added nullspace alignment calculation

helix-term/src/ui/editor.rs

@@ -88,19 +88,19 @@ impl EditorView {
         surface: &mut Surface,
         is_focused: bool,
     ) {
-        let inner = view.inner_area(doc);
+        let areas = view.get_view_areas(doc);
+
+        // TODO: use the 'areas' struct for these!
+        let inner = areas.text;
         let area = view.area;
         let theme = &editor.theme;
         let config = editor.config();
 
         if config.nullspace.enable {
-            if inner.width < view.area.width {
-                let null_style = theme
-                    .try_get("ui.nullspace")
-                    .or_else(|| Some(theme.get("ui.linenr")))
-                    .unwrap();
-
-                fn fill_area(s: &mut Surface, r: Rect, c: char) {
+            // helper:
+            fn fill_area(s: &mut Surface, r: Rect, c: char, style: Style) {
+                if r.width > 0 && r.height > 0 {
+                    s.set_style(r, style);
                     for y in r.top()..r.bottom() {
                         for x in r.left()..r.right() {
                             let cell = s.get_mut(x, y).unwrap();
@@ -109,20 +109,21 @@ impl EditorView {
                         }
                     }
                 }
+            }
 
-                let view_width = inner.width + view.gutter_offset(doc);
-                let (null_l, _, null_r) = area.clip_bottom(1).split_centre_vertical(view_width);
+            if areas.left.width > 0 || areas.right.width > 0 {
+                let style = theme
+                    .try_get("ui.nullspace")
+                    .or_else(|| Some(theme.get("ui.linenr")))
+                    .unwrap();
 
-                // We currently on use the first char in the 'pattern'
-                // but in future I would like to use the whole string
-                // to render nicer patterns.
+                // We currently on use the first
+                // char in the 'pattern'.
+                //
                 let c = config.nullspace.pattern.chars().nth(0).unwrap();
 
-                fill_area(surface, null_l, c);
-                fill_area(surface, null_r, c);
-
-                surface.set_style(null_l, null_style);
-                surface.set_style(null_r, null_style);
+                fill_area(surface, areas.left, c, style);
+                fill_area(surface, areas.right, c, style);
             }
         }
 
@@ -253,7 +254,7 @@ impl EditorView {
         // if we're not at the edge of the screen, draw a right border
         if viewport.right() != view.area.right() {
             let x = area.right();
-            let border_style = theme.get("ui.window");
+            let border_style = theme.try_get("ui.divide").unwrap_or(theme.get("ui.window"));
             for y in area.top()..area.bottom() {
                 surface[(x, y)]
                     .set_symbol(tui::symbols::line::VERTICAL)
@@ -265,7 +266,7 @@ impl EditorView {
         if config.inline_diagnostics.disabled()
             && config.end_of_line_diagnostics == DiagnosticFilter::Disable
         {
-            Self::render_diagnostics(doc, view, inner, surface, theme);
+            Self::render_diagnostics(doc, view, surface, theme);
         }
 
         let statusline_area = view
@@ -745,13 +746,7 @@ impl EditorView {
         }
     }
 
-    pub fn render_diagnostics(
-        doc: &Document,
-        view: &View,
-        viewport: Rect,
-        surface: &mut Surface,
-        theme: &Theme,
-    ) {
+    pub fn render_diagnostics(doc: &Document, view: &View, surface: &mut Surface, theme: &Theme) {
         use helix_core::diagnostic::Severity;
         use tui::{
             layout::Alignment,
@@ -773,27 +768,56 @@ impl EditorView {
         let info = theme.get("info");
         let hint = theme.get("hint");
 
-        let width = 50.min(viewport.width);
+        let areas = view.get_view_areas(doc);
+        let width = 50.min(areas.text.width);
+
+        let height = 15.min(areas.text.height); // .min(text.lines.len() as u16);
 
-        // place it in the nullspace if we have room, and on the same
-        // line as the cursor to make it easier to read
+        // decide where this diagnostic is gonna get rendered
         //
-        let gutter_size = view.gutter_offset(doc);
-        let left_nullspace = viewport.left() - view.area.left() - gutter_size;
-        let use_nullspace = left_nullspace > width;
+        let mut x = areas.text.right() - width;
+        let mut y = areas.text.top() + 1;
+        let mut align = Alignment::Right;
+        let mut background = theme.get("ui.background");
 
-        let background_style = if use_nullspace {
-            theme
-                .try_get("ui.nullspace")
-                .unwrap_or(theme.get("ui.background"))
-        } else {
-            theme.get("ui.background")
-        };
+        // do we have space in the nullspace to render the diagnostic?
+        //
+        const PADDING: u16 = 2;
+        let width_pad = width + PADDING;
 
+        if areas.left.width >= width_pad || areas.right.width >= width_pad {
+            if let Some(pos) = view.screen_coords_at_pos(doc, doc.text().slice(..), cursor) {
+                background = theme
+                    .try_get("ui.nullspace")
+                    .unwrap_or(theme.get("ui.background"));
+
+                // decide if we are placing the diagnositcs in the
+                // left or right nullspace?
+                //
+                y = pos.row as u16 + areas.text.top();
+
+                x = if areas.left.width >= width_pad {
+                    align = Alignment::Right;
+                    areas.left.right() - PADDING - width
+                } else {
+                    align = Alignment::Left;
+                    areas.right.left() + PADDING
+                };
+
+                // correct for overflow in y position
+                //
+                if y + height > areas.text.bottom() {
+                    y -= (y + height) - areas.text.bottom();
+                }
+            }
+        }
+
+        // build diagnostic lines
+        //
         let mut lines = Vec::new();
         for diagnostic in diagnostics {
             let style = Style::reset()
-                .patch(background_style)
+                .patch(background)
                 .patch(match diagnostic.severity {
                     Some(Severity::Error) => error,
                     Some(Severity::Warning) | None => warning,
@@ -813,29 +837,12 @@ impl EditorView {
         }
 
         let text = Text::from(lines);
+
         let paragraph = Paragraph::new(&text)
-            .alignment(Alignment::Right)
+            .alignment(align)
             .wrap(Wrap { trim: true });
-        let height = 15.min(viewport.height).min(text.lines.len() as u16);
-
-        // decide where this diagnostic is gonna get rendered
-        //
-        let mut diag_x = viewport.right() - width;
-        let mut diag_y = viewport.top() + 1;
-
-        if use_nullspace {
-            if let Some(pos) = view.screen_coords_at_pos(doc, doc.text().slice(..), cursor) {
-                diag_x = viewport.left() - width - gutter_size - 2;
-                diag_y = pos.row as u16 + viewport.top();
-
-                // correct for OOB
-                if diag_y + height > viewport.bottom() {
-                    diag_y -= (diag_y + height) - viewport.bottom();
-                }
-            }
-        }
 
-        paragraph.render(Rect::new(diag_x, diag_y, width, height), surface);
+        paragraph.render(Rect::new(x, y, width, height), surface);
     }
 
     /// Apply the highlighting on the lines where a cursor is active

helix-view/src/tree.rs

@@ -373,6 +373,7 @@ impl Tree {
             match &mut node.content {
                 Content::View(view) => {
                     // debug!!("setting view area {:?}", area);
+                    view.container_area = self.area;
                     view.area = area;
                 } // TODO: call f()
                 Content::Container(container) => {

helix-view/src/view.rs

@@ -25,6 +25,20 @@ use std::{
 
 const JUMP_LIST_CAPACITY: usize = 30;
 
+#[derive(Debug, Clone, Default)]
+pub struct ViewAreas {
+    pub left: Rect,
+    pub right: Rect,
+    pub gutter: Rect,
+    pub text: Rect,
+}
+
+impl ViewAreas {
+    pub fn has_nullspace(&self) -> bool {
+        self.left.width > 0 || self.right.width > 0
+    }
+}
+
 type Jump = (DocumentId, Selection);
 
 #[derive(Debug, Clone)]
@@ -129,6 +143,7 @@ pub struct ViewPosition {
 pub struct View {
     pub id: ViewId,
     pub area: Rect,
+    pub container_area: Rect,
     pub doc: DocumentId,
     pub jumps: JumpList,
     // documents accessed from this view from the oldest one to last viewed one
@@ -173,6 +188,7 @@ impl View {
             id: ViewId::default(),
             doc,
             area: Rect::default(), // will get calculated upon inserting into tree
+            container_area: Rect::default(), // will get calculated upon inserting into tree
             jumps: JumpList::new((doc, Selection::point(0))), // TODO: use actual sel
             docs_access_history: Vec::new(),
             last_modified_docs: [None, None],
@@ -190,26 +206,68 @@ impl View {
         self.docs_access_history.push(id);
     }
 
-    pub fn inner_area(&self, doc: &Document) -> Rect {
+    pub fn get_view_areas(&self, doc: &Document) -> ViewAreas {
         let config = doc.config.load();
-        let gutter_width = self.gutter_offset(doc);
-
-        if config.nullspace.enable {
-            let text_width = config.text_width as u16;
-            let view_width = gutter_width + text_width;
 
-            if self.area.width > view_width {
-                let null_width = (self.area.width - view_width) / 2;
+        let gutter = self.gutter_offset(doc);
+        let area = self.area.clip_bottom(1); // -1 for status line
+
+        // if we are not using nullspace, then we use the whole
+        // area (without nullspace)
+        //
+        if config.nullspace.enable == false {
+            let (gutter, text) = self.area.split_left(gutter);
+            return ViewAreas {
+                gutter,
+                text,
+                ..Default::default()
+            };
+        }
 
-                return self
-                    .area
-                    .clip_left(gutter_width + null_width)
-                    .clip_bottom(1)
-                    .with_width(text_width.min(self.area.width - gutter_width));
+        // midpoint (with tolerances)
+        //
+        let mid_lo = (self.container_area.width / 2) - 2;
+        let mid_hi = (self.container_area.width / 2) + 2;
+
+        let width = config.text_width as u16 + gutter;
+
+        if area.right() < mid_hi {
+            // align: right
+            let (left, text) = area.split_right(width);
+            let (gutter, text) = text.split_left(gutter);
+            ViewAreas {
+                left,
+                right: Rect::default(),
+                gutter,
+                text,
+            }
+        } else if area.left() > mid_lo {
+            // align: left
+            let (text, right) = area.split_left(width);
+            let (gutter, text) = text.split_left(gutter);
+            ViewAreas {
+                left: Rect::default(),
+                right,
+                gutter,
+                text,
+            }
+        } else {
+            // align: center
+            let (left, text, right) = area.split_centre_vertical(width);
+            let (gutter, text) = text.split_left(gutter);
+            ViewAreas {
+                left,
+                right,
+                gutter,
+                text,
             }
         }
+    }
 
-        self.area.clip_left(gutter_width).clip_bottom(1) // -1 for statusline
+    /// Returns the 'inner area' (the text renderable area) of the view.
+    ///
+    pub fn inner_area(&self, doc: &Document) -> Rect {
+        self.get_view_areas(doc).text
     }
 
     pub fn inner_height(&self) -> usize {