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 404685ab3b983e2f4d09e7572d8f25106649faf7..74d20a5ed65bef50c335757f1d941d99a76360f3 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 15a0adeaa0d954cb46437946ba6697a1b3104bbe..69dd5987a38d3a03cc1bba377fe8416e3a3cee42 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 bcb77404978026d3600ed59f8b6d73c8db5eddaf..e4f526a992b1b3a74f9d8e9825e54559494de15d 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)| {