如何使用Reportlab正确设置PDF文件的"作者"，"标题"和"主题"属性？ 我在第 56 页的 Reportlab 用户指南中找到了这些方法，但我不确定如何正确实现它们。
在我的 PDF 裁剪和缩放脚本下面，我添加了annotations方法，但我不知道从哪里调用它们，或者是否需要一个全新的Canvas对象。请原谅冗长的代码，但只有在第 113 行之后才创建doc，上面主要是辅助方法，包括第 30 行的annotations方法。
# All the necessary parameters are accessible after line 92,
# but can of course be changed manually in the Code
# imports for the crop, rename to avoid conflict with reportlab Image import
from PIL import Image as imgPIL
from PIL import ImageChops, ImageOps, ImageFilter
import os.path, sys
# import for the PDF creation
import glob
from reportlab.lib.pagesizes import A4
from reportlab.lib import utils
from reportlab.platypus import Image, SimpleDocTemplate, Spacer
from reportlab.pdfgen import canvas
# get os path for Cropping
path = (os.path.dirname(os.path.abspath("cropPDF.py")))
dirs = os.listdir(path)
def trim(im, border="white"):
bg = imgPIL.new(im.mode, im.size, border)
diff = ImageChops.difference(im, bg)
bbox = diff.getbbox()
if bbox:
return im.crop(bbox)
def annotations(canvas):
canvas.setAuthor("the ReportLab Team")
canvas.setTitle("ReportLab PDF Generation User Guide")
canvas.setSubject("How to Generate PDF files using the ReportLab modules")
def findMaxWidth():
maxWidth = 0
for item in dirs:
try:
fullpath = os.path.join(path, item)
if os.path.isfile(fullpath):
im = imgPIL.open(fullpath)
maxWidth = max(maxWidth, im.size[0])
except:
pass
return maxWidth
def padImages(docHeight):
maxWidth = findMaxWidth()
for item in dirs:
try:
fullpath = os.path.join(path, item)
if os.path.isfile(fullpath):
im = imgPIL.open(fullpath)
f, e = os.path.splitext(fullpath)
width, height = im.size # get the image dimensions, the height is needed for the blank image
if not docHeight <= height: # to prevent oversized images from bein padded, such that they remain centered
image = imgPIL.new('RGB', (maxWidth, height),
(255, 255, 255)) # create a white image with the max width
image.paste(im, (0, 0)) # paste the original image overtop the blank one, flush on the left side
image.save(f + ".png", "PNG", quality=100)
except:
pass
def crop():
for item in dirs:
try:
fullpath = os.path.join(path, item)
if os.path.isfile(fullpath):
im = imgPIL.open(fullpath)
f, e = os.path.splitext(fullpath)
imCrop = trim(im, "white")
imCrop.save(f + ".png", "PNG", quality=100)
except:
pass
def add_page_number(canvas, doc):
canvas.saveState()
canvas.setFont('Times-Roman', numberFontSize)
page_number_text = "%d" % (doc.page)
canvas.drawCentredString(
pageNumberSpacing * mm,
pageNumberSpacing * mm,
page_number_text
)
canvas.restoreState()
#############################
executeCrop = True
executePad = True
outputName = "output.pdf" #The name of the file that will be created
fileAuthor = "Roman Stadler" #these 3 attributes are visible in the file info menu
fileTitle = ""
fileSubject = ""
margin = 0.5
imageWidthDefault = 550
spacerHeight = 7
scalingIfImageTooTall = 0.95 # larger than 95 can result in an empty page after the image
includePagenumbers = True
numberFontSize = 10
pageNumberSpacing = 5
############################
doc = SimpleDocTemplate(
outputName,
topMargin=margin * mm,
leftMargin=margin * mm,
rightMargin=margin * mm,
bottomMargin=margin * mm,
pagesize=A4
)
if executeCrop:
crop()
if executePad:
padImages(doc.height)
filelist = glob.glob("*.png") # Get a list of files in the current directory
filelist.sort()
story = [] # create the list of images for the PDF
for fn in filelist:
img = utils.ImageReader(fn)
img_width, img_height = img.getSize() # necessary for the aspect ratio
aspect = img_height / float(img_width)
documentHeight = doc.height
imageWidth = imageWidthDefault
imageHeight = imageWidth * aspect
if imageHeight > documentHeight:
imageHeight = documentHeight * scalingIfImageTooTall
imageWidth = imageHeight / aspect
img = Image(
fn,
width=imageWidth,
height=imageHeight
)
story.append(img)
space = Spacer(width=0, height=spacerHeight)
story.append(space)
if includePagenumbers and not len(filelist) == 0: # if pagenumbers are desired, or not
doc.build(
story,
onFirstPage=add_page_number,
onLaterPages=add_page_number,
)
elif not len(filelist) == 0:
doc.build(story)
else: # to prevent an empty PDF that can't be opened
print("no files found")
在将文档定义为简单文档模板时，可以定义作者等属性
doc = SimpleDocTemplate(
outputName,
topMargin=margin * mm,
leftMargin=margin * mm,
rightMargin=margin * mm,
bottomMargin=margin * mm,
pagesize=A4,
title="This is the title of the document", #exchange with your title
author="John Smith", #exchange with your authors name
subject"Adding metadata to pdf via reportlab" #exchange with your subject
)
与此同时，我找到了另一种方法，不使用reportlab，而是依赖于PyPDF2：
需要以下导入：
# PyPDF2 for the metadata modification
from PyPDF2 import PdfFileReader, PdfFileWriter
然后可以像这样编辑元数据：
author = "Roman Stadler"
title = "CropPDF"
subject = "Stackoverflow"
#rest of the script
#attemp the metadate edit
try:
file = open('output.pdf', 'rb+')
reader = PdfFileReader(file)
writer = PdfFileWriter()
writer.appendPagesFromReader(reader)
metadata = reader.getDocumentInfo()
writer.addMetadata(metadata)
writer.addMetadata({
'/Author': author,
'/Title': title,
'/Subject' : subject,
'/Producer' : "CropPDF",
'/Creator' : "CropPDF",
})
writer.write(file)
file.close()
except:
print("Error while editing metadata")