Method: HexaPDF::Content::Canvas#arc

Defined in:

lib/hexapdf/content/canvas.rb

#arc(cx, cy, a:, b: a, start_angle: 0, end_angle: 360, clockwise: false, inclination: 0) ⇒ Object

:call-seq:

canvas.arc(cx, cy, a:, b: a, start_angle: 0, end_angle: 360, clockwise: false, inclination: 0)   => canvas

Appends an elliptical arc to the path and returns self. The endpoint of the arc becomes the new current point.

cx

x-coordinate of the center point of the arc

cy

y-coordinate of the center point of the arc

a

Length of semi-major axis

b

Length of semi-minor axis (default: a)

start_angle

Angle in degrees at which to start the arc (default: 0)

end_angle

Angle in degrees at which to end the arc (default: 360)

clockwise

If true the arc is drawn in clockwise direction, otherwise in counterclockwise direction (default: false).

inclination

Angle in degrees between the x-axis and the semi-major axis (default: 0)

If a and b are equal, a circular arc is drawn. If the difference of the start angle and end angle is equal to 360, a full ellipse (or circle) is drawn.

If there is no current path when the method is invoked, a new path is automatically begun.

This arc does not start from the current point (#current_point). If this functionality is needed, use #draw together with GraphicObject::EndpointArc.

Since PDF doesn’t have operators for drawing elliptical or circular arcs, they have to be approximated using Bezier curves (see #curve_to). The accuracy of the approximation can be controlled using the configuration option ‘graphic_object.arc.max_curves’.

Examples:

#>pdf
canvas.arc(50, 150, a: 10)                         # Circle with radius 10
canvas.arc(100, 150, a: 10, b: 5)                  # Ellipse with radii 10 and 5
canvas.arc(150, 150, a: 10, b: 5, inclination: 45) # The above ellipse inclined 45 degrees
canvas.stroke

# Circular and elliptical arcs from 30 degrees to 160 degrees
canvas.stroke_color("hp-blue")
canvas.arc(50, 100, a: 10, start_angle: 30, end_angle: 160)
canvas.arc(100, 100, a: 10, b: 5, start_angle: 30, end_angle: 160)
canvas.stroke

# Arcs from 135 degrees to 30 degrees, the first in counterclockwise direction (i.e. the
# big arc), the other in clockwise direction (i.e. the small arc)
canvas.stroke_color("hp-orange")
canvas.arc(50, 50, a: 10, start_angle: 135, end_angle: 30)
canvas.arc(100, 50, a: 10, start_angle: 135, end_angle: 30, clockwise: true)
canvas.stroke

See: #arc, #circle, #ellipse, GraphicObject::Arc, GraphicObject::EndpointArc

# File 'lib/hexapdf/content/canvas.rb', line 1385

def arc(cx, cy, a:, b: a, start_angle: 0, end_angle: 360, clockwise: false, inclination: 0)
  arc = GraphicObject::Arc.configure(cx: cx, cy: cy, a: a, b: b,
                                     start_angle: start_angle, end_angle: end_angle,
                                     clockwise: clockwise, inclination: inclination)
  arc.draw(self)
  self
end