dotnet/wpf · error · ArgumentException

SR.Format(SR.CollectionNumberOfElementsShouldBeEqualTo…

Error message

SR.Format(SR.CollectionNumberOfElementsShouldBeEqualTo, glyphIndices.Count)

What it means

If glyphOffsets is supplied and non-empty, GlyphRun.Initialize requires glyphOffsets.Count == glyphIndices.Count (one offset per glyph). Mismatched counts leave some glyphs without offsets, so it throws ArgumentException naming the glyphOffsets parameter.

Solutions

  1. Resize glyphOffsets to exactly glyphIndices.Count, filling with default Point(0,0) entries
  2. Pass null (or empty) glyphOffsets when no custom positioning is needed
  3. Recompute offsets whenever glyphIndices changes

Example fix

// before: offsets only for glyph 2
offsets = new Point[] { new Point(3,0) };
// after
offsets = glyphs.Select((g,i) => i == 2 ? new Point(3,0) : new Point(0,0)).ToArray();
Defensive patterns

Strategy: validation

Validate before calling

if (glyphOffsets != null && glyphOffsets.Count != 0 && glyphOffsets.Count != glyphIndices.Count)
    throw new ArgumentException("glyphOffsets must match glyphIndices count");
// or normalize:
if (glyphOffsets != null && glyphOffsets.Count != glyphIndices.Count)
    glyphOffsets = Enumerable.Range(0, glyphIndices.Count)
        .Select(i => i < glyphOffsets.Count ? glyphOffsets[i] : new Point(0,0)).ToArray();

Type guard

static bool OffsetsMatchGlyphs(Point[] offsets, int glyphCount) => offsets == null || offsets.Length == 0 || offsets.Length == glyphCount;

Try / catch

try { var run = new GlyphRun(...); }
catch (ArgumentException ex) when (ex.ParamName == "glyphOffsets") { /* pad with Point(0,0) or pass null */ }

Prevention

When it happens

Trigger: Calling the GlyphRun constructor, TryCreate, or EndInit with a non-null, non-empty glyphOffsets whose length differs from glyphIndices.Count — e.g. providing offsets only for repositioned glyphs instead of all glyphs (use Point(0,0) for default).

Common situations: Custom glyph positioning (kerning adjustments, markup highlights) where offsets were built for a subset of glyphs; off-by-one after trimming glyphIndices.

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/e2a1a8eb0687dc14. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Media/GlyphRun.cs:443

            else
            {
                ArgumentOutOfRangeException.ThrowIfEqual(renderingEmSize, double.NaN);
                ArgumentOutOfRangeException.ThrowIfNegative(renderingEmSize);
                ArgumentNullException.ThrowIfNull(glyphTypeface);
                ArgumentNullException.ThrowIfNull(glyphIndices);

                if (glyphIndices.Count <= 0)
                    throw new ArgumentException(SR.CollectionNumberOfElementsMustBeGreaterThanZero, nameof(glyphIndices));

                if (glyphIndices.Count > MaxGlyphCount)
                {
                    throw new ArgumentException(SR.Format(SR.CollectionNumberOfElementsMustBeLessOrEqualTo, MaxGlyphCount), nameof(glyphIndices));
                }

                ArgumentNullException.ThrowIfNull(advanceWidths);

                if (advanceWidths.Count != glyphIndices.Count)
                    throw new ArgumentException(SR.Format(SR.CollectionNumberOfElementsShouldBeEqualTo, glyphIndices.Count), nameof(advanceWidths));

                if (glyphOffsets != null && glyphOffsets.Count != 0 && glyphOffsets.Count != glyphIndices.Count)
                    throw new ArgumentException(SR.Format(SR.CollectionNumberOfElementsShouldBeEqualTo, glyphIndices.Count), nameof(glyphOffsets));

                // We should've caught all invalid cases above and thrown appropriate exceptions.
                Invariant.Assert(false);
            }

            IsInitialized = true; // The glyphrun is completely initialized
        }

        #endregion Constructors

        //------------------------------------------------------
        //
        //  Public Methods
        //
        //------------------------------------------------------

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