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from config import settings
class _UNIT(str): pass
# for now, we can't use _UNIT() yet; there is some code to be modified first
UNIT_CM = "cm" #_UNIT("cm")
UNIT_IN = "in" #_UNIT("in")
UNIT_PERCENT = "%" #_UNIT("%")
UNIT_PT = "pt" #_UNIT("pt")
UNIT_PX = "px" #_UNIT("px")
def _round(v): return (v < 0) and int(v - 0.5) or int(v + 0.5)
class Unit(object):
"""
Class for coordinate and size values with units. This class abstracts from
actual lengths with concrete units.
"""
__slots__ = ('__is_unset', '__unit', '__cache_px', '__cache_pt',
'__cache_cm', '__cache_in', '__cache_pcnt', '__in2pcnt',
'__original_value', '__value',
'__IN2PT_SCALE', '__PT2IN_SCALE', '__IN2PX_SCALE',
'__PX2IN_SCALE', '__IN2CM_SCALE', '__CM2IN_SCALE')
def __init__(self, value = None, unit = None, string = None):
# scaling factors
self.__IN2PT_SCALE = 72.0
self.__PT2IN_SCALE = 1 / self.__IN2PT_SCALE
self.__IN2PX_SCALE = float(settings.dpi)
self.__PX2IN_SCALE = 1 / self.__IN2PX_SCALE
self.__IN2CM_SCALE = 2.54
self.__CM2IN_SCALE = 1 / self.__IN2CM_SCALE
if (not string): string = None
if (value == unit == string == None):
value, unit = 0, UNIT_PX
self.__is_unset = True
else:
self.__is_unset = False
if (string):
if (string[-1] == "%"):
value = float(string[:-1])
unit = UNIT_PERCENT
elif (string[-2:] == "cm"):
value = float(string[:-2])
unit = UNIT_CM
elif (string[-2:] == "in"):
value = float(string[:-2])
unit = UNIT_IN
elif (string[-2:] == "pt"):
value = float(string[:-2])
unit = UNIT_PT
else:
value = int(float(string))
unit = UNIT_PX
# the unit type
self.__unit = unit
# cache for computed values
self.__cache_px = (unit != UNIT_PX) and value or None
self.__cache_pt = (unit == UNIT_PT) and value or None
self.__cache_cm = (unit == UNIT_CM) and value or None
self.__cache_in = (unit == UNIT_IN) and value or None
self.__cache_pcnt = (unit == UNIT_PERCENT) and value or None
# the scaling factor from inches to percents
self.__in2pcnt = 0.1
self.__validate(self.__unit)
# store value in inches
self.__original_value = value
self.__value = self.__unit_to_inch(value, unit)
self.set_100_percent(100)
#
# Validates the unit type.
#
def __validate(self, unit):
if (unit not in (UNIT_PX, UNIT_CM, UNIT_IN, UNIT_PT, UNIT_PERCENT)):
raise TypeError("%s is not a valid UNIT." % (unit,))
def __unit_to_inch(self, value, unit):
# trust no one
self.__validate(unit)
if (unit == UNIT_IN): return value
elif (unit == UNIT_CM): return value * self.__CM2IN_SCALE
elif (unit == UNIT_PX): return value * self.__PX2IN_SCALE
elif (unit == UNIT_PT): return value * self.__PT2IN_SCALE
# percentual values get converted at a later time
elif (unit == UNIT_PERCENT): return value
def __inch_to_unit(self, value, unit):
# trust no one
self.__validate(unit)
if (unit == UNIT_IN):
v = value
self.__cache_in = v
elif (unit == UNIT_CM):
v = value * self.__IN2CM_SCALE
self.__cache_cm = v
elif (unit == UNIT_PX):
v = _round(value * self.__IN2PX_SCALE)
self.__cache_px = v
elif (unit == UNIT_PT):
v = value * self.__IN2PT_SCALE
self.__cache_pt = v
elif (unit == UNIT_PERCENT):
v = value * self.__in2pcnt
self.__cache_pcnt = v
return v
def set_100_percent(self, size):
#assert (size > 0)
if (size <= 0): size = 1
# size is a value in pixels, therefore convert it to inches
size = self.__unit_to_inch(size, UNIT_PX)
if (self.__unit == UNIT_PERCENT):
self.__value = (self.__original_value) * (size / 100.0)
self.__in2pcnt = 100.0 / size
# invalidate cached values
self.__cache_pcnt = None
self.__cache_px = None
self.__cache_pt = None
self.__cache_cm = None
self.__cache_in = None
def as_px(self):
return self.__cache_px or self.__inch_to_unit(self.__value, UNIT_PX)
def as_pt(self):
return self.__cache_pt or self.__inch_to_unit(self.__value, UNIT_PT)
def as_cm(self):
return self.__cache_cm or self.__inch_to_unit(self.__value, UNIT_CM)
def as_in(self):
return self.__cache_in or self.__inch_to_unit(self.__value, UNIT_IN)
def as_percent(self):
return self.__cache_pcnt or self.__inch_to_unit(self.__value,
UNIT_PERCENT)
def get_unit(self): return self.__unit
def is_unset(self): return self.__is_unset
#
# Creates a new Unit object as a copy of this one.
# TODO: copy the set_100_percent value as well
#
def copy(self):
new = Unit(self.as_pt(), UNIT_PT)
return new
def __getitem__(self, unit):
log("Deprecation:\n"
"Accessing the Unit object as a dictionary is deprecated. "
"Please use the appropriate accessor methods instead.", True)
return self.__inch_to_unit(self.__value, unit)
def __add__(self, other):
return Unit(self.as_pt() + other.as_pt(), UNIT_PT)
def __sub__(self, other):
return Unit(self.as_pt() - other.as_pt(), UNIT_PT)
def __mul__(self, other):
if (isinstance(other, Unit)):
return Unit(self.as_pt() * other.as_pt(), UNIT_PT)
else:
return Unit(self.as_pt() * other, UNIT_PT)
def __div__(self, other):
if (isinstance(other, Unit)):
return Unit(self.as_pt() / other.as_pt(), UNIT_PT)
else:
return Unit(self.as_pt() / other, UNIT_PT)
def __cmp__(self, other):
assert (other == None or isinstance(other, Unit)), \
"Cannot compare with non-Unit object"
if (not other): return 1
else: return cmp(int(self.as_pt()), int(other.as_pt()))
def __repr__(self):
unit = self.get_unit()
if (self.is_unset()): return "unset"
if (unit == UNIT_CM): return "%fcm" % self.as_cm()
elif (unit == UNIT_IN): return "%fin" % self.as_in()
elif (unit == UNIT_PT): return "%fpt" % self.as_pt()
elif (unit == UNIT_PX): return "%f" % self.as_px()
elif (unit == UNIT_PERCENT): return "%f%%" % self.as_percent()
def __hash__(self):
return hash(repr(self))
import sys
# for convenience
ZERO = Unit(0, UNIT_PT)
ONE = Unit(1, UNIT_PT)
MAXIMUM = Unit(sys.maxint, UNIT_PT)
UNSET = Unit()
if (__name__ == "__main__"):
u = Unit(10, UNIT_PX)
u.set_100_percent(11)
print u.as_px()
print u.as_in()
print u.as_percent()
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