Impression CUPS réelle + stickers/cadres de démo

Service printer :
- crop_to_ratio() : recadrage auto au ratio du format
- prepare_for_print() : crop + resize aux pixels exacts (300 DPI)
- print_image() : envoi via lp à CUPS avec le bon nombre de copies
- list_printers() : détection des imprimantes disponibles

Print screen :
- Impression dans un thread (pas de freeze UI)
- Feedback : "Envoi à l'imprimante..." → "Impression terminée" / erreur
- Gestion des erreurs CUPS

Assets de démo :
- 5 stickers (heart, star, smile, thumbsup, camera)
- 2 cadres (gold, white)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/services/printer.py

@@ -0,0 +1,162 @@
+"""Service d'impression CUPS — prépare les images et envoie les jobs."""
+
+import os
+import subprocess
+import tempfile
+from PIL import Image
+
+# DPI pour l'impression sublimation
+PRINT_DPI = 300
+
+# Dimensions en pixels à 300 DPI
+FORMAT_PIXELS = {
+    "10x15": (1181, 1772),   # 10cm x 15cm
+    "13x18": (1535, 2126),   # 13cm x 18cm
+    "15x20": (1772, 2362),   # 15cm x 20cm
+}
+
+FORMAT_RATIOS = {
+    "10x15": 1.5,
+    "13x18": 1.385,
+    "15x20": 1.333,
+}
+
+
+def list_printers():
+    """Liste les imprimantes CUPS disponibles."""
+    try:
+        result = subprocess.run(
+            ["lpstat", "-p", "-d"],
+            capture_output=True, text=True, timeout=5
+        )
+        printers = []
+        default = ""
+        for line in result.stdout.splitlines():
+            if line.startswith("printer "):
+                name = line.split()[1]
+                printers.append(name)
+            if "system default destination:" in line:
+                default = line.split(":")[-1].strip()
+        return printers, default
+    except (FileNotFoundError, subprocess.TimeoutExpired):
+        return [], ""
+
+
+def crop_to_ratio(image, ratio):
+    """Crop centré au ratio donné (largeur/hauteur en paysage)."""
+    w, h = image.size
+    img_ratio = w / h
+
+    # Adapter le ratio au sens de l'image
+    if w < h:
+        target_ratio = 1.0 / ratio
+    else:
+        target_ratio = ratio
+
+    if img_ratio > target_ratio:
+        # Image trop large → crop horizontal
+        new_w = int(h * target_ratio)
+        offset = (w - new_w) // 2
+        return image.crop((offset, 0, offset + new_w, h))
+    else:
+        # Image trop haute → crop vertical
+        new_h = int(w / target_ratio)
+        offset = (h - new_h) // 2
+        return image.crop((0, offset, w, offset + new_h))
+
+
+def prepare_for_print(image_path, format_name, crop_rect=None):
+    """Prépare une image pour l'impression : crop, redimensionnement, export.
+
+    Args:
+        image_path: chemin de l'image source
+        format_name: "10x15", "13x18", "15x20"
+        crop_rect: (x, y, w, h) en pixels de l'image source, ou None pour auto
+
+    Returns:
+        chemin du fichier temporaire prêt à imprimer
+    """
+    img = Image.open(image_path)
+
+    # Appliquer le crop manuel si fourni
+    if crop_rect:
+        x, y, w, h = crop_rect
+        img = img.crop((x, y, x + w, y + h))
+    else:
+        # Auto-crop au ratio
+        ratio = FORMAT_RATIOS.get(format_name, 1.5)
+        img = crop_to_ratio(img, ratio)
+
+    # Redimensionner aux dimensions exactes du format
+    target = FORMAT_PIXELS.get(format_name, (1181, 1772))
+
+    # Orienter selon l'image
+    if img.width < img.height:
+        # Portrait
+        target = (min(target), max(target))
+    else:
+        # Paysage
+        target = (max(target), min(target))
+
+    img = img.resize(target, Image.Resampling.LANCZOS)
+
+    # Sauvegarder en JPEG haute qualité
+    output = os.path.join(tempfile.gettempdir(), f"photostation_print_{os.getpid()}.jpg")
+    img.save(output, "JPEG", quality=95, dpi=(PRINT_DPI, PRINT_DPI))
+    return output
+
+
+def print_image(image_path, format_name, printer="", copies=1, crop_rect=None):
+    """Prépare et imprime une image.
+
+    Args:
+        image_path: chemin de l'image source
+        format_name: "10x15", "13x18", "15x20"
+        printer: nom CUPS (vide = défaut)
+        copies: nombre de copies
+        crop_rect: (x, y, w, h) ou None
+
+    Returns:
+        (success, message)
+    """
+    try:
+        # Préparer l'image
+        print_file = prepare_for_print(image_path, format_name, crop_rect)
+
+        # Construire la commande lp
+        cmd = ["lp"]
+        if printer:
+            cmd.extend(["-d", printer])
+        cmd.extend(["-n", str(copies)])
+        # Options d'impression
+        cmd.extend(["-o", "fit-to-page"])
+        cmd.extend(["-o", f"resolution={PRINT_DPI}dpi"])
+        cmd.append(print_file)
+
+        result = subprocess.run(
+            cmd, capture_output=True, text=True, timeout=30
+        )
+
+        if result.returncode == 0:
+            # Extraire l'ID du job
+            job_info = result.stdout.strip()
+            print(f"[Impression] OK: {job_info}")
+            return True, job_info
+        else:
+            error = result.stderr.strip() or result.stdout.strip()
+            print(f"[Impression] Erreur: {error}")
+            return False, error
+
+    except FileNotFoundError:
+        return False, "Commande lp non trouvée — CUPS installé ?"
+    except subprocess.TimeoutExpired:
+        return False, "Timeout impression"
+    except Exception as e:
+        return False, str(e)
+    finally:
+        # Nettoyage
+        try:
+            if 'print_file' in locals():
+                os.unlink(print_file)
+        except OSError:
+            pass

src/ui/screens/print_screen.py

@@ -321,15 +321,42 @@ class PrintScreen(QWidget):
         self.price_label.setStyleSheet("color: #F44336; font-weight: bold;")
 
     def _do_print(self, printer=""):
-        """Lance l'impression réelle."""
+        """Lance l'impression réelle via CUPS."""
+        from services.printer import print_image
+        import threading
+
+        self.print_btn.setEnabled(False)
+        self.print_btn.setText("Impression en cours...")
+        self.price_label.setText("Envoi à l'imprimante...")
+        self.price_label.setStyleSheet("color: #FF9800; font-weight: bold;")
+
+        def run_print():
+            results = []
+            for path, qty in self.print_list:
+                success, msg = print_image(
+                    path, self.selected_format,
+                    printer=printer, copies=qty
+                )
+                results.append((path, qty, success, msg))
+
+            # Retour au thread principal
+            from PyQt6.QtCore import QTimer
+            from functools import partial
+            QTimer.singleShot(0, partial(self._print_done, results))
+
+        threading.Thread(target=run_print, daemon=True).start()
+
+    def _print_done(self, results):
+        """Callback après impression."""
         self.print_btn.setEnabled(True)
         self.print_btn.setText("IMPRIMER")
 
-        for path, qty in self.print_list:
-            print(f"[Impression] {path} x{qty} → {self.selected_format} cm"
-                  f" (printer: {printer or 'défaut'})")
-            # TODO: appel CUPS réel
+        total = sum(q for _, q, _, _ in results)
+        errors = [msg for _, _, ok, msg in results if not ok]
 
-        total = sum(q for _, q in self.print_list)
-        self.price_label.setText(f"Impression lancée — {total} photo{'s' if total > 1 else ''}")
-        self.price_label.setStyleSheet("color: #4CAF50; font-weight: bold;")
+        if errors:
+            self.price_label.setText(f"Erreur : {errors[0]}")
+            self.price_label.setStyleSheet("color: #F44336; font-weight: bold;")
+        else:
+            self.price_label.setText(f"Impression terminée — {total} photo{'s' if total > 1 else ''}")
+            self.price_label.setStyleSheet("color: #4CAF50; font-weight: bold;")