Dither badge photos before drawing them

src/printer.js

@@ -6,6 +6,8 @@ import { execFile } from 'node:child_process';
 import { createCanvas, loadImage, GlobalFonts } from '@napi-rs/canvas';
 import config from './config.js';
 import { photoAbsolutePath } from './photos.js';
+import { ditherPhoto } from './printing/dither.js';
+import { printPng, printerHealth } from './printing/ql-print.js';
 
 /**
  * Printing happens on the server, not in the kiosk browser.
@@ -113,6 +115,17 @@ async function drawBadge(ctx, widthDots, heightDots, visit, site, accent, startY
   }
 
   const photoSize = photo ? Math.round(unit * (portrait ? 0.52 : 0.5)) : 0;
+
+  // Thermal heads print pure black or nothing, so a photo has to be reduced to
+  // 1-bit before it lands on the canvas — otherwise the plane conversion
+  // thresholds it into a solid blob. Done once here rather than at each draw
+  // site, and at exactly photoSize: rescaling a dithered image resamples the
+  // dot pattern back into greys and undoes the whole thing.
+  //
+  // Skipped on the measuring pass, which never paints.
+  if (photo && photoSize > 0 && startY !== null) {
+    photo = ditherPhoto(photo, photoSize);
+  }
   let cursorY = startY === null ? pad : startY;
   let textLeft = pad;
   let textWidth = widthDots - pad * 2;
@@ -330,33 +343,24 @@ export async function printBadge(visit, site) {
   if (!isConfigured(site)) throw new Error('Server printing is not turned on for this site.');
 
   const png = await renderBadgePng(visit, site);
-  const file = path.join(os.tmpdir(), `badge-${crypto.randomBytes(6).toString('hex')}.png`);
-  fs.writeFileSync(file, png);
-
   const port = Number(site.printer_port) || 9100;
   const target = `tcp://${site.printer_host}:${port}`;
 
-  try {
-    await runBrotherQl(
-      [
-        '--backend', 'network',
-        '--model', site.printer_model || 'QL-820NWB',
-        '--printer', target,
-        'print',
-        '--label', labelFor(site),
-        file,
-      ],
-      config.printing.timeoutMs
-    );
-    note(site.id, true, `Printed to ${site.printer_host}`);
-    return { ok: true, target };
-  } catch (err) {
-    const friendly = explainPrintError(err.message, site.printer_host);
-    note(site.id, false, friendly);
-    throw new Error(friendly);
-  } finally {
-    fs.rm(file, { force: true }, () => {});
-  }
+  // The roll decides whether the job is two-colour, not the accent setting.
+  // A DK-22251 roll refuses a monochrome job even when the badge has no red
+  // on it, so labelFor() is passed straight through and ql-print maps it.
+  const result = await printPng(png, {
+    host: site.printer_host,
+    port,
+    label: labelFor(site),
+  });
+
+  note(site.id, result.ok, result.message);
+  if (!result.ok) throw new Error(result.message);
+
+  // confirmed is false when the printer accepted the bytes but never said the
+  // label came out. Over the network that is the normal case, not a fault.
+  return { ok: true, confirmed: Boolean(result.confirmed), target };
 }
 
 /** A sample badge, for checking the printer and the layout without a real visit. */
@@ -375,7 +379,23 @@ export function sampleVisit(site) {
 }
 
 export function available() {
-  return new Promise((resolve) => {
-    execFile(config.printing.command, ['--version'], (err) => resolve(!err));
+  // Kept for callers that only ask "can this server print at all?". The
+  // external brother_ql binary is no longer involved, so the answer is always
+  // yes; use health(site) to ask about a specific printer.
+  return Promise.resolve(true);
+}
+
+/**
+ * Reachability and, where the printer will say, roll state.
+ *
+ * ready is tri-state: true, false, or null meaning "reachable but it won't
+ * tell us". Null is the normal answer over the network — show it as unknown
+ * in the admin console rather than green or red.
+ */
+export function health(site) {
+  return printerHealth({
+    host: site?.printer_host,
+    port: Number(site?.printer_port) || 9100,
+    label: labelFor(site),
   });
 }