Let the merge example fill, wait for engines and dump the filler's input; add a fill example that re-runs it stage by stage

A fill that went wrong took a seven-minute merge to look at again. Now
DR_FILL_DUMP=dir makes the merge write what the filler was given, and
the fill example runs fill_border on that, or a crop of it, on the engine
and writes coarse, each band and the feathered result as PPMs — seconds
per attempt on TensorRT. Both examples take DARKROOM_ORT_DIR as the app
does, and --wait-engines lets a compiling rung finish before timing.

ui/dr-ui/examples/fill.rs

@@ -0,0 +1,183 @@
+//! Re-run the panorama border fill on what a merge dumped, stage by stage.
+//!
+//!   DR_FILL_DUMP=/var/tmp/fill cargo run --release -p dr-ui --example merge -- --fill a.CR2 b.CR2
+//!   cargo run --release -p dr-ui --example fill -- /var/tmp/fill [--crop X,Y,W,H] [--feather N] [--mirror N] [--band N] [--coarse N]
+//!
+//! Reads `input.ppm` and `known.pgm` from the directory (`dr_ui::merge`
+//! writes them when `DR_FILL_DUMP` is set), runs `fill_border` on the
+//! engine as the merge would, and writes `coarse.ppm`, `band-N.ppm` and
+//! `feathered.ppm` beside them — so a fill that went wrong can be looked
+//! at one stage at a time, in seconds, without the merge around it.
+//! `--crop` works on a window of the dump; the coverage edge must be in it.
+
+use std::path::PathBuf;
+use std::time::Instant;
+
+fn main() {
+    env_logger::init();
+    let mut args: Vec<String> = std::env::args().skip(1).collect();
+    let mut crop: Option<[usize; 4]> = None;
+    let mut params = dr_ui::merge::FillSettings::default().params;
+    let mut wait_engines = false;
+    let mut i = 0;
+    while i < args.len() {
+        match args[i].as_str() {
+            "--crop" => {
+                let v: Vec<usize> = args[i + 1]
+                    .split(',')
+                    .map(|s| s.parse().expect("--crop X,Y,W,H"))
+                    .collect();
+                crop = Some([v[0], v[1], v[2], v[3]]);
+                args.drain(i..i + 2);
+            }
+            "--feather" => {
+                params.feather = args[i + 1].parse().expect("--feather N");
+                args.drain(i..i + 2);
+            }
+            "--mirror" => {
+                params.mirror_depth = args[i + 1].parse().expect("--mirror N");
+                args.drain(i..i + 2);
+            }
+            "--band" => {
+                params.band = args[i + 1].parse().expect("--band N");
+                args.drain(i..i + 2);
+            }
+            "--coarse" => {
+                params.coarse = args[i + 1].parse().expect("--coarse N");
+                args.drain(i..i + 2);
+            }
+            "--wait-engines" => {
+                wait_engines = true;
+                args.remove(i);
+            }
+            _ => i += 1,
+        }
+    }
+    let Some(dir) = args.first().map(PathBuf::from) else {
+        eprintln!("usage: fill [--crop X,Y,W,H] [--feather N] [--mirror N] [--band N] [--coarse N] [--wait-engines] DIR");
+        std::process::exit(2);
+    };
+
+    let (w, h, mut rgb) = read_ppm(&dir.join("input.ppm"));
+    let (kw, kh, known) = read_pgm(&dir.join("known.pgm"));
+    assert_eq!((w, h), (kw, kh), "input and mask differ in size");
+    let mut known: Vec<bool> = known.into_iter().map(|v| v > 127).collect();
+    let (w, h) = if let Some([x0, y0, cw, ch]) = crop {
+        let mut r = Vec::with_capacity(cw * ch * 3);
+        let mut k = Vec::with_capacity(cw * ch);
+        for y in y0..y0 + ch {
+            r.extend_from_slice(&rgb[(y * w + x0) * 3..(y * w + x0 + cw) * 3]);
+            k.extend_from_slice(&known[y * w + x0..y * w + x0 + cw]);
+        }
+        rgb = r;
+        known = k;
+        (cw, ch)
+    } else {
+        (w, h)
+    };
+    eprintln!(
+        "{w}×{h}, {:.1}% to fill",
+        100.0 * known.iter().filter(|k| !**k).count() as f64 / known.len() as f64
+    );
+
+    let mut runtime_dirs = Vec::new();
+    if let Some(d) = std::env::var_os("DARKROOM_ORT_DIR") {
+        runtime_dirs.push(PathBuf::from(d));
+    }
+    runtime_dirs.push(PathBuf::from("/usr/lib/darkroom"));
+    runtime_dirs.push(PathBuf::from("/usr/lib"));
+    dr_ui::inference::init(runtime_dirs);
+    if wait_engines {
+        loop {
+            let s = dr_inference_engine::status();
+            eprintln!(
+                "inference: {} ({}), engines {}/{}",
+                s.line(),
+                s.reason,
+                s.engines.0,
+                s.engines.1
+            );
+            if !s.probing && s.engines.0 >= s.engines.1 {
+                break;
+            }
+            std::thread::sleep(std::time::Duration::from_secs(5));
+        }
+    }
+    let path = dr_ui::inpaint_model().expect("no migan-512.onnx in the model directory");
+    let mut model = dr_pano::migan::MiGan::from_path(&path).expect("open the filler");
+    eprintln!(
+        "filler on {}",
+        model.rung().map(|r| r.label()).unwrap_or("?")
+    );
+
+    struct Dump {
+        dir: PathBuf,
+        started: Instant,
+    }
+    impl dr_pano::Observer for Dump {
+        fn progress(&mut self, done: usize, total: usize) {
+            if done.is_multiple_of(8) || done == total {
+                eprintln!(
+                    "  {done}/{total} {:.1}s",
+                    self.started.elapsed().as_secs_f64()
+                );
+            }
+        }
+        fn stage(&mut self, name: &str, rgb: &[f32], width: usize, height: usize) {
+            eprintln!(
+                "{name}: {width}×{height} at {:.1}s",
+                self.started.elapsed().as_secs_f64()
+            );
+            write_ppm(&self.dir.join(format!("{name}.ppm")), rgb, width, height);
+        }
+    }
+    let mut dump = Dump {
+        dir: dir.clone(),
+        started: Instant::now(),
+    };
+    let tiles =
+        dr_pano::fill_border(&mut rgb, w, h, &known, &mut model, params, &mut dump).expect("fill");
+    eprintln!(
+        "{tiles} tiles in {:.1}s",
+        dump.started.elapsed().as_secs_f64()
+    );
+}
+
+fn read_header(bytes: &[u8], magic: &str) -> (usize, usize, usize) {
+    // P6/P5, width, height, maxval, one whitespace, then the data.
+    let text = std::str::from_utf8(&bytes[..64.min(bytes.len())]).unwrap_or("");
+    let mut it = text.split_ascii_whitespace();
+    assert_eq!(it.next(), Some(magic), "not a {magic} file");
+    let w: usize = it.next().unwrap().parse().unwrap();
+    let h: usize = it.next().unwrap().parse().unwrap();
+    let maxval: &str = it.next().unwrap();
+    assert_eq!(maxval, "255");
+    // The data starts one byte after the maxval token.
+    let header_len = text.find(maxval).unwrap() + maxval.len() + 1;
+    (w, h, header_len)
+}
+
+fn read_ppm(path: &std::path::Path) -> (usize, usize, Vec<f32>) {
+    let bytes = std::fs::read(path).unwrap_or_else(|e| panic!("{}: {e}", path.display()));
+    let (w, h, start) = read_header(&bytes, "P6");
+    let rgb = bytes[start..start + w * h * 3]
+        .iter()
+        .map(|&v| v as f32 / 255.0)
+        .collect();
+    (w, h, rgb)
+}
+
+fn read_pgm(path: &std::path::Path) -> (usize, usize, Vec<u8>) {
+    let bytes = std::fs::read(path).unwrap_or_else(|e| panic!("{}: {e}", path.display()));
+    let (w, h, start) = read_header(&bytes, "P5");
+    (w, h, bytes[start..start + w * h].to_vec())
+}
+
+fn write_ppm(path: &std::path::Path, rgb: &[f32], w: usize, h: usize) {
+    let mut out = format!("P6\n{w} {h}\n255\n").into_bytes();
+    out.extend(
+        rgb.iter()
+            .map(|v| (v.clamp(0.0, 1.0) * 255.0).round() as u8),
+    );
+    std::fs::write(path, out).expect("write stage");
+}

ui/dr-ui/examples/merge.rs

@@ -2,7 +2,7 @@
 //!
 //! ```sh
 //! cargo run -p dr-ui --example merge --release -- fixtures/pano/2025-08-05/*.CR2
-//! cargo run -p dr-ui --example merge --release -- --out /var/tmp frame1.CR2 …
+//! cargo run -p dr-ui --example merge --release -- --out /var/tmp --fill frame1.CR2 …
 //! ```
 //!
 //! The job the interface runs (`dr_ui::merge`), driven from a loop instead
@@ -18,18 +18,65 @@ fn main() {
     env_logger::init();
     let mut args: Vec<String> = std::env::args().skip(1).collect();
     let mut out_dir = None;
-    if args.first().map(String::as_str) == Some("--out") {
-        args.remove(0);
-        out_dir = Some(PathBuf::from(args.remove(0)));
+    let mut fill = false;
+    let mut wait_engines = false;
+    loop {
+        match args.first().map(String::as_str) {
+            Some("--out") => {
+                args.remove(0);
+                out_dir = Some(PathBuf::from(args.remove(0)));
+            }
+            Some("--fill") => {
+                args.remove(0);
+                fill = true;
+            }
+            Some("--wait-engines") => {
+                args.remove(0);
+                wait_engines = true;
+            }
+            _ => break,
+        }
     }
     if args.len() < 2 {
-        eprintln!("usage: merge [--out DIR] <frame> <frame>...");
+        eprintln!("usage: merge [--out DIR] [--fill] [--wait-engines] <frame> <frame>...");
         std::process::exit(2);
     }
     let Ok(gpu) = pollster::block_on(dr_gpu::GpuContext::new_headless()) else {
         eprintln!("no GPU");
         std::process::exit(1);
     };
+    // The inference engine as the desktop app starts it, so the border fill
+    // runs where the app would run it — TensorRT, ONNX Runtime's CPU pool —
+    // rather than on tract, which is a hundred times slower for this model.
+    // `DARKROOM_ORT_DIR` first, as the desktop app takes it: a runtime with
+    // the TensorRT provider where the distribution's has none.
+    let mut runtime_dirs = Vec::new();
+    if let Some(dir) = std::env::var_os("DARKROOM_ORT_DIR") {
+        runtime_dirs.push(std::path::PathBuf::from(dir));
+    }
+    runtime_dirs.push(std::path::PathBuf::from("/usr/lib/darkroom"));
+    runtime_dirs.push(std::path::PathBuf::from("/usr/lib"));
+    dr_ui::inference::init(runtime_dirs);
+    // A compiling rung (TensorRT) serves models from the fallback until
+    // their engines are built, in the background, on first run; the app
+    // lives long enough for that, this example does not. `--wait-engines`
+    // waits for the cache to fill so the fill's timing is the rung's.
+    if wait_engines {
+        loop {
+            let s = dr_inference_engine::status();
+            eprintln!(
+                "inference: {} ({}), engines {}/{}",
+                s.line(),
+                s.reason,
+                s.engines.0,
+                s.engines.1
+            );
+            if !s.probing && s.engines.0 >= s.engines.1 {
+                break;
+            }
+            std::thread::sleep(std::time::Duration::from_secs(5));
+        }
+    }
 
     let frames: Vec<dr_ui::merge::MergeInput> = args
         .iter()
@@ -41,8 +88,10 @@ fn main() {
             .map(std::path::Path::to_path_buf)
             .unwrap_or_else(|| PathBuf::from("."))
     });
-    let request =
+    let mut request =
         dr_ui::merge::MergeRequest::new(frames, dr_ui::merge::MergeDestination::Local(dir));
+    // The filler from the shared models directory, as the app finds it.
+    request.inpaint_model = dr_ui::merge::inpaint_model_path();
     let (tx, rx) = std::sync::mpsc::channel();
     let (decide, decision) = std::sync::mpsc::channel();
     let cancel = dr_ui::merge::Cancel::default();
@@ -75,8 +124,18 @@ fn main() {
                         Err(why) => println!("  frame {k}: NOT ALIGNED — {why}"),
                     }
                 }
+                println!(
+                    "  border fill: {}",
+                    match &r.filler {
+                        Ok(rung) => format!("available, runs on {rung}"),
+                        Err(why) => why.clone(),
+                    }
+                );
                 // Headless: the confirmation the dialog would ask for.
-                let _ = decide.send(dr_ui::merge::Decision::Merge { projection: None });
+                let _ = decide.send(dr_ui::merge::Decision::Merge {
+                    projection: None,
+                    fill: fill.then(dr_ui::merge::FillSettings::default),
+                });
             }
             Done {
                 path,