/usr/lib/python3/dist-packages/cairocffi/pixbuf.py is in python3-cairocffi 0.8.0-0ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 | # coding: utf-8
"""
cairocffi.pixbuf
~~~~~~~~~~~~~~~~
Loading various image formats with GDK-PixBuf
:copyright: Copyright 2013 by Simon Sapin
:license: BSD, see LICENSE for details.
"""
import sys
from io import BytesIO
from functools import partial
from array import array
from . import dlopen, ImageSurface, Context, constants
from ._ffi_pixbuf import ffi
from .compat import xrange
__all__ = ['decode_to_image_surface']
gdk_pixbuf = dlopen(ffi, 'gdk_pixbuf-2.0', 'gdk_pixbuf-2.0-0')
gobject = dlopen(ffi, 'gobject-2.0', 'gobject-2.0-0')
glib = dlopen(ffi, 'glib-2.0', 'glib-2.0-0')
try:
gdk = dlopen(ffi, 'gdk-3', 'gdk-x11-2.0', 'gdk-win32-2.0-0')
except OSError:
gdk = None
gobject.g_type_init()
class ImageLoadingError(ValueError):
"""PixBuf returned an error when loading an image.
The image data is probably corrupted.
"""
def handle_g_error(error, return_value):
"""Convert a :c:type:`GError**` to a Python :exception:`ImageLoadingError`,
and raise it.
"""
error = error[0]
assert bool(return_value) == (error == ffi.NULL)
if error != ffi.NULL:
if error.message != ffi.NULL:
message = ('Pixbuf error: ' +
ffi.string(error.message).decode('utf8', 'replace'))
else:
message = 'Pixbuf error'
glib.g_error_free(error)
raise ImageLoadingError(message)
class Pixbuf(object):
"""Wrap a :c:type:`GdkPixbuf` pointer and simulate methods."""
def __init__(self, pointer):
gobject.g_object_ref(pointer)
self._pointer = ffi.gc(pointer, gobject.g_object_unref)
def __getattr__(self, name):
function = getattr(gdk_pixbuf, 'gdk_pixbuf_' + name)
return partial(function, self._pointer)
def decode_to_pixbuf(image_data):
"""Decode an image from memory with GDK-PixBuf.
The file format is detected automatically.
:param image_data: A byte string
:returns:
A tuple of a new :class:`PixBuf` object
and the name of the detected image format.
:raises:
:exc:`ImageLoadingError` if the image data is invalid
or in an unsupported format.
"""
loader = ffi.gc(
gdk_pixbuf.gdk_pixbuf_loader_new(), gobject.g_object_unref)
error = ffi.new('GError **')
handle_g_error(error, gdk_pixbuf.gdk_pixbuf_loader_write(
loader, ffi.new('guchar[]', image_data), len(image_data), error))
handle_g_error(error, gdk_pixbuf.gdk_pixbuf_loader_close(loader, error))
format_ = gdk_pixbuf.gdk_pixbuf_loader_get_format(loader)
format_name = (
ffi.string(gdk_pixbuf.gdk_pixbuf_format_get_name(format_))
.decode('ascii')
if format_ != ffi.NULL else None)
pixbuf = gdk_pixbuf.gdk_pixbuf_loader_get_pixbuf(loader)
if pixbuf == ffi.NULL:
raise ImageLoadingError('Not enough image data (got a NULL pixbuf.)')
return Pixbuf(pixbuf), format_name
def decode_to_image_surface(image_data):
"""Decode an image from memory into a cairo surface.
The file format is detected automatically.
:param image_data: A byte string
:returns:
A tuple of a new :class:`~cairocffi.ImageSurface` object
and the name of the detected image format.
:raises:
:exc:`ImageLoadingError` if the image data is invalid
or in an unsupported format.
"""
pixbuf, format_name = decode_to_pixbuf(image_data)
surface = (
pixbuf_to_cairo_gdk(pixbuf) if gdk is not None
else pixbuf_to_cairo_slices(pixbuf) if not pixbuf.get_has_alpha()
else pixbuf_to_cairo_png(pixbuf))
return surface, format_name
def pixbuf_to_cairo_gdk(pixbuf):
"""Convert from PixBuf to ImageSurface, using GDK.
This method is fastest but GDK is not always available.
"""
dummy_context = Context(ImageSurface(constants.FORMAT_ARGB32, 1, 1))
gdk.gdk_cairo_set_source_pixbuf(
dummy_context._pointer, pixbuf._pointer, 0, 0)
return dummy_context.get_source().get_surface()
def pixbuf_to_cairo_slices(pixbuf):
"""Convert from PixBuf to ImageSurface, using slice-based byte swapping.
This method is 2~5x slower than GDK but does not support an alpha channel.
(cairo uses pre-multiplied alpha, but not Pixbuf.)
"""
assert pixbuf.get_colorspace() == gdk_pixbuf.GDK_COLORSPACE_RGB
assert pixbuf.get_n_channels() == 3
assert pixbuf.get_bits_per_sample() == 8
width = pixbuf.get_width()
height = pixbuf.get_height()
rowstride = pixbuf.get_rowstride()
pixels = ffi.buffer(pixbuf.get_pixels(), pixbuf.get_byte_length())
# TODO: remove this when cffi buffers support slicing with a stride.
pixels = pixels[:]
# Convert GdkPixbuf’s big-endian RGBA to cairo’s native-endian ARGB
cairo_stride = ImageSurface.format_stride_for_width(
constants.FORMAT_RGB24, width)
data = bytearray(cairo_stride * height)
big_endian = sys.byteorder == 'big'
pixbuf_row_length = width * 3 # stride == row_length + padding
cairo_row_length = width * 4 # stride == row_length + padding
alpha = b'\xff' * width # opaque
for y in xrange(height):
offset = rowstride * y
end = offset + pixbuf_row_length
red = pixels[offset:end:3]
green = pixels[offset + 1:end:3]
blue = pixels[offset + 2:end:3]
offset = cairo_stride * y
end = offset + cairo_row_length
if big_endian: # pragma: no cover
data[offset:end:4] = alpha
data[offset + 1:end:4] = red
data[offset + 2:end:4] = green
data[offset + 3:end:4] = blue
else:
data[offset + 3:end:4] = alpha
data[offset + 2:end:4] = red
data[offset + 1:end:4] = green
data[offset:end:4] = blue
data = array('B', data)
return ImageSurface(constants.FORMAT_RGB24,
width, height, data, cairo_stride)
def pixbuf_to_cairo_png(pixbuf):
"""Convert from PixBuf to ImageSurface, by going through the PNG format.
This method is 10~30x slower than GDK but always works.
"""
buffer_pointer = ffi.new('gchar **')
buffer_size = ffi.new('gsize *')
error = ffi.new('GError **')
handle_g_error(error, pixbuf.save_to_buffer(
buffer_pointer, buffer_size, ffi.new('char[]', b'png'), error,
ffi.new('char[]', b'compression'), ffi.new('char[]', b'0'),
ffi.NULL))
png_bytes = ffi.buffer(buffer_pointer[0], buffer_size[0])
return ImageSurface.create_from_png(BytesIO(png_bytes))
|