Android, loading images efficiently in a list adapter - android

I am writing an android app. I have an ArrayAdapter which I am using to display a list of items where part of each item is an image. I am downloading the images asynchronously in the adapers getView() method and I am using a cache to keep it as efficient as possible and stop too many re-downloads. The problem I am facing is that the getView() method for each item can be called by android as many times as it needs to. It is often called faster than the image can actually download and so the same image can be queued many times for download before it even gets into the cache. Is there a best practice for how to prevent the images from being queued for download repeatedly? It just seems like a big waste of mobile data.

If you want to use third party image downloader library then you can use Picasso
Its actullay pretty neat and simple to use. It does caching for your app.
You can refer this tutorial.
Happy learning :)

The accepted best practice that is recommend by Google for downloading and displaying images in a list or recyclerview is to use the Glide library
https://github.com/bumptech/glide
The api looks like this
Glide.with(context)
.load(url)
.centerCrop()
.placeholder(R.drawable.loading_spinner)
.crossFade()
.into(myImageView);

Related

How to load images from internet in android app quickly?

I'm a beginner in android and i want to load some images from internet in my app. I heard about libraries such as Glide and Picasso. Can anyone please tell me which library is the best.
In your title you use the word "quickly". Theres no such thing, unless you have a cache implementation. As you pointed out those two libraries help in retrieving images from the web and displaying them into imageView, also support cache features so that images previously displayed can load faster in the near future.
Simple example of Picasso:
Picasso.get().load("http://i.imgur.com/DvpvklR.png").into(imageView);
Want to know more about cache in Picasso? Check out this answer
According to this article here both are really nice to be used , but I would suggest Picasso because it just updated to 3.0 + it is lighter than Glide when it comes to :
library size and method count .

Do I need to delete files downloaded over http with picasso?

I am making an app that acts somewhat like a gallery, but the images are going to be stored on a Firebase database. I am using Picasso to make this easier. Each image can be quite large in size, and there are a lot of them.
I am currently using fragments on a viewpager to display the images, and also a FragmentStatePagerAdapter. I know the adapter gets rid of the fragments, but I was wondering whether I had to delete the images I downloaded from device storage, and if so how. (I don't know exactly how Picasso works)
I'm sorry if this is a stupid/obvious question but I'm paranoid about clogging up memory and I've looked around the internet to no avail.
Thanks a lot!
Try this
Picasso.with(this)
.load(url)
.memoryPolicy(MemoryPolicy.NO_CACHE, MemoryPolicy.NO_STORE)
.into(imageView);
or you can do something like this
mPicasso.with(appContext).invalidate(url);

Android I want to stream images from online database

I am new to Android so I want to create a background wallpaper app. I made the offline version already which displays images from an array using ImageAdapter.
But I want make it online so that the images will be downloaded and displayed from an online database. What would be the simple and best way to do it? An example would be preferred.
You can use Picasso library. Image loading using Picasso is very easy, you can do it like this way
Picasso.with(context).load("http://i.imgur.com/DvpvklR.png").into(imageView);
and in their website you can get every details.
and another Library is Glide. You can use Glide too for loading image..
Just use Picasso, it's pretty simple and lightweight library with good documentation. You also can save images from network with some hacks.
http://square.github.io/picasso/

Loading images in listview from remote location

This might seems to be repeated question, but could not get best answer
what is the best method to load images in listview?
AsyncTask or Android Universal Image Loader or Robospice UI Spice List?
Can any one explain me the advantages and disvantages?. Thanks in advance
Please use GLide Image Loader
Glide is a fast and efficient open source media management and image loading framework for Android that wraps media decoding, memory and disk caching, and resource pooling into a simple and easy to use interface.
https://github.com/bumptech/glide
You can use Picasso also
https://github.com/square/picasso
You can compare GLide and Picasso
http://inthecheesefactory.com/blog/get-to-know-glide-recommended-by-google/en

Android image downloading and caching using Picasso

In my project a background service downloads contents from remote database using asynctask. I would like to download all images from urls (saved in database) using Picasso in background service. These images will be used later in my app.
Is there any better solution to do this? or just use the one line code of Picasso in asynctask?
Is there any better solution to do this? or just use the one line code
of Picasso in asynctask?
What do you mean by better? Is it about performance?
If you will have to download a lot of images, you might want to download them on the service. With this, your download will not stopped if the activity is destroyed.
For the library, i never use Picasso. I always use Universal Image Loader but i dont know which one is better. I think the most important feature of those libraries is their capability to cache the images.
UPDATE
For performance, you may want to combine the Picasso/UIL library with PullToRefresh library, especially when your listview/gridview want to load a lot of images.

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