stride3d/stride · error · ArgumentNullException

uiControl

Error message

uiControl

What it means

InputSourceWindowsRawInput's constructor requires a WinForms Control to which raw input messages (WM_INPUT) are hooked. Passing a null uiControl throws ArgumentNullException immediately via the null-coalescing throw. Raw input cannot be registered without a window handle to receive messages.

Solutions

1. Create and show the main Form first, then construct InputSourceWindowsRawInput with it.
2. Verify the Control variable is assigned before constructing the input source.
3. Choose an input source appropriate for headless scenarios (or a non-RawInput backend) when no window exists.

Example fix

// before
var source = new InputSourceWindowsRawInput(mainForm);
// after
if (mainForm == null || mainForm.IsDisposed)
    throw new InvalidOperationException("Raw input requires a live WinForms control.");
var source = new InputSourceWindowsRawInput(mainForm);

if (uiControl == null || uiControl.IsDisposed)
    throw new InvalidOperationException("InputSourceWindowsRawInput requires a live WinForms control.");
var source = new InputSourceWindowsRawInput(uiControl);

bool HasLiveControl(Control c) => c != null && !c.IsDisposed && c.IsHandleCreated;

try
{
    var source = new InputSourceWindowsRawInput(uiControl);
}
catch (ArgumentNullException)
{
    // Wait for form creation, then retry input initialization.
}

When it happens

Trigger: Calling new InputSourceWindowsRawInput(null) or passing a Control field that is not yet created.

Common situations: Headless/server-side instantiation where no WinForms UI exists; constructing the input source before the main form is created; refactoring where the form reference is assigned later.

Related errors

• uiControl
• Failed to register a mouse device for raw input
• Failed to unregister a mouse device for raw input
• form
• renderCallback

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/030a414791b27f96. Report an issue: GitHub.

Appendix: source

Thrown at sources/engine/Stride.Input/Windows/InputSourceWindowsRawInput.cs:23

using System;
using System.Windows.Forms;
using SharpDX.Multimedia;
using SharpDX.RawInput;
using Stride.Games;

namespace Stride.Input
{
    /// <summary>
    /// Provides support for raw keyboard input on windows
    /// </summary>
    internal class InputSourceWindowsRawInput : InputSourceBase
    {
        private readonly Control uiControl;
        private KeyboardWindowsRawInput keyboard;

        public InputSourceWindowsRawInput(Control uiControl)
        {
            this.uiControl = uiControl ?? throw new ArgumentNullException(nameof(uiControl));
        }

        public override void Initialize(InputManager inputManager)
        {
            keyboard = new KeyboardWindowsRawInput(this);
            RegisterDevice(keyboard);
            BindRawInputKeyboard(uiControl);
        }

        public override void Update()
        {
        }

        public override void Dispose()
        {
            // Unregisters devices
            base.Dispose();

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