On Fri, Feb 17, 2012 at 10:14 AM, Benjamin Root <ben.r...@ou.edu> wrote: > Hello all, > > I tracked down an annoying problem in one of applications to the Lasso > widget I was using. The widget constructor lets you specify a function to > call when the lasso operation is complete. So, when I create a Lasso, I set > the canvas's widget lock to the new lasso, and the release function will > unlock it when it is done. What would occassionally happen is that the > canvas wouldn't get unlocked and I wouldn't be able to use any other widget > tools. > > It turns out that the release function is not called if the number of > vertices collected is not more than 2. So, accidental clicks that activate > the lasso never get cleaned up. Because of this design, it would be > impossible to guarantee a proper cleanup. One could add another > button_release callback to clean up if the canvas is still locked, but there > is no guarantee that that callback is not called before the lasso's > callback, thereby creating a race condition. > > The only solution I see is to guarantee that the release callback will be > called regardless of the length of the vertices array. Does anybody see a > problem with that?
Not having looked at the Lasso code, wouldn't it be possible to use one internal callback for the button_release event, and have this callback call the users' callbacks if points > 2 and always handle the unlocking of the canvas? Ryan -- Ryan May Graduate Research Assistant School of Meteorology University of Oklahoma ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
