Question

I have read that placing a canvas inside a scrollviewer won’t work because the canvas does not report its size. I have been experimenting with different containers (borders, grids, canvases and scrollviewers) and could really do with a simple explanation of how scrollviewers behave within nested containers. e.g. If I have a container hierarchy of UserControl>Grid1>Canvas1>ScrollViewer>Grid2>Canvas2 should scrollbars appear around Grid2 when Canvas2 becomes wider than Canvas1? (or indeed wider than UserControl) If not, how should I organise my containers so I can add loads of uielements to Canvas2 and have scrollbars appear as necessary. (My usercontrol width and height are set to 100%)

Answer 1

Canvas will work with a ScrollViewer if you explicitly give it a size. The problem comes from the fact that if you don’t supply a Height and Width for any control it will try and determine it’s available area based off it’s parent container. A ScrollViewer however has infinite available area.

Take a Grid for example. If I define a Grid that has 2 Star Width columns and 2 Star Height rows. How does the Grid know how wide each of those columns should be? The star says they should be half of the available area, but inside a ScrollViewer the available area is infinity.

What controls are you adding to Canvas2? If you are adding them with fixed positions than the ScrollViewer will expand to house all elements. If you aren’t giving them fixed positions than all the controls will stack on top of each other, because that is the arrange behavior of a Canvas