Hi Robert, instead of listening to visibleProperty(), listen to sceneProperty() and cancel loading when scene becomes null.
Tomas On Tue, Jan 27, 2015 at 1:16 PM, Robert Krüger <krue...@lesspain.de> wrote: > Hi, > > either I don't see the forest for the trees or something is missing in the > TableView API as I cannot seem to implement something that seems a common > requirement and was rather easy (not pretty though) in Swing. > > Imagine an application like OSX finder in its list view, i.e. something > that displays a possibly very long list of files and displays thumbnails > for them generated on the fly. For many files (e.g. video files) extracting > these thumbnails is an expensive operation and has to be performed in the > background. My application does a very similar thing and uses a TableView. > What I want is to begin extracting video thumbnails as soon as their > corresponding table row has become visible. I have done that in Swing in > the past without any problem (for more info, you can read > https://community.oracle.com/message/12810930). > > With JavaFX I have tried the following: > > 1) Trigger loading the thumbnail in the table cell when it is updated and > the corresponding thumbnail isn't already there > > Result: Triggering works more or less as desired but how do I stop the > loading process if the cell becomes invisible? If the user quickly scrolls > through a large number of rows and puts tons of thumbnail loading jobs on > the queue I have not found a way to dequeue them, so this is unusable. I > added output to the calls to the update method of the TableCell to see > which instances are used and how their data is reset but the pattern I see > is not suitable for deciding which cell is currently visible. > > 2) Register a change listener to the TableCell’s visible property to make > that control the image loading. > > Result: I don’t seem to get any change events when I do that, so it does > not work at all for my purpose. > > I see no public API in table view to explicitly compute the items visible > in the current viewport either. What am I missing. It can't be an oversight > in the API design, as the thing, I am trying to achieve appears rather > basic. > > Thanks in advance for any hints, > > Robert
