dotnet/wpf · error · ArgumentException

SR.TextProvider_InvalidPoint

Error message

SR.TextProvider_InvalidPoint

What it means

TextAdaptor's ITextProvider.RangeFromPoint throws ArgumentException when no text position can be resolved for the given screen point — i.e., the point is not over any text of this provider, so no TextRangeAdaptor could be constructed.

Solutions

  1. Convert the point to correct screen coordinates relative to the control before calling RangeFromPoint.
  2. Verify the point lies within the text provider's bounding rectangle (use BoundingRectangle first).
  3. Catch ArgumentException and fall back to a degenerate document range or ignore the hit.

Example fix

// before
var range = textPattern.RangeFromPoint(clientPoint);
// after
var screenPoint = targetElement.PointToScreen(clientPoint);
if (textProviderDocumentRange.GetBoundingRectangles().Any(r => ((Rect)r).Contains(screenPoint)))
{ var range = textPattern.RangeFromPoint(screenPoint); }
Defensive patterns

Strategy: validation

Validate before calling

var bounds = targetElement.BoundingRectangle;
if (!bounds.Contains(screenPoint)) return; // point not over this text

Type guard

static bool PointOverText(Rect boundingRect, Point p) => boundingRect.Contains(p);

Try / catch

try { var r = textPattern.RangeFromPoint(screenPoint); }
catch (ArgumentException) { /* point not over text */ }

Prevention

When it happens

Trigger: Calling TextPattern.RangeFromPoint with screen coordinates outside the rendered text (over margins, other controls, or off-screen), or with a point whose hit-testing yields no valid TextPosition in the container.

Common situations: Automation clients using stale window coordinates after a window move; hit-testing points over decorative or empty areas; coordinate conversion mistakes (client vs screen coordinates).

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/8c727bd33900d94d. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Controls/TextAdaptor.cs:667

        /// if they are not.</param>
        /// <returns>A degenerate range nearest the specified location.</returns>
        ITextRangeProvider ITextProvider.RangeFromPoint(Point location)
        {
            TextRangeAdaptor range = null;
            ITextView textView = GetUpdatedTextView();
            if (textView != null)
            {
                // Convert the screen point to the element space coordinates.
                location = ScreenToClient(location, textView.RenderScope);
                ITextPointer position = textView.GetTextPositionFromPoint(location, true);
                if (position != null)
                {
                    range = new TextRangeAdaptor(this, position, position, _textPeer);
                }
            }
            if (range == null)
            {
                throw new ArgumentException(SR.TextProvider_InvalidPoint);
            }
            return range;
        }

        /// <summary>
        /// A text range that encloses the main text of the document.  Some auxillary text such as 
        /// headers, footnotes, or annotations may not be included. 
        /// </summary>
        ITextRangeProvider ITextProvider.DocumentRange
        {
            get
            {
                return new TextRangeAdaptor(this, _textContainer.Start, _textContainer.End, _textPeer);
            }
        }

        /// <summary>
        /// True if the text container supports text selection. If the provider returns false then

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