Class: HexaPDF::Content::GraphicObject::EndpointArc

Inherits:
Object
  • Object
show all
Includes:
Utils::MathHelpers
Defined in:
lib/hexapdf/content/graphic_object/endpoint_arc.rb

Overview

This class describes an elliptical arc in endpoint parameterization. It allows one to generate an arc from the current point to a given point, similar to Content::Canvas#line_to.

This graphic object is registered under the :endpoint_arc key for use with the HexaPDF::Content::Canvas class.

Examples:

#>pdf-center
arc = canvas.graphic_object(:endpoint_arc, x: 50, y: 20, a: 30, b: 10)
canvas.move_to(0, 0).draw(arc).stroke

See: GraphicObject::Arc, ARC - www.w3.org/TR/SVG/implnote.html#ArcImplementationNotes

Constant Summary collapse

EPSILON = 
1e-10

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Utils::MathHelpers

deg_to_rad, rad_to_deg

Constructor Details

#initialize ⇒ EndpointArc

Creates an endpoint arc with default values x=0, y=0, a=0, b=0, inclination=0, large_arc=true, clockwise=false (a line to the origin).

Examples:

#>pdf-center
canvas.move_to(30, 30).draw(:endpoint_arc).stroke



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# File 'lib/hexapdf/content/graphic_object/endpoint_arc.rb', line 150

def initialize
  @x = @y = 0
  @a = @b = 0
  @inclination = 0
  @large_arc = true
  @clockwise = false
end

Instance Attribute Details

#a ⇒ Object (readonly)

Length of semi-major axis

Examples:

#>pdf-center
arc = canvas.graphic_object(:endpoint_arc, x: 50, y: 20, a: 30, b: 20)
canvas.move_to(0, 0).draw(arc).stroke
canvas.stroke_color("red").move_to(0, 0).draw(arc, a: 40).stroke



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# File 'lib/hexapdf/content/graphic_object/endpoint_arc.rb', line 97

def a
  @a
end

#b ⇒ Object (readonly)

Length of semi-minor axis

Examples:

#>pdf-center
arc = canvas.graphic_object(:endpoint_arc, x: 50, y: 20, a: 30, b: 20)
canvas.move_to(0, 0).draw(arc).stroke
canvas.stroke_color("red").move_to(0, 0).draw(arc, b: 50).stroke



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# File 'lib/hexapdf/content/graphic_object/endpoint_arc.rb', line 107

def b
  @b
end

#clockwise ⇒ Object (readonly)

Direction of arc - if true in clockwise direction, else in counterclockwise direction

This is needed, for example, when filling paths using the nonzero winding number rule to achieve different effects.

Examples:

#>pdf-center
arc = canvas.graphic_object(:endpoint_arc, x: 50, y: 20, a: 30, b: 20)
canvas.move_to(0, 0).draw(arc).stroke
canvas.stroke_color("red").move_to(0, 0).draw(arc, clockwise: true).stroke



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# File 'lib/hexapdf/content/graphic_object/endpoint_arc.rb', line 141

def clockwise
  @clockwise
end

#inclination ⇒ Object (readonly)

Inclination in degrees of semi-major axis in respect to x-axis

Examples:

#>pdf-center
arc = canvas.graphic_object(:endpoint_arc, x: 50, y: 20, a: 30, b: 20)
canvas.move_to(0, 0).draw(arc).stroke
canvas.stroke_color("red").move_to(0, 0).draw(arc, inclination: 45).stroke



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# File 'lib/hexapdf/content/graphic_object/endpoint_arc.rb', line 117

def inclination
  @inclination
end

#large_arc ⇒ Object (readonly)

Large arc choice - if true use the large arc (i.e. the one spanning more than 180 degrees), else the small arc

Examples:

#>pdf-center
arc = canvas.graphic_object(:endpoint_arc, x: 50, y: 20, a: 30, b: 20)
canvas.move_to(0, 0).draw(arc).stroke
canvas.stroke_color("red").move_to(0, 0).draw(arc, large_arc: false, clockwise: true).stroke



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# File 'lib/hexapdf/content/graphic_object/endpoint_arc.rb', line 128

def large_arc
  @large_arc
end

#x ⇒ Object (readonly)

x-coordinate of endpoint

Examples:

#>pdf-center
arc = canvas.graphic_object(:endpoint_arc, x: 50, y: 20, a: 30, b: 20)
canvas.move_to(0, 0).draw(arc).stroke
canvas.stroke_color("red").move_to(0, 0).draw(arc, x: -50).stroke



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# File 'lib/hexapdf/content/graphic_object/endpoint_arc.rb', line 77

def x
  @x
end

#y ⇒ Object (readonly)

y-coordinate of endpoint

Examples:

#>pdf-center
arc = canvas.graphic_object(:endpoint_arc, x: 50, y: 20, a: 30, b: 20)
canvas.move_to(0, 0).draw(arc).stroke
canvas.stroke_color("red").move_to(0, 0).draw(arc, y: -20).stroke



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# File 'lib/hexapdf/content/graphic_object/endpoint_arc.rb', line 87

def y
  @y
end

Class Method Details

.configure(**kwargs) ⇒ Object

Creates and configures a new endpoint arc object.

See #configure for the allowed keyword arguments.



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# File 'lib/hexapdf/content/graphic_object/endpoint_arc.rb', line 65

def self.configure(**kwargs)
  new.configure(**kwargs)
end

Instance Method Details

#configure(x: nil, y: nil, a: nil, b: nil, inclination: nil, large_arc: nil, clockwise: nil) ⇒ Object

Configures the endpoint arc with

  • endpoint (x, y),

  • semi-major axis a,

  • semi-minor axis b,

  • an inclination in respect to the x-axis of inclination degrees,

  • the given large_arc flag and

  • the given clockwise flag.

The large_arc option determines whether the large arc, i.e. the one spanning more than 180 degrees, is used (true) or the small arc (false).

The clockwise option determines if the arc is drawn in the counterclockwise direction (false) or in the clockwise direction (true).

Any arguments not specified are not modified and retain their old value, see #initialize for the inital values.

Returns self.



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# File 'lib/hexapdf/content/graphic_object/endpoint_arc.rb', line 177

def configure(x: nil, y: nil, a: nil, b: nil, inclination: nil, large_arc: nil,
              clockwise: nil)
  @x = x if x
  @y = y if y
  @a = a.abs if a
  @b = b.abs if b
  @inclination = inclination % 360 if inclination
  @large_arc = large_arc unless large_arc.nil?
  @clockwise = clockwise unless clockwise.nil?

  self
end

#draw(canvas) ⇒ Object

Draws the arc on the given Canvas.



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# File 'lib/hexapdf/content/graphic_object/endpoint_arc.rb', line 191

def draw(canvas)
  x1, y1 = *canvas.current_point

  # ARC F.6.2 - nothing to do if endpoint is equal to current point
  return if float_equal(x1, @x) && float_equal(y1, @y)

  if @a == 0 || @b == 0
    # ARC F.6.2, F.6.6 - just use a line if it is not really an arc
    canvas.line_to(@x, @y)
  else
    values = compute_arc_values(x1, y1)
    arc = canvas.graphic_object(:arc, **values)
    arc.draw(canvas, move_to_start: false)
  end
end