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/join_pages.py

@@ -0,0 +1,60 @@
+"""Moteur Joindre deux pages."""
+
+from pypdf import PdfReader, PdfWriter, PageObject, Transformation
+from .pdf_utils import get_page_size
+
+
+def join_pages(input_path, output_path, direction="horizontal"):
+    """Joindre les pages par paires.
+
+    direction: "horizontal" (cote a cote) ou "vertical" (dessus/dessous)
+    """
+    reader = PdfReader(input_path)
+    pages = reader.pages
+    writer = PdfWriter()
+
+    for i in range(0, len(pages), 2):
+        page1 = pages[i]
+        page2 = pages[i + 1] if i + 1 < len(pages) else None
+
+        w1, h1 = get_page_size(page1)
+
+        if page2:
+            w2, h2 = get_page_size(page2)
+        else:
+            w2, h2 = w1, h1
+
+        if direction == "horizontal":
+            new_w = w1 + w2
+            new_h = max(h1, h2)
+            sheet = PageObject.create_blank_page(width=new_w, height=new_h)
+
+            overlay1 = PageObject.create_blank_page(width=new_w, height=new_h)
+            overlay1.merge_page(page1)
+            sheet.merge_page(overlay1)
+
+            if page2:
+                overlay2 = PageObject.create_blank_page(width=new_w, height=new_h)
+                overlay2.merge_page(page2)
+                overlay2.add_transformation(Transformation().translate(w1, 0))
+                sheet.merge_page(overlay2)
+        else:  # vertical
+            new_w = max(w1, w2)
+            new_h = h1 + h2
+            sheet = PageObject.create_blank_page(width=new_w, height=new_h)
+
+            overlay1 = PageObject.create_blank_page(width=new_w, height=new_h)
+            overlay1.merge_page(page1)
+            overlay1.add_transformation(Transformation().translate(0, h2))
+            sheet.merge_page(overlay1)
+
+            if page2:
+                overlay2 = PageObject.create_blank_page(width=new_w, height=new_h)
+                overlay2.merge_page(page2)
+                sheet.merge_page(overlay2)
+
+        writer.add_page(sheet)
+
+    with open(output_path, "wb") as f:
+        writer.write(f)
+    return output_path