stride3d/stride · error · ArgumentNullException

Value cannot be null. (Parameter 'texts')

Error message

Value cannot be null. (Parameter 'texts')

What it means

DrawTexts renders a set of strings at given points on the WPF canvas. The library validates that the texts collection is non-null, throwing ArgumentNullException with parameter name 'texts'. Null texts cannot be paired with points for rendering, so the method fails fast.

Solutions

1. Initialize the texts list before calling DrawTexts, or pass an empty list.
2. Guard at the call site: if texts is null or empty, skip the call.
3. Default-deserialize string collections to empty lists.

Example fix

// before
string[] texts = LoadLabels(); // may return null
renderer.DrawTexts(points, color, texts, font, size, weight, hAlign, vAlign, false);
// after
string[] texts = LoadLabels() ?? Array.Empty<string>();
if (texts.Length > 0)
    renderer.DrawTexts(points, color, texts, font, size, weight, hAlign, vAlign, false);

if (texts == null || texts.Count == 0) return; // nothing to draw

bool hasTexts = texts != null && texts.Count > 0;

try { renderer.DrawTexts(points, color, texts, ...); } catch (ArgumentNullException ex) when (ex.ParamName == "texts") { /* substitute empty list */ }

When it happens

Trigger: Calling CanvasRenderer.DrawTexts with a null texts list (IList<string>) while points is valid, e.g. labels loaded from a source that returned null.

Common situations: Labels read from config/DB that were null instead of empty; forgetting to initialize the text array; an API returning null when no labels exist.

Related errors

• Value cannot be null. (Parameter 'source')
• Value cannot be null. (Parameter 'property')
• factory
• emitter
• type

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/2bd20237f6121d6d. Report an issue: GitHub.

Appendix: source

Thrown at sources/presentation/Stride.Core.Presentation.Wpf/Drawing/CanvasRenderer.cs:263

                    dx = -size.Width;

                if (vAlign == VerticalAlignment.Center)
                    dy = -size.Height / 2;

                if (vAlign == VerticalAlignment.Bottom)
                    dy = -size.Height;
            }

            textBlock.RenderTransform = new TranslateTransform(point.X + dx, point.Y + dy);
            textBlock.SetValue(RenderOptions.ClearTypeHintProperty, ClearTypeHint.Enabled);
        }

        /// <inheritdoc/>
        public void DrawTexts(IList<Point> points, Color color, IList<string> texts, FontFamily fontFamily, double fontSize, FontWeight fontWeight,
            HorizontalAlignment hAlign, VerticalAlignment vAlign, bool isHitTestVisible)
        {
            if (points == null) throw new ArgumentNullException(nameof(points));
            if (texts == null) throw new ArgumentNullException(nameof(texts));

            if (points.Count != texts.Count) throw new ArgumentException($"{nameof(points)} and {nameof(texts)} must have the same number of elements.");

            var brush = GetBrush(color);
            var typeFace = new Typeface(fontFamily, FontStyles.Normal, fontWeight, FontStretches.Normal);

            var visual = new DrawingVisual();
            var context = visual.RenderOpen();
            for (var i = 0; i < points.Count; ++i)
            {
                var text = texts[i];
                var point = points[i];
                var formatted = new FormattedText(text, CultureInfo.CurrentUICulture, FlowDirection.LeftToRight, typeFace, fontSize, brush);
                var dx = 0.0;
                var dy = 0.0;
                if (hAlign != HorizontalAlignment.Left || vAlign != VerticalAlignment.Top)
                {
                    var size = new Size(formatted.Width, formatted.Height);

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