageWidth, imageWidth));
listImage.setImageBitmap(image);
listImage.setOnClickListener(new OnImageClickListener(position));
}
});
return convertView;
}
I hope you got the general idea.
I highly suggest you use Picasso. Google it. You can do all this without having to implement your own threading, get the advantage of caching and do it in far lesser lines of code. You will run out of memory on low end devices because you are not recycling your bitmap.

Is it necessary to store images in memory to show on list view in android

I'm showing list with one ImageView on every row of list.
For that, I download images from net in another AsyncTask using Drawable.createFromStream
And store them as Drawable in ArrayList which I pass to my Adapter class extending BaseAdapter class.
But the images are taken with high-resolution camera, so may be of very large size.
And I'm getting OutOfMemory error.
So my questions :
What is more efficient, storing images as drawable or as bitmap or any other format?
Am I doing right, by storing all images in memory(in array list). i.e. I'm thinking, once I get a image, I will show it on ImageView and will not store in ArrayList.
is there any way, I can compress the images after download, so they will take less space in memory.
My total code is present here

Android documentation provides a very good example showing how to handle bitmaps in your android app. The example uses an on-disk and in-memory cache and loads the images in the background. By doing so, the main UI thread is not slowed down by loading the images.
Loading Bitmaps effectively
In the example the images are loaded from picasa. It's easy, however, to adapt the example, so that pictures stored locally are used. You simply have to write your own ImageLoader extending from the 'ImageResizer':
public class ImageLoader extends ImageResizer {
public ImageLoader(Context context, int imageWidth, int imageHeight) {
super(context, imageWidth, imageHeight);
}
public ImageLoader(Context context, int imageSize) {
super(context, imageSize);
}
#Override
protected Bitmap processBitmap(Object data) {
return decodeSampledBitmapFromFile((String)data, imageWidth, imageHeight);
}
}
But to answer your question directly: it's ok to load images as Bitmaps. But you have to use a cache and weak references, so that the images can be garbage collected in case they are not visible on the screen. Caching them and using a background task for loading allows for a slick UI.

I don't see any efficiency in storing high-density images into memory - it's totally not recommended to store large ammount of images as bitmaps in memory (good for you that you have a good device ;))
See p.1
Try downscaling the images to fit the device's needs - that's not a simple job though. Also, see View.setTag(Object tag)
The adapter
public class MyImageListAdapter extends BaseAdapter implements ImageLoadingNotifier {
private LayoutInflater inflater = null;
public MyImageListAdapter() {
inflater = LayoutInflater)HomeActivity.this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public int getCount() {
return listImageInfo.size();
}
public Object getItem(int position) {
return listImageInfo.get(position);
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
View vi = convertView;
if (convertView == null) {
vi = inflater.inflate(R.layout.list_row, null);
}
TextView tvName = (TextView) vi.findViewById(R.id.tv_name);
TextView tvTime = (TextView) vi.findViewById(R.id.tv_time);
ImageView image = (ImageView) vi.findViewById(R.id.iv_image);
final Button btnDelete = (Button) vi.findViewById(R.id.btn_delete);
image.setImageDrawable(R.drawable.default_placeholder);//set default place-holder
new GetDrawableFromUrl(listImageInfo.get(position), vi).execute();
tvName.setText("Name: " + listImageInfo.get(position).getImage_name());
tvTime.setText("Date: " + listImageInfo.get(position).getDate_created());
btnDelete.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
final int position = listView.getPositionForView((View) v.getParent());
positionOgBtnToDelete = position;
Log.v("delete btn clicked", "delete btn no: " + position);
Toast.makeText(HomeActivity.this, "Btn delete position: " + position, Toast.LENGTH_LONG).show();
showAlertToConfirmDelete();
}
});
return vi;
}
}
The AsyncTask GetDrawableFromUrl
public class GetDrawableFromUrl extends AsyncTask<Void, Void, Drawable> {
public ImageInfo imageInfoObj;
private ImageView view;
GetDrawableFromUrl(ImageInfo imageInfo, ImageView view) {
imageInfoObj = imageInfo;
this.view = view;
}
#Override
protected Drawable doInBackground(Void... params) {
try {
return Drawable.createFromStream(((java.io.InputStream) new java.net.URL(imageInfoObj.getImageUrl()).getContent()), "src_name");
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
protected void onPostExecute(Drawable drawable) {
if (drawable != null) {
//imageInfoObj.setImage(drawable);
this.view.setImageDrawable(drawable);
//listImageInfo.add(imageInfoObj); //this one is called when the json is parsed
showImagesInList(); //don't know what it does (??)
}
}
}
The JSON parsing
JSONArray jsonArray = jsonObj.getJSONArray("result");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObjInner = jsonArray.getJSONObject(i);
ImageInfo imageInfo = new ImageInfo();
imageInfo.setImageUrl("http://www.dvimaytech.com/markphoto/" + jsonObjInner.getString("image"));
//new GetDrawableFromUrl(imageInfo).execute(); //don't needed here
imageInfo.setEmail(jsonObjInner.getString("emailid"));
imageInfo.setImage_id(jsonObjInner.getString("image_id"));
imageInfo.setImage_name(jsonObjInner.getString("image_name"));
imageInfo.setAmount(jsonObjInner.getString("amount"));
imageInfo.setImage_description(jsonObjInner.getString("image_description"));
imageInfo.setDate_created(jsonObjInner.getString("date_created"));
listImageInfo.add(imageInfo);
}
And, the use of any kind of List of images becomes unnecesary :)
Instead of starting the async task (GetDrawableFromUrl) when parsing the json objects, you can start the task in getView(...) method. This way you will not be constrained to store the drawables into that ArrayList, since you'll be modifying the ImageView after the image was downloaded. And, by default, you can put a placeholder, until the image is downloaded (or in case there are some network errors).
This way the images will start downloading only when the getView method will be called for that specific item.
The bottom line is that each view from the ListView will keep a reference to it's specific drawable (that was set using vi.setTag(image).
If this helps somehow, you know what to do ;)

There is pretty good library calling AQuery. YOu can use it and simple get all stuff like memory and file caching by writting only 2 line of code. So you even wouldn't need to prepare a drawable, you can call it directly from Adapter.getView() callback.
AQuery aq = new AQuery(rowView);
aq.id(R.id.image).image(url, false, true);
Hope it help you!
From AQuery docs:
Down Sampling (handling huge images)
We are loading a huge image from the network, but we only need the image to be bigger than 200 pixels wide. Passing in the target width of 200 will down sample the image to conserve memory.Aquery will only down sample with power of 2 (2,4,8...) for good image quality and
efficiency.The resulting image width will be between 200 and 399 pixels
String imageUrl = "http://farm6.static.flickr.com/5035/5802797131_a729dac808_b.jpg";
aq.id(R.id.image1).image(imageUrl, true, true, 200, 0);