144 lines
3.2 KiB
Python
144 lines
3.2 KiB
Python
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# encoding: utf-8
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"""Utility functions and classes."""
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from __future__ import absolute_import, division, print_function, unicode_literals
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class Length(int):
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"""
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Base class for length classes Inches, Emu, Cm, Mm, Pt, and Px. Provides
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properties for converting length values to convenient units.
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"""
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_EMUS_PER_INCH = 914400
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_EMUS_PER_CENTIPOINT = 127
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_EMUS_PER_CM = 360000
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_EMUS_PER_MM = 36000
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_EMUS_PER_PT = 12700
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def __new__(cls, emu):
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return int.__new__(cls, emu)
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@property
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def inches(self):
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"""
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Floating point length in inches
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"""
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return self / float(self._EMUS_PER_INCH)
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@property
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def centipoints(self):
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"""
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Integer length in hundredths of a point (1/7200 inch). Used
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internally because PowerPoint stores font size in centipoints.
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"""
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return self // self._EMUS_PER_CENTIPOINT
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@property
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def cm(self):
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"""
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Floating point length in centimeters
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"""
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return self / float(self._EMUS_PER_CM)
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@property
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def emu(self):
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"""
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Integer length in English Metric Units
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"""
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return self
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@property
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def mm(self):
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"""
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Floating point length in millimeters
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"""
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return self / float(self._EMUS_PER_MM)
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@property
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def pt(self):
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"""
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Floating point length in points
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"""
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return self / float(self._EMUS_PER_PT)
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class Inches(Length):
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"""
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Convenience constructor for length in inches
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"""
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def __new__(cls, inches):
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emu = int(inches * Length._EMUS_PER_INCH)
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return Length.__new__(cls, emu)
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class Centipoints(Length):
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"""
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Convenience constructor for length in hundredths of a point
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"""
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def __new__(cls, centipoints):
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emu = int(centipoints * Length._EMUS_PER_CENTIPOINT)
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return Length.__new__(cls, emu)
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class Cm(Length):
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"""
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Convenience constructor for length in centimeters
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"""
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def __new__(cls, cm):
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emu = int(cm * Length._EMUS_PER_CM)
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return Length.__new__(cls, emu)
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class Emu(Length):
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"""
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Convenience constructor for length in english metric units
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"""
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def __new__(cls, emu):
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return Length.__new__(cls, int(emu))
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class Mm(Length):
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"""
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Convenience constructor for length in millimeters
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"""
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def __new__(cls, mm):
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emu = int(mm * Length._EMUS_PER_MM)
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return Length.__new__(cls, emu)
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class Pt(Length):
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"""
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Convenience value class for specifying a length in points
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"""
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def __new__(cls, points):
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emu = int(points * Length._EMUS_PER_PT)
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return Length.__new__(cls, emu)
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def lazyproperty(f):
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"""
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@lazyprop decorator. Decorated method will be called only on first access
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to calculate a cached property value. After that, the cached value is
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returned.
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"""
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cache_attr_name = "_%s" % f.__name__ # like '_foobar' for prop 'foobar'
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docstring = f.__doc__
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def get_prop_value(obj):
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try:
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return getattr(obj, cache_attr_name)
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except AttributeError:
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value = f(obj)
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setattr(obj, cache_attr_name, value)
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return value
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return property(get_prop_value, doc=docstring)
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