Get all Controls of a Type, including nested containers

Question

I have a winforms project with a multi-level container setup in place. As in, I have a set of Panels on the top layer, each of those Panels has another set of Panels nested within them, and each of those sub-panels have a set of Controls (TextBoxes, CheckBoxes, etc.) in each one.

What I want is to be able to retrieve Controls of a certain type, given only the top level Panel. For example, one set of this using the names in my project would be MainPanelTruck which has a PanelTruckCheck Panel under it, which itself has 8 CheckBox nested in it. I want to be able to retrieve those 8 CheckBox given just MainPanelTruck.

Here's an image of a section of the Panel structure for reference.

I have been trying to get OfType<>() to work but as far as I can tell, it only searches among the next level down, so when I search for CheckBox using it, I get nothing as a result, because it only looks at the sub-panels.

This would be a lot easier if the Find method in ControlCollection allowed for a predicate or condition instead of a specific string as key, because it has the searchAllChildren bool which would be very handy here.

I can think of many ways I can get the items I want here, but none of them feel particularly elegant, which is what I'm seeking here. Thanks :)

Sergey Berezovskiy · Answer 1 · 2021-01-23T02:50:25.983

1

You can write a simple (extension) method that returns all nested controls of given control:

public static class ControlExtensions
{
    public static IEnumerable<Control> GetAllNestedControls(this Control root)
    {        
        var stack = new Stack<Control>();
        stack.Push(root);

        do
        {
            var control = stack.Pop();

            foreach (Control child in control.Controls)
            {
                yield return child;
                stack.Push(child);
            }
        }
        while (stack.Count > 0);
    }
}

With this in hand getting all checkboxes is easy:

panel1.GetAllNestedControls().OfType<CheckBox>()

You can also pass an optional boolean flag to search all children if you want. Check the flag before pushing child controls to stack. I would rename the method in this case to the name suggested by 00110001:

IEnumerable<Control> EnumerateControls(this Control root, bool searchAllChildren)

Usage would be

 panel1.EnumerateControls(searchAllChildren: true).OfType<CheckBox>()

edited Jan 23 '21 at 02:50

answered Jan 23 '21 at 02:23

Sergey Berezovskiy

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haha jinx...... – TheGeneral Jan 23 '21 at 02:24
13 seconds ahead :)) – Sergey Berezovskiy Jan 23 '21 at 02:24
You can have points :) mine is completely untested and i haven't used winforms for years – TheGeneral Jan 23 '21 at 02:25
1

me neither) but looks like winforms is still alive (or walking dead) – Sergey Berezovskiy Jan 23 '21 at 02:28
1

Thanks, I like this approach - I only recently learned of extension methods (I'm relatively new to C# coming from other languages that don't have a concept of them) and was trying to avoid introducing this many lines when I could instead just manually retrieve the panels I need as I go. But, this works so nicely that I'll definitely do this :) – PhoenixAki Jan 23 '21 at 02:36

TheGeneral · Answer 2 · 2022-10-28T19:52:18.907

1

If I understand what you are asking, you want all controls of a certain type in a given parent container and include all sub containers

Given

public IEnumerable<T> EnumerateControls<T>(Control control) where T : Control
{
   var queue = new Queue<Control>(new []{ control });
   while (queue.Any())
   {
      var controls = queue.Dequeue().Controls;

      foreach (var item in controls.OfType<T>())
         yield return item;

      foreach (Control subControl in controls)
         queue.Enqueue(subControl);
   }
}

Usage

var allCheckBoxes = EnumerateControls<CheckBox>(somePanel);

edited Oct 28 '22 at 19:52

answered Jan 23 '21 at 02:23

TheGeneral

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There's a typo here: foreach (var item in Controls.OfType()) should be foreach (var item in controls.OfType()) – Jack Blackmore Oct 28 '22 at 15:38

Get all Controls of a Type, including nested containers

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