René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"PdfWriter add_page adds (re)writes old page instead of new","articleBody":"# Bug report\n\n### Bug description:\n\nThe purpose of the following code (as a simplification) is to add PDF pages alternatively from 2 different opencv images.\nTo make the sequence unique, a sequence number is written to each PDF page saved. The PDF is written every 2 images but this is not essential\nHerewith I expect a resulting PDF file with 60 pages numbered  #1, #2, #3, ... #59,  #60.\n\nHowever the resulting PDF file shows a sequence which in my case starts erratically from the 25th page:\n#1, #2, #3, #4, #5, #6, #7, #8, #9, #10, #11, #12, #13, #14, #15, #16, #17, #18, #19, #20, #21, #22, #23, #24, #20, #22, #18, #19, #29, #30.\n#31, #32, #33, #34, #35, #36, #37, #38, #39, #40, #36, #37, #34, #35, #32, #33, #30, #31, #19, #29, #21, #18, #24, #20, #55, #23, #57, #23, #59, #20\n \n#25, #26, #27, #28 are missing an have been substituted by #20, #21, #18, #19.\nThen everything is back on track to #40\nIn the remainder of the sequence #55, #57 and #59 are on the right page. The rest shows an 'older' page \n\nThe import of PyPDF2 is version 3.0.1\n\n[pythonSeq.pdf](https://github.com/user-attachments/files/20565415/pythonSeq.pdf)\n\n```if os.path.exists(\"pythonSeq.pdf\"):\n    os.remove(\"pythonSeq.pdf\")\n\npdf_writer = PdfWriter()\n\nimage1 = cv2.imread(\"Picture1.png\")\nimage2 = cv2.imread(\"Picture2.png\")\nfor seq in range(1,61,2):\n    clone = image1.copy()\n    cv2.putText(clone,f'Seq#{seq}', (200,30), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 0, 0), 3)\n    cv2.imwrite(\"python.jpg\",clone)\n    pdf_image = Image.open(\"python.jpg\")\n    pdf_image.save(\"python.pdf\", format=\"PDF\")\n    image_reader = PdfReader(\"python.pdf\")\n    pdf_writer.add_page(image_reader.pages[0])\n\n    clone = image2.copy()\n    cv2.putText(clone,f'Seq#{seq+1}', (200,30), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 0, 0), 3)\n    cv2.imwrite(\"python.jpg\",clone)\n    pdf_image = Image.open(\"python.jpg\")\n    pdf_image.save(\"python.pdf\", format=\"PDF\")\n    image_reader = PdfReader(\"python.pdf\")\n    pdf_writer.add_page(image_reader.pages[0])\n\n[pythonSeq.pdf](https://github.com/user-attachments/files/20565446/pythonSeq.pdf)\n\n    with open(\"pythonSeq.pdf\", \"wb\") as pdf_file:\n        pdf_writer.write(pdf_file)```\n\n\n### CPython versions tested on:\n\n3.13\n\n### Operating systems tested on:\n\nWindows","author":{"url":"https://github.com/DominiquePACCO","@type":"Person","name":"DominiquePACCO"},"datePublished":"2025-06-03T08:55:23.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/135062/cpython/issues/135062"}