I have built an app where I'm displaying a series of tabs and each tab has a Listview with images and texts (vertical layout).
I have almost finished and i'm running some final tests and I have noticed the following:
I believe the problem is that the listview isnt re-drawn after the cleared memory. But I cannot find how I will refresh the UI thread on application resume
Any ideas?
I have tried on application resume to invalidate the main_layout, also to notify the view pager for dataset changes..but nothing did the trick. The files are store new File(ctx.getExternalFilesDir(Environment.DIRECTORY_PICTURES) +"/"+ storeImagePath).
---Updating with some code
MainActivity implements ActionBar.TabListener
loads
ArticlesListFragment extends ListFragment
where on create method is the following
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
getActivity().getActionBar().setDisplayHomeAsUpEnabled(false);
final String categoryID = getArguments().getString("categoryID");
View rootView = inflater.inflate(R.layout.items_list, container, false);
final ArrayList<Item> items = new ArrayList<Item>();
DBAdapter dba = DBAdapter.getSharedObject(getActivity().getApplicationContext());
SparseArray<SparseArray<String>> articlesArray = dba.getArticleDetailsByID(categoryID, getActivity().getApplicationContext());
if (articlesArray!=null && articlesArray.size()>0) {
for (int i = 0; i < articlesArray.size(); i++) {
SparseArray<String> article = articlesArray.get(i);
items.add(ItemFactory.buildItem(ItemType.ARTICLE_ITEM, article.get(0), article.get(1), article.get(2), article.get(4), article.get(3)));
}
}
setListAdapter(new LazyImageLoadAdapter(getActivity(), items));
return rootView;
}
and the LazyImageLoader is the following
public LazyImageLoadAdapter(Activity a, ArrayList<Item> d) {
activity = a;
data=d;
inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
// Create ImageLoader object to download and show image in list
// Call ImageLoader constructor to initialize FileCache
imageLoader = new ImageLoader(activity.getApplicationContext());
}
It populates the view using this
//DisplayImage function from ImageLoader Class
imageLoader.DisplayImage(data.get(position).getImagePath(), image);
The imageLoader class
public class ImageLoader {
// Initialize MemoryCache
// MemoryCache memoryCache = new MemoryCache();
FileCache fileCache;
// Create Map (collection) to store image and image url in key value pair
private Map<ImageView, String> imageViews = Collections
.synchronizedMap(new WeakHashMap<ImageView, String>());
ExecutorService executorService;
private String resolution;
// handler to display images in UI thread
Handler handler = new Handler();
public ImageLoader(Context context) {
fileCache = new FileCache(context);
this.resolution = Utils.checkScreenResolution(context);
// Creates a thread pool that reuses a fixed number of
// threads operating off a shared unbounded queue.
executorService = Executors.newFixedThreadPool(5);
}
// default image show in list (Before online image download)
final int stub_id = R.drawable.no_article;
public void DisplayImage(String url, ImageView imageView) {
// /Store image and url in Map
imageViews.put(imageView, url);
// queue Photo to download from url
queuePhoto(url, imageView);
}
private void queuePhoto(String url, ImageView imageView) {
// Store image and url in PhotoToLoad object
if (url != null && url.contains("null")) {
url = url.replace("null", resolution);
}
PhotoToLoad p = new PhotoToLoad(url, imageView);
// pass PhotoToLoad object to PhotosLoader runnable class
// and submit PhotosLoader runnable to executers to run runnable
// Submits a PhotosLoader runnable task for execution
executorService.submit(new PhotosLoader(p));
}
// Task for the queue
private class PhotoToLoad {
public String url;
public ImageView imageView;
public PhotoToLoad(String u, ImageView i) {
url = u;
imageView = i;
}
}
class PhotosLoader implements Runnable {
PhotoToLoad photoToLoad;
PhotosLoader(PhotoToLoad photoToLoad) {
this.photoToLoad = photoToLoad;
}
@Override
public void run() {
try {
// Check if image already downloaded
if (imageViewReused(photoToLoad))
return;
// download image from web url
Bitmap bmp = getBitmap(photoToLoad.url);
// Get bitmap to display
BitmapDisplayer bd = new BitmapDisplayer(bmp, photoToLoad);
// Causes the Runnable bd (BitmapDisplayer) to be added to the
// message queue.
// The runnable will be run on the thread to which this handler
// is attached.
// BitmapDisplayer run method will call
handler.post(bd);
} catch (Throwable th) {
th.printStackTrace();
}
}
}
private Bitmap getBitmap(String url) {
File f = fileCache.getFile(url);
// from SD cache
// CHECK : if trying to decode file which not exist in cache return null
if (f.exists()) {
Bitmap b = decodeFile(f);
if (b != null)
return b;
}
// Download image file from web
try {
Bitmap bitmap = null;
URL imageUrl = new URL(MY_URL);
HttpURLConnection conn = (HttpURLConnection) imageUrl
.openConnection();
conn.setConnectTimeout(30000);
conn.setReadTimeout(30000);
conn.setInstanceFollowRedirects(true);
InputStream is = conn.getInputStream();
// Constructs a new FileOutputStream that writes to file
// if file not exist then it will create file
OutputStream os = new FileOutputStream(f);
// See Utils class CopyStream method
// It will each pixel from input stream and
// write pixels to output stream (file)
Utils.CopyStream(is, os);
os.close();
conn.disconnect();
// Now file created and going to resize file with defined height
// Decodes image and scales it to reduce memory consumption
bitmap = decodeFile(f);
return bitmap;
} catch (Throwable ex) {
ex.printStackTrace();
if (ex instanceof OutOfMemoryError)
;// memoryCache.clear();
return null;
}
}
// Decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f) {
try {
// Decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
FileInputStream stream1 = new FileInputStream(f);
BitmapFactory.decodeStream(stream1, null, o);
stream1.close();
// Find the correct scale value. It should be the power of 2.
// Set width/height of recreated image
final int REQUIRED_SIZE = 180;
int width_tmp = o.outWidth, height_tmp = o.outHeight;
int scale = 1;
while (true) {
if (width_tmp / 2 < REQUIRED_SIZE
|| height_tmp / 2 < REQUIRED_SIZE)
break;
width_tmp /= 2;
height_tmp /= 2;
scale *= 2;
}
// decode with current scale values
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
FileInputStream stream2 = new FileInputStream(f);
Bitmap bitmap = BitmapFactory.decodeStream(stream2, null, o2);
stream2.close();
return bitmap;
} catch (FileNotFoundException e) {
System.out.println("----------File wasnt there: "
+ f.getAbsolutePath());
e.printStackTrace();
} catch (IOException e) {
System.out
.println("----------io exception: " + f.getAbsolutePath());
e.printStackTrace();
}
return null;
}
boolean imageViewReused(PhotoToLoad photoToLoad) {
String tag = imageViews.get(photoToLoad.imageView);
// Check url is already exist in imageViews MAP
if (tag == null || !tag.equals(photoToLoad.url))
return true;
return false;
}
// Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable {
Bitmap bitmap;
PhotoToLoad photoToLoad;
public BitmapDisplayer(Bitmap b, PhotoToLoad p) {
bitmap = b;
photoToLoad = p;
}
public void run() {
if (imageViewReused(photoToLoad))
return;
// Show bitmap on UI
if (bitmap != null)
photoToLoad.imageView.setImageBitmap(bitmap);
}
}
}
and the FileCache
private File cacheDir;
public FileCache(Context context){
//Find the dir at SDCARD to save cached images
cacheDir = Utils.isExternalStorageReadable() ? context.getExternalFilesDir(Environment.DIRECTORY_PICTURES) :
new File(context.getFilesDir() + "/myAppFolder/");
if(!cacheDir.exists()){
// create cache dir in your application context
cacheDir.mkdirs();
}
}
public File getFile(String url){
//Identify images by hashcode or encode by URLEncoder.encode.
if (url!=null) {
String filename = String.valueOf(url.hashCode());
File f = new File(cacheDir, filename);
return f;
}else {
return null;
}
}
All my images are loaded for specific screen, therefore I use a static variable initialized on my Splashscreen which resolves the device resolution. On application resume the variable is not initialized cause splash screen is not displayed.
Therefore the imagepaths I used were wrong.