dotnet/wpf · error · ArgumentException

SR.InvalidStylusPointDescription

Error message

SR.InvalidStylusPointDescription

What it means

The StylusPointDescription constructor validates that its StylusPointPropertyInfoCollection contains at least the required properties (X, Y, NormalPressure) in the required order. This ArgumentException is thrown when the collection is missing one of these mandatory properties or has them in the wrong order, because a StylusPoint without X, Y and pressure data cannot be represented in WPF's stylus pipeline.

Solutions

  1. Ensure the StylusPointPropertyInfo collection starts with exactly StylusPointPropertyInfoForX, StylusPointPropertyInfoForY, then StylusPointPropertyInfoForNormalPressure, in that order.
  2. Append any additional properties (custom axes) after those first three.
  3. Append StylusPointPropertyInfo button entries last (buttons must come after all non-button properties).
  4. If constructing from raw device data, map each packet field to a StylusPointPropertyInfo and skip fields that do not map to X/Y/pressure, placing them after the required trio.

Example fix

// before
var infos = new StylusPointPropertyInfo[] {
    new StylusPointPropertyInfo(StylusPointPropertyIds.NormalPressure),
    new StylusPointPropertyInfo(StylusPointPropertyIds.X),
    new StylusPointPropertyInfo(StylusPointPropertyIds.Y)};
var desc = new StylusPointDescription(infos);
// after
var infos = new StylusPointPropertyInfo[] {
    StylusPointPropertyInfo.StylusPointPropertyInfoForX,
    StylusPointPropertyInfo.StylusPointPropertyInfoForY,
    StylusPointPropertyInfo.StylusPointPropertyInfoForNormalPressure};
var desc = new StylusPointDescription(infos);
Defensive patterns

Strategy: validation

Validate before calling

bool ok = infos != null && infos.Count >= 3 &&
    infos[0].Id == StylusPointPropertyIds.X &&
    infos[1].Id == StylusPointPropertyIds.Y &&
    infos[2].Id == StylusPointPropertyIds.NormalPressure;
if (!ok) throw new ArgumentException("First three properties must be X, Y, NormalPressure", nameof(infos));

Try / catch

try { var desc = new StylusPointDescription(infos); }
catch (ArgumentException) { /* fall back to stylusDevice.StylusPointDescription or default description */ }

Prevention

When it happens

Trigger: Calling new StylusPointDescription(stylusPointPropertyInfos) where the collection has fewer than 3 entries, or infos[0].Id != StylusPointPropertyIds.X, or infos[1].Id != StylusPointPropertyIds.Y, or infos[2].Id != StylusPointPropertyIds.NormalPressure.

Common situations: Building a custom StylusPointDescription for a digitizer/tablet integration and forgetting that X, Y, and NormalPressure must be the first three properties in exactly that order; copying property lists from raw device packets where pressure was omitted; reordering the collection to put buttons or custom properties first.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/e71f00f77f10f7f4. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/Stylus/Common/StylusPointDescription.cs:55

                    StylusPointPropertyInfoDefaults.NormalPressure
                };
        }

        /// <summary>
        /// StylusPointDescription
        /// </summary>
        public StylusPointDescription(IEnumerable<StylusPointPropertyInfo> stylusPointPropertyInfos)
        {
            ArgumentNullException.ThrowIfNull(stylusPointPropertyInfos);
            List<StylusPointPropertyInfo> infos =
                new List<StylusPointPropertyInfo>(stylusPointPropertyInfos);

            if (infos.Count < RequiredCountOfProperties ||
                infos[RequiredXIndex].Id != StylusPointPropertyIds.X ||
                infos[RequiredYIndex].Id != StylusPointPropertyIds.Y ||
                infos[RequiredPressureIndex].Id != StylusPointPropertyIds.NormalPressure)
            {
                throw new ArgumentException(SR.InvalidStylusPointDescription, nameof(stylusPointPropertyInfos));
            }

            //
            // look for duplicates, validate that buttons are last
            //
            List<Guid> seenIds = new List<Guid>();
            seenIds.Add(StylusPointPropertyIds.X);
            seenIds.Add(StylusPointPropertyIds.Y);
            seenIds.Add(StylusPointPropertyIds.NormalPressure);

            int buttonCount = 0;
            for (int x = RequiredCountOfProperties; x < infos.Count; x++)
            {
                if (seenIds.Contains(infos[x].Id))
                {
                    throw new ArgumentException(SR.InvalidStylusPointDescriptionDuplicatesFound, nameof(stylusPointPropertyInfos));
                }
                if (infos[x].IsButton)

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