After cropping the page, how to ignore the invisible text?

[guaguastandup]

Hello,
I am cutting a double-column pdf into a single-column pdf, and then combine these single-column pages in a new order.

Here is my code:

def split_and_merge(input_pdf, output_pdf):
    writer = PdfWriter()
    reader = PdfReader(input_pdf)
    for i in range(0, len(reader.pages), 2):
        original_media_box = reader.pages[i].mediabox
        width = original_media_box.width
        height = original_media_box.height

        left_page_1 = reader.pages[i]
        left_page_1.cropbox= RectangleObject((0, 0, width / 2, height))

        left_page_2 = reader.pages[i+1]
        left_page_2.cropbox = RectangleObject((0, 0, width / 2, height))

        right_page_1 = reader.pages[i]
        right_page_1.cropbox = RectangleObject((width / 2, 0, width, height))

        right_page_2 = reader.pages[i+1]
        right_page_2.cropbox = RectangleObject((width / 2, 0, width, height))

        blank_page_1 = writer.add_blank_page(width, height)
        blank_page_1.merge_transformed_page(left_page_1, (1, 0, 0, 1, 0, 0))
        blank_page_1.merge_transformed_page(left_page_2, (1, 0, 0, 1, width/2, 0))
        blank_page_2 = writer.add_blank_page(width, height)
        blank_page_2.merge_transformed_page(right_page_1, (1, 0, 0, 1, -width / 2, 0))
        blank_page_2.merge_transformed_page(right_page_2, (1, 0, 0, 1, 0, 0))

And I found that the invisible part of the pdf is still able to be copied and seleted, is there any way to avoid this?

[stefan6419846]

Changing the box values of the page basically just inserts a small code snippet into the PDF file to tell tools like PDF viewers what to show. No actual clipping is done.

Actually implementing clipping might be feasible, but comes with additional loads of complexity and thus AFAIK no FOSS tooling supports this out of the box.

[guaguastandup]

Thank you for your answer.