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Split a PDF vertically, used for imposed scanned double sided PDF pages
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| # see https://stackoverflow.com/questions/51973437/reverse-pdf-imposition | |
| import copy | |
| import sys | |
| import math | |
| import pyPdf | |
| """ | |
| Reverse imposing: | |
| --A3-- --A4-- | |
| [12| 1] [1] | |
| [ 2|11] [2] | |
| [10| 3] => [3] | |
| ... ... | |
| [ 6| 7] [6] | |
| [7] | |
| ... | |
| [12] | |
| """ | |
| def split_pages(src, dst): | |
| src_f = file(src, 'r+b') | |
| dst_f = file(dst, 'w+b') | |
| input_PDF = pyPdf.PdfFileReader(src_f) | |
| num_pages = input_PDF.getNumPages() | |
| first_half, second_half = [], [] | |
| for i in range(num_pages): | |
| p = input_PDF.getPage(i) | |
| q = copy.copy(p) | |
| q.mediaBox = copy.copy(p.mediaBox) | |
| x1, x2 = p.mediaBox.lowerLeft | |
| x3, x4 = p.mediaBox.upperRight | |
| x1, x2 = math.floor(x1), math.floor(x2) | |
| x3, x4 = math.floor(x3), math.floor(x4) | |
| x5, x6 = math.floor(x3/2), math.floor(x4/2) | |
| if x3 > x4: | |
| # horizontal | |
| p.mediaBox.upperRight = (x5, x4) | |
| p.mediaBox.lowerLeft = (x1, x2) | |
| q.mediaBox.upperRight = (x3, x4) | |
| q.mediaBox.lowerLeft = (x5, x2) | |
| else: | |
| # vertical | |
| p.mediaBox.upperRight = (x3, x4) | |
| p.mediaBox.lowerLeft = (x1, x6) | |
| q.mediaBox.upperRight = (x3, x6) | |
| q.mediaBox.lowerLeft = (x1, x2) | |
| if i in range(1,num_pages+1,2): | |
| first_half += [p] | |
| second_half += [q] | |
| else: | |
| first_half += [q] | |
| second_half += [p] | |
| output = pyPdf.PdfFileWriter() | |
| for page in first_half + second_half[::-1]: | |
| output.addPage(page) | |
| output.write(dst_f) | |
| src_f.close() | |
| dst_f.close() | |
| if len(sys.argv) < 3: | |
| print("\nusage:\n$ python reverse_impose.py input.pdf output.pdf") | |
| sys.exit() | |
| input_file = sys.argv[1] | |
| output_file = sys.argv[2] | |
| split_pages(input_file,output_file) |
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