Is it possible to detect a scrollbar release event in GWT?

开发者_如何学PythonI'm building a GWT app where I want to be able to detect when a user releases a scroll bar on one of my ScrollPanels.

My use case is that the horizontal scroll bar represents time. Since it's impossible to represent the full range of scrollable time I want to just represent a small window of time with the scroll bar. When the user moves and releases the scroll bar I want to do a smooth recentering where the new center is the release point.

I can work out how to do this by building a custom scroll bar widget, but I wanted to check if I was missing some way to do it using a "native" scroll bar first.

You might be able to do it with a ScrollPanel and implementing your own ScrollHandler. Just use the addScrollHandler() method and you should be able to override whatever functionality you need.

However, I would suggest that you re-think your approach. What you seem to really want is a slider control for time, that kind of looks like a scroll bar. You should check out the Composite class and the Widget Gallery to see if there is some combination of Widgets that would suit what you need more. Failing that, I'd also look at SmartGWT. They have a very extensive library of GUI Widgets available, and you may find something you can use already there.