loading of 1000 images effectively from network to GridView - android

In my application I have to show many images (say >1000).
All these images comes from network. For now, I am downloading all images and passing them to an adapter which was set to GridView.
My problem is downloading all images at once occupies a lot of runtime memory. So I want to change my design.
Is there any way to handle images/bitmaps in large number effectively? Like downloading 100 images, then again another 100 erasing previous 100 (as per need).

You can try these optimisations:
Decrease number of images, do you really need 100 in one go?
Download image thumbnails, do you really need full-sized non-compressed images?
Cache next images, pre-load some images before user asks for them
Profile your app, see where time is consumed
Use several threads, at least one for pulling data and one for UI

I think you need to take a look at UIL
Which is helpful to you.

Related

Getting large number of images in recyclerView android

in my recent android project I have to get a large number of images from the web and show them in my main activity (something like explore part of the Instagram app). I used a recyclerView with gridLayoutManager of 3 columns and I have to get something like 700 images from URL. When I open the app and comment the getting image part, app work perfectly fine (the app get the information of each tile but doesn't display the images). But when I start setting image bitmaps the app start becoming laggy and crash after about a hundred images loaded.
What do you recommend me to do ?
And another question: Was using recyclerView a smart idea ?
Thanks for your reply.
Don't load hundreds of images. That requires a few things:
1)Don't store images in memory in the adapter. Store the url/resourceid/whatever of the image so you can load it on demand.
2)Use an LRU cache of images, limited in size and load your images through that.
3)Make sure that however you download images does not spawn too many concurrent requests, and that requests are canceled when no longer needed (when the view it would go into is recycled).
4)I'd suggest downloading the images and writing them to disk, then loading them from disk as needed. This will prevent you from having to keep the entire file in memory to decode it while downloading it, which will reduce your memory usage while downloading.
5)Do not decode the image on the UI thread. Do it on another thread.
6)If you don't need to display images fullsize, make thumbnails.
Images in a RecyclerView, especially if being downloaded need a lot of work to do well and handle rapid scrolling.
You should post some code here but seems you are asking for some efficient setup.
First of all, try using some image caching libraries like Glide or
Picasso. It manages and caches your images locally so you don't end up
making multiple requests for the same image.
This solves most of your problem and don't try to load 700 images
altogether and display use lazy loading means load first 10-20 images
first and when user scrolls make another API call for another 10-20
and so on.
Here is an article on how to use Glide and how it works.
https://futurestud.io/tutorials/glide-image-resizing-scaling

Lazy Loading vs. Batch Download in Android (if all images will be used0

I am building an Android app that shows full screen images in a carousel. The app downloads 100 objects from the server and stores them in the app. Each object is represented by a full-screen image and some text.
The user will see all downloaded objects as full screen images.
Question: is it more efficient to use lazy loading one image at the time when the user goes through the carousel or download images in full batches?
Google suggests using batching and pre-fetching:
http://developer.android.com/training/efficient-downloads/efficient-network-access.html#BatchTransfers
Also, it is my understanding that one of the key benefits of lazy loading is avoiding downloading images that will not be used. In my case, the user will see all images of the all downloaded objects.
Thanks!
The first target is that the user sees the images without delay. By creating a batch starting from the first image it is probable that he will have the following images loaded when he scrolls through them. If in your case the user can scroll fast through the images, you can change the batch list and set a higher priority on the images he is going to see (like 3 plus and minus from the current position).

NetworkImageView. Save image in thumbnail [Server] / resize in client?

I'm trying to create a CRUD android application.
Now, when the List Activity is shown, it will display the items created along with a thumbnail of the original image.
What is the best practice for displaying a thumbnail in an Android application with Volley? Should I generate a thumbnail for the images uploaded or just re-size the image at the client side?
It's hard to come up with a general answer for this questions because it all depends on how many images you're trying to download and how important showing the thumbnails is.
I would personally generate the thumbnails on the server side as soon as they are uploaded by the user. Doing this has several advantages:
All your app has to do is request the thumbnail and render it, which is much simpler and less CPU-intensive than using Volley's ImageRequest.
Smaller images means less data usage. You definitely don't want your app to download a 10MB 25-megapixel image over a 3G connection just to shrink it to a 100x100 thumbnail that the user might not even care about.
The only drawback that I can think of is that you might have to generate multiple thumbnails, one for each screen size (e.g. one for hdpi screens and another for xxhdpi). This is slightly more expensive on the server side but might make your UI look much better.
Also, remember to cache thumbnails in your app's cache directory so you don't have to re-request them every single time you want to show them.

When should a photo be cached

Is there a general guideline or rule of thumb on when I should cache a photo?
For example I have a grid view of smaller icon images. This page isn't at the beginning of the app so there's no guarantee a user sees it, these images could change server-side but for the most part they won't. Should I cache them because there are so many or not worry about them because they are small?
Another example would be if I click on one of the images mentioned above it will lead me to a view with one larger image, should I cache this image since it's larger or should I let the user make a network request each time?
I'm not looking for an answer for these specific questions, but rather a guideline to follow.
To clarify by caching I mean saving the file to storage. Also, is there a better method than this?
Thanks for the help!
Caching is an important feature in user experience, so even if there's no guarantee the user sees that particular 'page', it a nice thing to have.
Saving images in a cache depends directly on many variables:
- How much time does it take to regenerate images if not cached
- How many images are we talking about
- How often do they change
- What size is each image
For example, having 100 thumbnails of images that change every month makes a lot of sense. Caching 200 images with 1024x768 resolution that change very often doesn't.... or does it? The answer is very variable.
Also cache should always have storage boundaries. Even in the previous example with the large images, you could limit the cache to a a certain storage capacity.
Normally the cache saves a local copy of the most recently used items. But you can implement a more sophisticated algorithm, for example, saving the most visited images instead of caching the most recently used.

The Best Way To Load Multiple Large Image in a GridView

My Problem deals with Memory, I have a Web service that provide me a List of Urls. Each URL corresponds to a large image. My Mobile app have to parse the xml provided by the web service and than show in a GridView these images. I tried several features in order to display images such as:
Multithreading
Lazy Loading
Reduce image size using inSampleSize ( this causes my app takes too long)
should i have to attach for each large image a thumbnail image, and make the web service return to me the list of all thumbnails, after that show these thumbnail to the user, and if he clicks on one of them than i have to show the large image in a separate view, i have this idea because i noticed when i show one image i don't get an outofMemory exception!!
Is this a reliable solution? is there a better way?
Welcome to one of the hardest issues on Android. First I would start by reading this new documentation google wrote on how to handle bitmaps. Its not a light read, but you probably need to read it all the way through. It has only been up for a few weeks so you may not have seen it. It details many of the things you mentioned such as multithreading, lazy loading, and down sampling. They also recommend using an image cache.
Downloading the large images for each image and then down sampling is going to be very inefficient. First the download size is larger than needed. Second you need to load it into memory to perform the down sample and third down sampling is somewhat slow.
I would have the web api return you a list of thumbnail urls and full image urls that you can lazy download as the view comes on screen and use the cache to keep them around a while. Make sure you down sample the sizes of the thumbnails as well. I would then when the user clicks on an image go download the full image and on the background when it arrives down sample it before displaying it.

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