Draft invisibles' tabs display

crates/gpui/src/text_layout.rs

@@ -11,6 +11,7 @@ use crate::{
     window::WindowContext,
     SceneBuilder,
 };
+use itertools::Itertools;
 use ordered_float::OrderedFloat;
 use parking_lot::{Mutex, RwLock, RwLockUpgradableReadGuard};
 use smallvec::SmallVec;
@@ -178,6 +179,7 @@ impl<'a> Hash for CacheKeyRef<'a> {
 pub struct Line {
     layout: Arc<LineLayout>,
     style_runs: SmallVec<[StyleRun; 32]>,
+    pub invisibles: SmallVec<[Invisible; 32]>,
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -211,6 +213,12 @@ pub struct Glyph {
     pub is_emoji: bool,
 }
 
+#[derive(Debug, Clone)]
+pub enum Invisible {
+    Tab { range: std::ops::Range<usize> },
+    Whitespace { range: std::ops::Range<usize> },
+}
+
 impl Line {
     fn new(layout: Arc<LineLayout>, runs: &[(usize, RunStyle)]) -> Self {
         let mut style_runs = SmallVec::new();
@@ -221,7 +229,11 @@ impl Line {
                 underline: style.underline,
             });
         }
-        Self { layout, style_runs }
+        Self {
+            layout,
+            style_runs,
+            invisibles: SmallVec::new(),
+        }
     }
 
     pub fn runs(&self) -> &[Run] {
@@ -298,6 +310,16 @@ impl Line {
         let mut color = Color::black();
         let mut underline = None;
 
+        let tab_ranges = self
+            .invisibles
+            .iter()
+            .filter_map(|invisible| match invisible {
+                Invisible::Tab { range } => Some(range),
+                Invisible::Whitespace { .. } => None,
+            })
+            .sorted_by(|tab_range_1, tab_range_2| tab_range_1.start.cmp(&tab_range_2.start))
+            .collect::<Vec<_>>();
+
         for run in &self.layout.runs {
             let max_glyph_width = cx
                 .font_cache
@@ -364,10 +386,19 @@ impl Line {
                         origin: glyph_origin,
                     });
                 } else {
+                    let id = if tab_ranges.iter().any(|tab_range| {
+                        tab_range.start <= glyph.index && glyph.index < tab_range.end
+                    }) {
+                        // TODO kb get a proper (cached) glyph
+                        glyph.id + 100
+                    } else {
+                        glyph.id
+                    };
+
                     scene.push_glyph(scene::Glyph {
                         font_id: run.font_id,
                         font_size: self.layout.font_size,
-                        id: glyph.id,
+                        id,
                         origin: glyph_origin,
                         color,
                     });