Resizable grid with orca's bindings: ( ) width, _ + height, Ctrl+arrows

Grid is now dynamic (w/h up to a max, fixed-stride storage so slot indices
stay stable and content isn't remapped). Ruler marks (+) on empty cells for
orientation; cursor clamps on shrink; status shows the size.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GLUwWE2KmFPzhKaf67tWbx

src/dsp.rs

@@ -9,7 +9,7 @@
 //! params, lowercase a-z read MIDI CC (a = CC 0). A neighbour to the left/right
 //! supplies a parameter; `M` instead reads the left cell as a second signal.
 
-use crate::grid::{Grid, H, SLOTS, W};
+use crate::grid::{Grid, MAX_W, SLOTS};
 
 pub const MAX_STATE: usize = 4 * SLOTS;
 pub const TAU: f32 = std::f32::consts::TAU;
@@ -110,20 +110,23 @@ pub fn compile(grid: &Grid) -> Program {
     let mut nodes = Vec::new();
     let mut st = 0usize;
     let mut has_env = false;
-    for row in 0..H {
-        for col in 0..W {
+    for row in 0..grid.h {
+        for col in 0..grid.w {
             let Some((op, ssize)) = op_of(grid.get(col, row)) else { continue };
             if matches!(op, Op::Env) {
                 has_env = true;
             }
-            let input =
-                if row > 0 && occupied(grid.get(col, row - 1)) { Some((row - 1) * W + col) } else { None };
-            let lsig = if col > 0 { Some(row * W + col - 1) } else { None };
+            let input = if row > 0 && occupied(grid.get(col, row - 1)) {
+                Some((row - 1) * MAX_W + col)
+            } else {
+                None
+            };
+            let lsig = if col > 0 { Some(row * MAX_W + col - 1) } else { None };
             let left = if col > 0 { param_of(grid.get(col - 1, row)) } else { Param::None };
-            let right = if col + 1 < W { param_of(grid.get(col + 1, row)) } else { Param::None };
+            let right = if col + 1 < grid.w { param_of(grid.get(col + 1, row)) } else { Param::None };
             let this_st = st;
             st = (st + ssize).min(MAX_STATE - 4);
-            nodes.push(Node { op, out: row * W + col, input, lsig, left, right, st: this_st });
+            nodes.push(Node { op, out: row * MAX_W + col, input, lsig, left, right, st: this_st });
         }
     }
     Program { nodes, has_env }

src/grid.rs

@@ -1,31 +1,55 @@
-//! The fixed-size character grid that is the editor surface.
+//! The character grid — the editor surface. Logical size (`w`×`h`) is
+//! resizable up to the max; cells are stored at a fixed `MAX_W` stride so a
+//! resize never remaps existing content and compiled slot indices stay stable.
 
-pub const W: usize = 24;
-pub const H: usize = 16;
-pub const SLOTS: usize = W * H;
+pub const MAX_W: usize = 40;
+pub const MAX_H: usize = 24;
+pub const SLOTS: usize = MAX_W * MAX_H;
+pub const DEFAULT_W: usize = 24;
+pub const DEFAULT_H: usize = 16;
+pub const RULER: usize = 8;
 
 #[derive(Clone)]
 pub struct Grid {
+    pub w: usize,
+    pub h: usize,
     cells: Vec<char>,
 }
 
 impl Grid {
     pub fn new() -> Self {
-        Grid { cells: vec!['.'; SLOTS] }
+        Grid { w: DEFAULT_W, h: DEFAULT_H, cells: vec!['.'; SLOTS] }
     }
 
     #[inline]
     pub fn get(&self, col: usize, row: usize) -> char {
-        if col < W && row < H {
-            self.cells[row * W + col]
+        if col < self.w && row < self.h {
+            self.cells[row * MAX_W + col]
         } else {
             '.'
         }
     }
 
     pub fn set(&mut self, col: usize, row: usize, c: char) {
-        if col < W && row < H {
-            self.cells[row * W + col] = c;
+        if col < self.w && row < self.h {
+            self.cells[row * MAX_W + col] = c;
         }
     }
+
+    /// Resize to nh×nw, clamped to [1, MAX]. Content keeps its position.
+    pub fn resize(&mut self, nh: usize, nw: usize) {
+        self.h = nh.clamp(1, MAX_H);
+        self.w = nw.clamp(1, MAX_W);
+    }
+}
+
+/// orca-c's ruler snap: resize by one ruler division, snapped to a
+/// ruler-aligned size (1, 9, 17, ...) rather than a plain +/-1.
+pub fn ruler_snap(size: usize, delta_rulers: isize) -> usize {
+    if size == 0 {
+        return if delta_rulers > 0 { RULER * delta_rulers as usize } else { 1 };
+    }
+    let size = if delta_rulers < 0 { size + RULER - 1 } else { size };
+    let n = ((size as isize - 1) / RULER as isize + delta_rulers).max(0);
+    (RULER as isize * n + 1) as usize
 }

src/tui.rs

@@ -1,7 +1,7 @@
 //! Grid editor. crossterm renderer adapted from orca-rs's grid view: a centered
-//! canvas with per-glyph colour and a change-diff so only cells that actually
-//! change get repainted (a full clear+redraw each frame flickers over SSH on
-//! terminals that ignore synchronized-update, e.g. macOS Terminal). `?` toggles
+//! canvas with per-glyph colour, ruler marks, resize bindings, and a change-diff
+//! so only cells that actually change repaint (a full clear+redraw each frame
+//! flickers over SSH on terminals that ignore synchronized-update). `?` toggles
 //! a detailed help overlay; run a spectrum analyzer on the side if you want one.
 
 use std::io::{self, Write};
@@ -19,7 +19,7 @@ use crossterm::terminal::{
 use crossterm::{execute, queue, terminal};
 
 use crate::dsp::{compile, Program};
-use crate::grid::{Grid, H, W};
+use crate::grid::{ruler_snap, Grid, RULER};
 
 const HELP: &[&str] = &[
     "galdr — grid synthesizer",
@@ -40,6 +40,7 @@ const HELP: &[&str] = &[
     "ROUTING   M mix — adds the cell to its LEFT      ! output to master",
     "",
     "KEYS      arrows move · type a glyph to place · Backspace clears",
+    "          ( ) width -/+   _ + height -/+   Ctrl+arrows resize by one",
     "          ? toggle this help · Esc quit",
 ];
 
@@ -58,7 +59,6 @@ fn glyph_color(c: char) -> Color {
         '!' => Color::Magenta,
         '0'..='9' => Color::Grey,
         'a'..='z' => Color::DarkYellow,
-        '.' => Color::DarkGrey,
         _ => Color::White,
     }
 }
@@ -68,13 +68,24 @@ struct Renderer {
     status: String,
     tw: u16,
     th: u16,
+    gw: usize,
+    gh: usize,
     help: bool,
     init: bool,
 }
 
 impl Renderer {
     fn new() -> Self {
-        Renderer { cells: Vec::new(), status: String::new(), tw: 0, th: 0, help: false, init: false }
+        Renderer {
+            cells: Vec::new(),
+            status: String::new(),
+            tw: 0,
+            th: 0,
+            gw: 0,
+            gh: 0,
+            help: false,
+            init: false,
+        }
     }
 }
 
@@ -102,6 +113,8 @@ pub fn run(
                 continue;
             }
             let ctrl = k.modifiers.contains(KeyModifiers::CONTROL);
+            let mut resized = false;
+            let mut edited = false;
             match k.code {
                 KeyCode::Esc => {
                     if help {
@@ -112,22 +125,61 @@ pub fn run(
                 }
                 KeyCode::Char('c') if ctrl => return Ok(()),
                 KeyCode::Char('?') => help = !help,
-                _ if help => {} // any other key: ignore while help is open
+                _ if help => {}
+                KeyCode::Char('(') => {
+                    grid.resize(grid.h, ruler_snap(grid.w, -1));
+                    resized = true;
+                }
+                KeyCode::Char(')') => {
+                    grid.resize(grid.h, ruler_snap(grid.w, 1));
+                    resized = true;
+                }
+                KeyCode::Char('_') => {
+                    grid.resize(ruler_snap(grid.h, -1), grid.w);
+                    resized = true;
+                }
+                KeyCode::Char('+') => {
+                    grid.resize(ruler_snap(grid.h, 1), grid.w);
+                    resized = true;
+                }
+                KeyCode::Left if ctrl => {
+                    grid.resize(grid.h, grid.w.saturating_sub(1));
+                    resized = true;
+                }
+                KeyCode::Right if ctrl => {
+                    grid.resize(grid.h, grid.w + 1);
+                    resized = true;
+                }
+                KeyCode::Up if ctrl => {
+                    grid.resize(grid.h.saturating_sub(1), grid.w);
+                    resized = true;
+                }
+                KeyCode::Down if ctrl => {
+                    grid.resize(grid.h + 1, grid.w);
+                    resized = true;
+                }
                 KeyCode::Left => cx = cx.saturating_sub(1),
-                KeyCode::Right => cx = (cx + 1).min(W - 1),
+                KeyCode::Right => cx = (cx + 1).min(grid.w - 1),
                 KeyCode::Up => cy = cy.saturating_sub(1),
-                KeyCode::Down => cy = (cy + 1).min(H - 1),
+                KeyCode::Down => cy = (cy + 1).min(grid.h - 1),
                 KeyCode::Backspace | KeyCode::Delete => {
                     grid.set(cx, cy, '.');
-                    prog.store(Arc::new(compile(&grid)));
+                    edited = true;
                 }
                 KeyCode::Char(c) => {
                     grid.set(cx, cy, if c == ' ' { '.' } else { c });
-                    prog.store(Arc::new(compile(&grid)));
-                    cx = (cx + 1).min(W - 1);
+                    edited = true;
+                    cx = (cx + 1).min(grid.w - 1);
                 }
                 _ => {}
             }
+            if resized {
+                cx = cx.min(grid.w - 1);
+                cy = cy.min(grid.h - 1);
+            }
+            if resized || edited {
+                prog.store(Arc::new(compile(&grid)));
+            }
         }
     })();
 
@@ -149,15 +201,20 @@ fn draw(
 ) -> io::Result<()> {
     let (tw, th) = terminal::size()?;
 
-    // Full repaint only on first frame, resize, or a help toggle - never every
-    // frame (that is the flicker).
-    let full = !r.init || tw != r.tw || th != r.th || help != r.help;
+    let full = !r.init
+        || tw != r.tw
+        || th != r.th
+        || help != r.help
+        || grid.w != r.gw
+        || grid.h != r.gh;
     if full {
         queue!(out, Clear(ClearType::All))?;
-        r.cells = vec![('\0', Cs::Fg(Color::Reset)); W * H];
+        r.cells = vec![('\0', Cs::Fg(Color::Reset)); grid.w * grid.h];
         r.status.clear();
         r.tw = tw;
         r.th = th;
+        r.gw = grid.w;
+        r.gh = grid.h;
         r.help = help;
         r.init = true;
     }
@@ -179,27 +236,40 @@ fn draw(
         return out.flush();
     }
 
-    let off_x = (tw as usize).saturating_sub(W) / 2;
-    let off_y = (th as usize).saturating_sub(H + 1) / 2;
-    for row in 0..H {
-        for col in 0..W {
-            let c = grid.get(col, row);
-            let cs = if col == cx && row == cy { Cs::Cursor } else { Cs::Fg(glyph_color(c)) };
-            let idx = row * W + col;
-            if r.cells[idx] == (c, cs) {
+    let off_x = (tw as usize).saturating_sub(grid.w) / 2;
+    let off_y = (th as usize).saturating_sub(grid.h + 1) / 2;
+    for row in 0..grid.h {
+        for col in 0..grid.w {
+            let raw = grid.get(col, row);
+            // ruler mark on empty intersections, for orientation while sizing
+            let disp = if raw == '.' {
+                if row % RULER == 0 && col % RULER == 0 { '+' } else { '.' }
+            } else {
+                raw
+            };
+            let cs = if col == cx && row == cy {
+                Cs::Cursor
+            } else if raw == '.' {
+                Cs::Fg(Color::DarkGrey)
+            } else {
+                Cs::Fg(glyph_color(raw))
+            };
+            let idx = row * grid.w + col;
+            if r.cells[idx] == (disp, cs) {
                 continue;
             }
-            r.cells[idx] = (c, cs);
+            r.cells[idx] = (disp, cs);
             queue!(out, MoveTo((off_x + col) as u16, (off_y + row) as u16), SetAttribute(Attribute::Reset))?;
             match cs {
                 Cs::Cursor => queue!(out, SetAttribute(Attribute::Reverse))?,
                 Cs::Fg(color) => queue!(out, SetForegroundColor(color))?,
             }
-            queue!(out, Print(c))?;
+            queue!(out, Print(disp))?;
         }
     }
 
-    let status = format!("voices {voices}   latency {latency}f   ? help   Esc quit");
+    let status =
+        format!("voices {voices}   {}x{}   latency {latency}f   ? help   Esc quit", grid.w, grid.h);
     if status != r.status {
         r.status = status.clone();
         let pad: String = format!("{status:<width$}", width = tw as usize);