Initial attempt at imposition

.gitignore

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+venv
+__pycache__

pympose.py

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+import pypdf
+
+
+def main(source, out, section_length):
+    assert section_length % 4 == 0
+    in_reader = pypdf.PdfReader(source)
+    out_writer = pypdf.PdfWriter()
+
+    to_add = section_length - len(in_reader.pages) % section_length
+    add_before = to_add // 2
+    add_after = to_add - add_before
+
+    pages = [pypdf.PageObject.create_blank_page(in_reader) for _ in range(add_before)]
+    pages += in_reader.pages
+    pages += [pypdf.PageObject.create_blank_page(in_reader) for _ in range(add_after)]
+
+    for sig_start in range(0, len(in_reader.pages), section_length):
+        for side in range(section_length // 4):
+            top = [
+                sig_start + section_length - side - 1,
+                sig_start + side,
+            ]
+            bottom = [
+                sig_start + section_length // 2 + side,
+                sig_start + section_length // 2 + side - 1,
+            ]
+
+            if side % 2 != 0:
+                top = list(reversed(top))
+                bottom = list(reversed(bottom))
+
+
+            print(top)
+            print(bottom)
+
+        continue
+        for si, pi in enumerate(range(sig_start, sig_start + section_length)):
+            page_box = pages[pi]
+            trans = pypdf.Transformation()
+
+            if si >= section_length // 4 and si < 3 * section_length // 4:
+                trans = trans.rotate(180)
+
+            trans = trans.scale(0.5, 0.5)