ui: Make editor more resilient about being shrunk too small.

helix-term/src/application.rs

@@ -70,10 +70,11 @@ impl Application {
         let area = self.terminal.size().unwrap();
 
         compositor.render(area, self.terminal.current_buffer_mut(), &mut cx);
-        let pos = compositor.cursor_position(area, &editor);
+        let pos = compositor
+            .cursor_position(area, &editor)
+            .map(|pos| (pos.col as u16, pos.row as u16));
 
-        self.terminal.draw();
-        self.terminal.set_cursor(pos.col as u16, pos.row as u16);
+        self.terminal.draw(pos);
     }
 
     pub async fn event_loop(&mut self) {

helix-term/src/commands.rs

@@ -1072,9 +1072,10 @@ pub fn completion(cx: &mut Context) {
         cx.callback = Some(Box::new(
             move |compositor: &mut Compositor, editor: &mut Editor| {
                 let area = tui::layout::Rect::default(); // TODO: unused remove from cursor_position
-                let mut pos = compositor.cursor_position(area, editor);
-                pos.row += 1; // shift down by one row
-                menu.set_position(pos);
+                if let Some(mut pos) = compositor.cursor_position(area, editor) {
+                    pos.row += 1; // shift down by one row
+                    menu.set_position(pos);
+                };
 
                 compositor.push(Box::new(menu));
             },
@@ -1133,9 +1134,10 @@ pub fn hover(cx: &mut Context) {
         cx.callback = Some(Box::new(
             move |compositor: &mut Compositor, editor: &mut Editor| {
                 let area = tui::layout::Rect::default(); // TODO: unused remove from cursor_position
-                let mut pos = compositor.cursor_position(area, editor);
-                pos.row += 1; // shift down by one row
-                popup.set_position(pos);
+                if let Some(mut pos) = compositor.cursor_position(area, editor) {
+                    pos.row += 1; // shift down by one row
+                    popup.set_position(pos);
+                };
 
                 compositor.push(Box::new(popup));
             },

helix-term/src/compositor.rs

@@ -120,12 +120,12 @@ impl Compositor {
         }
     }
 
-    pub fn cursor_position(&self, area: Rect, editor: &Editor) -> Position {
+    pub fn cursor_position(&self, area: Rect, editor: &Editor) -> Option<Position> {
         for layer in self.layers.iter().rev() {
             if let Some(pos) = layer.cursor_position(area, editor) {
-                return pos;
+                return Some(pos);
             }
         }
-        panic!("No layer returned a position!");
+        None
     }
 }

helix-term/src/terminal.rs

@@ -154,7 +154,7 @@ where
 
     /// Synchronizes terminal size, calls the rendering closure, flushes the current internal state
     /// and prepares for the next draw call.
-    pub fn draw(&mut self) -> io::Result<()> {
+    pub fn draw(&mut self, cursor_position: Option<(u16, u16)>) -> io::Result<()> {
         // // Autoresize - otherwise we get glitches if shrinking or potential desync between widgets
         // // and the terminal (if growing), which may OOB.
         // self.autoresize()?;
@@ -169,13 +169,13 @@ where
         // Draw to stdout
         self.flush()?;
 
-        // match cursor_position {
-        //     None => self.hide_cursor()?,
-        //     Some((x, y)) => {
-        //         self.show_cursor()?;
-        //         self.set_cursor(x, y)?;
-        //     }
-        // }
+        match cursor_position {
+            None => self.hide_cursor()?,
+            Some((x, y)) => {
+                self.show_cursor()?;
+                self.set_cursor(x, y)?;
+            }
+        }
 
         // Swap buffers
         self.buffers[1 - self.current].reset();

helix-term/src/ui/editor.rs

@@ -42,7 +42,7 @@ impl EditorView {
             viewport.x + OFFSET,
             viewport.y,
             viewport.width - OFFSET,
-            viewport.height - 1,
+            viewport.height.saturating_sub(1),
         ); // - 1 for statusline
         self.render_buffer(view, area, surface, theme, is_focused);
 
@@ -52,7 +52,7 @@ impl EditorView {
 
         let area = Rect::new(
             viewport.x,
-            viewport.y + viewport.height - 1,
+            viewport.y + viewport.height.saturating_sub(1),
             viewport.width,
             1,
         );
@@ -433,14 +433,16 @@ impl Component for EditorView {
         //     Mode::Insert => write!(stdout, "\x1B[6 q"),
         //     mode => write!(stdout, "\x1B[2 q"),
         // };
-        let view = editor.view();
-        let cursor = view.doc.selection().cursor();
-
-        let mut pos = view
-            .screen_coords_at_pos(view.doc.text().slice(..), cursor)
-            .expect("Cursor is out of bounds.");
-        pos.col += view.area.x as usize + area.x as usize + OFFSET as usize;
-        pos.row += view.area.y as usize + area.y as usize;
-        Some(pos)
+        // let view = editor.view();
+        // let cursor = view.doc.selection().cursor();
+
+        // if let Some(mut pos) = view.screen_coords_at_pos(view.doc.text().slice(..), cursor) {
+        //     pos.col += view.area.x as usize + area.x as usize + OFFSET as usize;
+        //     pos.row += view.area.y as usize + area.y as usize;
+        //     return Some(pos);
+        // }
+
+        // It's easier to just not render the cursor and use selection rendering instead.
+        None
     }
 }

helix-view/src/view.rs

@@ -65,7 +65,7 @@ impl View {
     /// Calculates the last visible line on screen
     #[inline]
     pub fn last_line(&self) -> usize {
-        let viewport = Rect::new(6, 0, self.area.width, self.area.height - 1); // - 1 for statusline
+        let viewport = Rect::new(6, 0, self.area.width, self.area.height.saturating_sub(1)); // - 1 for statusline
         std::cmp::min(
             self.first_line + (viewport.height as usize),
             self.doc.text().len_lines() - 1,