Why does scrolling a scrollview increase memory usage a lot? - android

I have a acrollview which contains maybe 15 rows in imageview (own special listview). Each row contains text and cross bitmap.
When I first create the scrollview there is almost no memory usage, but at the moment I touch it to scroll, memory usage is increased by ~2 MB.
This tends to make GC run which makes scrolling very choppy.
I'm reusing the views, so this can not be it. Any ideas?
I set bitmap into imageview immediately, not from internet, I generated bitmap from user data. sometimes 25 or more lines.
Can I somehow clear memoryusages? and Init with need value actualy?
I thing so code it's unnecessary, but If you want/need write.
If I scrool too long app crashed on outOfmemory error
===================EDIT===================================
I I found out I generated new image on every touch (as it's the same)..
now increase less, but increase.

A best practice in Android for such cases would be to use a Recycler View with an Adapter. This will keep your memory in check.
https://developer.android.com/reference/android/support/v7/widget/RecyclerView.html
Also check out this great video from udacity
https://www.youtube.com/watch?v=-VPM6ICgCk8

Related

Out of memory exception on inflating layouts

I am getting random out of memory exceptions in my app caused by inflate exceptions.
I have 7 fragment (difficulty) activities which launch their own activities via buttons. Each fragment has a scroll view with 30 buttons (levels).
I have set it up so that i can swipe across to each fragment and the fragment takes up the entire screen.
Occasionally when i swipe a few times and then select a random button from a group of 30 it will crash. It tries to load the activity and gives an out of memory exception with an inflate exception on a random line. The line always falls on an imageView or imageButton in the xml file. The activities that load are a grid of imageViews and imageButtons.
I do not get the exception much but it is something i want to fix. I have looked at many other out of memory exception questions although none have helped me. I have done a Memory analyser test and it shows nothing out of the ordinary.
I believe that the imageViews and imageButtons are using too much memory, although i only ever have one activity open at once.
It IS because of your images that are loading. When you load an image and you move around the page and view another image the heap increases. As you continue the process of viewing random images the heap grows even more until your app crashes. It's like stacking books on a glass table. You either move(cache) a book(image) or the glass(app) breaks. You should use an imageloader to load your images.
https://github.com/nostra13/Android-Universal-Image-Loader
You've mentioned that it always falls on an ImageView and ImageButton - and this is the clue to solve this problem. You get OOM 'cause background resource of this view has high resolution and takes a lot of memory. Try to lower resolution of this image.
Also you've mentioned that you have a ScrollView and this means that you keep in memory every 30 items. Probably you'd better change it to RecyclerView backed by adapter.
Just had the same problem and I'd like to simplify all the things said here:
Simply: reduce your images sizes.
Don't use 1080X1920 images... It's too high res.
Such image, even if compressed, when deployed will catch about 1080X1920X4B = 8.2MB (The GPU has to deploy it to it's full original resolution... That's why compression won't help but reducing the needed memory size...) and this i RAM that we're talking about..
Take Gimp or Photoshop and down scale the image to, say, 1/4: 540X960, and you won't feel the difference.. Belive me, been there already.
Beware of the memory consumption of images and videos.
Hope this helps,
James

How to use listview to render huge images?

I have a huge image to render (1024x25373p) cut into 99 images of 1024x256p.
I have tried to use a ListView, but without success : it crashes when scrolling, whithout any error (exept one line saying the proccess was stopped).
So, my question is, how do I render this huge image ?
Please note that I have tried to use TileView by moagrius, without success (I can't get it to work with navigation drawer)
As a suggestion ,
If this is listview, you may not need such larger size images "1024x256p" .
Actual size of your imageView may much for less than that. So its a wastage of
heap if you try to load those images directly without some processing.
Definitly you need to do some scaling down for your image based on actual size that you need. Nice exapmple and code has been published on the official doc
You need to deallocate memory or clear the all bitmaps which are not visible on the listview for particular moment.
You can use progressing loader in order to load your images in to the listview. Then loading will be happen based on the scrolling.
Also you can define lager heap enable in your manifest though it is not recommended but has to do in highly memory consumable apps.
android:largeHeap="true"

How to cope with jitter when using Android-Universal-Image-Loader in a ListView?

I'm using Android-Universal-Image-Loader in a ListView of mine and I'm trying to find the best solution to following:
using resetViewBeforeLoading is necessary or else I get the same image in my ConvertViews, but this causes jitter, unless..
I use PauseOnScrollListener which is otherwise great, except that it shows a blank in some ConvertViews even for images that are already downloaded (I'm using memory and disk caches), so it's confusing to the user who sees a blank for an image they saw only 2 swipes ago
So it seems that I can't get an instant image load (for already-downloaded images) on scroll without jitter, even for images in memory, is this about right? Is there a better or more standard way to do this? (Vertical list-view showing screen-width images, sort of like the Instagram app, which does it buttery-smooth)
Otherwise, is there a way to lengthen the number of convertViews in my ListView to prevent unnecessarily aggressive re-use?
Thanks in advance

Preparing LruCache in Appwidget

i have an appwidget which starts an activity as user clicks it.
In my Activity i have a gridview containing relatively small Drawables(Images, because drawable could be mor than just Images) but user can size them.
I noticed that it takes too Long to size them at runtime when Scrolling trough the gridview.
I want to prepare an lruCache only one time in my appWidget's onUpdate which is called at the very beginning when the user places the appwidget on the Screen.
The problem
When i define an lruCache in my appWidget with
private final int lruCacheSize = (int) (Runtime.getRuntime().maxMemory()/1024);
private LruCache<String, BitmapDrawable> myLruCache;
...
myLruCache = new LruCache<String, BitmapDrawable>(lruCacheSize) {
#Override
protected int sizeOf(String key, BitmapDrawable value) {
// TODO Auto-generated method stub
return super.sizeOf(key, value);
}
};
Will it only exist as Long as the process exist of the appWidget? Or does the Cache-File from lruCache stays in my cacheDir of my app? Or will it be deleted after the process of the appWidget is finished? If it does exist over the process-lifetime of my appWidget, how can i Access it from my Activity?
I don't want to create everytime the user clicks on the appWidget a LruCache and fill it up with all the relatively small Images the gridview will Need later. I want to do it once, or if user clears the Cache which will be checked every hour(to save battery).
The Question
How can i achieve that? Or is there a much better/ simpler way.
Time is not really (if it happens once at the very beginning) the Problem, i notify the user that the Cache is being prepared when placing the appWidget on the Screen.
Any help is appreciated.
Update regarding CommonsWare answere
Use Traceview to determine specifically why your implementation is slow.
The app Scrolling is slow because i provide three sizes (small, medium, large) and i scale them at while Scrolling trough my gridview.(Because it would take several seconds to scale them once at activity Startup, so i don't want that).
See here what i do in my imageview which will later Show the drawable(which is an appIcon):
android:scaleType="fitXY"
android:adjustViewBounds="true"
This causes the lag because i do this for everyimage depending if selected scale size is small medium or large.
There is no "Cache-File" in your code.
So then i i'm misunderstanding something. Doesn't the lruCache create an Cache-File in the Cache-Directory of my application? If not how does in works?
First, you cannot force the user to install the app widget. Work on solving the actual performance problem, rather than trying to build some optimization that will not help all users.
My "app" is only an appwidget. There is not appIcon like at FaceBook. It is only an appWidget when he doenloads my app. Which starts an activity when you click on the button.
Second, your process can readily be terminated milliseconds after onUpdate() completes. Do not fill a cache, only to have it never be used.
I want to use the Cache which i want to fill with the Drawables in the onUpdate of the appWidget, and then i want to use These Drawables from the Cache in my activity. So i don't understand why i never would use the Cache? Maybe i'm misunderstanding something.
Picasso would give you better performance from the user's standpoint.
Does it fit my Needs after the update right now?
---------------------------------------------------------------------------------------------
Update 2
Since the scaling should be done by the GPU and take microseconds, I have difficulty believing that is your problem. What specifically did Traceview show you that made you think that scaling has something to do with this?
I noticed that the Scrolling is very fluid at medium size because that's nearly the origin size of the appIcon from the PackageManager. If scroll trough large, where only 2 or 3 appIcons are displayed per row (at medium there are 5 or 6 displayed but it is much more fluid)m it lags. (With the same logic behind it). So the only Logical answere can be scaling in the XML at the ImageView. As i commented that XML-Scaling out and scaled the appIcons to the size Large and put them directly scalled to to my Adapter for GridView it runs really smooth( Only one or to really small lags at the beginning because convertView is null??)
onUpdate() will be called much more frequently than the user will actually use your app widget.
That's right after every onclick or at the specified time. But i check if the Cache has been cleared or not, if not don't Change anything, if so load Drawables to Cache.
I noticed that it takes too Long to size them at runtime when Scrolling trough the gridview.
Use Traceview to determine specifically why your implementation is slow.
Will it only exist as Long as the process exist of the appWidget?
It will only exist for the lifetime of the process of your app.
Or does the Cache-File from lruCache stays in my cacheDir of my app?
There is no "Cache-File" in your code.
I don't want to create everytime the user clicks on the appWidget a LruCache and fill it up with all the relatively small Images the gridview will Need later. I want to do it once, or if user clears the Cache which will be checked every hour(to save battery).
First, you cannot force the user to install the app widget. Work on solving the actual performance problem, rather than trying to build some optimization that will not help all users.
Second, your process can readily be terminated milliseconds after onUpdate() completes. Do not fill a cache, only to have it never be used.
Or is there a much better/ simpler way.
Use Traceview to determine exactly where your problem lies. Then, solve that problem. For example, the problem could be that you are loading these images on the main application thread, and using a library like Picasso would give you better performance from the user's standpoint.
The app Scrolling is slow because i provide three sizes (small, medium, large) and i scale them at while Scrolling trough my gridview
Since the scaling should be done by the GPU and take microseconds, I have difficulty believing that is your problem. What specifically did Traceview show you that made you think that scaling has something to do with this?
Doesn't the lruCache create an Cache-File in the Cache-Directory of my application?
No.
If not how does in works?
It is an in-memory cache.
So i don't understand why i never would use the Cache?
onUpdate() will be called much more frequently than the user will actually use your app widget.

GridView - hold more offscreen views?

I'm having an issue with an adapter for a grid view. The adapter causes a bitmap to be loaded every time a particular item is needed. I've got a disk cache and memory cache and I'm disabling loading while scrolling, so generally speaking, the gridview is quick.
But what I'd really like is to eliminate constantly having to rebind a particular Bitmap to an ImageView. Since the gridview is reusing views, the getView method has to keep reseting the ImageView and reloading the image from memory. This creates a really stupid effect as items slide offscreen and when returned to have a delay as the bitmap is read from the memory cache and posted to the ImageView.
Is there a way to get the GridView to 'hold on to' more views instead of being really frugal? I have a maximum of about 20 items and im scaling all the bitmaps, so I'd really like to just hold on to more of the views if possible.
I was able to solve this using a better in memory cache. The real distinction was to add a mechanism to check if the image was in memory and not 'reset' the view if the required image was in memory. It still seems bogus that there is not an easy way to set the number of cached views off screen for grid view, but better memory cache management made the problem less noticeable.

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