def test_clamp(x, lower_bound, upper_bound):
if lower_bound > upper_bound:
lower_bound, upper_bound = upper_bound, lower_bound
new_x = clamp(x, lower_bound, upper_bound)
# If x was already between the bounds, it shouldn't have changed
if lower_bound <= x <= upper_bound:
assert new_x == x
assert lower_bound <= new_x <= upper_bound
def _calc_offsets(off, src_size, dst_size):
"""
>>> _calc_offsets(11, 10, 12) # no overlap
(10, 0, 0)
>>> _calc_offsets(-11, 12, 10) # no overlap
(0, 10, 0)
>>> _calc_offsets(5, 10, 12) # overlap
(5, 0, 5)
>>> _calc_offsets(-5, 12, 10) # overlap
(0, 5, 5)
>>> _calc_offsets(5, 10, 4) # containment
(5, 0, 4)
>>> _calc_offsets(-5, 4, 10) # containment
(0, 5, 4)
"""
read_off = clamp(off, 0, src_size)
write_off = clamp(-off, 0, dst_size)
size = min(src_size - read_off, dst_size - write_off)
return read_off, write_off, size
def _calc_offsets_impl(off, scale, src_size, dst_size):
assert scale >= 1 - 1e-5
if off >= 0:
write_off = 0
else:
write_off = math.ceil((-off - 0.5) / scale)
read_off = round((write_off + 0.5) * scale - 0.5 + off) - round(
0.5 * (scale - 1.0)) # assuming read_size/write_size ~= scale
if read_off >= src_size:
return 0, 0, 0, 0
write_end = dst_size
write_size = write_end - write_off
read_end = read_off + round(write_size * scale)
if read_end > src_size:
# +0.5 below is a fudge that will return last row in more situations, but will change the scale more
write_end = math.floor((src_size - off + 0.5) / scale)
write_size = write_end - write_off
read_end = clamp(read_off + round(write_size * scale), read_off, src_size)
read_size = read_end - read_off
return int(read_off), int(write_off), int(read_size), int(write_size)
