Class: PerfectShape::Path

Inherits:
Shape
  • Object
show all
Includes:
MultiPoint
Defined in:
lib/perfect_shape/path.rb

Overview

Mostly ported from java.awt.geom: docs.oracle.com/javase/8/docs/api/java/awt/geom/Path2D.html

Constant Summary collapse

SHAPE_TYPES = 
[Array, Point, Line]
WINDING_RULES = 
[:wind_non_zero, :wind_even_odd]

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from MultiPoint

#max_x, #max_y, #min_x, #min_y

Methods inherited from Shape

#==, #bounding_box, #center_x, #center_y, #height, #max_x, #max_y, #min_x, #min_y, #normalize_point, #width

Constructor Details

#initialize(shapes: [], closed: false, winding_rule: :wind_non_zero) ⇒ Path

Constructs Path with winding rule, closed status, and shapes (must always start with PerfectShape::Point or Array of [x,y] coordinates) Shape class types can be any of SHAPE_TYPES: Array (x,y coordinates), PerfectShape::Point, or PerfectShape::Line winding_rule can be any of WINDING_RULES: :wind_non_zero (default) or :wind_even_odd



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# File 'lib/perfect_shape/path.rb', line 44

def initialize(shapes: [], closed: false, winding_rule: :wind_non_zero)
  self.closed = closed
  self.winding_rule = winding_rule
  self.shapes = shapes
end

Instance Attribute Details

#closed ⇒ Object Also known as: closed?

Returns the value of attribute closed.



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# File 'lib/perfect_shape/path.rb', line 38

def closed
  @closed
end

#shapes ⇒ Object

Returns the value of attribute shapes.



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# File 'lib/perfect_shape/path.rb', line 38

def shapes
  @shapes
end

#winding_rule ⇒ Object

Returns the value of attribute winding_rule.



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# File 'lib/perfect_shape/path.rb', line 37

def winding_rule
  @winding_rule
end

Instance Method Details

#contain?(x_or_point, y = nil) ⇒ @code true

Checks if path contains point (two-number Array or x, y args) using the Nonzero-Rule (aka Winding Number Algorithm): en.wikipedia.org/wiki/Nonzero-rule or using the Even-Odd Rule (aka Ray Casting Algorithm): en.wikipedia.org/wiki/Even%E2%80%93odd_rule

the path, false if the point lies outside of the path’s bounds.

Parameters:

  • x —

    The X coordinate of the point to test.

  • y (defaults to: nil) —

    The Y coordinate of the point to test.

Returns:

  • (@code true) —

    if the point lies within the bound of



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# File 'lib/perfect_shape/path.rb', line 108

def contain?(x_or_point, y = nil)
  x, y = normalize_point(x_or_point, y)
  return unless x && y
  if (x * 0.0 + y * 0.0) == 0.0
    # N * 0.0 is 0.0 only if N is finite.
    # Here we know that both x and y are finite.
    return false if shapes.count < 2
    mask = winding_rule == :wind_non_zero ? -1 : 1
    (point_crossings(x, y).to_i & mask) != 0
  else
    # Either x or y was infinite or NaN.
    # A NaN always produces a negative response to any test
    # and Infinity values cannot be "inside" any path so
    # they should return false as well.
    false
  end
end

#drawing_types ⇒ Object 



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# File 'lib/perfect_shape/path.rb', line 75

def drawing_types
  the_drawing_shapes = @shapes.map do |shape|
    case shape
    when Point
      :move_to
    when Array
      :move_to
    when Line
      :line_to
    when QuadraticBezierCurve
      :quad_to
#         when CubicBezierCurve # TODO
    end
  end
  the_drawing_shapes << :close if closed?
  the_drawing_shapes
end

#point_crossings(x_or_point, y = nil) ⇒ Object

Calculates the number of times the given path crosses the ray extending to the right from (x,y). If the point lies on a part of the path, then no crossings are counted for that intersection. +1 is added for each crossing where the Y coordinate is increasing -1 is added for each crossing where the Y coordinate is decreasing The return value is the sum of all crossings for every segment in the path. The path must start with a PerfectShape::Point (initial location) The caller must check for NaN values. The caller may also reject infinite values as well.



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# File 'lib/perfect_shape/path.rb', line 137

def point_crossings(x_or_point, y = nil)
  x, y = normalize_point(x_or_point, y)
  return unless x && y
  return BigDecimal('0') if shapes.count == 0
  movx = movy = curx = cury = endx = endy = 0
  coords = points.flatten
  curx = movx = coords[0]
  cury = movy = coords[1]
  crossings = BigDecimal('0')
  ci = BigDecimal('2')
  1.upto(shapes.count - 1).each do |i|
      case drawing_types[i]
      when :move_to
        if cury != movy
          line = PerfectShape::Line.new(points: [[curx, cury], [movx, movy]])
          crossings += line.point_crossings(x, y)
        end
        movx = curx = coords[ci]
        ci += 1
        movy = cury = coords[ci]
        ci += 1
      when :line_to
        endx = coords[ci]
        ci += 1
        endy = coords[ci]
        ci += 1
        line = PerfectShape::Line.new(points: [[curx, cury], [endx, endy]])
        crossings += line.point_crossings(x, y)
        curx = endx;
        cury = endy;
      when :quad_to
        quad_ctrlx = coords[ci]
        ci += 1
        quad_ctrly = coords[ci]
        ci += 1
        endx = coords[ci]
        ci += 1
        endy = coords[ci]
        ci += 1
        quad = PerfectShape::QuadraticBezierCurve.new(points: [[curx, cury], [quad_ctrlx, quad_ctrly], [endx, endy]])
        crossings += quad.point_crossings(x, y, 0)
        curx = endx;
        cury = endy;
#           when :cubic_to # TODO
#             crossings +=
#                 Curve.point_crossings_for_cubic(x, y,
#                                              curx, cury,
#                                              coords[ci++],
#                                              coords[ci++],
#                                              coords[ci++],
#                                              coords[ci++],
#                                              endx = coords[ci++],
#                                              endy = coords[ci++],
#                                              0);
#             curx = endx;
#             cury = endy;
      when :close
        if cury != movy
          line = PerfectShape::Line.new(points: [[curx, cury], [movx, movy]])
          crossings += line.point_crossings(x, y)
        end
        curx = movx
        cury = movy
      end
  end
  if cury != movy
    line = PerfectShape::Line.new(points: [[curx, cury], [movx, movy]])
    crossings += line.point_crossings(x, y)
  end
  crossings
end

#points ⇒ Object 



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# File 'lib/perfect_shape/path.rb', line 50

def points
  the_points = []
  @shapes.each do |shape|
    case shape
    when Point
      the_points << shape.to_a
    when Array
      the_points << shape.map {|n| BigDecimal(n.to_s)}
    when Line
      the_points << shape.points.last.to_a
    when QuadraticBezierCurve
      shape.points.each do |point|
        the_points << point.to_a
      end
#         when CubicBezierCurve # TODO
    end
  end
  the_points << @shapes.first.to_a if closed?
  the_points
end

#points=(some_points) ⇒ Object 



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# File 'lib/perfect_shape/path.rb', line 71

def points=(some_points)
  raise "Cannot assign points directly! Must set shapes instead and points are calculated from them automatically."
end