Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

207 lines (175 sloc) 7.628 kb
# coding: utf8
"""
weasyprint.images
-----------------
Fetch and decode images in various formats.
:copyright: Copyright 2011-2012 Simon Sapin and contributors, see AUTHORS.
:license: BSD, see LICENSE for details.
"""
from __future__ import division, unicode_literals
from io import BytesIO
import cairo
from .logger import LOGGER
from .text import USING_INTROSPECTION
# TODO: currently CairoSVG only support images with an explicit
# width and height. When it supports images with only an intrinsic ratio
# this API will need to change.
# None as a the target for PDFSurface is new in pycairo 1.8.8.
# This helps with compat with earlier versions:
_DUMMY_FILE = BytesIO()
DUMMY_SURFACE = cairo.PDFSurface(_DUMMY_FILE, 1, 1)
# Do not try to import PyGObject 3 if we already have PyGTK
# that tends to segfault.
if not USING_INTROSPECTION:
# Use PyGObject introspection
try:
from gtk import gdk
from gtk.gdk import PixbufLoader
# Old version of PyGTK raise RuntimeError when there is not X server.
except (ImportError, RuntimeError) as exception:
def gdkpixbuf_loader(file_obj, string, pixbuf_error=exception):
raise pixbuf_error
else:
def gdkpixbuf_loader(file_obj, string):
"""Load raster images with gdk-pixbuf through PyGTK."""
pixbuf = get_pixbuf(file_obj, string)
dummy_context = cairo.Context(DUMMY_SURFACE)
gdk.CairoContext(dummy_context).set_source_pixbuf(pixbuf, 0, 0)
surface = dummy_context.get_source().get_surface()
get_pattern = lambda: cairo.SurfacePattern(surface)
return get_pattern, pixbuf.get_width(), pixbuf.get_height()
else:
# Use PyGObject introspection
try:
from gi.repository import GdkPixbuf
from gi.repository.GdkPixbuf import PixbufLoader
except ImportError as exception:
def gdkpixbuf_loader(file_obj, string, pixbuf_error=exception):
raise pixbuf_error
else:
PIXBUF_VERSION = (GdkPixbuf.PIXBUF_MAJOR,
GdkPixbuf.PIXBUF_MINOR,
GdkPixbuf.PIXBUF_MICRO)
if PIXBUF_VERSION < (2, 25, 0):
LOGGER.warn('Using gdk-pixbuf %s.%s.%s with introspection. '
'Versions before 2.25.0 are known to be buggy. '
'Images formats other than PNG may not be supported.',
*PIXBUF_VERSION)
try:
# Unfornately cairo_set_source_pixbuf is not part of Pixbuf itself
from gi.repository import Gdk
def gdkpixbuf_loader(file_obj, string):
"""Load raster images with gdk-pixbuf through introspection
and Gdk.
"""
pixbuf = get_pixbuf(file_obj, string)
dummy_context = cairo.Context(DUMMY_SURFACE)
Gdk.cairo_set_source_pixbuf(dummy_context, pixbuf, 0, 0)
surface = dummy_context.get_source().get_surface()
get_pattern = lambda: cairo.SurfacePattern(surface)
return get_pattern, pixbuf.get_width(), pixbuf.get_height()
except ImportError:
# Gdk is not available, go through PNG.
def gdkpixbuf_loader(file_obj, string):
"""Load raster images with gdk-pixbuf through introspection,
without Gdk and going through PNG.
"""
pixbuf = get_pixbuf(file_obj, string)
_, png = pixbuf.save_to_bufferv('png', ['compression'], ['0'])
return cairo_png_loader(None, png)
def get_pixbuf(file_obj=None, string=None, chunck_size=16 * 1024):
"""Create a Pixbuf object."""
loader = PixbufLoader()
try:
if file_obj:
while 1:
chunck = file_obj.read(chunck_size)
if not chunck:
break
loader.write(chunck)
elif string:
loader.write(string)
else:
raise ValueError('Could not load image: empty content')
finally:
# Pixbuf is really unhappy if we don’t do this:
loader.close()
return loader.get_pixbuf()
def cairo_png_loader(file_obj, string):
"""Return a cairo Surface from a PNG byte stream."""
surface = cairo.ImageSurface.create_from_png(file_obj or BytesIO(string))
get_pattern = lambda: cairo.SurfacePattern(surface)
return get_pattern, surface.get_width(), surface.get_height()
def cairosvg_loader(file_obj, string, uri):
"""Return a cairo Surface from a SVG byte stream.
This loader uses CairoSVG: http://cairosvg.org/
"""
from cairosvg.surface import SVGSurface
from cairosvg.parser import Tree
class ScaledSVGSurface(SVGSurface):
"""
Have the cairo Surface object have intrinsic dimension
in pixels instead of points.
"""
@property
def device_units_per_user_units(self):
scale = super(ScaledSVGSurface, self).device_units_per_user_units
return scale / 0.75
if uri.startswith('data:'):
# Don’t pass data URIs to CairoSVG.
# They are useless for relative URIs anyway.
uri = None
if file_obj:
string = file_obj.read()
def get_surface():
tree = Tree(bytestring=string, url=uri)
# Draw to a cairo surface but do not write to a file
surface = ScaledSVGSurface(tree, output=None, dpi=96)
return surface.cairo, surface.width, surface.height
def get_pattern():
# Do not re-use the Surface object, but regenerate it as needed.
# If a surface for a SVG image is still alive by the time we call
# show_page(), cairo will rasterize the image instead writing vectors.
surface, _, _ = get_surface()
return cairo.SurfacePattern(surface)
# Render once to get the size and trigger any exception.
# If this does not raise, future calls to get_pattern() will hopefully
# not raise either.
_, width, height = get_surface()
if not (width > 0 and height > 0):
raise ValueError('Images without an intrinsic size are not supported.')
return get_pattern, width, height
def get_image_from_uri(cache, url_fetcher, uri, type_=None):
"""Get a :class:`cairo.Surface`` from an image URI."""
try:
missing = object()
image = cache.get(uri, missing)
if image is not missing:
return image
result = url_fetcher(uri)
try:
if not type_:
type_ = result['mime_type'] # Use eg. the HTTP header
#else: the type was forced by eg. a 'type' attribute on <embed>
if type_ == 'image/svg+xml':
image = cairosvg_loader(
result.get('file_obj'), result.get('string'), uri)
elif type_ == 'image/png':
image = cairo_png_loader(
result.get('file_obj'), result.get('string'))
else:
image = gdkpixbuf_loader(
result.get('file_obj'), result.get('string'))
finally:
if 'file_obj' in result:
try:
result['file_obj'].close()
except Exception: # pragma: no cover
# May already be closed or something.
# This is just cleanup anyway.
pass
except Exception as exc:
LOGGER.warn('Error for image at %s : %r', uri, exc)
image = None
cache[uri] = image
return image
Jump to Line
Something went wrong with that request. Please try again.