git blame gutter: Use smallest possible space (#18145)

Before:
![screenshot-2024-09-26-15 00
20@2x](https://github.com/user-attachments/assets/f6706325-5bef-404e-a0b4-63a5121969fa)

After:

![screenshot-2024-09-26-15 02
24@2x](https://github.com/user-attachments/assets/739d0831-0b4a-457f-917e-10f3a662e74d)


Release Notes:

- Improved the git blame gutter to take up only the space required to
display the longest git author name in the current file.

---------

Co-authored-by: Bennet Bo Fenner <bennet@zed.dev>

crates/editor/src/editor.rs

@@ -663,7 +663,7 @@ pub struct EditorSnapshot {
     show_git_diff_gutter: Option<bool>,
     show_code_actions: Option<bool>,
     show_runnables: Option<bool>,
-    render_git_blame_gutter: bool,
+    git_blame_gutter_max_author_length: Option<usize>,
     pub display_snapshot: DisplaySnapshot,
     pub placeholder_text: Option<Arc<str>>,
     is_focused: bool,
@@ -673,7 +673,7 @@ pub struct EditorSnapshot {
     gutter_hovered: bool,
 }
 
-const GIT_BLAME_GUTTER_WIDTH_CHARS: f32 = 53.;
+const GIT_BLAME_MAX_AUTHOR_CHARS_DISPLAYED: usize = 20;
 
 #[derive(Default, Debug, Clone, Copy)]
 pub struct GutterDimensions {
@@ -2211,6 +2211,19 @@ impl Editor {
     }
 
     pub fn snapshot(&mut self, cx: &mut WindowContext) -> EditorSnapshot {
+        let git_blame_gutter_max_author_length = self
+            .render_git_blame_gutter(cx)
+            .then(|| {
+                if let Some(blame) = self.blame.as_ref() {
+                    let max_author_length =
+                        blame.update(cx, |blame, cx| blame.max_author_length(cx));
+                    Some(max_author_length)
+                } else {
+                    None
+                }
+            })
+            .flatten();
+
         EditorSnapshot {
             mode: self.mode,
             show_gutter: self.show_gutter,
@@ -2218,7 +2231,7 @@ impl Editor {
             show_git_diff_gutter: self.show_git_diff_gutter,
             show_code_actions: self.show_code_actions,
             show_runnables: self.show_runnables,
-            render_git_blame_gutter: self.render_git_blame_gutter(cx),
+            git_blame_gutter_max_author_length,
             display_snapshot: self.display_map.update(cx, |map, cx| map.snapshot(cx)),
             scroll_anchor: self.scroll_manager.anchor(),
             ongoing_scroll: self.scroll_manager.ongoing_scroll(),
@@ -12989,9 +13002,19 @@ impl EditorSnapshot {
 
         let show_runnables = self.show_runnables.unwrap_or(gutter_settings.runnables);
 
-        let git_blame_entries_width = self
-            .render_git_blame_gutter
-            .then_some(em_width * GIT_BLAME_GUTTER_WIDTH_CHARS);
+        let git_blame_entries_width =
+            self.git_blame_gutter_max_author_length
+                .map(|max_author_length| {
+                    // Length of the author name, but also space for the commit hash,
+                    // the spacing and the timestamp.
+                    let max_char_count = max_author_length
+                        .min(GIT_BLAME_MAX_AUTHOR_CHARS_DISPLAYED)
+                        + 7 // length of commit sha
+                        + 14 // length of max relative timestamp ("60 minutes ago")
+                        + 4; // gaps and margins
+
+                    em_advance * max_char_count
+                });
 
         let mut left_padding = git_blame_entries_width.unwrap_or(Pixels::ZERO);
         left_padding += if show_code_actions || show_runnables {

crates/editor/src/element.rs

@@ -21,7 +21,7 @@ use crate::{
     EditorSnapshot, EditorStyle, ExpandExcerpts, FocusedBlock, GutterDimensions, HalfPageDown,
     HalfPageUp, HandleInput, HoveredCursor, HoveredHunk, LineDown, LineUp, OpenExcerpts, PageDown,
     PageUp, Point, RowExt, RowRangeExt, SelectPhase, Selection, SoftWrap, ToPoint,
-    CURSORS_VISIBLE_FOR, MAX_LINE_LEN,
+    CURSORS_VISIBLE_FOR, GIT_BLAME_MAX_AUTHOR_CHARS_DISPLAYED, MAX_LINE_LEN,
 };
 use client::ParticipantIndex;
 use collections::{BTreeMap, HashMap};
@@ -1445,7 +1445,7 @@ impl EditorElement {
             AvailableSpace::MaxContent
         };
         let scroll_top = scroll_position.y * line_height;
-        let start_x = em_width * 1;
+        let start_x = em_width;
 
         let mut last_used_color: Option<(PlayerColor, Oid)> = None;
 
@@ -4228,7 +4228,7 @@ fn render_blame_entry(
     let short_commit_id = blame_entry.sha.display_short();
 
     let author_name = blame_entry.author.as_deref().unwrap_or("<no name>");
-    let name = util::truncate_and_trailoff(author_name, 20);
+    let name = util::truncate_and_trailoff(author_name, GIT_BLAME_MAX_AUTHOR_CHARS_DISPLAYED);
 
     let details = blame.read(cx).details_for_entry(&blame_entry);
 
@@ -4240,22 +4240,21 @@ fn render_blame_entry(
 
     h_flex()
         .w_full()
+        .justify_between()
         .font_family(style.text.font().family)
         .line_height(style.text.line_height)
         .id(("blame", ix))
-        .children([
-            div()
-                .text_color(sha_color.cursor)
-                .child(short_commit_id)
-                .mr_2(),
-            div()
-                .w_full()
-                .h_flex()
-                .justify_between()
-                .text_color(cx.theme().status().hint)
-                .child(name)
-                .child(relative_timestamp),
-        ])
+        .text_color(cx.theme().status().hint)
+        .pr_2()
+        .gap_2()
+        .child(
+            h_flex()
+                .items_center()
+                .gap_2()
+                .child(div().text_color(sha_color.cursor).child(short_commit_id))
+                .child(name),
+        )
+        .child(relative_timestamp)
         .on_mouse_down(MouseButton::Right, {
             let blame_entry = blame_entry.clone();
             let details = details.clone();

crates/editor/src/git/blame.rs

@@ -207,6 +207,27 @@ impl GitBlame {
         })
     }
 
+    pub fn max_author_length(&mut self, cx: &mut ModelContext<Self>) -> usize {
+        self.sync(cx);
+
+        let mut max_author_length = 0;
+
+        for entry in self.entries.iter() {
+            let author_len = entry
+                .blame
+                .as_ref()
+                .and_then(|entry| entry.author.as_ref())
+                .map(|author| author.len());
+            if let Some(author_len) = author_len {
+                if author_len > max_author_length {
+                    max_author_length = author_len;
+                }
+            }
+        }
+
+        max_author_length
+    }
+
     pub fn blur(&mut self, _: &mut ModelContext<Self>) {
         self.focused = false;
     }