neovim like scroll function

helix-term/src/commands.rs

@@ -1501,6 +1501,57 @@ fn switch_to_lowercase(cx: &mut Context) {
     });
 }
 
+pub fn scroll_page_and_cursor(cx: &mut Context, offset: usize, direction: Direction) {
+    let config = cx.editor.config();
+    let cursor_pos = cx.editor.cursor().0.unwrap();
+    let (view, doc) = current!(cx.editor);
+
+    let height = view.inner_height();
+    let scrolloff = config.scrolloff.min(height.saturating_sub(1) / 2);
+
+    let offset = match direction {
+        Direction::Forward => offset as isize,
+        Direction::Backward => -(offset as isize),
+    };
+
+    let doc_text = doc.text().slice(..);
+    let viewport = view.inner_area(doc);
+    let text_fmt = doc.text_format(viewport.width, None);
+    let mut annotations = view.text_annotations(doc, None);
+
+    (view.offset.anchor, view.offset.vertical_offset) = char_idx_at_visual_offset(
+        doc_text,
+        view.offset.anchor,
+        view.offset.vertical_offset as isize + offset,
+        0,
+        &text_fmt,
+        &annotations,
+    );
+
+    let movement = match cx.editor.mode {
+        Mode::Select => Movement::Extend,
+        _ => Movement::Move,
+    };
+
+    let mut offset = offset.abs() as usize;
+    if cursor_pos.row <= scrolloff {
+        offset += scrolloff - cursor_pos.row + 1;
+    }
+
+    let selection = doc.selection(view.id).clone().transform(|range| {
+            move_vertically_visual(
+                doc_text,
+                range,
+                direction,
+                offset,
+                movement,
+                &text_fmt,
+                &mut annotations,
+            )
+        });
+    doc.set_selection(view.id, selection);
+}
+
 pub fn scroll(cx: &mut Context, offset: usize, direction: Direction) {
     use Direction::*;
     let config = cx.editor.config();