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#
# Copyright (C) 2010 Gianluca Sforna
#
# All Rights Reserved
#
# This file is part of the RDKit.
# The contents are covered by the terms of the BSD license
# which is included in the file license.txt, found at the root
# of the RDKit source tree.
import math
class CanvasBase:
"""Base class for specialized canvas backends"""
def addCanvasLine(self, p1, p2, color=(0, 0, 0), color2=None, **kwargs):
"""Draw a single line on the canvas
This function will draw a line between `p1` and `p2` with the
given `color`.
If `color2` is specified, it will be used to draw the second half
of the segment
"""
raise NotImplementedError('This should be implemented')
def addCanvasText(self, text, pos, font, color=(0, 0, 0), **kwargs):
"""Draw some text
The provided `text` is drawn at position `pos` using the given
`font` and the chosen `color`.
"""
raise NotImplementedError('This should be implemented')
def addCanvasPolygon(self, ps, color=(0, 0, 0), **kwargs):
"""Draw a polygon
Draw a polygon identified by vertexes given in `ps` using
the given `color`
"""
raise NotImplementedError('This should be implemented')
def addCanvasDashedWedge(self, p1, p2, p3, dash=(2, 2), color=(0, 0, 0), color2=None, **kwargs):
"""Draw a dashed wedge
The wedge is identified by the three points `p1`, `p2`, and `p3`.
It will be drawn using the given `color`; if `color2` is specified
it will be used for the second half of the wedge
TODO: fix comment, I'm not sure what `dash` does
"""
raise NotImplementedError('This should be implemented')
def flush(self):
"""Complete any remaining draw operation
This is supposed to be the last operation on the canvas before
saving it
"""
raise NotImplementedError('This should be implemented')
def _getLinePoints(self, p1, p2, dash):
x1, y1 = p1
x2, y2 = p2
dx = x2 - x1
dy = y2 - y1
lineLen = math.sqrt(dx * dx + dy * dy)
theta = math.atan2(dy, dx)
cosT = math.cos(theta)
sinT = math.sin(theta)
pos = (x1, y1)
pts = [pos]
dist = 0
currDash = 0
while dist < lineLen:
currL = dash[currDash % len(dash)]
if dist + currL > lineLen:
currL = lineLen - dist
endP = (pos[0] + currL * cosT, pos[1] + currL * sinT)
pts.append(endP)
pos = endP
dist += currL
currDash += 1
return pts
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