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/insert_blank.py

@@ -0,0 +1,58 @@
+"""Moteur Insertion de pages blanches."""
+
+from pypdf import PdfReader, PdfWriter
+from .pdf_utils import get_page_size
+
+
+def insert_blank_pages(input_path, output_path, mode="after", position=None,
+                       every_n=None, target_multiple=None, page_size=None):
+    """Inserer des pages blanches.
+
+    mode: "before", "after", "every_n", "pad_to_multiple"
+    position: numero de page (1-based) pour before/after
+    every_n: inserer apres chaque N pages
+    target_multiple: arrondir au multiple de N
+    page_size: (w, h) en points ou None pour meme taille que page adjacente
+    """
+    reader = PdfReader(input_path)
+    writer = PdfWriter()
+
+    if mode == "pad_to_multiple" and target_multiple:
+        for page in reader.pages:
+            writer.add_page(page)
+        num = len(reader.pages)
+        remainder = num % target_multiple
+        if remainder != 0:
+            to_add = target_multiple - remainder
+            last_w, last_h = get_page_size(reader.pages[-1])
+            w, h = page_size if page_size else (last_w, last_h)
+            for _ in range(to_add):
+                writer.add_blank_page(w, h)
+
+    elif mode == "every_n" and every_n:
+        for i, page in enumerate(reader.pages):
+            writer.add_page(page)
+            if (i + 1) % every_n == 0 and i + 1 < len(reader.pages):
+                w, h = get_page_size(page)
+                bw, bh = page_size if page_size else (w, h)
+                writer.add_blank_page(bw, bh)
+
+    elif mode in ("before", "after") and position:
+        idx = position - 1  # 0-based
+        for i, page in enumerate(reader.pages):
+            if mode == "before" and i == idx:
+                w, h = get_page_size(page)
+                bw, bh = page_size if page_size else (w, h)
+                writer.add_blank_page(bw, bh)
+            writer.add_page(page)
+            if mode == "after" and i == idx:
+                w, h = get_page_size(page)
+                bw, bh = page_size if page_size else (w, h)
+                writer.add_blank_page(bw, bh)
+    else:
+        for page in reader.pages:
+            writer.add_page(page)
+
+    with open(output_path, "wb") as f:
+        writer.write(f)
+    return output_path