使用PyPDF2对pdf切边并保留书签addBookMark

　　最近再网上下了一本pdf电子书（扫描版），质量不错。只是边缘太宽了，看起来不方便，就想着找一个切边工具。搜了一圈二，没有找到好用的，就自己动手。

win10 下载python3 官方网址：https://www.python.org/

安装包

pip install PyPDF2

这里用到了PdfFileReader PageObject PdfFileWriter 这几个主要的类，以下简单的pdf操作

import PyPDF2
            
pdfFile = open('123.pdf','rb')

pdfReader = PyPDF2.PdfFileReader(pdfFile)
pdfWriter = PyPDF2.PdfFileWriter()

#获取页数
count = pdfReader.numPages

#获取目录信息
outlines = pdfReader.getOutlines()
   
#获取原始页面的size
firstpage = pdfReader.getPage(0)
w = float(firstpage.mediaBox.getWidth())
h = float(firstpage.mediaBox.getHeight())

#读取pdf文件第一页
pageObj = pdfReader.getPage(0) 

#写入pdf页
pdfWriter.addPage(pageObj)

#写入书签
pdfWriter.addBookmark(title='Hello PyPDF2', pagenum=1)

#写入文件
pdfWriter.write(open('321.pdf','wb'))

pdfFile.close()

　完整切边代码

# -*- coding: utf-8 -*-
"""
Created on Tue Apr 21 17:51:20 2020

@author: teyond

下载的pdf边缘很大，代码切了一下，同样加载了标签
"""


import PyPDF2

#-----------------------------------------------------------------------------
#解析目录
page_marks = {} #标签
#信息整理：父索引序号，页内索引号，标题，类型
def get_bookmark_info(strline,level_id):
    dtn = strline
    idobj = dtn.page 

    return level_id,pageLabels[idobj.idnum],dtn.title,dtn.typ
    
#第一级索引信息
def get_fist_grade(strline,level1_id=0):
    num = level1_id
    parent_id = level1_id
    for subline in strline:
        if isinstance(subline, list):
            num,parent_id = get_second_grade(subline,num)
        else:
            num = num+1
            page_marks[num] = get_bookmark_info(subline,level1_id)
            #print('level1---:',num,parent_id)
    return num,parent_id
#第二级索引信息
def get_second_grade(strline,level2_id=0):    
    num = level2_id
    parent_id = level2_id
    for subline in strline:
        if isinstance(subline, list):
            num,parent_id= get_third_grade(subline,num)
        else:
            num = num+1
            page_marks[num] = get_bookmark_info(subline,level2_id)
            #print('level2---:',num,parent_id)
    return num,parent_id
#第三级索引信息
def get_third_grade(strline,level3_id=0):    
    num = level3_id
    parent_id = level3_id
    for subline in strline:
        if isinstance(subline, list):
            num,parent_id = get_fourth_grade(subline,num)
        else:
            num = num+1
            page_marks[num] = get_bookmark_info(subline,level3_id)
            #print('level3---:',num,parent_id)
    return num,parent_id
#第四级索引信息
def get_fourth_grade(strline,level4_id=0):    
    num = level4_id
    parent_id = level4_id
    for subline in strline:
        if isinstance(subline, list):
            continue
        else:
            num = num+1
            page_marks[num] = get_bookmark_info(subline,level4_id)
            #print('level4---:',num,parent_id)
    return num,parent_id
#-----------------------------------------------------------------------------
            
pdfFile = open('123.pdf','rb')

pdfReader = PyPDF2.PdfFileReader(pdfFile)
pdfWriter = PyPDF2.PdfFileWriter()

#-----------------------------------------------------------------------------
#检索页面
count = pdfReader.numPages
pageLabels = {} #标签页
for index in range(count):
    pageObj = pdfReader.getPage(index)   
    pageLabels[pageObj.indirectRef.idnum] = index  #页码索引

outlines = pdfReader.getOutlines()
get_fist_grade(outlines)
#print(page_marks)
#------------------------------------------------------------------------------
   
#获取原始页面的size
firstpage = pdfReader.getPage(0)
w = float(firstpage.mediaBox.getWidth())
h = float(firstpage.mediaBox.getHeight())

#切边后在原页面位置
xs = w*0.21    #截取页面left
xe = w*0.79    #截取页面right
ys = 0
ye = h
#-----------------------------------------------------------------------------    
#页面剪切 页面四个顶点，位置需要输出自己调整
for index in range(count):
    pageObj = pdfReader.getPage(index)    
    pageObj.mediaBox.uppderLeft = (xs,ye)
    pageObj.mediaBox.uppderRight = (xe,ye)
    pageObj.mediaBox.lowerLeft = (xs,ys)
    pageObj.mediaBox.lowerRight = (xe,ys)  
    pdfWriter.addPage(pageObj)    
#-----------------------------------------------------------------------------    
#添加书签 
pg_marks={}
for index in range(1,len(page_marks)+1):
    (pt_index,pgnum,pgtitle,bktyp) = page_marks[index]
    if pt_index==0:
        #添加书签，建书签索引
        pg_marks[index]=pdfWriter.addBookmark(title=pgtitle, pagenum=pgnum, fit=bktyp)
    else:
        #存在父节点，书签定向到父节点下面        
        pts = pg_marks[pt_index]
        pg_marks[index]=pdfWriter.addBookmark(title=pgtitle, pagenum=pgnum,parent=pts, fit=bktyp)
#-----------------------------------------------------------------------------  
#写入文件
pdfWriter.write(open('321.pdf','wb'))

pdfFile.close()