Initial commit — Copydev Imposing Tool

Outil d'imposition PDF desktop (PyQt6) remplacant Quite Imposing Plus.
9 fonctions : livret, n-up, step & repeat, imposition manuelle,
jointure pages, pages blanches, numerotation, masquage, fonds perdus.

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

app/engine/masking.py

@@ -0,0 +1,53 @@
+"""Moteur Masquage (Masking Tape) — rectangles blancs."""
+
+from pypdf import PdfReader, PdfWriter
+from reportlab.pdfgen import canvas
+from .pdf_utils import get_page_size
+import io
+
+
+def apply_masking(input_path, output_path, rectangles, apply_to="all"):
+    """Appliquer des rectangles blancs de masquage.
+
+    rectangles: liste de dicts {"x": pt, "y": pt, "width": pt, "height": pt}
+    apply_to: "all", "even", "odd", ou un numero de page (1-based)
+    """
+    reader = PdfReader(input_path)
+    writer = PdfWriter()
+
+    for i, page in enumerate(reader.pages):
+        page_num = i + 1
+
+        should_apply = False
+        if apply_to == "all":
+            should_apply = True
+        elif apply_to == "even":
+            should_apply = page_num % 2 == 0
+        elif apply_to == "odd":
+            should_apply = page_num % 2 != 0
+        elif isinstance(apply_to, int):
+            should_apply = page_num == apply_to
+
+        if should_apply and rectangles:
+            w, h = get_page_size(page)
+            packet = io.BytesIO()
+            c = canvas.Canvas(packet, pagesize=(w, h))
+            c.setFillColorRGB(1, 1, 1)
+            c.setStrokeColorRGB(1, 1, 1)
+
+            for rect in rectangles:
+                c.rect(rect["x"], rect["y"], rect["width"], rect["height"],
+                       fill=1, stroke=0)
+
+            c.showPage()
+            c.save()
+            packet.seek(0)
+
+            overlay_reader = PdfReader(packet)
+            page.merge_page(overlay_reader.pages[0])
+
+        writer.add_page(page)
+
+    with open(output_path, "wb") as f:
+        writer.write(f)
+    return output_path