TextBox caret has incorrect position at the end of the string

[HermanKirshin]

Describe the bug
Caret in the end of the string overlaps letter

To Reproduce
Steps to reproduce the behavior:

1. Create text box with Inter font and a bit smaller font size (i.e. 11.92)
2. Write some text and compare caret position relative to letter in the end of the string and in the middle.
   <LayoutTransformControl> <LayoutTransformControl.LayoutTransform> <ScaleTransform ScaleX="5" ScaleY="5" /> </LayoutTransformControl.LayoutTransform> <TextBox FontFamily="avares://Avalonia.Fonts.Inter/Assets#Inter" FontSize="11.92" /> </LayoutTransformControl>

Expected behavior
Caret offset from letter is always the same

Screenshots
I applied x5 scaling to window for better visibility.

here you can see distance between number and caret

and here they overlap

Desktop (please complete the following information):

• OS: Any
• Version 11

[timunie]

@HermanKirshin we had this #12765 merged recently. Maybe you can test latest master (nightly) in order to check if that PR also fixes your issue. Thx 🙏

[HermanKirshin]

@timunie I had tested latest master and unfortunately no, issue still exists.

[Gillibald]

https://github.com/AvaloniaUI/Avalonia/blob/master/src/Avalonia.Controls/Presenters/TextPresenter.cs#L410

[Gillibald]

The issue is most likely that we can't draw outside the bounds of the control so we introduced this hack. We could either make the desired size of the TextPresenter slightly bigger or use the adorner layer to draw the caret.

[timunie]

@Gillibald I guess making it slightly bigger would be the better fix as otherwise one may have the caret sitting on the border

[HermanKirshin]

@Gillibald Thank you, moving this code from GetCaretPoints to MeasureOverride with adding +1 to width solved the problem.

Index: src/Avalonia.Controls/Presenters/TextPresenter.cs
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/Avalonia.Controls/Presenters/TextPresenter.cs b/src/Avalonia.Controls/Presenters/TextPresenter.cs
--- a/src/Avalonia.Controls/Presenters/TextPresenter.cs	(revision fa8e1985f3e97e9d358130aaa19742834beacb7a)
+++ b/src/Avalonia.Controls/Presenters/TextPresenter.cs	(revision e8e0aa4c625f56d346b91e77813a2f0dc4675969)
@@ -401,15 +401,6 @@
             var y = Math.Floor(_caretBounds.Y) + 0.5;
             var b = Math.Ceiling(_caretBounds.Bottom) - 0.5;
 
-            var caretIndex = _lastCharacterHit.FirstCharacterIndex + _lastCharacterHit.TrailingLength;
-            var lineIndex = TextLayout.GetLineIndexFromCharacterIndex(caretIndex, _lastCharacterHit.TrailingLength > 0);
-            var textLine = TextLayout.TextLines[lineIndex];
-
-            if (_caretBounds.X > 0 && _caretBounds.X >= textLine.WidthIncludingTrailingWhitespace)
-            {
-                x -= 1;
-            }
-
             return (new Point(x, y), new Point(x, b));
         }
 
@@ -565,6 +556,15 @@
 
             var textWidth = TextLayout.OverhangLeading + TextLayout.WidthIncludingTrailingWhitespace + TextLayout.OverhangTrailing;
 
+            var caretIndex = _lastCharacterHit.FirstCharacterIndex + _lastCharacterHit.TrailingLength;
+            var lineIndex = TextLayout.GetLineIndexFromCharacterIndex(caretIndex, _lastCharacterHit.TrailingLength > 0);
+            var textLine = TextLayout.TextLines[lineIndex];
+
+            if (_caretBounds.X > 0 && _caretBounds.X >= textLine.WidthIncludingTrailingWhitespace)
+            {
+                textWidth += 1;
+            }
+
             return new Size(textWidth, TextLayout.Height);
         }