This could potentially be a duplicate but I after spending several hours reading about ImageView, ImageSwitcher, Gallery Views, Lazy Loads, and more I decided I should just ask.
I am working on an app and in one of the screens there may be an image or multiple images associate with what I am talking about. The other data for this intent will be pulled from a local database. In the database it will also have a list of URLs of images that are associate with each thing that I am discussing. So I would like to know the best way to display a thumbnail of these pictures (if there are any) on the screen. Then if these pictures are clicked on it can open up the bigger version of these pictures. I don't necessarily want to download these pictures since I don't want to save them locally for the app. Plus I don't want to make the page delay in loading while it waits to download the pictures.
What is the best way to handle this scenario?
I have to caution you, that with newer versions of Android, applications can't make connections to the internet that build the UI directly on the UI thread. Instead, it must be accomplished in a background thread such as ASyncTask. So if you're going to go with making ImageViews without src in your XML, that's fine, but you can't just have the ImageViews go download their images via URL in the onCreate of your main activity any longer. It has to be done in the background, else you'll get an error.
It makes the process fairly more complex, to be honest, but it does improve application responsiveness.
For now, since images aren't the main focus of my app, I decided to just embed a webview in my page and then display the image in some custom html ( I had a list of URLs to the images online). I also calculate the width of the screen and then I adjust how wide the images are going to be in my html.
This was the easiest since the webview takes care of the "threaded" part and I don't have to worry about how to handle/save/and display the images.
It would have been helpful to see a best practices guide when it comes to android and handeling images.
Related
I'm currently building an app for learning purpose (new to android programming) that lets the users to upload
image to the server and watch other users images (by swipe the screen for example).
I finally succeeded to let the user upload image to the server and I was wondering how to code the part that retrieve the images from the server and present them in the app.
Assuming I have at the time million images, I don't want the app to load all the images in the same time because it will take a lot of time.
And all the guides I'v seen makes the app to load all the images at once.
So my question is what is the recommended way to do so?
Hope I was clear.
Thanks.
Let's say you have an array with a million images in your server to load in your app that will be shown in a RecyclerViewand assuming a screen can fit about 5 images.
In this case scenario a good approach would be to fetch 10 images at a time and load them in a RecyclerView. Load the first 10 images and once the user reaches the end of the scroll load some more images, add them to the previous retrieved image list, and finally update your RecyclerView to present them. With some effort you may be able to create a Facebook look alike effect.
RecyclerView has methods that will easily help you detect the end of scroll (there are plenty of ways you can find in StackOverFlow). Every time you detect an end of scroll, just upload more images.
This is one example: How to know whether a RecyclerView / LinearLayoutManager is scrolled to top or bottom?
Use FlexBox Layout for better UI Design to show images
https://github.com/google/flexbox-layout
See how this cat images are shown using FlexBox Layout
I am working on an Android app where, once a user clicks a login button, the app launches an AsyncTask to verify account details with a remote server. That part works fine by itself and doesn't make my app slow. However, when you click the login button, it launches a second activity where I have 4 ImageViews. When I added that part of the app, it became significantly slower (from less than a second to about 5 seconds loading time). I load the images into the ImageView from the XML layout file directly, so I'm not sure what I'm doing wrong.
My question is that do ImageViews make your app slow, and if so, how do you optimize their performance?
I was working my own app when I actually experienced this too. The reason is because if the files are to big they take a while to load into memory and set as the Image View. There is two ways you could really sort it out.
1: Get a smaller version of the picture. Smaller pictures come up faster and aren't prone to an OutOfMemory exception which kills the app :(.
2: A better way is to use the Picasso api. I used this APIs to add images in list views, expandable list view with pictures in them. The app was fast and fluid :)
Picasso's api would be your best bet ant it is easy to implement.
Edit:
Here is the link to the site to get the APIs :)
Picasso
The only way I could figure this out is to create an image in photoshop that has all the buttons laid out where you want them on top of the image. Interpret it into your app and put regular buttons over top of the imagebutton pictures that you placed onto your background image. Set the size accordingly to your images of your buttons and then set the background of each button to #null so they aren't seen. Now trying to figure out how to interpret this into orientation view even though I don't think I'll be using orientationview. OH AND CHANGED THE EXTENSION TO A GIF TO SAVE ON DATA RATHER THEN PNG.
Hope this helps I'm sort of new at coding on android as I have lots of experience with HTML .
Cheers
THANKS FOR THE DOWN LIKE I WAS SORT OF NEW AT THE TIME OF NOT KNOW OTHER WAYS TO SET THIS... THANKS THOUGH, MORONS
OK so there are 2 concepts for Lazy Loading from all I have read.
Load images in a background thread.
Only display the image when the user is not interacting with the screen. (i.e. display it when the user have stopped scrolling)
My question would be, which one of those would be the right one.
For implementation, I'm using Universal Image Loader. Is it possible to implement concept #2 with this library natively, or should I add some extra code?
First off, you should know there isn't "right" or "wrong" one when it comes to user experience. It all depends on your way of thinking. However, based on Android guidelines, you should never perform heavy tasks on the main tread as it might affect user experience. It means you should always try to load images on a background thread.
But the question is whether you should keep loading and unloading the images as the user scrolls or you should only display the image once the user stops scrolling. I "personally" believe that the answer depends on the situation. For example imagine a your facebook friends list where there is names tags beside the images. In this case, you might not need to load all pictures as the user is able to search the list, scroll up and down and pick the right friend based on the name. However, if the user is expected to pick and select merely on the image. Then for sure the answer is to display the image once it is available.
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.
I want to create a main menu with a gallery that gets images from my website.
and shows them in the gallery for a user to scroll through and see upcoming event pictures.
The images will change just about every month. What is the best way to go about achieving this?
I was thinking maybe storing the images in a particular directory and having a URL set to the image.
The only question is... What happens when the images change? How would i go about updating the URL in the application? No way right?
Another thing... When the images are scrolled off the screen how do we make these images where they wont reload when out of view, causing unnecessary use of bandwidth and possibly outofmemory error.
So from what i have discovered so far, What is the best way a
You could store the urls in a database, have the app download a small text file upon launch containing the newest urls. if there is a difference, then download the new images and update the links in the database.