no i use CursorAdapter, as the underlying objects are coming out of the database. once the AsyncTask completes, i update the database record, so the next time round, it just inflates the bitmap and sets the imageview directly.
back in the day i did this synchronously and the scrolling sucked. but when the image loading is async, it's smooth -- at the price of a little book-keeping in the view recycling. another option is not to recycle at all, which in the end i might go for, as often i don't seem to be able to cancel AsyncTasks. hth j >Thanks Jason, sounds good. Are you extending BaseAdapter for your >listview adapter? I thought it'd be a bit slow since every time getView >() is called, I have to do the re-setting of my row's ImageView, but >it's for the most part pretty smooth, just wondering how you find >performance in your case? > >Thanks > >On Nov 19, 5:07 pm, Jason Proctor <[email protected]> >wrote: >> i have almost the same situation as you, but the way i do it is a >> little different -- >> >> when a list item view is made or recycled, it checks to see whether >> its image is loaded or not. if it's not, it kicks off an AsyncTask >> whose job it is to grab it using its URL. when that completes, it >> calls the list item view back again and that in turn inflates the >> bitmap and setImageBitmap() on the appropriate image view. >> >> have to keep track of the view being recycled while the task is >> ongoing etc, but that awkwardness aside, this system seems to work ok. >> >> >> >> >Hi, >> >> >I have a ListView, its rows each have an image downloaded from the net >> >in a separate thread. >> >> >When the image is done downloading, I notify my main thread, and need >> >to invalidate the corresponding row if it's on screen. I'm doing this: >> >> > // run on the main thread. >> > public void onThumbnailDownloaded(String url, Bitmap bmp) { >> > for (int i = 0; i < mListView.getChildCount(); i++) { >> > PanelMyRow panel = (PanelMyRow)mListView.getChildAt(i); >> > if (panel.getUrl().equals(url)) { >> > panel.getImageView().setImageBitmap(bmp); >> > break; >> > } >> > } >> > } >> >> >this seems to work ok. Ideally though, I think it'd be better if I >> >could somehow trigger my adapter to call its getView() method for this >> >'dirty' row. I can't find a method within ListView or BaseAdapter to >> >do this. Calling any of the invalidate methods has no effect, and any >> >of these: >> >> > ListView.invalidateViews() >> > BaseAdapter.notifyDatasetInvalidated(); >> > BaseAdapter.notifyDatasetChanged(); >> >> >seem pretty heavyweight and my ListView scrolling will be very choppy >> >if the images are still downloading and one of the above three is >> >called during the callback. Is there some way I can simply mark the >> >child view as dirty which notifies the ListView that it should call >> >getView() on the adapter for that row again? Seems safer. >> >> >Thanks >> >> >-- >> >You received this message because you are subscribed to the Google >> >Groups "Android Developers" group. >> >To post to this group, send email to [email protected] >> >To unsubscribe from this group, send email to >> >[email protected] >> >For more options, visit this group at >> >http://groups.google.com/group/android-developers?hl=en >> >> -- >> jason.vp.engineering.particle > >-- >You received this message because you are subscribed to the Google >Groups "Android Developers" group. >To post to this group, send email to [email protected] >To unsubscribe from this group, send email to >[email protected] >For more options, visit this group at >http://groups.google.com/group/android-developers?hl=en -- jason.vp.engineering.particle -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
