What causes "captureMode" in dotnet/wpf?

dotnet/wpf · error · InvalidEnumArgumentException

captureMode

Error message

captureMode

What it means

WispStylusDevice.Capture (WispStylusDevice.cs:228) throws InvalidEnumArgumentException("captureMode", ...) when the passed captureMode is not one of CaptureMode.None, CaptureMode.Element, or CaptureMode.SubTree. This is an argument validation guard on a public API accepting an enum.

Solutions

Pass only CaptureMode.None, CaptureMode.Element, or CaptureMode.SubTree.
Validate/normalize any externally supplied mode value against the enum before calling Capture.
Fix casts of int literals to CaptureMode in interop layers.

Example fix

// before
stylusDevice.Capture(el, (CaptureMode)rawInt);
// after
var mode = Enum.IsDefined(typeof(CaptureMode), rawInt) ? (CaptureMode)rawInt : CaptureMode.None;
stylusDevice.Capture(el, mode);

Defensive patterns

Strategy: validation

Validate before calling

if (captureMode != CaptureMode.None && captureMode != CaptureMode.Element && captureMode != CaptureMode.SubTree)
    throw new ArgumentException("Invalid CaptureMode value");

Type guard

static bool IsDefinedCaptureMode(CaptureMode m) => m == CaptureMode.None || m == CaptureMode.Element || m == CaptureMode.SubTree;

Try / catch

try { stylusDevice.Capture(el, captureMode); } catch (System.ComponentModel.InvalidEnumArgumentException) { /* fall back to CaptureMode.None */ }

Prevention

Never cast raw ints to CaptureMode without Enum.IsDefined validation
Persist enum names, not numeric values, in config
Keep interop layers strongly typed

When it happens

Trigger: Calling StylusDevice.Capture(element, mode) with a cast or uninitialized value outside the defined CaptureMode range, e.g. (CaptureMode)99.

Common situations: Interop code passing raw ints as CaptureMode; deserializing mode values from config/persisted state; copies of CaptureMode enums that have drifted in versioning.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/b3b37d3469457da6. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/Stylus/Wisp/WispStylusDevice.cs:228

        {
            get
            {
                return _captureMode;
            }
        }

        /////////////////////////////////////////////////////////////////////
        /// <summary>
        ///     Captures the stylus to a particular element.
        /// </summary>
        internal override bool Capture(IInputElement element, CaptureMode captureMode)
        {
            int timeStamp = Environment.TickCount;
            VerifyAccess();

            if (!(captureMode == CaptureMode.None || captureMode == CaptureMode.Element || captureMode == CaptureMode.SubTree))
            {
                throw new System.ComponentModel.InvalidEnumArgumentException("captureMode", (int)captureMode, typeof(CaptureMode));
            }

            if (element == null)
            {
                captureMode = CaptureMode.None;
            }

            if (captureMode == CaptureMode.None)
            {
                element = null;
            }

            // Validate that element is either a UIElement, a ContentElement or a UIElement3D.
            DependencyObject doStylusCapture = element as DependencyObject;
            if (doStylusCapture != null && !InputElement.IsValid(element))
            {
                throw new InvalidOperationException(SR.Format(SR.Invalid_IInputElement, doStylusCapture.GetType()));
            }

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