Detecting whether a resize/move comes from the user?


Hello, Juceys.

I’m in the final stages of making my app slick and I notice a weird height flickering in certain cases when I’m resizing the main window. (The content in my window doesn’t flick, that works rock-solidly during resizes, very slick!)

I traced it down to a feedback loop with my persistence layer that would occasionally trigger for a few rounds. It seems hard to avoid, now I’ve traced it down…

So, is there any way to detect whether a resize() (or moved()) update to your main window was triggered by a user action? Failing that, is there a way to get a callback when the user finishes resizing (or moving) your main window? (That’s really what I want - right now, I get a stream of changes which I apply, but for my persistence layer I’d much rather just store the value once, when the user has finished the operation…)


AsyncUpdater sounds like a good solution if you can’t find an alternative.


Everything’s already done asynchronously exactly that way.

In fact, that’s part of the issue. When someone’s vigorously resizing my fairly complex window, a lot of events get posted and then appear quite a bit later on the MessageManagerLock. My persistence layer sees these as a new event, undoing the event that the persistence layer just stored, when in fact it’s a late arrival from the window being resized in a hurry.

Really, what I need is an event when a user has finished resizing or moving a window. That’s the sort of thing that pretty well anyone who was trying to persist the state of their main window could make good use of…


AFAIK I don’t think there is a reliable way to get an event for that on all platforms… It could be possible to have a method that can ask whether the user is currently resizing, but again I’m not 100% sure if that’s possible everywhere. Hmm.


I had to have something similar for the component layout editor… the code is all in here:

… but I’ve no idea if the approach I use there is going to be suitable for you - that’s just a solution that worked for my simpler requirements


haydnx: wow, that’s an incredibly useful bit of code you have there, noted!

However, I don’t think this will work for me. The trouble is that I’m interested in the resizing of the main window, so I don’t think I get an initial mouse-down event anywhere…

So right now my best guess is to have another thread that makes sure that you haven’t done anything for a few hundred milliseconds before actually sending off the “official” window resize event into the persistence system - sort of an extension of the “call async” strategy. This prevents the underlying issue, where callbacks from the persistence system and the GUI are interleaving.

This is really not a bad idea anyway, so I’m on it. One more thread, not a huge cost…


That appeared to work really well the first time. On to the next!