Implement line numbers

src/config.rs

@@ -150,6 +150,7 @@ pub struct Config {
     pub auto_indent: bool,
     pub font_name: String,
     pub font_size: u16,
+    pub line_numbers: bool,
     pub syntax_theme_dark: String,
     pub syntax_theme_light: String,
     pub tab_width: u16,
@@ -165,6 +166,7 @@ impl Default for Config {
             auto_indent: true,
             font_name: "Fira Mono".to_string(),
             font_size: 14,
+            line_numbers: true,
             syntax_theme_dark: "gruvbox-dark".to_string(),
             syntax_theme_light: "gruvbox-light".to_string(),
             tab_width: 4,

src/line_number.rs

@@ -0,0 +1,49 @@
+use cosmic_text::{
+    Align, Attrs, AttrsList, BufferLine, Family, FontSystem, LayoutLine, ShapeBuffer, Shaping, Wrap,
+};
+use std::collections::HashMap;
+
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
+pub struct LineNumberKey {
+    pub number: usize,
+    pub width: usize,
+}
+
+#[derive(Debug)]
+pub struct LineNumberCache {
+    cache: HashMap<LineNumberKey, Vec<LayoutLine>>,
+    scratch: ShapeBuffer,
+}
+
+impl LineNumberCache {
+    pub fn new() -> Self {
+        Self {
+            cache: HashMap::new(),
+            scratch: ShapeBuffer::default(),
+        }
+    }
+
+    pub fn clear(&mut self) {
+        self.cache.clear();
+    }
+
+    pub fn get(&mut self, font_system: &mut FontSystem, key: LineNumberKey) -> &Vec<LayoutLine> {
+        self.cache.entry(key).or_insert_with(|| {
+            //TODO: do not repeat, used in App::init
+            let attrs = Attrs::new().family(Family::Monospace);
+            let text = format!("{:width$}", key.number, width = key.width);
+            let mut buffer_line = BufferLine::new(text, AttrsList::new(attrs), Shaping::Advanced);
+            buffer_line.set_wrap(Wrap::None);
+            buffer_line.set_align(Some(Align::Left));
+            buffer_line
+                .layout_in_buffer(
+                    &mut self.scratch,
+                    font_system,
+                    1.0,    /* font size adjusted later */
+                    1000.0, /* dummy width */
+                    Wrap::None,
+                )
+                .to_vec()
+        })
+    }
+}

src/main.rs

@@ -32,6 +32,9 @@ mod config;
 use icon_cache::IconCache;
 mod icon_cache;
 
+use line_number::LineNumberCache;
+mod line_number;
+
 mod localize;
 
 pub use self::mime_icon::{mime_icon, FALLBACK_MIME_ICON};
@@ -56,6 +59,7 @@ mod text_box;
 lazy_static::lazy_static! {
     static ref FONT_SYSTEM: Mutex<FontSystem> = Mutex::new(FontSystem::new());
     static ref ICON_CACHE: Mutex<IconCache> = Mutex::new(IconCache::new());
+    static ref LINE_NUMBER_CACHE: Mutex<LineNumberCache> = Mutex::new(LineNumberCache::new());
     static ref SWASH_CACHE: Mutex<SwashCache> = Mutex::new(SwashCache::new());
     static ref SYNTAX_SYSTEM: SyntaxSystem = {
         let lazy_theme_set = two_face::theme::LazyThemeSet::from(two_face::theme::extra());
@@ -190,6 +194,7 @@ pub enum Message {
     Todo,
     ToggleAutoIndent,
     ToggleContextPage(ContextPage),
+    ToggleLineNumbers,
     ToggleWordWrap,
     Undo,
     VimBindings(bool),
@@ -734,6 +739,12 @@ impl Application for App {
                                 font_system.db_mut().set_monospace_family(font_name);
                             }
 
+                            // Reset line number cache
+                            {
+                                let mut line_number_cache = LINE_NUMBER_CACHE.lock().unwrap();
+                                line_number_cache.clear();
+                            }
+
                             // This does a complete reset of shaping data!
                             let entities: Vec<_> = self.tab_model.iter().collect();
                             for entity in entities {
@@ -1130,6 +1141,20 @@ impl Application for App {
                     }
                 }
             }
+            Message::ToggleLineNumbers => {
+                self.config.line_numbers = !self.config.line_numbers;
+
+                // This forces a redraw of all buffers
+                let entities: Vec<_> = self.tab_model.iter().collect();
+                for entity in entities {
+                    if let Some(tab) = self.tab_model.data_mut::<Tab>(entity) {
+                        let mut editor = tab.editor.lock().unwrap();
+                        editor.buffer_mut().set_redraw(true);
+                    }
+                }
+
+                return self.save_config();
+            }
             Message::ToggleWordWrap => {
                 self.config.word_wrap = !self.config.word_wrap;
                 return self.save_config();
@@ -1424,11 +1449,14 @@ impl Application for App {
                         }
                     }
                 };
-                let text_box = text_box(&tab.editor, self.config.metrics())
+                let mut text_box = text_box(&tab.editor, self.config.metrics())
                     .on_changed(Message::TabChanged(tab_id))
                     .on_context_menu(move |position_opt| {
                         Message::TabContextMenu(tab_id, position_opt)
                     });
+                if self.config.line_numbers {
+                    text_box = text_box.line_numbers();
+                }
                 let tab_element: Element<'_, Message> = match tab.context_menu {
                     Some(position) => widget::popover(
                         text_box.context_menu(position),

src/menu.rs

@@ -230,7 +230,11 @@ pub fn menu_bar<'a>(config: &Config) -> Element<'a, Message> {
                 ),
                 MenuTree::new(horizontal_rule(1)),
                 menu_checkbox(fl!("word-wrap"), config.word_wrap, Message::ToggleWordWrap),
-                menu_checkbox(fl!("show-line-numbers"), false, Message::Todo),
+                menu_checkbox(
+                    fl!("show-line-numbers"),
+                    config.line_numbers,
+                    Message::ToggleLineNumbers,
+                ),
                 menu_checkbox(fl!("highlight-current-line"), false, Message::Todo),
                 menu_item(fl!("syntax-highlighting"), Message::Todo),
                 MenuTree::new(horizontal_rule(1)),