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improved Arc class docstring

pull/10/head
Andy 2017-02-20 19:46:16 -08:00
parent 058b23585f
commit c219d1e671
1 changed files with 20 additions and 16 deletions
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svgpathtools/path.py
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@ -1145,28 +1145,21 @@ class Arc(object):
and minor axes (radii) which connect start and end. One which
connects them in a CCW fashion and one which connected them in a
CW fashion. If sweep is 1, the CCW ellipse will be used. If
sweep is 0, the CW ellipse will be used.
sweep is 0, the CW ellipse will be used. See note on curve
orientation below.
end : complex
The end point of the large_arc (must be distinct from start).
autoscale_radius : bool
If autoscale_radius == True, then will also scale self.radius
in the case that no ellipse exists with the input parameters
(see in-line comments for further explanation).
Note on CW and CCW: The notions of CW and CCW are reversed in some
sense when viewing SVGs (as the y coordinate starts at the top of the
image and increases towards the bottom).
Derived Parameters
------------------
self._parameterize() sets self.center, self.theta and self.delta
for use in self.point() and other methods. If
autoscale_radius == True, then this will also scale self.radius in the
case that no ellipse exists with the given parameters (see usage
below).
Derived Parameters/Attributes
-----------------------------
self.theta : float
This is the phase (in degrees) of self.u1transform(self.start).
It is $\theta_1$ in the official documentation and ranges from
-180 to 180.
self.delta : float
This is the angular distance (in degrees) between the start and
end of the arc after the arc has been sent to the unit circle
@ -1174,9 +1167,20 @@ class Arc(object):
It is $\Delta\theta$ in the official documentation and ranges from
-360 to 360; being positive when the arc travels CCW and negative
otherwise (i.e. is positive/negative when sweep == True/False).
self.center : complex
This is the center of the arc's ellipse.
self.phi : float
The arc's rotation in radians, i.e. `radians(self.rotation)`.
self.rot_matrix : complex
Equal to `exp(1j * self.phi)` which is also equal to
`cos(self.phi) + 1j*sin(self.phi)`.
Note on curve orientation (CW vs CCW)
-------------------------------------
The notions of clockwise (CW) and counter-clockwise (CCW) are reversed
in some sense when viewing SVGs (as the y coordinate starts at the top
of the image and increases towards the bottom).
"""
self.start = start