def testUnfilterScanlinePaeth(self):
"""This tests more edge cases in the paeth unfilter"""
scanprev = array('B', [2, 0, 0, 0, 9, 11])
scanline = array('B', [4, 6, 10, 9, 100, 101, 102])
filter_ = png.Filter(24, prev=scanprev)
out = filter_.undo_filter(scanline[0], scanline[1:])
self.assertEqual(list(out), [8, 10, 9, 108, 111, 113]) # paeth
def testFilterScanline(self):
"""Test filtering with previous line"""
prev = array('B', [20, 21, 22, 210, 211, 212])
line = array('B', [30, 32, 34, 230, 233, 236])
filter_ = png.Filter(24, prev=prev)
res = filter_.filter_all(line)
# None
self.assertEqual(list(res[0]), [0, 30, 32, 34, 230, 233, 236])
# sub
self.assertEqual(list(res[1]), [1, 30, 32, 34, 200, 201, 202])
# up
self.assertEqual(list(res[2]), [2, 10, 11, 12, 20, 22, 24])
# average
self.assertEqual(list(res[3]), [3, 20, 22, 23, 110, 112, 113])
# paeth
self.assertEqual(list(res[4]), [
4,
self.paeth(30, 0, 20, 0),
self.paeth(32, 0, 21, 0),
self.paeth(34, 0, 22, 0),
self.paeth(230, 30, 210, 20),
self.paeth(233, 32, 211, 21),
self.paeth(236, 34, 212, 22)
])
def testFilterScanlineFirstLine(self):
"""Test filter without previous line"""
line = array('B', [30, 31, 32, 230, 231, 232])
filter_ = png.Filter(24, prev=None)
res = filter_.filter_all(line)
# none
self.assertEqual(list(res[0]), [0, 30, 31, 32, 230, 231, 232])
# sub
self.assertEqual(list(res[1]), [1, 30, 31, 32, 200, 200, 200])
# up
self.assertEqual(list(res[2]), [2, 30, 31, 32, 230, 231, 232])
# average
self.assertEqual(list(res[3]), [3, 30, 31, 32, 215, 216, 216])
# paeth
self.assertEqual(list(res[4]), [
4,
self.paeth(30, 0, 0, 0),
self.paeth(31, 0, 0, 0),
self.paeth(32, 0, 0, 0),
self.paeth(230, 30, 0, 0),
self.paeth(231, 31, 0, 0),
self.paeth(232, 32, 0, 0)
])
def undo_filter(filter_type, line, prev):
"""undoing filter"""
filter_ = png.Filter(24, prev=prev)
line = array('B', line)
return filter_.undo_filter(filter_type, line)