dotnet/wpf · error · ArgumentException

SR.StrokeCollectionCountTooBig

Error message

SR.StrokeCollectionCountTooBig

What it means

GestureRecognizer.Recognize accepts at most 2 strokes per recognition call; larger StrokeCollections throw ArgumentException (SR.StrokeCollectionCountTooBig). Gesture recognition in WPF is defined for one- and two-stroke gestures only.

Solutions

1. Split the StrokeCollection into groups of at most 2 strokes and call Recognize per group
2. Assert strokes.Count is 1 or 2 before calling
3. If multi-stroke analysis is needed, use InkAnalyzer instead of GestureRecognizer

Example fix

// before
var results = recognizer.Recognize(allStrokes);
// after
foreach (var chunk in Chunk(allStrokes, 2)) results.AddRange(recognizer.Recognize(chunk));

if (strokes == null || strokes.Count == 0 || strokes.Count > 2) return; // invalid input for Recognize

static bool CanRecognize(StrokeCollection s) => s != null && s.Count is >= 1 and <= 2;

try { results = recognizer.Recognize(strokes); } catch (ArgumentException) { results = EmptyResults; }

When it happens

Trigger: Calling recognizer.Recognize(strokes) (or CriticalRecognize) with strokes.Count > 2.

Common situations: Passing an entire ink page's strokes instead of individual gestures; batching strokes for performance and exceeding the limit; misunderstanding that the API is per-gesture, not per-document.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• ExtendedProperty is already part of the…
• Failed to set enabled gestures.
• Gesture recognition failed.
• GUID cannot be empty.
• InvalidMatrixContainsInfinity

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/c803e98326cb3677. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Ink/GestureRecognizer.cs:164

        /// <returns></returns>
        // Built into Core, also used by Framework.
        internal ReadOnlyCollection<GestureRecognitionResult> CriticalRecognize(StrokeCollection strokes)
        {
            return RecognizeImpl(strokes);
        }

        /// <summary>
        /// Performs gesture recognition on the StrokeCollection if a gesture recognizer
        /// is present and installed on the system.
        /// </summary>
        /// <param name="strokes">The StrokeCollection to perform gesture recognition on</param>
        /// <returns></returns>
        private ReadOnlyCollection<GestureRecognitionResult> RecognizeImpl(StrokeCollection strokes)
        {
            ArgumentNullException.ThrowIfNull(strokes);
            if (strokes.Count > 2)
            {
                throw new ArgumentException(SR.StrokeCollectionCountTooBig, nameof(strokes));
            }
            VerifyAccess();
            VerifyDisposed();
            VerifyRecognizerAvailable();

            return new ReadOnlyCollection<GestureRecognitionResult>(_nativeRecognizer.Recognize(strokes));
        }

        

        #endregion Public Methods

        //-------------------------------------------------------------------------------
        //
        // Public Properties
        //
        //-------------------------------------------------------------------------------

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