Currently I have a GridView, and every element should have a separate ProgressBar. The elements represent separate downloads, and I’d like to show the state of the downloads using these ProgressBars.
But how should I update them? My problem is, that according to the docs (and what I’ve heard on the Google IO videos), the only way to update elements in AdapterViews is to update the assigned adapter, and call .notifyDatasetChanged() after every update.
Of course this does actually work in this case too, but the updates are quite frequent (5-10 updates sec). And calling .notifyDatasetChanged in this frequency breaks any interaction with the GridView. E.g. the user tries to long-click on an item in the Grid, but the clicking event stops, because a .notifyDatasetChanged was called to update the progress of a download.
Is there any other way to do this? Should I ditch AdapterViews and use something else?
For situations like yours with many frequent updates (many times a second), notifyDatasetChanged isn’t the right way to go – You need to update the individual views directly.
Without seeing your code and the relationship between a file download and an entry in the GridView, it’s hard to say exactly what calls you’ll need, but:
-GridView has a “getChildAt” you can use to grab a view at a specific index.
-There’s no point in updating the view if it’s not even visible. If it’s not between getFirstVisiblePosition() and getLastVisiblePosition(), ignore it, it’ll get drawn with updated data whenever it gets redrawn.