From c929533e0045fe05606c0d39e3cb82ac7d230a30 Mon Sep 17 00:00:00 2001
From: Bennet Bo Fenner <bennet@zed.dev>
Date: Sat, 18 Jan 2025 22:50:07 +0100
Subject: [PATCH] editor: Hide horizontal scrollbar if not visible (#23337)

This PR fixes two visual issues, that were caused by the fact that we
were always painting the horizontal scrollbar even if there is no
horizontal scrolling possible

Obscuring deleted lines when using the inline assistant:

https://github.com/user-attachments/assets/f8460c3f-403e-40a6-8622-65268ba2d875

Cutting off text even when horizontal scrolling is not possible:

https://github.com/user-attachments/assets/23c909f7-1c23-4693-8edc-40a2f089d4a8

This issue was only present in some themes (e.g. Nord, Catpuccin)


Closes #22716

Release Notes:

- Fixed an issue where horizontal scrollbars of editors would always be
painted (even if there is no horizontal scrolling to be done)
---
 crates/assistant/src/inline_assistant.rs  | 1 +
 crates/assistant2/src/inline_assistant.rs | 1 +
 crates/editor/src/element.rs              | 8 ++++++--
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/crates/assistant/src/inline_assistant.rs b/crates/assistant/src/inline_assistant.rs
index 404685ab3b..74d20a5ed6 100644
--- a/crates/assistant/src/inline_assistant.rs
+++ b/crates/assistant/src/inline_assistant.rs
@@ -1206,6 +1206,7 @@ impl InlineAssistant {
                     editor.set_show_wrap_guides(false, cx);
                     editor.set_show_gutter(false, cx);
                     editor.scroll_manager.set_forbid_vertical_scroll(true);
+                    editor.set_show_scrollbars(false, cx);
                     editor.set_read_only(true);
                     editor.set_show_inline_completions(Some(false), cx);
                     editor.highlight_rows::<DeletedLines>(
diff --git a/crates/assistant2/src/inline_assistant.rs b/crates/assistant2/src/inline_assistant.rs
index 15a0adeaa0..69dd5987a3 100644
--- a/crates/assistant2/src/inline_assistant.rs
+++ b/crates/assistant2/src/inline_assistant.rs
@@ -1280,6 +1280,7 @@ impl InlineAssistant {
                     editor.set_show_wrap_guides(false, cx);
                     editor.set_show_gutter(false, cx);
                     editor.scroll_manager.set_forbid_vertical_scroll(true);
+                    editor.set_show_scrollbars(false, cx);
                     editor.set_read_only(true);
                     editor.set_show_inline_completions(Some(false), cx);
                     editor.highlight_rows::<DeletedLines>(
diff --git a/crates/editor/src/element.rs b/crates/editor/src/element.rs
index bcb7740497..e4f526a992 100644
--- a/crates/editor/src/element.rs
+++ b/crates/editor/src/element.rs
@@ -1335,11 +1335,15 @@ impl EditorElement {
             total_text_units
                 .horizontal
                 .zip(track_bounds.horizontal)
-                .map(|(total_text_units_x, track_bounds_x)| {
+                .and_then(|(total_text_units_x, track_bounds_x)| {
+                    if text_units_per_page.horizontal >= total_text_units_x {
+                        return None;
+                    }
+
                     let thumb_percent =
                         (text_units_per_page.horizontal / total_text_units_x).min(1.);
 
-                    track_bounds_x.size.width * thumb_percent
+                    Some(track_bounds_x.size.width * thumb_percent)
                 }),
             total_text_units.vertical.zip(track_bounds.vertical).map(
                 |(total_text_units_y, track_bounds_y)| {