Visible whitespace only for selections

book/src/configuration.md

@@ -189,7 +189,7 @@ Options for rendering whitespace with visible characters. Use `:set whitespace.r
 
 | Key | Description | Default |
 |-----|-------------|---------|
-| `render` | Whether to render whitespace. May either be `"all"` or `"none"`, or a table with sub-keys `space`, `tab`, and `newline`. | `"none"` |
+| `render` | Whether to render whitespace. May either be `"all"`, `"selection"`, or `"none"`, or a table with sub-keys `space`, `tab`, and `newline`. | `"none"` |
 | `characters` | Literal characters to use when rendering whitespace. Sub-keys may be any of `tab`, `space`, `nbsp` or `newline` | See example below |
 
 Example

helix-term/src/ui/editor.rs

@@ -375,6 +375,19 @@ impl EditorView {
         spans
     }
 
+    fn render_whitespace<'a>(
+        hidden: &'a str,
+        visible: &'a str,
+        pref: helix_view::editor::WhitespaceRenderValue,
+    ) -> (&'a str, &'a str) {
+        use helix_view::editor::WhitespaceRenderValue;
+        match pref {
+            WhitespaceRenderValue::None => (hidden, hidden),
+            WhitespaceRenderValue::All => (visible, visible),
+            WhitespaceRenderValue::Selection => (visible, hidden),
+        }
+    }
+
     pub fn render_text_highlights<H: Iterator<Item = HighlightEvent>>(
         doc: &Document,
         offset: Position,
@@ -395,19 +408,21 @@ impl EditorView {
         let mut visual_x = 0u16;
         let mut line = 0u16;
         let tab_width = doc.tab_width();
-        let tab = if whitespace.render.tab() == WhitespaceRenderValue::All {
-            (1..tab_width).fold(whitespace.characters.tab.to_string(), |s, _| s + " ")
-        } else {
-            " ".repeat(tab_width)
-        };
-        let space = whitespace.characters.space.to_string();
-        let nbsp = whitespace.characters.nbsp.to_string();
-        let newline = if whitespace.render.newline() == WhitespaceRenderValue::All {
-            whitespace.characters.newline.to_string()
-        } else {
-            " ".to_string()
-        };
+        let tab_hidden = " ".repeat(tab_width);
+        let tab_visible =
+            (1..tab_width).fold(whitespace.characters.tab.to_string(), |s, _| s + " ");
+        let space_visible = whitespace.characters.space.to_string();
+        let nbsp_visible = whitespace.characters.nbsp.to_string();
+        let newline_visible = whitespace.characters.newline.to_string();
         let indent_guide_char = config.indent_guides.character.to_string();
+        let (tab_selected, tab_unselected) =
+            Self::render_whitespace(&tab_hidden, &tab_visible, whitespace.render.tab());
+        let (space_selected, space_unselected) =
+            Self::render_whitespace(" ", &space_visible, whitespace.render.space());
+        let (nbsp_selected, nbsp_unselected) =
+            Self::render_whitespace(" ", &nbsp_visible, whitespace.render.nbsp());
+        let (newline_selected, newline_unselected) =
+            Self::render_whitespace(" ", &newline_visible, whitespace.render.newline());
 
         let text_style = theme.get("ui.text");
         let whitespace_style = theme.get("ui.virtual.whitespace");
@@ -441,16 +456,25 @@ impl EditorView {
             }
         };
 
+        let mut selection_scope_depth = 0usize;
+
         'outer: for event in highlights {
             match event {
                 HighlightEvent::HighlightStart(span) => {
                     spans.push(span);
+
+                    let in_selection = selection_scope_depth > 0;
+                    if in_selection || theme.selection_scopes().contains(&span.0) {
+                        selection_scope_depth += 1;
+                    }
                 }
                 HighlightEvent::HighlightEnd => {
                     spans.pop();
+                    selection_scope_depth = selection_scope_depth.saturating_sub(1);
                 }
                 HighlightEvent::Source { start, end } => {
                     let is_trailing_cursor = text.len_chars() < end;
+                    let in_selection = selection_scope_depth > 0;
 
                     // `unwrap_or_else` part is for off-the-end indices of
                     // the rope, to allow cursor highlighting at the end
@@ -460,18 +484,26 @@ impl EditorView {
                         .iter()
                         .fold(text_style, |acc, span| acc.patch(theme.highlight(span.0)));
 
-                    let space = if whitespace.render.space() == WhitespaceRenderValue::All
+                    let space = if whitespace.render.space() != WhitespaceRenderValue::None
                         && !is_trailing_cursor
                     {
-                        &space
+                        if in_selection {
+                            &space_selected
+                        } else {
+                            &space_unselected
+                        }
                     } else {
                         " "
                     };
 
-                    let nbsp = if whitespace.render.nbsp() == WhitespaceRenderValue::All
+                    let nbsp = if whitespace.render.nbsp() != WhitespaceRenderValue::None
                         && text.len_chars() < end
                     {
-                        &nbsp
+                        if in_selection {
+                            &nbsp_selected
+                        } else {
+                            &nbsp_unselected
+                        }
                     } else {
                         " "
                     };
@@ -488,7 +520,11 @@ impl EditorView {
                                 surface.set_string(
                                     viewport.x + visual_x - offset.col as u16,
                                     viewport.y + line,
-                                    &newline,
+                                    if in_selection {
+                                        &newline_selected
+                                    } else {
+                                        &newline_unselected
+                                    },
                                     style.patch(whitespace_style),
                                 );
                             }
@@ -511,8 +547,13 @@ impl EditorView {
                                 is_whitespace = true;
                                 // make sure we display tab as appropriate amount of spaces
                                 let visual_tab_width = tab_width - (visual_x as usize % tab_width);
+                                let tab = if in_selection {
+                                    &tab_selected
+                                } else {
+                                    &tab_unselected
+                                };
                                 let grapheme_tab_width =
-                                    helix_core::str_utils::char_to_byte_idx(&tab, visual_tab_width);
+                                    helix_core::str_utils::char_to_byte_idx(tab, visual_tab_width);
 
                                 (&tab[..grapheme_tab_width], visual_tab_width)
                             } else if grapheme == " " {

helix-view/src/editor.rs

@@ -392,8 +392,7 @@ pub enum WhitespaceRender {
 #[serde(rename_all = "kebab-case")]
 pub enum WhitespaceRenderValue {
     None,
-    // TODO
-    // Selection,
+    Selection,
     All,
 }
 

helix-view/src/theme.rs

@@ -102,6 +102,7 @@ pub struct Theme {
     styles: HashMap<String, Style>,
     // tree-sitter highlight styles are stored in a Vec to optimize lookups
     scopes: Vec<String>,
+    selection_scopes: Vec<usize>,
     highlights: Vec<Style>,
 }
 
@@ -112,6 +113,7 @@ impl<'de> Deserialize<'de> for Theme {
     {
         let mut styles = HashMap::new();
         let mut scopes = Vec::new();
+        let mut selection_scopes = Vec::new();
         let mut highlights = Vec::new();
 
         if let Ok(mut colors) = HashMap::<String, Value>::deserialize(deserializer) {
@@ -138,13 +140,20 @@ impl<'de> Deserialize<'de> for Theme {
 
                 // these are used both as UI and as highlights
                 styles.insert(name.clone(), style);
+                if name.starts_with("ui.selection")
+                    || name == "ui.cursor"
+                    || name.starts_with("ui.cursor.")
+                {
+                    selection_scopes.push(scopes.len());
+                }
                 scopes.push(name);
                 highlights.push(style);
             }
         }
 
         Ok(Self {
             scopes,
+            selection_scopes,
             styles,
             highlights,
         })
@@ -174,6 +183,11 @@ impl Theme {
         &self.scopes
     }
 
+    #[inline]
+    pub fn selection_scopes(&self) -> &[usize] {
+        &self.selection_scopes
+    }
+
     pub fn find_scope_index(&self, scope: &str) -> Option<usize> {
         self.scopes().iter().position(|s| s == scope)
     }