Python实现为pdf添加水印功能
作者:KjPrime
这篇文章主要介绍了Python实现给普通PDF添加水印的方法,文中通过示例代码介绍的非常详细,对大家的学习或者工作具有一定的参考学习价值,需要的朋友们下面随着小编来一起学习学习吧
创建需要的水印模板
wps创建
输出pdf
水印pdf
实现步骤
安装依赖
pip install PyPDF2
代码
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: # 这一段try except是一个让我超级麻烦的bug,让我解决了一天。 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]: # 一个文件夹里面有多少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), "个pdf文件") return file_list def group_write_watermark(path_array: list[str], watermark_pdf_path: str): # 一组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 = "目录" # 需要添加水印的pdf的目录 pdf_list = folder_pdf_files(folder_pdf) group_write_watermark(pdf_list, watermark_pdf_path)
问题
UnicodeEncodeError: ‘latin-1’ codec can’t encode characters in position 8-9: ordinal not in range(256)
如果出现该错误,可以参考以下内容。
使用pypdf2出现编码问题
报错信息
‘latin-1’ codec can’t encode characters in position 8-11: ordinal not in range(256)
通常这情况是出现了中文字符编码问题
以下是使用pypdf2复制 pdf 时报错信息
//报错信息 <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)
解决方法
1、修改pypdf2包中的generic.py文件
由于我使用的是anaconda,路径为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
修改为
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
问题解决
感悟
此代码的创新点在于可以实现文件夹遍历添加水印。
其实第一点也没有什么,我感觉我最有成功感的就是write_watermark函数里那段try except语句处,这个一段代码解决pdf空白页而发送的错误。解决了一天,网络上都没有解决方法。我摸着石头过河。
有一个问题就是,这个代码对于图片pdf的水印效果不好,因为图片pdf的也页面大小比普通的文字pdf大一些,难以控制水印的位置。我想的是在创建水印pdf的时候就把pdf的大小放大。
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