From a7e677efa502aa05dd46efa5994b00b034e34ff0 Mon Sep 17 00:00:00 2001
From: Pratik Karki <pratik@prertik.com>
Date: Wed, 8 Apr 2026 22:08:00 +0545
Subject: [PATCH] gpui: Prevent underline and strikethrough artifacts on final
 glyph in text runs (#50934)

Closes #50587

Before you mark this PR as ready for review, make sure that you have:
- [x] Added a solid test coverage and/or screenshots from doing manual
testing
- [x] Done a self-review taking into account security and performance
aspects
- [x] Aligned any UI changes with the [UI
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)

Release Notes:
- Fixed issue that showed underline and strikethrough when markdown
preview screen was scaled to a smaller size


Previously:

<img width="741" height="457" alt="image"
src="https://github.com/user-attachments/assets/f127cf44-c679-4140-b246-e0756c9fca32"
/>



Now:

<img width="742" height="592" alt="image"
src="https://github.com/user-attachments/assets/a29fdc24-cac0-438f-8538-4e85c4df995a"
/>

---------

Signed-off-by: Pratik Karki <pratik@prertik.com>
Co-authored-by: Smit Barmase <heysmitbarmase@gmail.com>
---
 crates/gpui/src/text_system/line.rs | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/crates/gpui/src/text_system/line.rs b/crates/gpui/src/text_system/line.rs
index 611c979bc29f488fa18386c7b319a7310b6ce1c6..9c6ffdbe3f6fe630ea27651a09006819f0c281ce 100644
--- a/crates/gpui/src/text_system/line.rs
+++ b/crates/gpui/src/text_system/line.rs
@@ -385,8 +385,12 @@ fn paint_line(
                             glyph_origin.x - underline_origin.x,
                             underline_style,
                         );
-                        underline_origin.x = origin.x;
-                        underline_origin.y += line_height;
+                        if glyph.index < run_end {
+                            underline_origin.x = origin.x;
+                            underline_origin.y += line_height;
+                        } else {
+                            current_underline = None;
+                        }
                     }
                     if let Some((strikethrough_origin, strikethrough_style)) =
                         current_strikethrough.as_mut()
@@ -399,8 +403,12 @@ fn paint_line(
                             glyph_origin.x - strikethrough_origin.x,
                             strikethrough_style,
                         );
-                        strikethrough_origin.x = origin.x;
-                        strikethrough_origin.y += line_height;
+                        if glyph.index < run_end {
+                            strikethrough_origin.x = origin.x;
+                            strikethrough_origin.y += line_height;
+                        } else {
+                            current_strikethrough = None;
+                        }
                     }
 
                     glyph_origin.x = aligned_origin_x(
@@ -618,8 +626,12 @@ fn paint_line_background(
                             },
                             *background_color,
                         ));
-                        background_origin.x = origin.x;
-                        background_origin.y += line_height;
+                        if glyph.index < run_end {
+                            background_origin.x = origin.x;
+                            background_origin.y += line_height;
+                        } else {
+                            current_background = None;
+                        }
                     }
 
                     glyph_origin.x = aligned_origin_x(