如何在 pylatex 中添加页面背景图像?

Question

我已经编写了以下代码，并使用NoEscape模块给出了用于绘制背景的latex命令。

我有一个图像报告bg.png与程序位于同一目录中。现在，我希望此图像在报表的所有页面中显示为背景。

types = ('../Faults/*.png', '../Faults/*.jpg')
imgnames = []
for files in types:
imgnames.extend(natsort.natsorted(glob.glob(files)))
geometry_options = { "head": "30pt",
"margin": "0.3in",
"top": "0.2in",
"bottom": "0.4in",
"includeheadfoot": True}
doc = Document(geometry_options=geometry_options)
first_page = PageStyle("firstpage")
doc.preamble.append(first_page)
doc.change_document_style("firstpage")
new_comm1 = NoEscape(r'usepackage{wallpaper}')
doc.append(new_comm1)
new_comm2 = NoEscape(r'CenterWallPaper{reportbg.png}')
doc.append(new_comm2)
with doc.create(Section('Faults identified')):
doc.append("Report")
with doc.create(Subsection('Fault pictures')):
for i,imgname in enumerate(imgnames): 
with doc.create(Figure(position='h!')) as f_pic:
f_pic.add_image(imgname, width='220px')
f_pic.add_caption('Height: '+str(56)+', Angle: '+str(20))
doc.append('Some regular text')

但是，我收到以下错误：

! LaTeX Error: Can be used only in preamble.
See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
...                                              
l.23 usepackage
{wallpaper}%
! Undefined control sequence.
l.24 CenterWallPaper
{reportbg.png}%
<../Faults/1.jpg, id=1, 1927.2pt x 1084.05pt> <use ../Faults/1.jpg>
<../Faults/2.jpg, id=2, 1927.2pt x 1084.05pt> <use ../Faults/2.jpg>
<../Faults/3.jpg, id=3, 1927.2pt x 1084.05pt> <use ../Faults/3.jpg>
<../Faults/4.jpg, id=4, 1003.75pt x 1003.75pt> <use ../Faults/4.jpg>
LaTeX Warning: '!h' float specifier changed to '!ht'.

Answer 1

要在文档的所有页面上实现背景图像，您可以先在pylatex中生成PDF文档，然后使用PyPDF2将图像添加为水印。为此，您需要将"reportbg.png"图像转换为pdf格式(reportbg.pdf)。

下面是一个基于 pylatex 文档 (https://jeltef.github.io/PyLaTeX/current/examples/basic.html) 的修改示例：

法典

from pylatex import Document, Section, Subsection, Command
from pylatex.utils import italic, NoEscape
import PyPDF2
class Document_Watermark():
def __init__(self, doc):
self.doc = doc
self.fill_document()
self.create_document()
self.Watermark()
def fill_document(self):
"""Add a section, a subsection and some text to the document.
:param doc: the document
:type doc: :class:`pylatex.document.Document` instance
"""
with self.doc.create(Section('A section')):
self.doc.append('Some regular text and some ')
self.doc.append(italic('italic text. '))
with self.doc.create(Subsection('A subsection')):
self.doc.append('Also some crazy characters: $&#{}')
def create_document(self):
# Add stuff to the document
with self.doc.create(Section('A second section')):
self.doc.append('Some text.')
self.doc.generate_pdf('basic_maketitle2', clean_tex=False, compiler='pdflatex')
tex = self.doc.dumps()  # The document as string in LaTeX syntax
def Watermark(self):
Doc = open('basic_maketitle2.pdf', 'rb')
pdfReader = PyPDF2.PdfFileReader(Doc)
pdfWatermark = PyPDF2.PdfFileReader(open('watermark3.pdf', 'rb'))
pdfWriter = PyPDF2.PdfFileWriter()
for pageNum in range(0, pdfReader.numPages):
pageObj = pdfReader.getPage(pageNum)
pageObj.mergePage(pdfWatermark.getPage(0))
pdfWriter.addPage(pageObj)
resultPdfFile = open('PDF_Watermark.pdf', 'wb')
pdfWriter.write(resultPdfFile)
Doc.close()
resultPdfFile.close()

# Basic document
doc = Document('basic')

# Document with `maketitle` command activated
doc = Document()
doc.preamble.append(Command('title', 'Awesome Title'))
doc.preamble.append(Command('author', 'Anonymous author'))
doc.preamble.append(Command('date', NoEscape(r'today')))
doc.append(NoEscape(r'maketitle'))
Document_Watermark(doc)

• 示例水印是这样的：水印3.pdf
• 初始 PDF 文档：basic_maketitle2.pdf
• 最后文件：PDF_Watermark.pdf

PS：水印，初始生成的pdf和.py文件必须位于同一目录中。我无法上传PDF文件，因为这是我的第一个答案帖子，我不太确定我怎么能，但我分享了一些图像。我希望这会有所帮助。 欲了解更多信息，我建议阅读以下书籍：Al Sweigart的"Automate the Boring stuff with Python"，第13章。