rhenter/base_print.html

## base_print.html
{% load i18n %}
{% load l10n %}
{% load static %}
{% load app_utils %}

<!DOCTYPE html>

<html lang="en">
<head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="description" content="Desc Example">
  <meta name="keywords" content="">
  <meta name="author" content="Example Again">
  <title>
    {{ page_title }}
  </title>
  <!-- Tell the browser to be responsive to screen width -->
  <meta content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no" name="viewport">
{#  <link rel="stylesheet" href="{% static 'dist/css/adminlte.css' %}">#}
  <link rel="stylesheet" href="{% static 'css/print.css' %}">

</head>
<body>
<div class="wrapper">
  <!-- Main content -->
  <section class="pdf">
    <!-- title row -->
    <div class="row">
      <div class="col-12">
        {% block content %}
        {% endblock %}

      </div>
    </div>
  </section>
  <!-- /.content -->
</div>
<!-- ./wrapper -->
</body>
</html>

## base_print_header.html
{% extends 'base_print.html' %}
{% load i18n %}
{% load l10n %}
{% load static %}
{% load app_utils %}

{% block content %}
  <div class="card">
    <div class="vertical-center text-center">
      <img class="logo" src="{% static 'img/logo.png' %}" alt="">
      <span class="title-text"> {{ object.name }}</span>
    </div>
  </div>
{% endblock %}

## pdf.py
import tempfile

from django.http import HttpResponse
from django.template.loader import render_to_string
from weasyprint import CSS, HTML

side_margin = 2
extra_vertical_margin = 20
footer_size = 0


class PdfGenerator:
    """
    Generate a PDF out of a rendered template, with the possibility to integrate nicely
    a header and a footer if provided.

    Notes:
    ------
    - When Weasyprint renders an html into a PDF, it goes though several intermediate steps.
      Here, in this class, we deal mostly with a box representation: 1 `Document` have 1 `Page`
      or more, each `Page` 1 `Box` or more. Each box can contain other box. Hence the recursive
      method `get_element` for example.
      For more, see:
      https://weasyprint.readthedocs.io/en/stable/hacking.html#dive-into-the-source
      https://weasyprint.readthedocs.io/en/stable/hacking.html#formatting-structure
    - Warning: the logic of this class relies heavily on the internal Weasyprint API. This
      snippet was written at the time of the release 47, it might break in the future.
    - This generator draws its inspiration and, also a bit of its implementation, from this
      discussion in the library github issues: https://github.com/Kozea/WeasyPrint/issues/92
    """
    OVERLAY_LAYOUT = '@page {size: A4 portrait; margin: 0;}'

    def __init__(self, main_html, header_html=None, footer_html=None,
                 base_url=None, side_margin=2, extra_vertical_margin=30):
        """
        Parameters
        ----------
        main_html: str
            An HTML file (most of the time a template rendered into a string) which represents
            the core of the PDF to generate.
        header_html: str
            An optional header html.
        footer_html: str
            An optional footer html.
        base_url: str
            An absolute url to the page which serves as a reference to Weasyprint to fetch assets,
            required to get our media.
        side_margin: int, interpreted in cm, by default 2cm
            The margin to apply on the core of the rendered PDF (i.e. main_html).
        extra_vertical_margin: int, interpreted in pixel, by default 30 pixels
            An extra margin to apply between the main content and header and the footer.
            The goal is to avoid having the content of `main_html` touching the header or the
            footer.
        """
        self.main_html = main_html
        self.header_html = header_html
        self.footer_html = footer_html
        self.base_url = base_url
        self.side_margin = side_margin
        self.extra_vertical_margin = extra_vertical_margin

    def _compute_overlay_element(self, element: str):
        """
        Parameters
        ----------
        element: str
            Either 'header' or 'footer'

        Returns
        -------
        element_body: BlockBox
            A Weasyprint pre-rendered representation of an html element
        element_height: float
            The height of this element, which will be then translated in a html height
        """
        html = HTML(
            string=getattr(self, f'{element}_html'),
            base_url=self.base_url,
        )
        element_doc = html.render(stylesheets=[CSS(string=self.OVERLAY_LAYOUT)])
        element_page = element_doc.pages[0]
        element_body = PdfGenerator.get_element(element_page._page_box.all_children(), 'body')
        element_body = element_body.copy_with_children(element_body.all_children())
        element_html = PdfGenerator.get_element(element_page._page_box.all_children(), element)

        element_height = 20
        if element == 'header' and element_html:
            element_height = element_html.height
        if element == 'footer' and element_html:
            element_height = element_page.height - element_html.position_y

        return element_body, element_height

    def _apply_overlay_on_main(self, main_doc, header_body=None, footer_body=None):
        """
        Insert the header and the footer in the main document.

        Parameters
        ----------
        main_doc: Document
            The top level representation for a PDF page in Weasyprint.
        header_body: BlockBox
            A representation for an html element in Weasyprint.
        footer_body: BlockBox
            A representation for an html element in Weasyprint.
        """
        for page in main_doc.pages:
            page_body = PdfGenerator.get_element(page._page_box.all_children(), 'body')

            if header_body:
                page_body.children += header_body.all_children()
            if footer_body:
                page_body.children += footer_body.all_children()

    def render_pdf(self):
        """
        Returns
        -------
        pdf: a bytes sequence
            The rendered PDF.
        """
        if self.header_html:
            header_body, header_height = self._compute_overlay_element('header')
        else:
            header_body, header_height = None, 0
        if self.footer_html:
            footer_body, footer_height = self._compute_overlay_element('footer')
        else:
            footer_body, footer_height = None, 0

        margins = '{header_size}px {side_margin} {footer_size}px {side_margin}'.format(
            header_size=header_height + self.extra_vertical_margin,
            footer_size=footer_height + self.extra_vertical_margin,
            side_margin=f'{self.side_margin}cm',
        )
        content_print_layout = '@page {size: A4 portrait; margin: %s;}' % margins

        html = HTML(
            string=self.main_html,
            base_url=self.base_url,
        )
        main_doc = html.render(stylesheets=[CSS(string=content_print_layout)])

        if self.header_html or self.footer_html:
            self._apply_overlay_on_main(main_doc, header_body, footer_body)
        pdf = main_doc.write_pdf()

        return pdf

    @staticmethod
    def get_element(boxes, element):
        """
        Given a set of boxes representing the elements of a PDF page in a DOM-like way, find the
        box which is named `element`.

        Look at the notes of the class for more details on Weasyprint insides.
        """
        for box in boxes:
            if box.element_tag == element:
                return box
            return PdfGenerator.get_element(box.all_children(), element)


def generate_pdf(template, filename, context_data, base_url=''):
    # Rendered
    header_html = render_to_string('base_print_header.html', context_data)
    html_string = render_to_string(template, context_data)

    pdf = PdfGenerator(
        main_html=html_string,
        header_html=header_html,
        base_url=base_url,
        side_margin=side_margin,
        extra_vertical_margin=extra_vertical_margin
    )
    result = pdf.render_pdf()

    # Creating http response
    response = HttpResponse(content_type='application/pdf;')
    response['Content-Disposition'] = 'inline; filename={}.pdf'.format(filename)
    response['Content-Transfer-Encoding'] = 'binary'
    with tempfile.NamedTemporaryFile(delete=True) as output:
        output.write(result)
        output.flush()

        with open(output.name, 'rb+') as output_file:
            response.write(output_file.read())

    return response

## views.py
from django.views.generic import TemplateView
from .pdf import generate_pdf

...

class ExamplePrintView(TemplateView):
    template_name = 'example/example_print.html'
    page_title = 'Example'

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        object = Example.objects.get(pk=self.kwargs.get('pk'))

        context.update({
            'page_title': self.page_title,
            'object': object,
        })
        return context

    def get(self, request, *args, **kwargs):
        data = self.get_context_data(**kwargs)
        return generate_pdf(
            template=self.template_name,
            filename=self.page_title,
            context_data=data,
            base_url=self.request.build_absolute_uri()
        )
	{% load i18n %}
	{% load l10n %}
	{% load static %}
	{% load app_utils %}

	<!DOCTYPE html>

	<html lang="en">
	<head>
	<meta charset="utf-8">
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<meta name="description" content="Desc Example">
	<meta name="keywords" content="">
	<meta name="author" content="Example Again">
	<title>
	{{ page_title }}
	</title>
	<!-- Tell the browser to be responsive to screen width -->
	<meta content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no" name="viewport">
	{# <link rel="stylesheet" href="{% static 'dist/css/adminlte.css' %}">#}
	<link rel="stylesheet" href="{% static 'css/print.css' %}">

	</head>
	<body>
	<div class="wrapper">
	<!-- Main content -->
	<section class="pdf">
	<!-- title row -->
	<div class="row">
	<div class="col-12">
	{% block content %}
	{% endblock %}

	</div>
	</div>
	</section>
	<!-- /.content -->
	</div>
	<!-- ./wrapper -->
	</body>
	</html>
	{% extends 'base_print.html' %}
	{% load i18n %}
	{% load l10n %}
	{% load static %}
	{% load app_utils %}

	{% block content %}
	<div class="card">
	<div class="vertical-center text-center">
	<img class="logo" src="{% static 'img/logo.png' %}" alt="">
	<span class="title-text"> {{ object.name }}</span>
	</div>
	</div>
	{% endblock %}
	import tempfile

	from django.http import HttpResponse
	from django.template.loader import render_to_string
	from weasyprint import CSS, HTML

	side_margin = 2
	extra_vertical_margin = 20
	footer_size = 0


	class PdfGenerator:
	"""
	Generate a PDF out of a rendered template, with the possibility to integrate nicely
	a header and a footer if provided.

	Notes:
	------
	- When Weasyprint renders an html into a PDF, it goes though several intermediate steps.
	Here, in this class, we deal mostly with a box representation: 1 `Document` have 1 `Page`
	or more, each `Page` 1 `Box` or more. Each box can contain other box. Hence the recursive
	method `get_element` for example.
	For more, see:
	https://weasyprint.readthedocs.io/en/stable/hacking.html#dive-into-the-source
	https://weasyprint.readthedocs.io/en/stable/hacking.html#formatting-structure
	- Warning: the logic of this class relies heavily on the internal Weasyprint API. This
	snippet was written at the time of the release 47, it might break in the future.
	- This generator draws its inspiration and, also a bit of its implementation, from this
	discussion in the library github issues: https://github.com/Kozea/WeasyPrint/issues/92
	"""
	OVERLAY_LAYOUT = '@page {size: A4 portrait; margin: 0;}'

	def __init__(self, main_html, header_html=None, footer_html=None,
	base_url=None, side_margin=2, extra_vertical_margin=30):
	"""
	Parameters
	----------
	main_html: str
	An HTML file (most of the time a template rendered into a string) which represents
	the core of the PDF to generate.
	header_html: str
	An optional header html.
	footer_html: str
	An optional footer html.
	base_url: str
	An absolute url to the page which serves as a reference to Weasyprint to fetch assets,
	required to get our media.
	side_margin: int, interpreted in cm, by default 2cm
	The margin to apply on the core of the rendered PDF (i.e. main_html).
	extra_vertical_margin: int, interpreted in pixel, by default 30 pixels
	An extra margin to apply between the main content and header and the footer.
	The goal is to avoid having the content of `main_html` touching the header or the
	footer.
	"""
	self.main_html = main_html
	self.header_html = header_html
	self.footer_html = footer_html
	self.base_url = base_url
	self.side_margin = side_margin
	self.extra_vertical_margin = extra_vertical_margin

	def _compute_overlay_element(self, element: str):
	"""
	Parameters
	----------
	element: str
	Either 'header' or 'footer'

	Returns
	-------
	element_body: BlockBox
	A Weasyprint pre-rendered representation of an html element
	element_height: float
	The height of this element, which will be then translated in a html height
	"""
	html = HTML(
	string=getattr(self, f'{element}_html'),
	base_url=self.base_url,
	)
	element_doc = html.render(stylesheets=[CSS(string=self.OVERLAY_LAYOUT)])
	element_page = element_doc.pages[0]
	element_body = PdfGenerator.get_element(element_page._page_box.all_children(), 'body')
	element_body = element_body.copy_with_children(element_body.all_children())
	element_html = PdfGenerator.get_element(element_page._page_box.all_children(), element)

	element_height = 20
	if element == 'header' and element_html:
	element_height = element_html.height
	if element == 'footer' and element_html:
	element_height = element_page.height - element_html.position_y

	return element_body, element_height

	def _apply_overlay_on_main(self, main_doc, header_body=None, footer_body=None):
	"""
	Insert the header and the footer in the main document.

	Parameters
	----------
	main_doc: Document
	The top level representation for a PDF page in Weasyprint.
	header_body: BlockBox
	A representation for an html element in Weasyprint.
	footer_body: BlockBox
	A representation for an html element in Weasyprint.
	"""
	for page in main_doc.pages:
	page_body = PdfGenerator.get_element(page._page_box.all_children(), 'body')

	if header_body:
	page_body.children += header_body.all_children()
	if footer_body:
	page_body.children += footer_body.all_children()

	def render_pdf(self):
	"""
	Returns
	-------
	pdf: a bytes sequence
	The rendered PDF.
	"""
	if self.header_html:
	header_body, header_height = self._compute_overlay_element('header')
	else:
	header_body, header_height = None, 0
	if self.footer_html:
	footer_body, footer_height = self._compute_overlay_element('footer')
	else:
	footer_body, footer_height = None, 0

	margins = '{header_size}px {side_margin} {footer_size}px {side_margin}'.format(
	header_size=header_height + self.extra_vertical_margin,
	footer_size=footer_height + self.extra_vertical_margin,
	side_margin=f'{self.side_margin}cm',
	)
	content_print_layout = '@page {size: A4 portrait; margin: %s;}' % margins

	html = HTML(
	string=self.main_html,
	base_url=self.base_url,
	)
	main_doc = html.render(stylesheets=[CSS(string=content_print_layout)])

	if self.header_html or self.footer_html:
	self._apply_overlay_on_main(main_doc, header_body, footer_body)
	pdf = main_doc.write_pdf()

	return pdf

	@staticmethod
	def get_element(boxes, element):
	"""
	Given a set of boxes representing the elements of a PDF page in a DOM-like way, find the
	box which is named `element`.

	Look at the notes of the class for more details on Weasyprint insides.
	"""
	for box in boxes:
	if box.element_tag == element:
	return box
	return PdfGenerator.get_element(box.all_children(), element)


	def generate_pdf(template, filename, context_data, base_url=''):
	# Rendered
	header_html = render_to_string('base_print_header.html', context_data)
	html_string = render_to_string(template, context_data)

	pdf = PdfGenerator(
	main_html=html_string,
	header_html=header_html,
	base_url=base_url,
	side_margin=side_margin,
	extra_vertical_margin=extra_vertical_margin
	)
	result = pdf.render_pdf()

	# Creating http response
	response = HttpResponse(content_type='application/pdf;')
	response['Content-Disposition'] = 'inline; filename={}.pdf'.format(filename)
	response['Content-Transfer-Encoding'] = 'binary'
	with tempfile.NamedTemporaryFile(delete=True) as output:
	output.write(result)
	output.flush()

	with open(output.name, 'rb+') as output_file:
	response.write(output_file.read())

	return response
	from django.views.generic import TemplateView
	from .pdf import generate_pdf

	...

	class ExamplePrintView(TemplateView):
	template_name = 'example/example_print.html'
	page_title = 'Example'

	def get_context_data(self, **kwargs):
	context = super().get_context_data(**kwargs)
	object = Example.objects.get(pk=self.kwargs.get('pk'))

	context.update({
	'page_title': self.page_title,
	'object': object,
	})
	return context

	def get(self, request, args, *kwargs):
	data = self.get_context_data(**kwargs)
	return generate_pdf(
	template=self.template_name,
	filename=self.page_title,
	context_data=data,
	base_url=self.request.build_absolute_uri()
	)