fix(linux): make FieldLens an explicit PDF to PWG CUPS filter

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@fieldlens/print",
-  "version": "0.1.11",
+  "version": "0.1.12",
   "private": true,
   "type": "module",
   "scripts": {

src-tauri/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "fieldlens-print"
-version = "0.1.11"
+version = "0.1.12"
 description = "FieldLens print-stream barcode capture companion"
 authors = ["Arrowstack"]
 edition = "2021"

src-tauri/src/printers.rs

@@ -25,85 +25,91 @@ const FIELDLENS_CUPS_SPOOL_DIR: &str = "/var/cache/cups/fieldlens-print";
 const FIELDLENS_CUPS_FILTER: &str = r#"#!/usr/bin/python3
 import os
 import re
+import shutil
+import subprocess
 import sys
+import tempfile
 
-SPOOL = os.path.join(os.environ.get("CUPS_CACHEDIR", "/var/cache/cups"), "fieldlens-print")
+CACHE = os.path.join(os.environ.get("CUPS_CACHEDIR", "/var/cache/cups"), "fieldlens-print")
 
 def safe(value):
     value = re.sub(r"[^A-Za-z0-9._-]+", "-", value or "job").strip("-")
     return value[:80] or "job"
 
+def find_pdftoraster():
+    for path in (
+        "/usr/lib/cups/filter/pdftoraster",
+        "/usr/libexec/cups/filter/pdftoraster",
+    ):
+        if os.path.isfile(path) and os.access(path, os.X_OK):
+            return path
+    return None
+
 job_id = safe(sys.argv[1] if len(sys.argv) > 1 else "job")
 title = safe(sys.argv[3] if len(sys.argv) > 3 else "print")
 printer = safe(os.environ.get("PRINTER", "printer"))
-content_type = os.environ.get("CONTENT_TYPE", "application/pdf")
+prefix = "test-" if printer.lower() == "fieldlens-test-capture" else "print-"
-is_test = printer.lower() == "fieldlens-test-capture"
+name = f"{prefix}{printer}-{job_id}-{title}.pdf"
-prefix = "test-" if is_test else "print-"
+final_path = os.path.join(CACHE, name)
-ext = "pdf" if "pdf" in content_type else "dat"
-
-# Use a deterministic name so multiple PDF pre-filter stages for the same
-# CUPS job do not create duplicate FieldLens jobs.
-name = f"{prefix}{printer}-{job_id}-{title}.{ext}"
-final_path = os.path.join(SPOOL, name)
 part_path = final_path + ".part"
 
-source = None
+input_path = None
-capture = None
+temporary_input = None
-captured_ok = False
+
 try:
     if len(sys.argv) > 6 and sys.argv[6]:
-        source = open(sys.argv[6], "rb")
+        input_path = sys.argv[6]
     else:
-        source = sys.stdin.buffer
+        fd, temporary_input = tempfile.mkstemp(prefix="fieldlens-cups-", suffix=".pdf")
+        with os.fdopen(fd, "wb") as target:
+            shutil.copyfileobj(sys.stdin.buffer, target)
+        input_path = temporary_input
 
-    # If an earlier pre-filter stage already captured this job, only pass the
+    try:
-    # bytes onward. Otherwise tee the pre-driver document into CUPS_CACHEDIR.
+        os.makedirs(CACHE, exist_ok=True)
-    if not os.path.exists(final_path):
+        if not os.path.exists(final_path):
-        try:
+            shutil.copyfile(input_path, part_path)
-            os.makedirs(SPOOL, exist_ok=True)
+            os.chmod(part_path, 0o644)
-            capture = open(part_path, "wb")
+            os.replace(part_path, final_path)
-        except OSError as error:
+            print(f"INFO: FieldLens captured {name}", file=sys.stderr)
-            print(f"WARNING: FieldLens capture cache unavailable: {error}", file=sys.stderr)
+    except OSError as error:
-            capture = None
+        print(f"WARNING: FieldLens capture cache failed: {error}", file=sys.stderr)
 
-    while True:
+    pdftoraster = find_pdftoraster()
-        chunk = source.read(65536)
+    if pdftoraster is None:
-        if not chunk:
+        print("ERROR: FieldLens could not find the standard CUPS pdftoraster filter", file=sys.stderr)
-            break
+        sys.exit(1)
 
-        if capture is not None:
+    env = os.environ.copy()
-            try:
+    env["FINAL_CONTENT_TYPE"] = "image/pwg-raster"
-                capture.write(chunk)
-            except OSError as error:
-                print(f"WARNING: FieldLens capture write failed: {error}", file=sys.stderr)
-                try:
-                    capture.close()
-                except OSError:
-                    pass
-                capture = None
 
-        sys.stdout.buffer.write(chunk)
+    args = [
+        pdftoraster,
+        sys.argv[1] if len(sys.argv) > 1 else "0",
+        sys.argv[2] if len(sys.argv) > 2 else "unknown",
+        sys.argv[3] if len(sys.argv) > 3 else "FieldLens Print",
+        sys.argv[4] if len(sys.argv) > 4 else "1",
+        sys.argv[5] if len(sys.argv) > 5 else "",
+        input_path,
+    ]
 
-    sys.stdout.buffer.flush()
+    result = subprocess.run(
-
+        args,
-    if capture is not None:
+        stdout=sys.stdout.buffer,
-        capture.flush()
+        stderr=sys.stderr.buffer,
-        capture.close()
+        env=env,
-        capture = None
+    )
-        os.chmod(part_path, 0o644)
+    sys.exit(result.returncode)
-        os.replace(part_path, final_path)
-        captured_ok = True
-        print(f"INFO: FieldLens captured {name}", file=sys.stderr)
 finally:
-    if source is not None and source is not sys.stdin.buffer:
+    if temporary_input is not None:
-        source.close()
-    if capture is not None:
-        capture.close()
-    if not captured_ok:
         try:
-            os.unlink(part_path)
+            os.unlink(temporary_input)
         except OSError:
             pass
+    try:
+        os.unlink(part_path)
+    except OSError:
+        pass
 "#;
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -583,9 +589,9 @@ fn build_fieldlens_ppd(target_printer: &str) -> Result<PathBuf> {
     cleaned.push('\n');
 
     let prefilter = concat!(
-        "*% FieldLens original-document capture before printer rendering\n",
+        "*% FieldLens original-document capture and PDF-to-PWG conversion\n",
-        "*cupsPreFilter: \"application/pdf 0 fieldlens-capture\"\n",
+        "*cupsFilter2: \"application/pdf image/pwg-raster 10 fieldlens-capture\"\n",
-        "*cupsPreFilter: \"application/vnd.cups-pdf 0 fieldlens-capture\"\n"
+        "*cupsFilter2: \"application/vnd.cups-pdf image/pwg-raster 10 fieldlens-capture\"\n"
     );
     if let Some(index) = cleaned.rfind("*% End") {
         cleaned.insert_str(index, prefilter);

src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "FieldLens Print",
-  "version": "0.1.11",
+  "version": "0.1.12",
   "identifier": "dev.arrowstack.fieldlens.print",
   "build": {
     "beforeDevCommand": "npm run dev",

src/main.ts

@@ -85,7 +85,7 @@ let config: AppConfig
 let jobs: Job[] = []
 let status: Status
 let loginTimer: number | undefined
-let currentVersion = '0.1.11'
+let currentVersion = '0.1.12'
 let bundleType: BundleType | null = null
 let availableUpdate: Update | null = null
 let availableManualUpdate: ManualUpdate | null = null