render: cursor shapes, visibility, and focus

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: Iad508cceb2c8417147ad71b5c1ffc4bc6a6a6964

src/grid.rs

@@ -61,6 +61,15 @@ pub enum Underline {
     Dashed,
 }
 
+/// Cursor shape (DECSCUSR).
+#[derive(Clone, Copy, PartialEq, Eq, Debug, Default)]
+pub enum CursorShape {
+    #[default]
+    Block,
+    Underline,
+    Beam,
+}
+
 /// One grid cell: a character plus its rendering style.
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub struct Cell {
@@ -113,6 +122,10 @@ pub struct Grid {
     tabs: Vec<bool>,
     /// Saved primary screen while the alternate screen is active.
     alt_saved: Option<Vec<Vec<Cell>>>,
+    cursor_shape: CursorShape,
+    cursor_visible: bool,
+    /// Cursor colour from OSC 12; `None` follows the cell under the cursor.
+    cursor_color: Option<(u8, u8, u8)>,
 }
 
 fn default_tabs(cols: usize) -> Vec<bool> {
@@ -138,6 +151,9 @@ impl Grid {
             wrap_pending: false,
             tabs: default_tabs(cols),
             alt_saved: None,
+            cursor_shape: CursorShape::default(),
+            cursor_visible: true,
+            cursor_color: None,
         }
     }
 
@@ -210,6 +226,30 @@ impl Grid {
         self.alt_saved.is_some()
     }
 
+    pub fn set_cursor_shape(&mut self, shape: CursorShape) {
+        self.cursor_shape = shape;
+    }
+
+    pub fn cursor_shape(&self) -> CursorShape {
+        self.cursor_shape
+    }
+
+    pub fn set_cursor_visible(&mut self, visible: bool) {
+        self.cursor_visible = visible;
+    }
+
+    pub fn cursor_visible(&self) -> bool {
+        self.cursor_visible
+    }
+
+    pub fn set_cursor_color(&mut self, color: Option<(u8, u8, u8)>) {
+        self.cursor_color = color;
+    }
+
+    pub fn cursor_color(&self) -> Option<(u8, u8, u8)> {
+        self.cursor_color
+    }
+
     // --- printing ---
 
     /// Place a printable character at the cursor, honouring width and autowrap.

src/render.rs

@@ -6,7 +6,7 @@
 //! neighbouring cell's background fill.
 
 use crate::font::{CellMetrics, Fonts, GlyphData, Style};
-use crate::grid::{Cell, Color, Flags, Grid, Underline};
+use crate::grid::{Cell, Color, CursorShape, Flags, Grid, Underline};
 
 /// Foreground/background used for `Color::Default`.
 const DEFAULT_FG: Rgb = Rgb(0xc5, 0xc8, 0xc6);
@@ -94,9 +94,16 @@ impl Renderer {
         self.fonts.metrics()
     }
 
-    /// Compose `grid` into `pixels` (BGRA, `width`×`height` px). The cursor cell
-    /// is drawn reversed.
-    pub fn render(&mut self, grid: &Grid, pixels: &mut [u8], width: usize, height: usize) {
+    /// Compose `grid` into `pixels` (BGRA, `width`×`height` px). `focused`
+    /// selects a solid or hollow cursor.
+    pub fn render(
+        &mut self,
+        grid: &Grid,
+        pixels: &mut [u8],
+        width: usize,
+        height: usize,
+        focused: bool,
+    ) {
         let mut canvas = Canvas {
             pixels,
             width,
@@ -105,11 +112,10 @@ impl Renderer {
         canvas.fill_rect(0, 0, width as u32, height as u32, DEFAULT_BG);
 
         let m = self.fonts.metrics();
-        let cursor = grid.cursor();
 
         for y in 0..grid.rows() {
             for x in 0..grid.cols() {
-                let (_, bg) = cell_colors(grid.cell(x, y), (x, y) == cursor);
+                let (_, bg) = cell_colors(grid.cell(x, y));
                 let (px, py) = (x as i32 * m.width as i32, y as i32 * m.height as i32);
                 canvas.fill_rect(px, py, m.width, m.height, bg);
             }
@@ -121,18 +127,14 @@ impl Renderer {
                 if cell.flags.contains(Flags::WIDE_CONT) {
                     continue;
                 }
-                let (fg, _) = cell_colors(cell, (x, y) == cursor);
+                let (fg, _) = cell_colors(cell);
                 let origin_x = x as i32 * m.width as i32;
                 let cell_top = y as i32 * m.height as i32;
                 if cell.c != ' ' {
-                    let style = Style {
-                        bold: cell.flags.contains(Flags::BOLD),
-                        italic: cell.flags.contains(Flags::ITALIC),
-                    };
                     self.draw_glyph(
                         &mut canvas,
                         cell.c,
-                        style,
+                        cell_style(cell),
                         origin_x,
                         cell_top + m.ascent as i32,
                         fg,
@@ -141,6 +143,54 @@ impl Renderer {
                 draw_decorations(&mut canvas, cell, origin_x, cell_top, m, fg);
             }
         }
+
+        self.draw_cursor(&mut canvas, grid, m, focused);
+    }
+
+    /// Draw the cursor: a solid block/underline/beam when focused, a hollow
+    /// outline when not.
+    fn draw_cursor(&mut self, canvas: &mut Canvas, grid: &Grid, m: CellMetrics, focused: bool) {
+        if !grid.cursor_visible() {
+            return;
+        }
+        let (cx, cy) = grid.cursor();
+        let x0 = cx as i32 * m.width as i32;
+        let top = cy as i32 * m.height as i32;
+        let color = grid
+            .cursor_color()
+            .map_or(DEFAULT_FG, |(r, g, b)| Rgb(r, g, b));
+
+        if !focused {
+            let right = x0 + m.width as i32 - 1;
+            let bottom = top + m.height as i32 - 1;
+            canvas.hline(x0, top, m.width, color);
+            canvas.hline(x0, bottom, m.width, color);
+            canvas.fill_rect(x0, top, 1, m.height, color);
+            canvas.fill_rect(right, top, 1, m.height, color);
+            return;
+        }
+
+        match grid.cursor_shape() {
+            CursorShape::Block => {
+                canvas.fill_rect(x0, top, m.width, m.height, color);
+                let cell = grid.cell(cx, cy);
+                if cell.c != ' ' && !cell.flags.contains(Flags::WIDE_CONT) {
+                    let (_, bg) = cell_colors(cell);
+                    self.draw_glyph(
+                        canvas,
+                        cell.c,
+                        cell_style(cell),
+                        x0,
+                        top + m.ascent as i32,
+                        bg,
+                    );
+                }
+            }
+            CursorShape::Underline => {
+                canvas.fill_rect(x0, top + m.height as i32 - 2, m.width, 2, color);
+            }
+            CursorShape::Beam => canvas.fill_rect(x0, top, 2, m.height, color),
+        }
     }
 
     fn draw_glyph(
@@ -188,13 +238,20 @@ impl Renderer {
     }
 }
 
+fn cell_style(cell: &Cell) -> Style {
+    Style {
+        bold: cell.flags.contains(Flags::BOLD),
+        italic: cell.flags.contains(Flags::ITALIC),
+    }
+}
+
 /// Resolve a cell's (foreground, background) RGB, applying reverse video,
 /// bold-as-bright, dim, and hidden.
-fn cell_colors(cell: &Cell, cursor: bool) -> (Rgb, Rgb) {
+fn cell_colors(cell: &Cell) -> (Rgb, Rgb) {
     let bold = cell.flags.contains(Flags::BOLD);
     let mut fg = resolve(cell.fg, DEFAULT_FG, bold);
     let mut bg = resolve(cell.bg, DEFAULT_BG, false);
-    if cell.flags.contains(Flags::REVERSE) ^ cursor {
+    if cell.flags.contains(Flags::REVERSE) {
         std::mem::swap(&mut fg, &mut bg);
     }
     if cell.flags.contains(Flags::DIM) {

src/vt.rs

@@ -4,7 +4,7 @@ use std::io::Write as _;
 
 use vte::{Params, Perform};
 
-use crate::grid::{Color, Flags, Grid, Underline};
+use crate::grid::{Color, CursorShape, Flags, Grid, Underline};
 
 /// G0/G1 character set designation.
 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
@@ -26,6 +26,31 @@ fn set_reset(on: bool) -> u8 {
     if on { 1 } else { 2 }
 }
 
+/// Parse an X11 colour spec from an OSC string: `rgb:rr/gg/bb` (1-4 hex
+/// digits per channel) or `#rrggbb`.
+fn parse_color(spec: &[u8]) -> Option<(u8, u8, u8)> {
+    let spec = std::str::from_utf8(spec).ok()?;
+    if let Some(rest) = spec.strip_prefix("rgb:") {
+        let mut it = rest.split('/');
+        let chan = |s: &str| -> Option<u8> {
+            // Normalize an n-hex-digit fraction to 8 bits (X11 rule).
+            let v = u32::from_str_radix(s, 16).ok()?;
+            let max = (1u32 << (4 * s.len() as u32)) - 1;
+            Some((v * 255 / max) as u8)
+        };
+        let r = chan(it.next()?)?;
+        let g = chan(it.next()?)?;
+        let b = chan(it.next()?)?;
+        return Some((r, g, b));
+    }
+    let hex = spec.strip_prefix('#')?;
+    if hex.len() == 6 {
+        let byte = |i: usize| u8::from_str_radix(&hex[i..i + 2], 16).ok();
+        return Some((byte(0)?, byte(2)?, byte(4)?));
+    }
+    None
+}
+
 /// Map an SGR 4 param (`4` or `4:x`) to an underline style.
 fn underline_from(param: &[u16]) -> Underline {
     match param.get(1).copied().unwrap_or(1) {
@@ -108,6 +133,7 @@ impl Term {
                     }
                 }
                 (false, 4) => self.grid.set_insert(on),
+                (true, 25) => self.grid.set_cursor_visible(on),
                 // App-cursor/bracketed-paste/mouse/sync modes affect input and
                 // rendering, which arrive with the keyboard and renderer.
                 _ => tracing::trace!("unhandled mode {code} private={private} on={on}"),
@@ -400,6 +426,13 @@ impl Perform for Term {
                 _ => DaLevel::Primary,
             }),
             'q' if intermediates.first() == Some(&b'>') => self.report_version(),
+            'q' if intermediates.first() == Some(&b' ') => {
+                self.grid.set_cursor_shape(match raw(params, 0) {
+                    3 | 4 => CursorShape::Underline,
+                    5 | 6 => CursorShape::Beam,
+                    _ => CursorShape::Block,
+                });
+            }
             'p' if intermediates.contains(&b'$') => self.report_mode(params, private),
             'n' => self.device_status(params),
             's' => self.grid.save_cursor(),
@@ -445,6 +478,12 @@ impl Perform for Term {
                     self.title = Some(String::from_utf8_lossy(text).into_owned());
                 }
             }
+            // OSC 12: set cursor colour; OSC 112: reset to default.
+            Some(&n) if n == b"12" => {
+                self.grid
+                    .set_cursor_color(params.get(1).and_then(|s| parse_color(s)));
+            }
+            Some(&n) if n == b"112" => self.grid.set_cursor_color(None),
             _ => {}
         }
     }
@@ -529,6 +568,57 @@ mod tests {
         assert_eq!(t.grid().cell(1, 0).underline, Underline::None);
     }
 
+    #[test]
+    fn decscusr_and_cursor_visibility() {
+        let mut t = Term::new(20, 1);
+        feed(&mut t, b"\x1b[4 q");
+        assert_eq!(t.grid().cursor_shape(), CursorShape::Underline);
+        feed(&mut t, b"\x1b[6 q");
+        assert_eq!(t.grid().cursor_shape(), CursorShape::Beam);
+        feed(&mut t, b"\x1b[0 q");
+        assert_eq!(t.grid().cursor_shape(), CursorShape::Block);
+
+        feed(&mut t, b"\x1b[?25l");
+        assert!(!t.grid().cursor_visible());
+        feed(&mut t, b"\x1b[?25h");
+        assert!(t.grid().cursor_visible());
+    }
+
+    #[test]
+    fn osc12_sets_and_resets_cursor_color() {
+        let mut t = Term::new(20, 1);
+        feed(&mut t, b"\x1b]12;#ff0000\x07");
+        assert_eq!(t.grid().cursor_color(), Some((255, 0, 0)));
+        feed(&mut t, b"\x1b]12;rgb:00/80/ff\x07");
+        assert_eq!(t.grid().cursor_color(), Some((0, 0x80, 0xff)));
+        feed(&mut t, b"\x1b]112\x07");
+        assert_eq!(t.grid().cursor_color(), None);
+    }
+
+    #[test]
+    fn decscusr_and_cursor_color() {
+        use crate::grid::CursorShape;
+        let mut t = Term::new(20, 1);
+        feed(&mut t, b"\x1b[5 q"); // blinking bar
+        assert_eq!(t.grid().cursor_shape(), CursorShape::Beam);
+        feed(&mut t, b"\x1b[4 q"); // steady underline
+        assert_eq!(t.grid().cursor_shape(), CursorShape::Underline);
+        feed(&mut t, b"\x1b]12;#ff3030\x07");
+        assert_eq!(t.grid().cursor_color(), Some((0xff, 0x30, 0x30)));
+        feed(&mut t, b"\x1b]112\x07");
+        assert_eq!(t.grid().cursor_color(), None);
+        feed(&mut t, b"\x1b[?25l"); // hide cursor
+        assert!(!t.grid().cursor_visible());
+    }
+
+    #[test]
+    fn parse_color_forms() {
+        assert_eq!(parse_color(b"rgb:ff/00/80"), Some((255, 0, 128)));
+        assert_eq!(parse_color(b"rgb:ffff/0000/8080"), Some((255, 0, 128)));
+        assert_eq!(parse_color(b"#ff0080"), Some((255, 0, 128)));
+        assert_eq!(parse_color(b"nonsense"), None);
+    }
+
     #[test]
     fn title_stack_push_pop() {
         let mut t = Term::new(20, 4);

src/wayland.rs

@@ -128,6 +128,7 @@ pub fn run() -> anyhow::Result<ExitCode> {
         width: DEFAULT_W,
         height: DEFAULT_H,
         dirty: false,
+        focused: true,
         exit: false,
         exit_code: ExitCode::SUCCESS,
     };
@@ -182,6 +183,8 @@ struct App {
     height: u32,
     /// The grid changed and the window needs repainting.
     dirty: bool,
+    /// Whether the toplevel currently has keyboard focus (drives the cursor).
+    focused: bool,
     exit: bool,
     /// Exit code to return, taken from the shell when it exits.
     exit_code: ExitCode,
@@ -252,8 +255,13 @@ impl App {
                 }
             };
 
-        self.renderer
-            .render(self.term.grid(), canvas, w as usize, h as usize);
+        self.renderer.render(
+            self.term.grid(),
+            canvas,
+            w as usize,
+            h as usize,
+            self.focused,
+        );
 
         let surface = self.window.wl_surface();
         if let Err(err) = buffer.attach_to(surface) {
@@ -322,6 +330,7 @@ impl WindowHandler for App {
             self.width = w.get();
             self.height = h.get();
         }
+        self.focused = configure.is_activated();
         self.resize_grid();
         self.draw();
     }