z230

2026-05-18 11:03:53 +02:00
parent 1f25bcbc14
commit 6498c4e444
4 changed files with 359 additions and 0 deletions
@@ -0,0 +1,76 @@
+"""
+Rozlozi naskenovanou brozuru do PDF se strankami razenymi od 1.
+
+Predpoklady:
+  - Kazda PDF stranka obsahuje dve stranky brozury vedle sebe (leva + prava).
+  - Sken probíhal duplexne od stredoveho listu smerem ven.
+  - Stredove stranky se odvodi automaticky z poctu PDF stranek.
+
+Pouziti:
+  python rozloz_brozuru.py <vstup.pdf> [vystup.pdf]
+"""
+
+import sys
+import copy
+from pypdf import PdfReader, PdfWriter
+from pypdf.generic import RectangleObject
+
+
+def rozloz(input_path, output_path):
+    reader = PdfReader(input_path)
+    n_pdf = len(reader.pages)
+
+    center_left  = n_pdf           # napr. 12 nebo 40
+    center_right = n_pdf + 1       # napr. 13 nebo 41
+    total_pages  = n_pdf * 2       # celkovy pocet stran brozury
+
+    print(f"PDF stranek : {n_pdf}")
+    print(f"Stran brozury: {total_pages}  (stred: {center_left}+{center_right})")
+
+    # Mapovani: brozurova strana -> (pdf_idx 0-based, 'L'/'P')
+    page_map = {}
+    n_sheets = n_pdf // 2
+
+    for k in range(n_sheets):
+        front_pdf = 2 * k
+        back_pdf  = 2 * k + 1
+
+        page_map[center_left  - 2 * k]     = (front_pdf, 'L')
+        page_map[center_right + 2 * k]     = (front_pdf, 'P')
+        page_map[center_right + 2 * k + 1] = (back_pdf,  'L')
+        page_map[center_left  - 2 * k - 1] = (back_pdf,  'P')
+
+    writer = PdfWriter()
+
+    for bp in range(1, total_pages + 1):
+        pdf_idx, lr = page_map[bp]
+        src = reader.pages[pdf_idx]
+
+        width  = float(src.mediabox.width)
+        height = float(src.mediabox.height)
+        half_w = width / 2
+
+        new_page = copy.copy(src)
+        if lr == 'L':
+            box = RectangleObject([0,      0, half_w, height])
+        else:
+            box = RectangleObject([half_w, 0, width,  height])
+        new_page.mediabox = box
+        new_page.cropbox  = box
+
+        writer.add_page(new_page)
+
+    with open(output_path, "wb") as f:
+        writer.write(f)
+
+    print(f"Hotovo: {output_path}  ({total_pages} stranek)")
+
+
+if __name__ == "__main__":
+    if len(sys.argv) < 2:
+        print("Pouziti: python rozloz_brozuru.py <vstup.pdf> [vystup.pdf]")
+        sys.exit(1)
+
+    inp = sys.argv[1]
+    out = sys.argv[2] if len(sys.argv) > 2 else inp.replace(".pdf", "_serazena.pdf")
+    rozloz(inp, out)