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305 lines
10 KiB
305 lines
10 KiB
#!/usr/bin/python2 -O
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'''Qubes Image Converter
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Toolkit for secure transfer and conversion of images between Qubes VMs.'''
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# The Qubes OS Project, http://www.qubes-os.org
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#
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# Copyright (C) 2013 Wojciech Porczyk <wojciech@porczyk.eu>
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#
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# This program is free software; you can redistribute it and/or
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# modify it under the terms of the GNU General Public License
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# as published by the Free Software Foundation; either version 2
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# of the License, or (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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import colorsys
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import math
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import os
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import re
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import cStringIO as StringIO
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import subprocess
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import sys
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import unittest
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import cairo
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# those are for "zOMG UlTRa HD! WalLLpapPer 8K!!1!" to work seamlessly;
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# 8192 * 5120 * 4 B = 160 MiB, so DoS by memory exhaustion is unlikely
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MAX_WIDTH = 8192
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MAX_HEIGHT = 5120
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# current max raster icon size in hicolor theme is 256 as of 2013/fedora-18
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# beyond that one probably shall use scalable icons
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# (SVG is currently unsupported)
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ICON_MAXSIZE = 512
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# header consists of two decimal numbers, SPC and LF
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re_imghdr = re.compile(r'^\d+ \d+\n$')
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imghdrlen = lambda w, h: int(math.ceil(math.log10(w)) \
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+ math.ceil(math.log10(h)) \
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+ 2)
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class Image(object):
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def __init__(self, rgba, size):
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'''This class is not meant to be instantiated directly. Use one of:
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get_from_stream(), get_from_vm(), get_xdg_icon_from_vm(), get_through_dvm()'''
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self._rgba = rgba
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self._size = size
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def save(self, dst):
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'Save image to disk. dst may specify format, like png:aqq.gif'
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p = subprocess.Popen(['convert',
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'-depth', '8',
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'-size', '{0[0]}x{0[1]}'.format(self._size),
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'rgba:-', dst], stdin=subprocess.PIPE)
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p.stdin.write(self._rgba)
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p.stdin.close()
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if p.wait():
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raise Exception('Conversion failed')
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def tint(self, colour):
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'''Return new tinted image'''
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r, g, b = hex_to_float(colour)
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h, _, s = colorsys.rgb_to_hls(r, g, b)
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result = StringIO.StringIO()
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for i in xrange(0, self._size[0] * self._size[1] * 4, 4):
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r, g, b, a = tuple(ord(c) / 255. for c in self._rgba[i:i+4])
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_, l, _ = colorsys.rgb_to_hls(r, g, b)
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r, g, b = colorsys.hls_to_rgb(h, l, s)
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result.write(''.join(chr(int(i * 255)) for i in [r, g, b, a]))
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return self.__class__(rgba=result.getvalue(), size=self._size)
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@classmethod
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def load_from_file(cls, filename):
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'''Loads image from local file.
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WARNING: always load trusted images.'''
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p = subprocess.Popen(['identify', '-format', '%w %h', filename],
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stdout=subprocess.PIPE)
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size = tuple(int(i) for i in p.stdout.read().strip().split())
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p.stdout.close()
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p.wait()
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p = subprocess.Popen(['convert', filename, '-depth', '8', 'rgba:-'],
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stdout=subprocess.PIPE)
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rgba = p.stdout.read()
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p.stdout.close()
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p.wait()
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return cls(rgba=rgba, size=size)
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@classmethod
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def get_from_stream(cls, stream, max_width=MAX_WIDTH, max_height=MAX_HEIGHT):
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'''Carefully parse image data from stream.
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THIS METHOD IS SECURITY-SENSITIVE'''
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maxhdrlen = imghdrlen(max_width, max_height)
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untrusted_header = stream.readline(maxhdrlen)
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if len(untrusted_header) == 0:
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raise ValueError('No icon received')
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if not re_imghdr.match(untrusted_header):
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raise ValueError('Image format violation')
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header = untrusted_header
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del untrusted_header
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untrusted_width, untrusted_height = (int(i) for i in header.rstrip().split())
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if not (0 < untrusted_width <= max_width \
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and 0 < untrusted_height <= max_height):
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raise ValueError('Image size constraint violation:'
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' width={width} height={height}'
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' max_width={max_width} max_height={max_height}'.format(
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width=untrusted_width, height=untrusted_height,
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max_width=max_width, max_height=max_height))
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width, height = untrusted_width, untrusted_height
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del untrusted_width, untrusted_height
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expected_data_len = width * height * 4 # RGBA
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untrusted_data = stream.read(expected_data_len)
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if len(untrusted_data) != expected_data_len:
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raise ValueError( \
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'Image data length violation (is {0}, should be {1})'.format( \
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len(untrusted_data), expected_data_len))
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data = untrusted_data
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del untrusted_data
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return cls(rgba=data, size=(width, height))
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@classmethod
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def get_from_vm(cls, vm, src, **kwargs):
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'Get image from VM by QUBESRPC (qubes.GetImageRGBA).'
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p = vm.run('QUBESRPC qubes.GetImageRGBA dom0', passio_popen=True)
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p.stdin.write('{0}\n'.format(src))
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p.stdin.close()
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try:
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img = cls.get_from_stream(p.stdout, **kwargs)
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finally:
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p.stdout.close()
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if p.wait():
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raise Exception('Something went wrong with receiver')
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return img
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@classmethod
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def get_xdg_icon_from_vm(cls, vm, icon, **kwargs):
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'Get image from VM. If path is not absolute, get it from hicolor theme.'
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if not os.path.isabs(icon):
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icon = 'xdgicon:' + icon
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return cls.get_from_vm(vm, icon,
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max_width=ICON_MAXSIZE, max_height=ICON_MAXSIZE, **kwargs)
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@classmethod
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def get_through_dvm(cls, filename, **kwargs):
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'''Master end of image filter: writes untrusted image to stdout and
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expects header+RGBA on stdin. This method is invoked from qvm-imgconverter-client.'''
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filetype = None
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if ':' in filename:
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filetype, filename = filename.split(':', 1)[0]
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sys.stdout.write('{0}:-\n'.format(filetype))
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else:
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sys.stdout.write('-\n')
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try:
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sys.stdout.write(open(filename).read())
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except Exception, e:
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raise Exception('Something went wrong: {0!s}'.format(e))
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finally:
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sys.stdout.close()
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# sys.stdout.close() is not enough and documentation is silent about this
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os.close(1)
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return cls.get_from_stream(sys.stdin, **kwargs)
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def hex_to_float(colour, channels=3, depth=8):
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'''Convert hex colour definition to tuple of floats.'''
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if depth % 4 != 0:
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raise NotImplementedError('depths not divisible by 4 are unsupported')
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length = channels * depth / 4
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step = depth / 4
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# get rid of '#' or '0x' in front of hex values
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colour = colour[-length:]
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return tuple(int(colour[i:i+step], 0x10) / float(2**depth - 1) for i in range(0, length, step))
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def tint(src, dst, colour):
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'''Tint image to reflect vm label.
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src and dst may specify format, like png:aqq.gif'''
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Image.load_from_file(src).tint(colour).save(dst)
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def make_padlock(dst, colour, size=ICON_MAXSIZE):
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cs = cairo.ImageSurface(cairo.FORMAT_ARGB32, size, size)
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cr = cairo.Context(cs)
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cr.set_source_rgb(*hex_to_float(colour))
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cr.set_line_width(.125 * size)
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cr.rectangle(.125 * size, .5 * size, .75 * size, .4375 * size)
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cr.fill()
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cr.move_to(.25 * size, .5 * size)
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cr.line_to(.25 * size, .375 * size)
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cr.arc(.5 * size, .375 * size, .25 * size, math.pi, 2 * math.pi)
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cr.move_to(.75 * size, .375 * size) # this is unneccessary, but helps readability
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cr.line_to(.75 * size, .5 * size)
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cr.stroke()
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cs.write_to_png(dst)
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class TestCaseImage(unittest.TestCase):
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def setUp(self):
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self.rgba = \
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'\x00\x00\x00\xff' '\xff\x00\x00\xff' \
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'\x00\xff\x00\xff' '\x00\x00\x00\xff'
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self.size = (2, 2)
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self.image = Image(rgba=self.rgba, size=self.size)
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def test_00_init(self):
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self.assertEqual(self.image._rgba, self.rgba)
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self.assertEqual(self.image._size, self.size)
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def test_01_tint(self):
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image = self.image.tint('#0000ff')
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self.assertEqual(image._rgba,
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'\x00\x00\x00\xff' '\x00\x00\xff\xff'
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'\x00\x00\xff\xff' '\x00\x00\x00\xff')
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def test_10_get_from_stream(self):
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io = StringIO.StringIO('{0[0]} {0[1]}\n{1}'.format(self.size, self.rgba))
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image = Image.get_from_stream(io)
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self.assertEqual(image._rgba, self.rgba)
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self.assertEqual(image._size, self.size)
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def test_11_get_from_stream_malformed(self):
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io = StringIO.StringIO('{0[0]} {0[1]}\n{1}'.format(self.size, self.rgba[-1])) # one byte too short
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with self.assertRaises(Exception):
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image = Image.get_from_stream(io)
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def test_12_get_from_stream_too_big(self):
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io = StringIO.StringIO('{0[0]} {0[1]}\n{1}'.format(self.size, self.rgba)) # 2x2
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with self.assertRaises(Exception):
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image = Image.get_from_stream(io, max_width=1)
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io.seek(0)
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with self.assertRaises(Exception):
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image = Image.get_from_stream(io, max_height=1)
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class TestCaseFunctionsAndConstants(unittest.TestCase):
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def test_00_imghdrlen(self):
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self.assertEqual(imghdrlen(8, 15), len('8 15\n'))
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def test_01_re_imghdr(self):
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self.assertTrue(re_imghdr.match('8 15\n'))
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self.assertIsNone(re_imghdr.match('8 15'))
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self.assertIsNone(re_imghdr.match('815\n'))
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self.assertIsNone(re_imghdr.match('x yx\n'))
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def test_10_hex_to_float_result_00(self):
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self.assertEqual(hex_to_float('#000000'), (0.0, 0.0, 0.0))
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def test_11_hex_to_float_result_ff(self):
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self.assertEqual(hex_to_float('0xffffff'), (1.0, 1.0, 1.0))
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def test_12_hex_to_float_depth_3_not_implemented(self):
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with self.assertRaises(NotImplementedError):
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hex_to_float('123456', depth=3)
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if __name__ == '__main__':
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unittest.main()
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# vim: ft=python sw=4 ts=4 et
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