mirror of
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282 lines
9.8 KiB
Python
282 lines
9.8 KiB
Python
"""Draw paths."""
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from math import atan2, cos, isclose, pi, radians, sin, tan
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from ..matrix import Matrix
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from .utils import normalize, point
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PATH_LETTERS = 'achlmqstvzACHLMQSTVZ'
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def _rotate(x, y, angle):
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"""Rotate (x, y) point of given angle around (0, 0)."""
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return x * cos(angle) - y * sin(angle), y * cos(angle) + x * sin(angle)
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def path(svg, node, font_size):
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"""Draw path node."""
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string = node.get('d', '')
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for letter in PATH_LETTERS:
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string = string.replace(letter, f' {letter} ')
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string = normalize(string)
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# TODO: get current point
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current_point = 0, 0
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svg.stream.move_to(*current_point)
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last_letter = None
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while string:
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string = string.strip()
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if string.split(' ', 1)[0] in PATH_LETTERS:
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letter, string = (f'{string} ').split(' ', 1)
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if last_letter in (None, 'z', 'Z') and letter not in 'mM':
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node.vertices.append(current_point)
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first_path_point = current_point
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elif letter == 'M':
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letter = 'L'
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elif letter == 'm':
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letter = 'l'
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if last_letter in (None, 'm', 'M', 'z', 'Z'):
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first_path_point = None
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if letter not in (None, 'm', 'M', 'z', 'Z') and (
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first_path_point is None):
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first_path_point = current_point
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if letter in 'aA':
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# Elliptic curve
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# Drawn as an approximation using Bézier curves
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x1, y1 = current_point
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rx, ry, string = point(svg, string, font_size)
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rotation, string = string.split(' ', 1)
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rotation = radians(float(rotation))
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# The large and sweep values are not always separated from the
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# following values. These flags can only be 0 or 1, so reading a
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# single digit suffices.
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large, string = string[0], string[1:].strip()
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sweep, string = string[0], string[1:].strip()
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# Retrieve end point and set remainder (before checking flags)
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x3, y3, string = point(svg, string, font_size)
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if letter == 'a':
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x3 += x1
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y3 += y1
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# Only allow 0 or 1 for flags
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large, sweep = int(large), int(sweep)
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if large not in (0, 1) or sweep not in (0, 1):
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continue
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large, sweep = bool(large), bool(sweep)
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# rx=0 or ry=0 means straight line
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if not rx or not ry:
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if string and string[0] not in PATH_LETTERS:
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# As we replace the current operation by l, we must be sure
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# that the next letter is set to the real current letter (a
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# or A) in case it’s omitted
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next_letter = f'{letter} '
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else:
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next_letter = ''
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string = f'L {x3} {y3} {next_letter}{string}'
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continue
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# Cancel the rotation of the second point
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xe, ye = _rotate(x3 - x1, y3 - y1, -rotation)
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y_scale = ry / rx
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ye /= y_scale
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# Find the angle between the second point and the x axis
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angle = atan2(ye, xe)
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# Put the second point onto the x axis
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xe = (xe ** 2 + ye ** 2) ** .5
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ye = 0
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# Update the x radius if it is too small
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rx = max(rx, xe / 2)
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# Find one circle centre
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xc = xe / 2
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yc = (rx ** 2 - xc ** 2) ** .5
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# Choose between the two circles according to flags
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if large == sweep:
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yc = -yc
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# Put the second point and the center back to their positions
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xe, ye = _rotate(xe, ye, angle)
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xc, yc = _rotate(xc, yc, angle)
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# Find the drawing angles
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angle1 = atan2(-yc, -xc)
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angle2 = atan2(ye - yc, xe - xc)
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while angle1 < 0 or angle2 < 0:
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angle1 += 2 * pi
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angle2 += 2 * pi
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# Store the tangent angles
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node.vertices.append((-angle1, -angle2))
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# Fix angles to follow large arc flag
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if isclose(abs(angle2 - angle1), pi):
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if sweep and (angle2 < angle1):
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angle1 -= 2 * pi
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elif not sweep and (angle2 > angle1):
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angle2 -= 2 * pi
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elif large == (abs(angle2 - angle1) < pi):
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if angle1 > angle2:
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angle1 -= 2 * pi
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else:
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angle2 -= 2 * pi
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# Split arc into 3 Bézier curves when larger than pi
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if large:
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step = (angle2 - angle1) / 3
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angles = (
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(angle1, angle1 + step),
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(angle1 + step, angle1 + 2 * step),
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(angle1 + 2 * step, angle2))
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else:
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angles = ((angle1, angle2),)
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# Draw Bézier curves
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matrix = Matrix(
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cos(rotation), sin(rotation),
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-sin(rotation) * y_scale, cos(rotation) * y_scale,
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x1, y1)
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h = 4 / 3 * tan((angles[0][1] - angles[0][0]) / 4)
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for angle1, angle2 in angles:
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point1 = matrix.transform_point(
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xc + rx * cos(angle1) - h * rx * sin(angle1),
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yc + rx * sin(angle1) + h * rx * cos(angle1))
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point2 = matrix.transform_point(
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xc + rx * cos(angle2) + h * rx * sin(angle2),
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yc + rx * sin(angle2) - h * rx * cos(angle2))
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point3 = matrix.transform_point(
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xc + rx * cos(angle2),
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yc + rx * sin(angle2))
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svg.stream.curve_to(*point1, *point2, *point3)
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current_point = x3, y3
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elif letter in 'cC':
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# Curve
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x1, y1, string = point(svg, string, font_size)
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x2, y2, string = point(svg, string, font_size)
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x3, y3, string = point(svg, string, font_size)
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if letter == 'c':
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x, y = current_point
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x1 += x
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x2 += x
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x3 += x
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y1 += y
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y2 += y
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y3 += y
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node.vertices.append((
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atan2(y1 - y2, x1 - x2), atan2(y3 - y2, x3 - x2)))
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svg.stream.curve_to(x1, y1, x2, y2, x3, y3)
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current_point = x3, y3
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elif letter in 'hH':
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# Horizontal line
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x, string = (f'{string} ').split(' ', 1)
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old_x, old_y = current_point
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x, _ = svg.point(x, 0, font_size)
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if letter == 'h':
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x += old_x
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angle = 0 if x > old_x else pi
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node.vertices.append((pi - angle, angle))
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svg.stream.line_to(x, old_y)
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current_point = x, old_y
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elif letter in 'lL':
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# Straight line
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x, y, string = point(svg, string, font_size)
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old_x, old_y = current_point
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if letter == 'l':
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x += old_x
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y += old_y
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angle = atan2(y - old_y, x - old_x)
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node.vertices.append((pi - angle, angle))
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svg.stream.line_to(x, y)
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current_point = x, y
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elif letter in 'mM':
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# Current point move
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x, y, string = point(svg, string, font_size)
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if last_letter and last_letter not in 'zZ':
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node.vertices.append(None)
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if letter == 'm':
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x += current_point[0]
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y += current_point[1]
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svg.stream.move_to(x, y)
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current_point = x, y
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elif letter in 'qQtT':
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# Quadratic curve
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x1, y1 = current_point
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if letter in 'qQ':
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x2, y2, string = point(svg, string, font_size)
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else:
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if last_letter not in 'QqTt':
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x2, y2, x3, y3 = x, y, x, y
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x2 = x1 + x3 - x2
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y2 = y1 + y3 - y2
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x3, y3, string = point(svg, string, font_size)
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if letter == 'q':
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x2 += x1
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y2 += y1
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if letter in 'qt':
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x3 += x1
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y3 += y1
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xq1 = x2 * 2 / 3 + x1 / 3
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yq1 = y2 * 2 / 3 + y1 / 3
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xq2 = x2 * 2 / 3 + x3 / 3
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yq2 = y2 * 2 / 3 + y3 / 3
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svg.stream.curve_to(xq1, yq1, xq2, yq2, x3, y3)
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node.vertices.append((0, 0))
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current_point = x3, y3
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elif letter in 'sS':
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# Smooth curve
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x, y = current_point
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x1 = x3 + (x3 - x2) if last_letter in 'csCS' else x
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y1 = y3 + (y3 - y2) if last_letter in 'csCS' else y
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x2, y2, string = point(svg, string, font_size)
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x3, y3, string = point(svg, string, font_size)
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if letter == 's':
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x2 += x
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x3 += x
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y2 += y
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y3 += y
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node.vertices.append((
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atan2(y1 - y2, x1 - x2), atan2(y3 - y2, x3 - x2)))
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svg.stream.curve_to(x1, y1, x2, y2, x3, y3)
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current_point = x3, y3
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elif letter in 'vV':
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# Vertical line
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y, string = (f'{string} ').split(' ', 1)
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old_x, old_y = current_point
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_, y = svg.point(0, y, font_size)
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if letter == 'v':
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y += old_y
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angle = pi / 2 if y > old_y else -pi / 2
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node.vertices.append((pi - angle, angle))
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svg.stream.line_to(old_x, y)
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current_point = old_x, y
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elif letter in 'zZ' and first_path_point:
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# End of path
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node.vertices.append(None)
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svg.stream.close()
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current_point = first_path_point
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if letter not in 'zZ':
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node.vertices.append(current_point)
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string = string.strip()
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last_letter = letter
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