Clear background after start new activity - android

I had a problem with lack of memory thus I decided to clean the background before starting a new activity.
It works, but I have the bad side-effect that I have a black screen before a new activity is started.
This is my code:
I set it here:
#Override
protected void onResume() {
super.onResume();
bg.setBackgroundDrawable(new BitmapDrawable(decodeSampledBitmapFromResource(getResources(), R.drawable.bg, sizeWigth, sizeHeight)));
}
I clear it here:
#Override
protected void onPause() {
super.onPause();
bg.setBackgroundDrawable(null);
System.gc();
}
Have you any idea to fix it?

When you loading large image make sure you follow following rules
Load the image based on your Screen DPI. if your screen is small their no reason load a huge image into memory.
Bitmap Sampling. read this for Sub-sampling a large image
Monitor your HeapSize and make you have enough space after loading the image to do other processing. Check this link
load image using java references. Make sure to reload the image when it is null. This will help you to avoid out of memory issue.
System.gc();
is a hints to garbage collector and and their are no guarantee that garbage collector will collect garbage after execution of this line.
Putting this image on XML layout will not help you with memory issue.

Related

Picasso Android memory issues

I am using Picasso to load 5 images, first thing first, I am resizing my image to match my screen width, which am also using as my height to have a square imageview, then am calling centercrop to make it look realistic and also removing the Alpha channel but even after all this my memory hikes to 85mb, the images are being downloaded from a server, below is the code am using
Picasso.with(context)
.load(sale.getImage())
.config(Bitmap.Config.RGB_565)
.centerCrop()
.resize((int) Utils.convertDpToPixel((int) Utils.getScreenWidth(context)), (int) Utils.convertDpToPixel((int) Utils.getScreenWidth(context)))
.into(viewHolder.img_image, new Callback() {
#Override
public void onSuccess() {
}
#Override
public void onError() {
viewHolder.img_image.setVisibility(View.GONE);
viewHolder.img_image.destroyDrawingCache();
}
});
}
Here is an image showing the memory usage
One other thing I have noticed is Picasso does not clear memory after usage, sometimes it shows am using 20mb but when I call the GC from Android Studio memory falls to about 8mb is there anything I need to do about this?
You are calling GC and memory falls into minimum value? This says that there is no strong references to used bitmaps. Everything is OK.
Large memory usage happens due to decoding large images into bitmaps. Bitmap format is pretty heavy. There is nothing to do about this. I recommend you to lower resolution of the resulting images.

Continuous crossfade of images and out of memory

I have an activity that show some full screen images in crossfade. There are a total of 6 images. To do this I used 2 ImageViews and 2 animation playing at the same time, one that fades out the first image and one that fades in the second. I used this video as a reference https://www.youtube.com/watch?v=9XbKMUtVnJA
Because I need this to run continuously, I used a timer to schedule the animation every 4 seconds. Everything works, but it uses a huge quantity of memory. To load the images I tried:
the basic not recommended way used in the video, i.e loading all images in a drawable array
setting the images using imageview.setImageResource
loading the images from assets using Picasso
All this method are memory intensive a cause an out of memory exception on older devices (like a Galaxy S2). The Picasso approach isn't working properly.
I'm sure there's a better way of doing this, but I don't know it, any suggestions?
Here's the relevant code:
private void animateImageview(){
prevImageView.animate().alpha(0);
nextImageView.animate().alpha(1).setListener(new AnimatorListenerAdapter() {
#Override
public void onAnimationEnd(Animator animation) {
mCurrentDrawable =
(mCurrentDrawable + 1) % imagesToShow.length;
int nextDrawableIndex =
(mCurrentDrawable + 1) % imagesToShow.length;
prevImageView.setImageResource(imagesToShow[mCurrentDrawable]);
nextImageView.setImageResource(imagesToShow[nextDrawableIndex]);
nextImageView.setAlpha(0f);
prevImageView.setAlpha(1f);
}
});
protected void onCreate(Bundle savedInstanceState) {
...
prevImageView.setImageResource(imagesToShow[0]);
nextImageView.setImageResource(imagesToShow[1]);
new Timer().scheduleAtFixedRate(new TimerTask() {
#Override
public void run() {
animateImageview();
}
}, 5000, 4000);
}
Edit:
the largeHeap option in the manifest seems to solve the problem, but I'm not convinced that I'm doing this thing right anyway.
Edit2:
A gist with the solution I used https://gist.github.com/alexmazza/003e3449c02fe58848a9
Please remove the largeHeap option from the manifest. It's not fixing the problem, it's sweeping the problem under the rug.
This is the problem
The images are 1536x2048 loaded in an imageview
You shouldn't just try to load the image at maximum resolution, because, as you said, in a S2 for instance, which has a display of 800 x 480, what's the point?
Generally speaking, what you should do instead is load a bitmap into memory as big as you need it to be (in your case it should be as big as the ImageView). You can follow a very good tutorial for this in the official docs.
To avoid java.lang.OutOfMemory exceptions, check the dimensions of a bitmap before decoding it, unless you absolutely trust the source to provide you with predictably sized image data that comfortably fits within the available memory.
[....]
For example, it’s not worth loading a 1024x768 pixel image into memory if it will eventually be displayed in a 128x96 pixel thumbnail in an ImageView.
Hope this helps.

Android Bitmap Cache

I'm working on implementing a cache for a lot of bitmap tiles I have. What I've done so far:
Successfully implemented a LRU Cache system, but the tiles still load slowly when they must be loaded from the app's resources. The cache currently has about an 85% hit rate.
Whenever I must load the bitmap from resources, it is still slow like I said. With this in mind, I am now loading the Bitmaps from an Async task. Before this, everything would load without error, but it was fairly slow. Now, it's faster since it's not working on the main thread, but I inevitably run into an OOM error. Here's the code for my Async task:
public class loadBitmap extends AsyncTask<Void,Void,Void>
{
Bitmap bit;
#Override
protected Void doInBackground(Void... params)
{
Options opts = new Options();
bit = BitmapFactory.decodeResource(reso, drawable, opts);
return null;
}
#Override
protected void onPostExecute(Void result)
{
// TODO Auto-generated method stub
drawLoadedBit(bit);
super.onPostExecute(result);
}
}
Any ideas on how I can implement this so I don't get the Out of Memory error? Since this is called in the draw method, I'm thinking that the multiple calls to it are causing it. Thanks for any advice.
Refer to this link
He gives a good tutorial on using regenative bitmaps. Further, to decouple the bitmap from the view [once the view is disposed], you can #Override View#onRemovedFromWindow() to recycle the bitmap. Going even further, if you still have this issue, you can create a BitmapPool in which you allocate your bitmaps. You can implement an algorithm go calculate the sizes of the bitmaps and release older bitmaps that would push you over an arbitrary memory amount (bitamp memory is about width*height*4 + object size which should be nominal)
When the Bitmap is loaded, keep it around in a class variable. Then next time a draw is requested, check to see if the class variable is non-null before loading it from resources again.

Recycling Bitmap in android

When one should take care of Bitmap memory management or recycling bitmap in android ?
For example , there are few ways to create a bitmaps in android like following
Bitmap.createBitmap
Bitmap.createScaledBitmap
BitmapFactory
But when android allocate memory for bitmap which must be cleared so that in future application we won't face running out of memory error problem
In Android versions prior to 3.0, the Bitmaps are allocated outside of the VM. Android gets back this memory in Bitmap's finalize() method. You can let Android reclaim the memory faster by calling Bitmap.recycle() instead of waiting on the GC to call finalize() on them.
This is only really a problem if you're creating and discarding a lot of the Bitmaps. That is, if you are allocating memory faster then the GC can clean up the garbage left behind, at which point you get an OutOfMemoryError.
In android 3.0 and later, the Bitmap memory is allocated inside of the VM, so Bitmap memory can be reclaimed without having to call finalize() on them.
you recycle the bitmap whenever you don't need it. for example
#Override
protected void onPause(){
super.onPause();
if(bitmap !=null){
bitmap.recycle();
bitmap = null;
}
}
#Override
protected void onResume() {
super.onResume();
if(bitmap !=null){
bitmap.recycle();
bitmap = null;
}
}
P.S bitmaps memory are acting different from each devices, what i mean is
Growing Heap
is different from device to another
for example Bitmap size can exceed VM budget(Growing Heap) up to 240MB on the S4 tested and confirmed by personal testing and it doesn't cause OutOfMemoryError but in some other devices if the bitmap size exceed (Growing Heap) up to 16MB it may cause OutOfMemoryError its quite different from device to another because some devices has large heap while some not. and trust me dealing with Growing Heap is not easy task.
additional advice is to use android:largeHeap="true" in your application tag inside of the manifest.
`

java.lang.OutOfMemoryError: bitmap size exceeds VM budget - Android

I developed an application that uses lots of images on Android.
The app runs once, fills the information on the screen (Layouts, Listviews, Textviews, ImageViews, etc) and user reads the information.
There is no animation, no special effects or anything that can fill the memory.
Sometimes the drawables can change. Some are android resources and some are files saved in a folder in the SDCARD.
Then the user quits (the onDestroy method is executed and app stays in memory by the VM ) and then at some point the user enters again.
Each time the user enters to the app, I can see the memory growing more and more until user gets the java.lang.OutOfMemoryError.
So what is the best/correct way to handle many images?
Should I put them in static methods so they are not loaded all the time?
Do I have to clean the layout or the images used in the layout in a special way?
One of the most common errors that I found developing Android Apps is the “java.lang.OutOfMemoryError: Bitmap Size Exceeds VM Budget” error. I found this error frequently on activities using lots of bitmaps after changing orientation: the Activity is destroyed, created again and the layouts are “inflated” from the XML consuming the VM memory available for bitmaps.
Bitmaps on the previous activity layout are not properly de-allocated by the garbage collector because they have crossed references to their activity. After many experiments I found a quite good solution for this problem.
First, set the “id” attribute on the parent view of your XML layout:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="#+id/RootView"
>
...
Then, on the onDestroy() method of your Activity, call the unbindDrawables() method passing a reference to the parent View and then do a System.gc().
#Override
protected void onDestroy() {
super.onDestroy();
unbindDrawables(findViewById(R.id.RootView));
System.gc();
}
private void unbindDrawables(View view) {
if (view.getBackground() != null) {
view.getBackground().setCallback(null);
}
if (view instanceof ViewGroup) {
for (int i = 0; i < ((ViewGroup) view).getChildCount(); i++) {
unbindDrawables(((ViewGroup) view).getChildAt(i));
}
((ViewGroup) view).removeAllViews();
}
}
This unbindDrawables() method explores the view tree recursively and:
Removes callbacks on all the background drawables
Removes children on every viewgroup
It sounds like you have a memory leak. The problem isn't handling many images, it's that your images aren't getting deallocated when your activity is destroyed.
It's difficult to say why this is without looking at your code. However, this article has some tips that might help:
http://android-developers.blogspot.de/2009/01/avoiding-memory-leaks.html
In particular, using static variables is likely to make things worse, not better. You might need to add code that removes callbacks when your application redraws -- but again, there's not enough information here to say for sure.
To avoid this problem you can use native method Bitmap.recycle() before null-ing Bitmap object (or setting another value). Example:
public final void setMyBitmap(Bitmap bitmap) {
if (this.myBitmap != null) {
this.myBitmap.recycle();
}
this.myBitmap = bitmap;
}
And next you can change myBitmap w/o calling System.gc() like:
setMyBitmap(null);
setMyBitmap(anotherBitmap);
I've ran into this exact problem. The heap is pretty small so these images can get out of control rather quickly in regards to memory. One way is to give the garbage collector a hint to collect memory on a bitmap by calling its recycle method.
Also, the onDestroy method is not guaranteed to get called. You may want to move this logic/clean up into the onPause activity. Check out the Activity Lifecycle diagram/table on this page for more info.
This explanation might help:
http://code.google.com/p/android/issues/detail?id=8488#c80
"Fast Tips:
1) NEVER call System.gc() yourself. This has been propagated as a fix here, and it doesn't work. Do not do it. If you noticed in my explanation, before getting an OutOfMemoryError, the JVM already runs a garbage collection so there is no reason to do one again (its slowing your program down). Doing one at the end of your activity is just covering up the problem. It may causes the bitmap to be put on the finalizer queue faster, but there is no reason you couldn't have simply called recycle on each bitmap instead.
2) Always call recycle() on bitmaps you don't need anymore. At the very least, in the onDestroy of your activity go through and recycle all the bitmaps you were using. Also, if you want the bitmap instances to be collected from the dalvik heap faster, it doesn't hurt to clear any references to the bitmap.
3) Calling recycle() and then System.gc() still might not remove the bitmap from the Dalvik heap. DO NOT BE CONCERNED about this. recycle() did its job and freed the native memory, it will just take some time to go through the steps I outlined earlier to actually remove the bitmap from the Dalvik heap. This is NOT a big deal because the large chunk of native memory is already free!
4) Always assume there is a bug in the framework last. Dalvik is doing exactly what its supposed to do. It may not be what you expect or what you want, but its how it works. "
I had the exact same problem. After a few testing I found that this error is appearing for large image scaling. I reduced the image scaling and the problem disappeared.
P.S. At first I tried to reduce the image size without scaling the image down. That did not stop the error.
Following points really helped me a lot. There might be other points too, but these are very crucial:
Use application context(instead of activity.this) where ever possible.
Stop and release your threads in onPause() method of activity
Release your views / callbacks in onDestroy() method of activity
I suggest a convenient way to solve this problem.
Just assign the attribute "android:configChanges" value as followed in the Mainfest.xml for your errored activity.
like this:
<activity android:name=".main.MainActivity"
android:label="mainActivity"
android:configChanges="orientation|keyboardHidden|navigation">
</activity>
the first solution I gave out had really reduced the frequency of OOM error to a low level. But, it did not solve the problem totally. And then I will give out the 2nd solution:
As the OOM detailed, I have used too much runtime memory. So, I reduce the picture size in ~/res/drawable of my project. Such as an overqualified picture which has a resolution of 128X128, could be resized to 64x64 which would also be suitable for my application. And after I did so with a pile of pictures, the OOM error doesn't occur again.
I too am frustrated by the outofmemory bug. And yes, I too found that this error pops up a lot when scaling images. At first I tried creating image sizes for all densities, but I found this substantially increased the size of my app. So I'm now just using one image for all densities and scaling my images.
My application would throw an outofmemory error whenever the user went from one activity to another. Setting my drawables to null and calling System.gc() didn't work, neither did recycling my bitmapDrawables with getBitMap().recycle(). Android would continue to throw the outofmemory error with the first approach, and it would throw a canvas error message whenever it tried using a recycled bitmap with the second approach.
I took an even third approach. I set all views to null and the background to black. I do this cleanup in my onStop() method. This is the method that gets called as soon as the activity is no longer visible. If you do it in the onPause() method, users will see a black background. Not ideal. As for doing it in the onDestroy() method, there is no guarantee that it will get called.
To prevent a black screen from occurring if the user presses the back button on the device, I reload the activity in the onRestart() method by calling the startActivity(getIntent()) and then finish() methods.
Note: it's not really necessary to change the background to black.
The BitmapFactory.decode* methods, discussed in the Load Large Bitmaps Efficiently lesson, should not be executed on the main UI thread if the source data is read from disk or a network location (or really any source other than memory). The time this data takes to load is unpredictable and depends on a variety of factors (speed of reading from disk or network, size of image, power of CPU, etc.). If one of these tasks blocks the UI thread, the system flags your application as non-responsive and the user has the option of closing it (see Designing for Responsiveness for more information).
Well I've tried everything I found on the internet and none of them worked. Calling System.gc() only drags down the speed of app. Recycling bitmaps in onDestroy didn't work for me too.
The only thing that works now is to have a static list of all the bitmap so that the bitmaps survive after a restart. And just use the saved bitmaps instead of creating new ones every time the activity if restarted.
In my case the code looks like this:
private static BitmapDrawable currentBGDrawable;
if (new File(uriString).exists()) {
if (!uriString.equals(currentBGUri)) {
freeBackground();
bg = BitmapFactory.decodeFile(uriString);
currentBGUri = uriString;
bgDrawable = new BitmapDrawable(bg);
currentBGDrawable = bgDrawable;
} else {
bgDrawable = currentBGDrawable;
}
}
I had the same problem just with switching the background images with reasonable sizes. I got better results with setting the ImageView to null before putting in a new picture.
ImageView ivBg = (ImageView) findViewById(R.id.main_backgroundImage);
ivBg.setImageDrawable(null);
ivBg.setImageDrawable(getResources().getDrawable(R.drawable.new_picture));
FWIW, here's a lightweight bitmap-cache I coded and have used for a few months. It's not all-the-bells-and-whistles, so read the code before you use it.
/**
* Lightweight cache for Bitmap objects.
*
* There is no thread-safety built into this class.
*
* Note: you may wish to create bitmaps using the application-context, rather than the activity-context.
* I believe the activity-context has a reference to the Activity object.
* So for as long as the bitmap exists, it will have an indirect link to the activity,
* and prevent the garbaage collector from disposing the activity object, leading to memory leaks.
*/
public class BitmapCache {
private Hashtable<String,ArrayList<Bitmap>> hashtable = new Hashtable<String, ArrayList<Bitmap>>();
private StringBuilder sb = new StringBuilder();
public BitmapCache() {
}
/**
* A Bitmap with the given width and height will be returned.
* It is removed from the cache.
*
* An attempt is made to return the correct config, but for unusual configs (as at 30may13) this might not happen.
*
* Note that thread-safety is the caller's responsibility.
*/
public Bitmap get(int width, int height, Bitmap.Config config) {
String key = getKey(width, height, config);
ArrayList<Bitmap> list = getList(key);
int listSize = list.size();
if (listSize>0) {
return list.remove(listSize-1);
} else {
try {
return Bitmap.createBitmap(width, height, config);
} catch (RuntimeException e) {
// TODO: Test appendHockeyApp() works.
App.appendHockeyApp("BitmapCache has "+hashtable.size()+":"+listSize+" request "+width+"x"+height);
throw e ;
}
}
}
/**
* Puts a Bitmap object into the cache.
*
* Note that thread-safety is the caller's responsibility.
*/
public void put(Bitmap bitmap) {
if (bitmap==null) return ;
String key = getKey(bitmap);
ArrayList<Bitmap> list = getList(key);
list.add(bitmap);
}
private ArrayList<Bitmap> getList(String key) {
ArrayList<Bitmap> list = hashtable.get(key);
if (list==null) {
list = new ArrayList<Bitmap>();
hashtable.put(key, list);
}
return list;
}
private String getKey(Bitmap bitmap) {
int width = bitmap.getWidth();
int height = bitmap.getHeight();
Config config = bitmap.getConfig();
return getKey(width, height, config);
}
private String getKey(int width, int height, Config config) {
sb.setLength(0);
sb.append(width);
sb.append("x");
sb.append(height);
sb.append(" ");
switch (config) {
case ALPHA_8:
sb.append("ALPHA_8");
break;
case ARGB_4444:
sb.append("ARGB_4444");
break;
case ARGB_8888:
sb.append("ARGB_8888");
break;
case RGB_565:
sb.append("RGB_565");
break;
default:
sb.append("unknown");
break;
}
return sb.toString();
}
}

Categories

Resources