Image.py 文件源码

def _getscaleoffset(expr):
    stub = ["stub"]
    data = expr(_E(stub)).data
    try:
        (a, b, c) = data # simplified syntax
        if (a is stub and b == "__mul__" and isNumberType(c)):
            return c, 0.0
        if (a is stub and b == "__add__" and isNumberType(c)):
            return 1.0, c
    except TypeError: pass
    try:
        ((a, b, c), d, e) = data # full syntax
        if (a is stub and b == "__mul__" and isNumberType(c) and
            d == "__add__" and isNumberType(e)):
            return c, e
    except TypeError: pass
    raise ValueError("illegal expression")


# --------------------------------------------------------------------
# Implementation wrapper

##
# This class represents an image object.  To create Image objects, use
# the appropriate factory functions.  There's hardly ever any reason
# to call the Image constructor directly.
#
# @see #open
# @see #new
# @see #fromstring