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# coding: utf8
Entry point to the rendering process.
:copyright: Copyright 2011-2012 Simon Sapin and contributors, see AUTHORS.
:license: BSD, see LICENSE for details.
from __future__ import division, unicode_literals
import io
import math
import cairo
from .css import get_all_computed_styles
from .css.computed_values import LENGTHS_TO_PIXELS
from import build_formatting_structure
from . import layout
from . import draw
from . import images
from . import utils
class Document(object):
"""Abstract output document."""
def __init__(self, dom, user_stylesheets, user_agent_stylesheets):
#: lxml HtmlElement object
self.dom = dom
self.user_stylesheets = user_stylesheets
self.user_agent_stylesheets = user_agent_stylesheets
self._image_cache = {}
# TODO: remove this when Margin boxes variable dimension is correct.
self._auto_margin_boxes_warning_shown = False
def style_for(self, element, pseudo_type=None):
Convenience method to get the computed styles for an element.
return self.computed_styles.get((element, pseudo_type))
def computed_styles(self):
dict of (element, pseudo_element_type) -> StyleDict
StyleDict: a dict of property_name -> PropertyValue,
also with attribute access
return get_all_computed_styles(
def formatting_structure(self):
The root of the formatting structure tree, ie. the Box
for the root element.
return build_formatting_structure(self, self.computed_styles)
def pages(self):
List of layed-out pages with an absolute size and postition
for every box.
return layout.layout_document(self, self.formatting_structure)
def get_image_from_uri(self, uri, type_=None):
Same as ``weasy.images.get_image_from_uri`` but cache results
missing = object()
surface = self._image_cache.get(uri, missing)
if surface is missing:
surface = images.get_image_from_uri(uri, type_)
self._image_cache[uri] = surface
return surface
def write_to(self, target=None):
"""Like .write_to() but returns a byte stringif target is None."""
if target is None:
target = io.BytesIO()
return target.getvalue()
class PNGDocument(Document):
"""PNG output document."""
def __init__(self, dom, *args, **kwargs):
super(PNGDocument, self).__init__(dom, *args, **kwargs)
self.surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, 1, 1)
def draw_page(self, page):
"""Draw a single page and return an ImageSurface."""
width = int(math.ceil(page.outer_width))
height = int(math.ceil(page.outer_height))
surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
context = draw.CairoContext(surface)
draw.draw_page(self, page, context)
return width, height, surface
def write_page_to(self, page_index, target):
"""Write a single page as PNG into a file-like or filename `target`."""
_width, _height, surface = self.draw_page(self.pages[page_index])
def draw_all_pages(self):
"""Draw all pages and return a single ImageSurface.
Pages are layed out vertically each above the next and centered
pages = [self.draw_page(page) for page in self.pages]
if len(pages) == 1:
return pages[0]
total_height = sum(height for width, height, surface in pages)
max_width = max(width for width, height, surface in pages)
surface = cairo.ImageSurface(cairo.FORMAT_ARGB32,
max_width, total_height)
context = draw.CairoContext(surface)
position_y = 0
for width, height, page_surface in pages:
position_x = (max_width - width) // 2
context.set_source_surface(page_surface, position_x, position_y)
position_y += height
return max_width, total_height, surface
def _write_to(self, target):
"""Write all pages as PNG into a file-like or filename `target`.
Pages are layed out vertically each above the next and centered
_width, _height, surface = self.draw_all_pages()
class PDFDocument(Document):
"""PDF output document."""
def __init__(self, dom, *args, **kwargs):
super(PDFDocument, self).__init__(dom, *args, **kwargs)
# Use a dummy page size initially
self.surface = cairo.PDFSurface(None, 1, 1)
def _write_to(self, target):
Write the whole document as PDF into a file-like or filename `target`.
# The actual page size is set for each page.
surface = cairo.PDFSurface(target, 1, 1)
px_to_pt = 1 / LENGTHS_TO_PIXELS['pt']
for page in self.pages:
# Actual page size is here. May be different between pages.
page.outer_width * px_to_pt,
page.outer_height * px_to_pt)
context = draw.CairoContext(surface)
context.scale(px_to_pt, px_to_pt)
draw.draw_page(self, page, context)
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