ElementFlow: Exception in MeasureOverride

Question

I'm trying to use FluidKits ElementFlow-control in my application, but get an exception in the MeasureOverride method of ElementFlow.

Layout measurement override of element 'FluidKit.Controls.ElementFlow' should not return PositiveInfinity as its DesiredSize, even if Infinity is passed in as available size.

In the sample application following FluidKit everything goes alright. When MeasureOverride gets called, the availableSize-struct is initialized with the bounds of the control, but in my application it comes with INF for both width and height.

I have tried to find whats different between the sample and my app, but both is a window with a grid with a listbox who uses the ElementFlow for ItemsPanel.

I have found others struggling with the same exception, but I have not found any solution to it, other than giving the listbox an explicit size. But I don't want to give it a size, I want the grid to manage its layout.

Any suggestions?

Answer 1

You simply cannot use the ElementFlow control within a variable sized grid or panel. It is not written to handle that situation as indicated by the exception that you get.

You did not show your code. I can only assume that you have your controls nested and defined in a way that allows one of them to grow indefinitely. For instance, stick a ScrollViewer in a page as the root element and enable scrolling in a particular direction. Then you have a control that allows itself to get bigger in that direction and it passes infinity to child controls when asking for their measurement (in that particular direction). If the ElementFlow control were a child of the ScrollViewer, you would get this exact exception.

If you show your xaml for the page, it should be easy to see which parent control is allowing it's content to grow indefinitely.

Answer 2

Any chance you could post some sample code?

I had a similar problem, turned out I had to have the grid as the root element (previously the grid was in a Canvas, I ended up moving it to a user control and everything worked fine).

Answer 3

See the discussion on the FluidKit CodePlex site. The simple answer is to open the ElementFlow code and change the return value in MeasureOverride from availableSize to _viewport.DesiredSize.