c# - Resizing a Single Control In WinForms

Question

How might I design a UI in C#/WinForms which happens to contain several different control types such that only the ListView control gets resized if the user resizes the window?

Answer 1

There are two primary ways to make a control automatically resize based on size changes of the parent container (a Form in your case):

1. Set the Dock property of the control to DockStyle.Fill.
2. Set the Anchor property to "Top, Bottom, Left, Right"

Use the Dock property with Dock.Fill

The advantage of this method is that it takes the entire control and tells it to always fill the entire client area of the parent container (in your case, the Form client area). That's useful if you want to do something like fill a Form with a ListControl or TreeView or something like that. But it's not as useful if you want to scale a single control while using other controls (as you indicate is your need). In that case, you would need to set the Dock property on those other controls to DockStyle.Top or DockStyle.Bottom to have them float above or below your main resizing control.

That's a hassle and it also limits the layout options of the other controls. You can mitigate that problem by docking two Panel controls, one at the top and another at the bottom of the Form. Those panels will remain in fixed positions while the middle area (with your DockStyle.Fill control) scales with the parent Form. You can then put any controls in any layout configuration in those "header" and "footer" panels.

This kind of composite form-building using docked panels is incredibly powerful. Quite frankly, it was game changing in .NET when they introduced this with .NET 1.0 WinForms.

Use the Anchor property with "Top, Bottom, Left, Right"

If all you want to do is have a single control on a form scale, while others stay "stuck" to the edges, use the Anchor property. For the controls that you want to stay at the top, set the Anchor property to "Top, Left" (the default). For controls that you want to stay at the bottom, set the Anchor property to "Bottom, Left". For controls that you want to grow in width with the form/dialog (such as a single-line textbox control), set the Anchor property to "Left, Right" (and set Top or Bottom depending whether you want it move as the top or the bottom of the dialog changes.

And if you want a control to resize in all directions with a Form, set the Anchor property to "Top, Left, Bottom, Right". Very useful for "main control" type of things, such as a dominant listbox, tree control, or multi-line textbox.

For what you need, don't mess with the AutoSize or AutoSizeMode... those properties control how a control changes size based on its own contents, not how it resizes based on its container's behavior. Think of AutoSize/AutoSize mode as inward looking, while Anchor/Dock are outward looking. You get some very bizarre behavior if you use both sizing methods at the same time. Generally not useful.