Consistently maintain view position (helix-editor#10559)

* replicate t-monaghan's changes

* remove View.offset in favour of Document.view_data.view_position

* improve access patterns for Document.view_data

* better borrow checker wrangling with doc_mut!()

* reintroduce ensure_cursor_in_view in handle_config_events

since we sorted out the borrow checker issues using partial borrows,
there's nothing stopping us from going back to the simpler implementation

* introduce helper functions on Document .view_offset, set_view_offset

* fix rebase breakage

helix-term/src/application.rs

@@ -416,9 +416,9 @@ impl Application {
 
         // reset view position in case softwrap was enabled/disabled
         let scrolloff = self.editor.config().scrolloff;
-        for (view, _) in self.editor.tree.views_mut() {
-            let doc = &self.editor.documents[&view.doc];
-            view.ensure_cursor_in_view(doc, scrolloff)
+        for (view, _) in self.editor.tree.views() {
+            let doc = doc_mut!(self.editor, &view.doc);
+            view.ensure_cursor_in_view(doc, scrolloff);
         }
     }
 

helix-term/src/commands.rs

@@ -1056,6 +1056,7 @@ fn goto_window(cx: &mut Context, align: Align) {
     let count = cx.count() - 1;
     let config = cx.editor.config();
     let (view, doc) = current!(cx.editor);
+    let view_offset = doc.view_offset(view.id);
 
     let height = view.inner_height();
 
@@ -1068,15 +1069,15 @@ fn goto_window(cx: &mut Context, align: Align) {
     let last_visual_line = view.last_visual_line(doc);
 
     let visual_line = match align {
-        Align::Top => view.offset.vertical_offset + scrolloff + count,
-        Align::Center => view.offset.vertical_offset + (last_visual_line / 2),
+        Align::Top => view_offset.vertical_offset + scrolloff + count,
+        Align::Center => view_offset.vertical_offset + (last_visual_line / 2),
         Align::Bottom => {
-            view.offset.vertical_offset + last_visual_line.saturating_sub(scrolloff + count)
+            view_offset.vertical_offset + last_visual_line.saturating_sub(scrolloff + count)
         }
     };
     let visual_line = visual_line
-        .max(view.offset.vertical_offset + scrolloff)
-        .min(view.offset.vertical_offset + last_visual_line.saturating_sub(scrolloff));
+        .max(view_offset.vertical_offset + scrolloff)
+        .min(view_offset.vertical_offset + last_visual_line.saturating_sub(scrolloff));
 
     let pos = view
         .pos_at_visual_coords(doc, visual_line as u16, 0, false)
@@ -1689,6 +1690,7 @@ pub fn scroll(cx: &mut Context, offset: usize, direction: Direction, sync_cursor
     use Direction::*;
     let config = cx.editor.config();
     let (view, doc) = current!(cx.editor);
+    let mut view_offset = doc.view_offset(view.id);
 
     let range = doc.selection(view.id).primary();
     let text = doc.text().slice(..);
@@ -1705,15 +1707,19 @@ pub fn scroll(cx: &mut Context, offset: usize, direction: Direction, sync_cursor
     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(
+    (view_offset.anchor, view_offset.vertical_offset) = char_idx_at_visual_offset(
         doc_text,
-        view.offset.anchor,
-        view.offset.vertical_offset as isize + offset,
+        view_offset.anchor,
+        view_offset.vertical_offset as isize + offset,
         0,
         &text_fmt,
-        &annotations,
+        // &annotations,
+        &view.text_annotations(&*doc, None),
     );
+    doc.set_view_offset(view.id, view_offset);
+
+    let doc_text = doc.text().slice(..);
+    let mut annotations = view.text_annotations(&*doc, None);
 
     if sync_cursor {
         let movement = match cx.editor.mode {
@@ -1740,14 +1746,16 @@ pub fn scroll(cx: &mut Context, offset: usize, direction: Direction, sync_cursor
         return;
     }
 
+    let view_offset = doc.view_offset(view.id);
+
     let mut head;
     match direction {
         Forward => {
             let off;
             (head, off) = char_idx_at_visual_offset(
                 doc_text,
-                view.offset.anchor,
-                (view.offset.vertical_offset + scrolloff) as isize,
+                view_offset.anchor,
+                (view_offset.vertical_offset + scrolloff) as isize,
                 0,
                 &text_fmt,
                 &annotations,
@@ -1760,8 +1768,8 @@ pub fn scroll(cx: &mut Context, offset: usize, direction: Direction, sync_cursor
         Backward => {
             head = char_idx_at_visual_offset(
                 doc_text,
-                view.offset.anchor,
-                (view.offset.vertical_offset + height - scrolloff - 1) as isize,
+                view_offset.anchor,
+                (view_offset.vertical_offset + height - scrolloff - 1) as isize,
                 0,
                 &text_fmt,
                 &annotations,
@@ -5162,7 +5170,7 @@ fn split(editor: &mut Editor, action: Action) {
     let (view, doc) = current!(editor);
     let id = doc.id();
     let selection = doc.selection(view.id).clone();
-    let offset = view.offset;
+    let offset = doc.view_offset(view.id);
 
     editor.switch(id, action);
 
@@ -5171,7 +5179,7 @@ fn split(editor: &mut Editor, action: Action) {
     doc.set_selection(view.id, selection);
     // match the view scroll offset (switch doesn't handle this fully
     // since the selection is only matched after the split)
-    view.offset = offset;
+    doc.set_view_offset(view.id, offset);
 }
 
 fn hsplit(cx: &mut Context) {
@@ -5266,14 +5274,21 @@ fn align_view_middle(cx: &mut Context) {
         return;
     }
     let doc_text = doc.text().slice(..);
-    let annotations = view.text_annotations(doc, None);
     let pos = doc.selection(view.id).primary().cursor(doc_text);
-    let pos =
-        visual_offset_from_block(doc_text, view.offset.anchor, pos, &text_fmt, &annotations).0;
+    let pos = visual_offset_from_block(
+        doc_text,
+        doc.view_offset(view.id).anchor,
+        pos,
+        &text_fmt,
+        &view.text_annotations(doc, None),
+    )
+    .0;
 
-    view.offset.horizontal_offset = pos
+    let mut offset = doc.view_offset(view.id);
+    offset.horizontal_offset = pos
         .col
         .saturating_sub((view.inner_area(doc).width as usize) / 2);
+    doc.set_view_offset(view.id, offset);
 }
 
 fn scroll_up(cx: &mut Context) {
@@ -6155,7 +6170,7 @@ fn jump_to_word(cx: &mut Context, behaviour: Movement) {
 
     // This is not necessarily exact if there is virtual text like soft wrap.
     // It's ok though because the extra jump labels will not be rendered.
-    let start = text.line_to_char(text.char_to_line(view.offset.anchor));
+    let start = text.line_to_char(text.char_to_line(doc.view_offset(view.id).anchor));
     let end = text.line_to_char(view.estimate_last_doc_line(doc) + 1);
 
     let primary_selection = doc.selection(view.id).primary();

helix-term/src/commands/lsp.rs

@@ -1299,7 +1299,8 @@ fn compute_inlay_hints_for_view(
     // than computing all the hints for the full file (which could be dozens of time
     // longer than the view is).
     let view_height = view.inner_height();
-    let first_visible_line = doc_text.char_to_line(view.offset.anchor.min(doc_text.len_chars()));
+    let first_visible_line =
+        doc_text.char_to_line(doc.view_offset(view_id).anchor.min(doc_text.len_chars()));
     let first_line = first_visible_line.saturating_sub(view_height);
     let last_line = first_visible_line
         .saturating_add(view_height.saturating_mul(2))

helix-term/src/commands/typed.rs

@@ -1596,7 +1596,7 @@ fn tree_sitter_highlight_name(
         // Query the same range as the one used in syntax highlighting.
         let range = {
             // Calculate viewport byte ranges:
-            let row = text.char_to_line(view.offset.anchor.min(text.len_chars()));
+            let row = text.char_to_line(doc.view_offset(view.id).anchor.min(text.len_chars()));
             // Saturating subs to make it inclusive zero indexing.
             let last_line = text.len_lines().saturating_sub(1);
             let height = view.inner_area(doc).height;

helix-term/src/ui/editor.rs

@@ -93,6 +93,8 @@ impl EditorView {
         let theme = &editor.theme;
         let config = editor.config();
 
+        let view_offset = doc.view_offset(view.id);
+
         let text_annotations = view.text_annotations(doc, Some(theme));
         let mut decorations = DecorationManager::default();
 
@@ -119,13 +121,13 @@ impl EditorView {
         }
 
         let syntax_highlights =
-            Self::doc_syntax_highlights(doc, view.offset.anchor, inner.height, theme);
+            Self::doc_syntax_highlights(doc, view_offset.anchor, inner.height, theme);
 
         let mut overlay_highlights =
-            Self::empty_highlight_iter(doc, view.offset.anchor, inner.height);
+            Self::empty_highlight_iter(doc, view_offset.anchor, inner.height);
         let overlay_syntax_highlights = Self::overlay_syntax_highlights(
             doc,
-            view.offset.anchor,
+            view_offset.anchor,
             inner.height,
             &text_annotations,
         );
@@ -203,7 +205,7 @@ impl EditorView {
             surface,
             inner,
             doc,
-            view.offset,
+            view_offset,
             &text_annotations,
             syntax_highlights,
             overlay_highlights,
@@ -259,11 +261,13 @@ impl EditorView {
             .and_then(|config| config.rulers.as_ref())
             .unwrap_or(editor_rulers);
 
+        let view_offset = doc.view_offset(view.id);
+
         rulers
             .iter()
             // View might be horizontally scrolled, convert from absolute distance
             // from the 1st column to relative distance from left of viewport
-            .filter_map(|ruler| ruler.checked_sub(1 + view.offset.horizontal_offset as u16))
+            .filter_map(|ruler| ruler.checked_sub(1 + view_offset.horizontal_offset as u16))
             .filter(|ruler| ruler < &viewport.width)
             .map(|ruler| viewport.clip_left(ruler).with_width(1))
             .for_each(|area| surface.set_style(area, ruler_theme))
@@ -825,6 +829,7 @@ impl EditorView {
         let inner_area = view.inner_area(doc);
 
         let selection = doc.selection(view.id);
+        let view_offset = doc.view_offset(view.id);
         let primary = selection.primary();
         let text_format = doc.text_format(viewport.width, None);
         for range in selection.iter() {
@@ -835,11 +840,11 @@ impl EditorView {
                 visual_offset_from_block(text, cursor, cursor, &text_format, text_annotations).0;
 
             // if the cursor is horizontally in the view
-            if col >= view.offset.horizontal_offset
-                && inner_area.width > (col - view.offset.horizontal_offset) as u16
+            if col >= view_offset.horizontal_offset
+                && inner_area.width > (col - view_offset.horizontal_offset) as u16
             {
                 let area = Rect::new(
-                    inner_area.x + (col - view.offset.horizontal_offset) as u16,
+                    inner_area.x + (col - view_offset.horizontal_offset) as u16,
                     view.area.y,
                     1,
                     view.area.height,

helix-term/src/ui/mod.rs

@@ -84,7 +84,7 @@ pub fn raw_regex_prompt(
     let (view, doc) = current!(cx.editor);
     let doc_id = view.doc;
     let snapshot = doc.selection(view.id).clone();
-    let offset_snapshot = view.offset;
+    let offset_snapshot = doc.view_offset(view.id);
     let config = cx.editor.config();
 
     let mut prompt = Prompt::new(
@@ -96,7 +96,7 @@ pub fn raw_regex_prompt(
                 PromptEvent::Abort => {
                     let (view, doc) = current!(cx.editor);
                     doc.set_selection(view.id, snapshot.clone());
-                    view.offset = offset_snapshot;
+                    doc.set_view_offset(view.id, offset_snapshot);
                 }
                 PromptEvent::Update | PromptEvent::Validate => {
                     // skip empty input
@@ -137,7 +137,7 @@ pub fn raw_regex_prompt(
                         Err(err) => {
                             let (view, doc) = current!(cx.editor);
                             doc.set_selection(view.id, snapshot.clone());
-                            view.offset = offset_snapshot;
+                            doc.set_view_offset(view.id, offset_snapshot);
 
                             if event == PromptEvent::Validate {
                                 let callback = async move {

helix-view/src/document.rs

@@ -37,9 +37,12 @@ use helix_core::{
     ChangeSet, Diagnostic, LineEnding, Range, Rope, RopeBuilder, Selection, Syntax, Transaction,
 };
 
-use crate::editor::Config;
-use crate::events::{DocumentDidChange, SelectionDidChange};
-use crate::{DocumentId, Editor, Theme, View, ViewId};
+use crate::{
+    editor::Config,
+    events::{DocumentDidChange, SelectionDidChange},
+    view::ViewPosition,
+    DocumentId, Editor, Theme, View, ViewId,
+};
 
 /// 8kB of buffer space for encoding and decoding `Rope`s.
 const BUF_SIZE: usize = 8192;
@@ -130,6 +133,7 @@ pub struct Document {
     pub(crate) id: DocumentId,
     text: Rope,
     selections: HashMap<ViewId, Selection>,
+    view_data: HashMap<ViewId, ViewData>,
 
     /// Inlay hints annotations for the document, by view.
     ///
@@ -267,6 +271,7 @@ impl fmt::Debug for Document {
             .field("selections", &self.selections)
             .field("inlay_hints_oudated", &self.inlay_hints_oudated)
             .field("text_annotations", &self.inlay_hints)
+            .field("view_data", &self.view_data)
             .field("path", &self.path)
             .field("encoding", &self.encoding)
             .field("restore_cursor", &self.restore_cursor)
@@ -658,6 +663,7 @@ impl Document {
             selections: HashMap::default(),
             inlay_hints: HashMap::default(),
             inlay_hints_oudated: false,
+            view_data: Default::default(),
             indent_style: DEFAULT_INDENT,
             line_ending,
             restore_cursor: false,
@@ -1187,12 +1193,14 @@ impl Document {
         self.set_selection(view_id, Selection::single(origin.anchor, origin.head));
     }
 
-    /// Initializes a new selection for the given view if it does not
-    /// already have one.
+    /// Initializes a new selection and view_data for the given view
+    /// if it does not already have them.
     pub fn ensure_view_init(&mut self, view_id: ViewId) {
         if self.selections.get(&view_id).is_none() {
             self.reset_selection(view_id);
         }
+
+        self.view_data_mut(view_id);
     }
 
     /// Mark document as recent used for MRU sorting
@@ -1238,6 +1246,12 @@ impl Document {
                     .ensure_invariants(self.text.slice(..));
             }
 
+            for view_data in self.view_data.values_mut() {
+                view_data.view_position.anchor = transaction
+                    .changes()
+                    .map_pos(view_data.view_position.anchor, Assoc::Before);
+            }
+
             // if specified, the current selection should instead be replaced by transaction.selection
             if let Some(selection) = transaction.selection() {
                 self.selections.insert(
@@ -1762,6 +1776,28 @@ impl Document {
         &self.selections
     }
 
+    fn view_data(&self, view_id: ViewId) -> &ViewData {
+        self.view_data
+            .get(&view_id)
+            .expect("This should only be called after ensure_view_init")
+    }
+
+    fn view_data_mut(&mut self, view_id: ViewId) -> &mut ViewData {
+        self.view_data.entry(view_id).or_default()
+    }
+
+    pub(crate) fn get_view_offset(&self, view_id: ViewId) -> Option<ViewPosition> {
+        Some(self.view_data.get(&view_id)?.view_position)
+    }
+
+    pub fn view_offset(&self, view_id: ViewId) -> ViewPosition {
+        self.view_data(view_id).view_position
+    }
+
+    pub fn set_view_offset(&mut self, view_id: ViewId, new_offset: ViewPosition) {
+        self.view_data_mut(view_id).view_position = new_offset;
+    }
+
     pub fn relative_path(&self) -> Option<Cow<Path>> {
         self.path
             .as_deref()
@@ -2038,6 +2074,11 @@ impl Document {
     }
 }
 
+#[derive(Debug, Default)]
+pub struct ViewData {
+    view_position: ViewPosition,
+}
+
 #[derive(Clone, Debug)]
 pub enum FormatterError {
     SpawningFailed {