Develop Reference

How to refresh the content of an ImageView

I have a screen with an ImageView containing the actual profile picture. I can edit that profile picture either by taking a picture with the camera or by picking a picture from the sd card. I store the new chosen profile picture under the same path as the old (i overwrite it) which is logical i guess.
However when i set a new profile picture to my ImageView it does not get refreshed. I have to restart the App to see the change.
this.imageView.invalidate();
is what all people are telling me to do when i brows google but no, this is not working! So how can i force my imageview to load the new profile picture?
I load the image into the ImageView with help of Picasso:
Picasso picasso = Picasso.with(context);
if(reload) {
picasso.invalidate(new File(fileName));
}
RequestCreator requestCreator = picasso.load(new File(fileName));
requestCreator.into(imageView);

Picasso caches loaded images to speed up the loading process. This means that if you are trying to reload the same exact picture it loads the cached version and it does not read the changed File from the disk.
You need to tell Picasso that the picture has changed and that it needs to reload the picture from the disk by invalidating the cache. The way you do this is like this:
File file = new File(fileName);
Picasso picasso = Picasso.with(context);
picasso.invalidate(file);
picasso.load(file).into(imageView);

To skip Picasso's cache, you can use .memoryPolicy(MemoryPolicy.NO_CACHE) static method:
Picasso
.with(context)
.load(file)
.memoryPolicy(MemoryPolicy.NO_CACHE)
.into(imageView);

How to delete cached image from android app

I am using square picasso library to download some images from one of our servers and load it in a list view. In my Android application I have a feature to change that downloaded image from app side and upload it to server.
I do know how to load the image from URL because it is well documented. What I need is to change/delete a particular cached item and replace it with my new image from Android application side.
Please help me.
Thanks in Advance....!

Suppose you have a List which stores your images, used by your ListView. You assign an Adapter
to your ListView which fills ListView from the List.
This is how you can replace an old (cached item) by the new one and release space for the old one:
public void replaceListItem (List<Bitmap> list, int position, Bitmap newBitmap) {
Bitmap oldBitmap = list.set(position, newBitmap);
if (oldBitmap != null)
oldBitmap.recycle(); // This will release space for the old bitmap
}
The function does not check if position is within the size, neither it checks if the new bitmap is already there, etc. I just wanted to concentrate on the question you asked.

Set Image to a ImageView from URL [duplicate]

This question already has answers here:
How to load an ImageView by URL in Android?
(23 answers)
Closed 9 years ago.
I have Imageview and a link to the picture on the Internet. I set this picture to the ImageView like this,
public ImageView iv;
iv = (ImageView) findViewById(R.id.imageView);
String img = "https://www.google.com/images/srpr/logo11w.png";
iv.setImageDrawable(Drawable.createFromPath(img));
What I want to do is download a picture from the internet to my android application and apply it to an ImageView. I want to make it as easy as possible.
helped me
String img_url= //url of the image
URL url=new URL(img_url);
Bitmap bmp;
bmp=BitmapFactory.decodeStream(url.openConnection().getInputStream());
ImageView iv=(ImageView)findviewById(R.id.imageview);
iv.setImageBitmap(bmp);

There many libs to do this, my favourite is Picasso.
Here an example of usage:
Picasso.with(context).load("http://i.imgur.com/DvpvklR.png").into(imageView);
give it a try :)

This method create a Drawable from file path name.
Check this answer.

There are many libraries available on doing this, I recommend using a library, because a they have many extra options availble.
Take Universal Image Loader
Features
Multithread image loading
Possibility of wide tuning ImageLoader's configuration (thread executors, downloader, decoder, memory and disc cache, display image options, and others)
Possibility of image caching in memory and/or on device's file system (or SD card)
Possibility to "listen" loading process
Possibility to customize every display image call with separated options
Widget support
Possibility to show an custom Image on loading, error, etc.
You have to set the options one time using:
DisplayImageOptions defaultOptions = new DisplayImageOptions.Builder()
.cacheInMemory(true)
.cacheOnDisc(true)
.build();
ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(getApplicationContext())
.defaultDisplayImageOptions(defaultOptions)
.build();
ImageLoader.getInstance().init(config);
Then, lateron you can use this anywhere in your code:
ImageView iv = (ImageView) findViewById(R.id.imageView);
String str = "http://google.com/img.jpg";
ImageLoader.getInstance().displayImage(str, iv);
Ofcourse there are many other libraries you can use like picasso, Smart Image View, Url Image View and many others.

What's LazyList?

I can't find in any really credible source explaining what LazyList is. Anyone?

Lazy List is lazy loading of images from sd-card or from server using urls. It is like on demand loading of images.
Images can be cached to a local sd-card or your phone's memory. URL is considered the key. If the key is present in the sd-card, images get displayed from sd-card, otherwise it downloads the image from the server and caches it to a location of your choice. You can set a cache limit. You can also choose your own location to cache images. Cache can also be cleared.
Instead of the user waiting to download large images and then displaying them, lazy list loads images on demand. Since images are cached, you can display images offline.
https://github.com/thest1/LazyList. Lazy List
In your getview
imageLoader.DisplayImage(imageurl, imageview);
ImageLoader Display method
public void DisplayImage(String url, ImageView imageView) //url and imageview as parameters
{
imageViews.put(imageView, url);
Bitmap bitmap=memoryCache.get(url); //get image from cache using url as key
if(bitmap!=null) //if image exists
imageView.setImageBitmap(bitmap); //display iamge
else //downlaod image and dispaly. add to cache.
{
queuePhoto(url, imageView);
imageView.setImageResource(stub_id);
}
}
An alternative to Lazy List is Universal Image Loader
https://github.com/nostra13/Android-Universal-Image-Loader. It is based on Lazy List (it works on the same principle), but it has lot of other configurations. I would prefer to use Universal Image Loader because it gives you more configuration options. It can display an error image if a download failed. It can display images with rounded corners. It can cache on disc or memory. It can compress an image.
In your custom adapter constructor
File cacheDir = StorageUtils.getOwnCacheDirectory(a, "your folder");
// Get singletone instance of ImageLoader
imageLoader = ImageLoader.getInstance();
// Create configuration for ImageLoader (all options are optional)
ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(a)
// You can pass your own memory cache implementation
.discCache(new UnlimitedDiscCache(cacheDir)) // You can pass your own disc cache implementation
.discCacheFileNameGenerator(new HashCodeFileNameGenerator())
.enableLogging()
.build();
// Initialize ImageLoader with created configuration. Do it once.
imageLoader.init(config);
options = new DisplayImageOptions.Builder()
.showStubImage(R.drawable.stub_id)//display stub image
.cacheInMemory()
.cacheOnDisc()
.displayer(new RoundedBitmapDisplayer(20))
.build();
In your getView()
ImageView image=(ImageView)vi.findViewById(R.id.imageview);
imageLoader.displayImage(imageurl, image,options);//provide imageurl, imageview and options
You can configure Universal Image Loader with other options to suit your needs.
Along with LazyList/Universal Image Loader you can view this website for smooth scrolling and performance.
http://developer.android.com/training/improving-layouts/smooth-scrolling.html.

AFAIK, I'll explain you with the example
If you list contain lot of images with Text, it will take some time for your list to load because you need to download images and you need to populate them in the list. Suppose if your list contains 100 images It will take lot of time to download each image and to show it the listitem. To make the user wait until the images loads is not user friendly.
so What we need to do. At this point of time lazy list comes into picture. It is the idea that let the images be loaded in background and show text mean while.
Everybody know that listview recycle its views for every view. i.e if your listview contains 40 elemtns then listview won't allocate memory for 40 items instead it allocate memory for the visible items, i.e say you can see only 10 items at a time. so listview will allocate 10 items meemory.
So When ever you scroll the view, then the view will refresh. because of the you'll lose your reference to images and you need to download them agian. in order to avoid that, caching comes into picture.
This example is based on my knowledge in listview, I am not saying this is only correct. There might be wrong in the answer, if any body find feel free to inform me.

I think this is the other way around. AFAIK, Lazy Loading is the definition, where you actually load the data only when you need it, and it's a good design practice.
So I believe the same applies for this, only this time it's being referring to the List View.
If I'm wrong, please correct me.

The best example of lazy list is facebook notifications,messages,requests. when you scroll then data will be load.

Novoda ImageLoader - loaded same image

I'm using Novoda ImageLoader (https://github.com/novoda/ImageLoader) and when I use this loader in CursorAdapter everything is fine. But when I want to use without any Adapter in Activity with one ImageView, I get same image for different URLs.
//onCreate in Activity
imageManager = MyApplication.getImageLoader();
imageTagFactory = new ImageTagFactory(this, R.drawable.ic_refresh_inverse);
imgView = (ImageView) findViewById(R.id.imgIV);
//fillData - when I finish loading img URL from DB with CursorLoader
imgView.setTag(imageTagFactory.build(imgURL));
imageManager.getLoader().load(imgView);
//code in onCreate Application
LoaderSettings settings = new SettingsBuilder().withDisconnectOnEveryCall(true).withCacheManager(new LruBitmapCache(this)).build(this);
imageManager = new ImageManager(this, settings);
When I looked to the cache directory, the different image is loaded, but not used.
Any idea where can be problem or how to properly use this library to simply load only one image?
Thank you!

The issue is probably similar to this https://github.com/novoda/ImageLoader/issues/41
do you have query parameters in the url? if so try to add this
.withEnableQueryInHashGeneration(false) on the setting builder
This is a bug that is inverting the logic behind the parameter enableQueryInHashGeneration. This parameter should enable/disable (by default should be enable) the query part of the url in the generation of the hashname of the image. This is useful when you have session token in the url as a parameter and you don't want to download the same image over and over.
The problem will be solved in the 1.5.6 version