Python實現(xiàn)為pdf添加水印功能
創(chuàng)建需要的水印模板
wps創(chuàng)建
輸出pdf
水印pdf
實現(xiàn)步驟
安裝依賴
pip install PyPDF2
代碼
import os from PyPDF2 import PdfFileReader as pr from PyPDF2 import PdfFileWriter as pw def write_watermark(watermark_pdf_path: str, target_pdf_path: str): result_pdf = pw() pdf_file_name = os.path.basename(target_pdf_path) f_target = open(target_pdf_path, 'rb') f_watermark = open(watermark_pdf_path, 'rb') target_pdf = pr(f_target) watermark_page = pr(f_watermark).getPage(0) for page in range(target_pdf.getNumPages()): try: # 這一段try except是一個讓我超級麻煩的bug,讓我解決了一天。 target_pdf.getPage(page).mergePage(watermark_page) result_pdf.addPage(target_pdf.getPage(page)) except Exception as e: result_pdf.addPage(watermark_page) if not os.path.exists("output"): os.makedirs("output") result_pdf.write(open("output/已添加水印_" + pdf_file_name, 'wb')) f_target.close() f_watermark.close() def folder_pdf_files(folder: str) -> list[str]: # 一個文件夾里面有多少pdf文件 file_list = [] for a, b, c in os.walk(folder): if b == []: for filename in c: if filename[-3:].lower() == 'pdf': file_path = os.path.join(a, filename) file_list.append(file_path) print(folder, ": 有", len(file_list), "個pdf文件") return file_list def group_write_watermark(path_array: list[str], watermark_pdf_path: str): # 一組pdf文件添加水印 for pdf_path in path_array: print(pdf_path, "添加水印中...") write_watermark(watermark_pdf_path, pdf_path) print("完成") if __name__ == '__main__': watermark_pdf_path = "水印文件.pdf" folder_pdf = "目錄" # 需要添加水印的pdf的目錄 pdf_list = folder_pdf_files(folder_pdf) group_write_watermark(pdf_list, watermark_pdf_path)
問題
UnicodeEncodeError: ‘latin-1’ codec can’t encode characters in position 8-9: ordinal not in range(256)
如果出現(xiàn)該錯誤,可以參考以下內(nèi)容。
使用pypdf2出現(xiàn)編碼問題
報錯信息
‘latin-1’ codec can’t encode characters in position 8-11: ordinal not in range(256)
通常這情況是出現(xiàn)了中文字符編碼問題
以下是使用pypdf2復(fù)制 pdf 時報錯信息
//報錯信息 <ipython-input-1-4f7e1b354328> in <module>() 14 output.addPage(p) 15 with open('D:\\Program Files\\2.pdf', 'wb') as f: ---> 16 output.write(f) D:\Program Files (x86)\anaconda\lib\site-packages\PyPDF2\pdf.py in write(self, stream) 499 md5_hash = md5(key).digest() 500 key = md5_hash[:min(16, len(self._encrypt_key) + 5)] --> 501 obj.writeToStream(stream, key) 502 stream.write(b_("\nendobj\n")) 503 D:\Program Files (x86)\anaconda\lib\site-packages\PyPDF2\generic.py in writeToStream(self, stream, encryption_key) 547 key.writeToStream(stream, encryption_key) 548 stream.write(b_(" ")) --> 549 value.writeToStream(stream, encryption_key) 550 stream.write(b_("\n")) 551 stream.write(b_(">>")) D:\Program Files (x86)\anaconda\lib\site-packages\PyPDF2\generic.py in writeToStream(self, stream, encryption_key) 470 471 def writeToStream(self, stream, encryption_key): --> 472 stream.write(b_(self)) 473 474 def readFromStream(stream, pdf): D:\Program Files (x86)\anaconda\lib\site-packages\PyPDF2\utils.py in b_(s) 236 return s 237 else: --> 238 r = s.encode('latin-1') 239 if len(s) < 2: 240 bc[s] = r UnicodeEncodeError: 'latin-1' codec can't encode characters in position 8-11: ordinal not in range(256)
解決方法
1、修改pypdf2包中的generic.py文件
由于我使用的是anaconda,路徑為anaconda\Lib\site-packages\PyPDF2\generic.py
generic.py文件第488行原文
try: return NameObject(name.decode('utf-8')) except (UnicodeEncodeError, UnicodeDecodeError) as e: # Name objects should represent irregular characters # with a '#' followed by the symbol's hex number if not pdf.strict: warnings.warn("Illegal character in Name Object", utils.PdfReadWarning) return NameObject(name) else: raise utils.PdfReadError("Illegal character in Name Object")
改成
try: return NameObject(name.decode('utf-8')) except (UnicodeEncodeError, UnicodeDecodeError) as e: try: return NameObject(name.decode('gbk')) except (UnicodeEncodeError, UnicodeDecodeError) as e: # Name objects should represent irregular characters # with a '#' followed by the symbol's hex number if not pdf.strict: warnings.warn("Illegal character in Name Object", utils.PdfReadWarning) return NameObject(name) else: raise utils.PdfReadError("Illegal character in Name Object")
2、修改pypdf2包中的utils.py文件
utils.py238行原文
r = s.encode('latin-1') if len(s) < 2: bc[s] = r return r
修改為
try: r = s.encode('latin-1') if len(s) < 2: bc[s] = r return r except Exception as e: print(s) r = s.encode('utf-8') if len(s) < 2: bc[s] = r return r
問題解決
感悟
此代碼的創(chuàng)新點在于可以實現(xiàn)文件夾遍歷添加水印。
其實第一點也沒有什么,我感覺我最有成功感的就是write_watermark函數(shù)里那段try except語句處,這個一段代碼解決pdf空白頁而發(fā)送的錯誤。解決了一天,網(wǎng)絡(luò)上都沒有解決方法。我摸著石頭過河。
有一個問題就是,這個代碼對于圖片pdf的水印效果不好,因為圖片pdf的也頁面大小比普通的文字pdf大一些,難以控制水印的位置。我想的是在創(chuàng)建水印pdf的時候就把pdf的大小放大。
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