I had similar issues. I managed to fix the performance of the list- view, but i ran into memory issues.
My app downloads images from Smugmug, images that are 'front-page' images of galleries/albums. First, my app needed to get the information about the album, to get the image-id of the album's front-page image. This would result in a URL and then my app downloads the image using this URL and then shows it in a list-item. I used the ExecutorService to fetch the necessary album information and image-retrieval and image decoding in a limited number of background threads. In the list-adpater's getView method, i would tag (setTag) the list- item view with the album-id and submit a new (cancelable) task using the ExecutorService (java.util.concurrent packages). This task downloads the album info and then downloads the image. While the album information and the image were downloading, i showed a place-holder picture in my list-item's imageview (a bitmap from the res/drawable directory) When the task that has been submitted finishes, it posts the result back to the main-thread: Loop over the current list-view children (which are the visible list-items). For each child get its tag (getTag) and if this tag matched the task-result, i would set the child's imageview's bitmap to the image i just downloaded. This all worked quite well, with images downloading at their own pace and the list-view kept performing well. However, at some point i got memory errors when calling ImageView.setImageBitmap(Bitmap). I checked my code. I made sure to recycle not-used bitmaps, i did not cache bimtaps, etc., but i kept getting memory errors (note that the smugmug images downloaded were small: 100x100 pixels). I was not able to solve these memory errors and i abandoned this idea. Any ideas to prevent these memory errors? :-) On Mar 17, 7:28 am, ifuller1 <ifuller1mob...@gmail.com> wrote: > Thanks gesh - as suggested the problem was related to recycling. > Preformance is pretty good now, sadly my images keep shuffling but > given your recent input this should be easy to fix. > > On Mar 15, 10:03 pm, Gesh <geo...@neofonie.de> wrote: > > > > > > I'm currently using the ImageAdapter from the Hello GridView sample. > > > But loading the images from the web rather than using resources. > > > I think you need a better understanding of how adapters work to solve > > your problem. The getView() method of your Adapter is inkoved every > > time an image in your grid becomes visible (yes, including when you > > scroll back and forth to previously visible images). So if you have > > just replaced that one line image.setImageResource(int) with > > image.setImageDrawable(Drawable.createFromStream()) it means you are > > re-downloading images every time they get scrolled into view. > > > So you need to cache those downloaded images and while you are at it > > make sure you cache scaled thumbnail of the image, just as big as you > > need them to avoid the possible problem Romain suggested. Use > > Bitmap.createScaledBitmap() - it's worked great for me. > > > Also be aware that the emulator is running on your PC using that same > > network speed. If you want to test for real network problems you might > > get on a real device try starting the emulator with limited network > > (or on your G1 disable wireless and 3G). I alwasy run my emulator with > > network speed and latency set to EDGE, or for some debugging purposes > > even GPRS or GSM. > > > hope that helps you, > > gesh. > > > On Mar 15, 7:22 am, ifuller1 <ifuller1mob...@gmail.com> wrote: > > > > Hi Gesh, > > > > Thanks for the response. I'll certainly give the bitmap factory a go. > > > I'm currently using the ImageAdapter from the Hello GridView sample. > > > But loading the images from the web rather than using resources. The > > > problem is immediate, in that the performance doesn't degrade after re- > > > visits to the activity, but is instead directly proportional to the > > > number of images I'm displaying. > > > > As well as trying the bitmap factory can I ask what you think is the > > > best way to encourage garbage collection? Will nulling my objects be a > > > big help. > > > > Once I have it optimized I'm going to release it for free... I think > > > there's a big hole in androids picasa support. > > > > Ian > > > > On Mar 14, 11:38 pm, Gesh <geo...@neofonie.de> wrote: > > > > > hi, > > > > > I have written 2 connected apps with some image content pulled from > > > > the web and must say if you handle your resources right it shouldn't > > > > be a problem at all. > > > > > Do you use your own Adapter for theGridViewor do you use some of the > > > > already available ones in the SDK? If you use your own you should keep > > > > in mind that when you deal with AdapterViews in general they keep > > > > references to Views you create in your adapter and recycle them, so > > > > try to reuse the convertView reference you get in the Adapter.getView > > > > (int position, View convertView, ViewGroup parent) method. > > > > > And although memory leaks are difficult to achieve in what sounds like > > > > a single activity app the other thing that comes to mind is that you > > > > might have memory leaks due to the way you use Drawables. Try using > > > > Bitmaps from the BitmapFactory.decodeStream(InputStream) method and > > > > maybe read this blog for more info why Drawables could cause memory > > > > leaks > > > > -http://android-developers.blogspot.com/2009/01/avoiding-memory-leaks..... > > > > > cheers, > > > > gesh. > > > > > On Mar 14, 12:47 pm, ifuller1 <ifuller1mob...@gmail.com> wrote: > > > > > > I've managed to successfully connect to the picasa web services using > > > > > JSON and download a list of thumbnails from my picasa album. The > > > > > thumbnails are all very small but I'm getting pretty terrible > > > > > performance (especially when compared to the native picture viewer). > > > > > As my main goal was getting the application working their is obviously > > > > > lots of optimisation work I can do but I just wanted to know where the > > > > > most likely cause of poor performance is coming from. Is it the memory > > > > > usage (so I should try cleaning up existing objects) or is it display > > > > > performance (can't cope with 30 thumbnails at once)? > > > > > > Example thumbnail > > > > > imagehttp://lh6.ggpht.com/_QIFTbqmwS8U/Samo30_xoBI/AAAAAAAAAEk/VeBxiukdKzU... > > > > > > being loaded via Drawable.createFromStream > > > > > > Thanks in advanced. > > > > > > Ian- Hide quoted text - > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~----------~----~----~----~------~----~------~--~---
