I am very familiar with OOM concept. I have come across so many questions that have been asked here and I know this could sound like a repeated question on OOM, but I have a different problem now.
I have hundreds and hundreds of images, which I have to show in a single ListView in a single Activity.
I have made use of the Fedor's lazy loading concept.
The code works fine when the images are little(something like 50-100 images), but if I get around 200 to 300 images, as soon as the user makes a scroll through the ListView (eventually) I am getting an out of memory exception.
I am using the efficient Adapter concept as shown here in developer site and I believe that this is the best custom adapter usage method.
All the suggestion what I have seen so far is based on reducing the bitmap size by scaling it or some other means. I have already tried those methods. But still the OOM occurs in some point of time.
Reducing the quality of the image doesn't look like the way to handle this Exception , because which seems to affect user experience and, also, it doesn't work for a large amount of bitmaps.
My questions here are:
How do you display n images in a single ListView without facing OOM?
What are the best strategies to follow in this scenario?
Is it possible to show around 500 images in a single ListView?
Any help is much appreciated.
Look into googles shelvesproject.
Shelvesproject does following: uses a placeholder image while loading image, use weakreference for storring images, delayed handler updated with clearing.
Yes and no, it is possible to have listview with this many items but its not possible to have this many images all in memory at the same time.
Try with API Level 11+ images before this API Level are placed in application heap. And yes it is possible to have a List View with a 500 images and working smooth (Contacts application for example).
This http://code.google.com/p/android-imagedownloader/ may help you getting images, cache and recycle them.
Related
The question regarding thumbnail creation seems to get asked a great deal, and each time there seems to be a great many different solutions proposed. From my experience none of the supplied answers are actually sufficient and all seem to have their own flaws.
a) Memory issues when re-sizing
b) Performance issues / slow to render
I therefore wanted to post a question regarding a very common functional requirement that I am hoping someone can assist with.
'User generates a report using activity and takes associated photo using internal camera. The report along with the image path is saved to SQLLite database. User wants to view reports in a scrollable list view at some point in the future. Number of reports could be 1..100'
So given these requirements the questions I have are as follows
1) Given that to data I have not found a reliable / performent / memory optimised way of resizing full size images at run time to a given thumbnail, should I create a smaller image at image capture time?
2) If you need to display many items in a ListView should you use paging or should it be possible to display a 100 items in one ListView?
Thanks
Regarding number 2: What you could do is load a subset first (say the first 30, depending on your listview item size), and load the rest asynchronously and append them to your adapter. This will decrease the loading time of your screen.
1/ Why do you want to reinvent the wheel :) There are libraries that already do for you and do it well. See picasso or AQuery for instance (there are other libraries too).
Basically, they have a thumbnail cache somewhere on the SDcard/internal memory to keep last N requested thumbnails.
I don't know if you are keeping the image data within the database, in which case you may have to adapt one of those libraries to load the image data from the DB and not from a file as it is usually the case.
2/ Why do you want to reinvent the wheel :) There are libraries that already do for you and do it well. See https://github.com/commonsguy/cwac-endless for instance (and google for more)
I have 3 sets of 50 images and I have to create the animations for each set of images in Android application. I am able to create a simple application which animate first set of 50 images using the below method,
Added Animation-list xml in drawable folder and called it using frameAnimation.start().
This method didn't work until I kept the following "android:largeHeap="true" in manifest file.
I am not sure whether this is the good way to animate the images (if we have more number of images and each image of more size like 60 KB. Image is JPG format) or not
I browsed and I found that, if we are able to clear the memory and if we are able to maintain less number of images in memory, then our application will work very fine. So I want to know how to clear the memory?
Please let me know do I need to follow different method to animate the images other than I explained above, so that I can clear the memory.
Thanks for your help.
After looking into several posts and doing much research, I finally ended up modifying the images in Imageview programmatically to simulate frame animation. That way I am just maintaining three images in cache at any point of time (previous, current and next one). I hope that this will be useful to others.
It is not a good thing to process a large amount of images in a frame like manner in Android itself as it will trigger the dreaded "Out of Memory" exception.
Clearing the memory itself is not possible. The best fix for this is proper bitmap handling of the app.
I'm not sure but you might want to check on PhoneGap.
Its an HTML5 Engine that we used before to create a game.
By drawing into the canvas itself, we've recreated frame animation with it. It just requires WebDev skills though.
Hi and happy new year!
I'm trying to download images from internet and put them into different ImageViews. The ImageViews are dynamically created as the user scrolls. When user arrives to the bottom of the scrollview, I load 10 images more.
The images are loading ok, but when i have a lot of images I get a java.lang.OutOfMemoryError.
I know the problem is that I have a lot of images consuming a lot of memory, so... what's the way to go on my scenario?
Thanks!
Try using a ListView instead of a ScrollView. Then you can use a lazy loading technique like Universal Image Loader. The ListView utilizes view recycling which will be easier on your memory, and you can also cache images using the image loader. This library also has a few options for memory management as well.
You are going to have to keep track of the images you have loaded and start recycling them when they are out of view.
You might find the LruCache a valuable tool. There was a good talk at IO12 "Doing More With Less: Being a Good Android Citizen" that went over lots of memory issues and includes some discussion on how to use the LruCache starting around the 4 minute mark.
I have to believe there's a way to clear image data from memory once it's no longer required, but despite exhaustive searching I can't find a solution. Both stack and the google android dev list are full of questions regarding OOM errors, specifically "bitmap size exceeds VM budget", but I still don't see a clear answer.
I understand there are hard memory limits on devices, and I understand it's not realistic to load up and display or cache large amounts of image data, but there should be away to discard data that's no longer required.
For example, imagine this very basic hypothetical app, that emulates a lot of the behavior of the native gallery app:
An image gallery that allows the user to peruse images from a remote server.
There might be any number of images on that server.
The app displays 1 image at a time, and allows a user to go back or forward 1 image at a time through button presses or swiping.
There'd be a maximum of 3 images rendered at any one time (so the user can see the one immediately to the left or right of the current image when swiping). All other image data should be discarded.
Images are loaded using URL.openStream and Drawable.createFromStream or BitmapFactory.decodeStream. Streams are closed appropriately.
Images are sized appropriately on the server before being fetched.
Loading happens in AsyncTasks. Tasks that are no longer needed (due to moving away from an image with an incomplete task) are cancelled. Any references in the AyncTask are WeaklyReferenced.
When any image is no longer required, it's "cleared" via:
getBackground().setCallback(null)
Listeners are set to null
setImageDrawable/Bitmap(null)
removeView
This simple construct, that takes into account all the suggest practices I'm aware of, will inevitably crash with an OOM error at some point. Using BitmapFactory.Options inSampleSize and inPreferredConfig will delay the inevitable, but not forever, and at the cost of image quality. In this example, I've used remote images, but the issue exists with images stored in /assets/ or in internal memory, etc.
My feeling is that if we can display X amount of image data at one point, and we take all steps to remove that image data from memory, we should be able to display that same amount of data later, without having to compensate for what has happened before.
With the sheer quantity of questions about this very issue, I'd hope to have a standard solution documented, but if there is one, I can't find it. I've seen answers posted by Romain Guy, who otherwise seems very generous with his knowledge and active in the community, that say something like "Simple. Don't use so much memory". OK. Tell me how.
I should also mention that System.gc does nothing to help this. I'm also aware of bitmap.recycle, but unless I'm mistaken this can't be used in this fashion.
Am I missing something fundamental? Is there a way to discard image data once it's no longer being used? What is missing from the above to create a simple photo gallery? Assuming the built-in gallery app uses the framework and not the NDK, I imagine there has to be a way...
TYIA.
/this question has also been posted on the android developer google group list.
Through my work with Prime I found a few tips, one of which you have not mentioned. When you decode your Bitmaps make sure to use the inPurgeable and inInputShareable flags in your BitmapFactory.Options. That will help a little bit but I would recommend you look at my implementation of image loading in Prime. I use it in all of my products without any memory issues. I have found that 95% of memory problems are from the incorrect usage of the Bitmap class.
There is a very detailed article about the use of bitmaps on the android developer website.
Did you look at it ?
It explains how to load, cache and display bitmaps efficently and how to get rid of this famous OutofMemoryError.
There is also a sample application from an image gallery.
I think that's what you're looking for.
We have an Android application that throws out of memory error on Android 1.6. It is working fine on 2.0 onwards. We are trying to cut down on the runtime memory usage at this point.
We were thinking of reusing images – such as the background image of each screen. Is it possible to load the background image once in the memory at the time of app launch and reuse this cached copy in each screen rather than each screen loading the same background image increasing the overall footprint in the RAM?
We understand that there many other ways and best practices around runtime memory usage. But at this point, we just wanted to know whether this “image reuse” approach is really feasible?
If yes, how can we do this? Will it at all save any memory or the Android OS will still create multiple copies of the same asset for each screen not giving any benefit from the memory perspective?
Thank you very much for your time in reading my post.
If that background image is loaded as a Drawable from a Resource, it's bitmap data is already shared between all Drawables created that way. So no, it probably wouldn't benefit you in your particular case.
Yes you can reuse images.
It is usually done for ListViews where each row contains the same image.
In this case, you can get the Bitmap once in the constructor of your adapter, and reuse it in the getView() method, so you don't have to load it for each row. This trick is presented here
In your case, you could load your background bitmap in the onCreate() method of your main activity, save it as a public static attribute and then re-use it in all your activities.
But I think it won't make that much of a difference and surcharge the code for nothing.
As you are working on tweaking your UI, I suggest you watch the 2009 Google I/O Presentation by Romain Guy, if you did not see it yet. It shows a lot of useful tricks for boosting an UI's performances, especially when it comes to Bitmap manipulation.