mirror of
https://github.com/Kozea/WeasyPrint.git
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352 lines
12 KiB
Python
352 lines
12 KiB
Python
# coding: utf8
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"""
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weasyprint.images
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-----------------
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Fetch and decode images in various formats.
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:copyright: Copyright 2011-2012 Simon Sapin and contributors, see AUTHORS.
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:license: BSD, see LICENSE for details.
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"""
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from __future__ import division
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# XXX No unicode_literals, cffi likes native strings
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import sys
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from io import BytesIO
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from functools import partial
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import cffi
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import cairocffi as cairo
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cairo.install_as_pycairo() # for CairoSVG
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import cairosvg.parser
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import cairosvg.surface
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assert cairosvg.surface.cairo is cairo, (
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'CairoSVG is using pycairo instead of cairocffi. '
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'Make sure it is not imported before WeasyPrint.')
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from .logger import LOGGER
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from .compat import xrange
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ffi = cffi.FFI()
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ffi.cdef('''
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typedef unsigned long gsize;
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typedef unsigned int guint32;
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typedef unsigned int guint;
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typedef unsigned char guchar;
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typedef char gchar;
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typedef int gint;
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typedef gint gboolean;
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typedef guint32 GQuark;
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typedef void* gpointer;
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typedef struct {
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GQuark domain;
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gint code;
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gchar *message;
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} GError;
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typedef struct {
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gchar *name;
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/* ... */
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} GdkPixbufFormat;
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typedef enum {
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GDK_COLORSPACE_RGB
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} GdkColorspace;
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typedef ... GdkPixbufLoader;
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typedef ... GdkPixbuf;
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typedef ... cairo_t;
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GdkPixbufLoader * gdk_pixbuf_loader_new (void);
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GdkPixbufFormat * gdk_pixbuf_loader_get_format (GdkPixbufLoader *loader);
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GdkPixbuf * gdk_pixbuf_loader_get_pixbuf (GdkPixbufLoader *loader);
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gboolean gdk_pixbuf_loader_write (
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GdkPixbufLoader *loader, const guchar *buf, gsize count,
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GError **error);
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gboolean gdk_pixbuf_loader_close (
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GdkPixbufLoader *loader, GError **error);
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GdkColorspace gdk_pixbuf_get_colorspace (const GdkPixbuf *pixbuf);
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int gdk_pixbuf_get_n_channels (const GdkPixbuf *pixbuf);
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gboolean gdk_pixbuf_get_has_alpha (const GdkPixbuf *pixbuf);
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int gdk_pixbuf_get_bits_per_sample (const GdkPixbuf *pixbuf);
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int gdk_pixbuf_get_width (const GdkPixbuf *pixbuf);
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int gdk_pixbuf_get_height (const GdkPixbuf *pixbuf);
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int gdk_pixbuf_get_rowstride (const GdkPixbuf *pixbuf);
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guchar * gdk_pixbuf_get_pixels (const GdkPixbuf *pixbuf);
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gsize gdk_pixbuf_get_byte_length (const GdkPixbuf *pixbuf);
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gboolean gdk_pixbuf_save_to_buffer (
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GdkPixbuf *pixbuf, gchar **buffer, gsize *buffer_size,
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const char *type, GError **error, ...);
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void gdk_cairo_set_source_pixbuf (
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cairo_t *cr, const GdkPixbuf *pixbuf, double pixbuf_x, double pixbuf_y);
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void g_object_ref (gpointer object);
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void g_object_unref (gpointer object);
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void g_error_free (GError *error);
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void g_type_init (void);
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''')
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try:
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gobject = ffi.dlopen('gobject-2.0')
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gdk_pixbuf = ffi.dlopen('gdk_pixbuf-2.0')
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except OSError:
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gdk_pixbuf = gobject = gdk = None
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else:
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try:
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gdk = ffi.dlopen('gdk-3')
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except OSError:
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try:
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gdk = ffi.dlopen('gdk-x11-2.0')
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except OSError:
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gdk = None
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gobject.g_type_init()
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# TODO: currently CairoSVG only support images with an explicit
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# width and height. When it supports images with only an intrinsic ratio
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# this API will need to change.
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def handle_g_error(error, raise_=False):
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if error != ffi.NULL:
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error_message = ffi.string(error.message).decode('utf8', 'replace')
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gobject.g_error_free(error)
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exception = ValueError('Pixbuf error: ' + error_message)
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if raise_:
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raise exception
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else:
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return exception
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class Pixbuf(object):
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def __init__(self, handle):
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self._pointer = ffi.gc(handle, gobject.g_object_unref)
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def __getattr__(self, name):
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return partial(getattr(gdk_pixbuf, 'gdk_pixbuf_' + name), self._pointer)
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def get_pixbuf(file_obj=None, string=None):
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"""Create a Pixbuf object."""
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if file_obj:
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string = file_obj.read()
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if not string:
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raise ValueError('Could not load image: empty content')
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loader = ffi.gc(
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gdk_pixbuf.gdk_pixbuf_loader_new(), gobject.g_object_unref)
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error = ffi.new('GError **')
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gdk_pixbuf.gdk_pixbuf_loader_write(
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loader, ffi.new('guchar[]', string), len(string), error)
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write_exception = handle_g_error(error[0])
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gdk_pixbuf.gdk_pixbuf_loader_close(loader, error)
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close_exception = handle_g_error(error[0])
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if write_exception is not None:
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raise write_exception # Only after closing
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if close_exception is not None:
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raise close_exception
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format_ = gdk_pixbuf.gdk_pixbuf_loader_get_format(loader)
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is_jpeg = format_ != ffi.NULL and ffi.string(format_.name) == b'jpeg'
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jpeg_data = string if is_jpeg else None
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pixbuf = gdk_pixbuf.gdk_pixbuf_loader_get_pixbuf(loader)
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assert pixbuf != ffi.NULL
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gobject.g_object_ref(pixbuf)
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return Pixbuf(pixbuf), jpeg_data
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def gdkpixbuf_loader(file_obj, string):
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"""Load raster images with gdk-pixbuf through introspection
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and Gdk.
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"""
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if gdk_pixbuf is None:
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raise OSError(
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'Could not load GDK-Pixbuf. '
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'PNG and SVG are the only image formats available.')
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pixbuf, jpeg_data = get_pixbuf(file_obj, string)
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surface = (
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pixbuf_to_cairo_gdk(pixbuf) if gdk is not None
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else pixbuf_to_cairo_slices(pixbuf) if not pixbuf.get_has_alpha()
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else pixbuf_to_cairo_png(pixbuf))
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if jpeg_data:
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surface.set_mime_data('image/jpeg', jpeg_data)
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get_pattern = lambda: cairo.SurfacePattern(surface)
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return get_pattern, surface.get_width(), surface.get_height()
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def pixbuf_to_cairo_gdk(pixbuf):
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"""Convert with GDK.
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This method is fastest but GDK is not always available.
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"""
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dummy_context = cairo.Context(cairo.PDFSurface(None, 1, 1))
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gdk.gdk_cairo_set_source_pixbuf(
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ffi.cast('cairo_t *', dummy_context._pointer), pixbuf._pointer, 0, 0)
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return dummy_context.get_source().get_surface()
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def pixbuf_to_cairo_slices(pixbuf):
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"""Slice-based byte swapping.
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This method is 2~5x slower than GDK but does not support an alpha channel.
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(cairo uses pre-multiplied alpha, but not Pixbuf.)
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"""
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assert pixbuf.get_colorspace() == 'GDK_COLORSPACE_RGB'
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assert pixbuf.get_n_channels() == 3
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assert pixbuf.get_bits_per_sample() == 8
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width = pixbuf.get_width()
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height = pixbuf.get_height()
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rowstride = pixbuf.get_rowstride()
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pixels = ffi.buffer(pixbuf.get_pixels(), pixbuf.get_byte_length())
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# TODO: remove this when cffi buffers support slicing with a stride.
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pixels = pixels[:]
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# Convert GdkPixbuf’s big-endian RGBA to cairo’s native-endian ARGB
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cairo_stride = cairo.ImageSurface.format_stride_for_width('RGB24', width)
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data = bytearray(cairo_stride * height)
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big_endian = sys.byteorder == 'big'
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pixbuf_row_length = width * 3 # stride == row_length + padding
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cairo_row_length = width * 4 # stride == row_length + padding
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for y in xrange(height):
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offset = rowstride * y
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end = offset + pixbuf_row_length
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red = pixels[offset:end:3]
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green = pixels[offset + 1:end:3]
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blue = pixels[offset + 2:end:3]
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offset = cairo_stride * y
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end = offset + cairo_row_length
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if big_endian:
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# data[offset:end:4] is left un-initialized
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data[offset + 1:end:4] = red
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data[offset + 2:end:4] = green
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data[offset + 3:end:4] = blue
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else:
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# data[offset + 3:end:4] is left un-initialized
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data[offset + 2:end:4] = red
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data[offset + 1:end:4] = green
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data[offset:end:4] = blue
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return cairo.ImageSurface('ARGB32', width, height, data, cairo_stride)
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def pixbuf_to_cairo_png(pixbuf):
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"""Going through PNG.
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This method is 20~30x slower than GDK but always works.
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"""
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buffer_pointer = ffi.new('gchar **')
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buffer_size = ffi.new('gsize *')
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error = ffi.new('GError **')
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pixbuf.save_to_buffer(
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buffer_pointer, buffer_size, ffi.new('char[]', b'png'), error,
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ffi.new('char[]', b'compression'), ffi.new('char[]', b'0'),
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ffi.NULL)
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handle_g_error(error[0], raise_=True)
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png_bytes = ffi.buffer(buffer_pointer[0], buffer_size[0])
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return cairo.ImageSurface.create_from_png(BytesIO(png_bytes))
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def cairo_png_loader(file_obj, string):
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"""Return a cairo Surface from a PNG byte stream."""
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surface = cairo.ImageSurface.create_from_png(file_obj or BytesIO(string))
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get_pattern = lambda: cairo.SurfacePattern(surface)
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return get_pattern, surface.get_width(), surface.get_height()
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class ScaledSVGSurface(cairosvg.surface.SVGSurface):
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"""
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Have the cairo Surface object have intrinsic dimension
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in pixels instead of points.
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"""
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@property
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def device_units_per_user_units(self):
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scale = super(ScaledSVGSurface, self).device_units_per_user_units
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return scale / 0.75
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def cairosvg_loader(file_obj, string, uri):
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"""Return a cairo Surface from a SVG byte stream.
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This loader uses CairoSVG: http://cairosvg.org/
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"""
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if uri.startswith('data:'):
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# Don’t pass data URIs to CairoSVG.
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# They are useless for relative URIs anyway.
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uri = None
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if file_obj:
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string = file_obj.read()
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def get_surface():
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tree = cairosvg.parser.Tree(bytestring=string, url=uri)
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# Draw to a cairo surface but do not write to a file
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surface = ScaledSVGSurface(tree, output=None, dpi=96)
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return surface.cairo, surface.width, surface.height
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def get_pattern():
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# Do not re-use the Surface object, but regenerate it as needed.
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# If a surface for a SVG image is still alive by the time we call
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# show_page(), cairo will rasterize the image instead writing vectors.
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surface, _, _ = get_surface()
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return cairo.SurfacePattern(surface)
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# Render once to get the size and trigger any exception.
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# If this does not raise, future calls to get_pattern() will hopefully
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# not raise either.
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_, width, height = get_surface()
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if not (width > 0 and height > 0):
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raise ValueError('Images without an intrinsic size are not supported.')
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return get_pattern, width, height
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def get_image_from_uri(cache, url_fetcher, uri, type_=None):
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"""Get a :class:`cairo.Surface`` from an image URI."""
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try:
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missing = object()
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image = cache.get(uri, missing)
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if image is not missing:
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return image
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result = url_fetcher(uri)
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try:
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if not type_:
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type_ = result['mime_type'] # Use eg. the HTTP header
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#else: the type was forced by eg. a 'type' attribute on <embed>
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if type_ == 'image/svg+xml':
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image = cairosvg_loader(
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result.get('file_obj'), result.get('string'), uri)
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elif type_ == 'image/png':
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image = cairo_png_loader(
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result.get('file_obj'), result.get('string'))
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else:
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image = gdkpixbuf_loader(
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result.get('file_obj'), result.get('string'))
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finally:
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if 'file_obj' in result:
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try:
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result['file_obj'].close()
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except Exception: # pragma: no cover
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# May already be closed or something.
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# This is just cleanup anyway.
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pass
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except Exception as exc:
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LOGGER.warn('Error for image at %s : %r', uri, exc)
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image = None
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cache[uri] = image
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return image
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