editor: Preserve scroll position when jumping from multibuffer (#9921)

This is a best-effort attempt, as the target offset from the top is just
an estimate; furthermore, this does not account for things like project
search header (which adds a bit of vertical offset by itself and is
removed once we jump into a buffer), but it still should improve the
situation quite a bit.

Fixes: #5296

Release Notes:

- Improved target selection when jumping from multibuffer; final
position in the buffer should more closely match the original position
of the cursor in the multibuffer.

crates/editor/src/editor.rs

@@ -7670,7 +7670,7 @@ impl Editor {
                         let range = target.range.to_offset(target.buffer.read(cx));
                         let range = editor.range_for_match(&range);
                         if Some(&target.buffer) == editor.buffer.read(cx).as_singleton().as_ref() {
-                            editor.change_selections(Some(Autoscroll::fit()), cx, |s| {
+                            editor.change_selections(Some(Autoscroll::focused()), cx, |s| {
                                 s.select_ranges([range]);
                             });
                         } else {
@@ -7690,7 +7690,7 @@ impl Editor {
                                     // to avoid creating a history entry at the previous cursor location.
                                     pane.update(cx, |pane, _| pane.disable_history());
                                     target_editor.change_selections(
-                                        Some(Autoscroll::fit()),
+                                        Some(Autoscroll::focused()),
                                         cx,
                                         |s| {
                                             s.select_ranges([range]);
@@ -9504,6 +9504,7 @@ impl Editor {
         path: ProjectPath,
         position: Point,
         anchor: language::Anchor,
+        offset_from_top: u32,
         cx: &mut ViewContext<Self>,
     ) {
         let workspace = self.workspace();
@@ -9531,9 +9532,13 @@ impl Editor {
                 };
 
                 let nav_history = editor.nav_history.take();
-                editor.change_selections(Some(Autoscroll::newest()), cx, |s| {
-                    s.select_ranges([cursor..cursor]);
-                });
+                editor.change_selections(
+                    Some(Autoscroll::top_relative(offset_from_top as usize)),
+                    cx,
+                    |s| {
+                        s.select_ranges([cursor..cursor]);
+                    },
+                );
                 editor.nav_history = nav_history;
 
                 anyhow::Ok(())