RMagick supports a full set of 2D drawing methods. Here are some examples of the drawing API.

require 'RMagick'

canvas = Magick::Image.new(240, 300,
              Magick::HatchFill.new('white','lightcyan2'))
gc = Magick::Draw.new

# Draw ellipse
gc.stroke('red')
gc.stroke_width(3)
gc.fill_opacity(0)
gc.ellipse(120, 150, 80, 120, 0, 270)

# Draw endpoints
gc.stroke('gray50')
gc.stroke_width(1)
gc.circle(120, 150, 124, 150)
gc.circle(200, 150, 204, 150)
gc.circle(120,  30, 124,  30)

# Draw lines
gc.line(120, 150, 200, 150)
gc.line(120, 150, 120,  30)

# Annotate
gc.stroke('transparent')
gc.fill('black')
gc.text(130, 35, "End")
gc.text(188, 135, "Start")
gc.text(130, 95, "'Height=120'")
gc.text(55, 155, "'Width=80'")

gc.draw(canvas)
canvas.write('shapes.gif')

require 'RMagick'

canvas = Magick::Image.new(240, 300,
              Magick::HatchFill.new('white','lightcyan2'))
gc = Magick::Draw.new

# Draw curve
gc.stroke('blue')
gc.stroke_width(3)
gc.fill_opacity(0)
gc.bezier(45,150, 45,20, 195,280, 195,150)

# Draw endpoints
gc.stroke('gray50')
gc.stroke_width(1)
gc.circle(45,150, 49,150)
gc.circle(195,150, 199,150)

# Draw control points
gc.fill_opacity(1)
gc.fill('gray50')
gc.circle(45,17, 49,17)
gc.circle(195,280, 199,280)

# Connect the points
gc.line(45,150, 45,17)
gc.line(195,280, 195,150)

# Annotate
gc.stroke('transparent').fill('black')
gc.text(27, 175, "'45,150'")
gc.text(175,138, "'195,150'")
gc.text(55,22, "'45,20'")
gc.text(143,285, "'195,280'")
gc.draw(canvas)

canvas.write('bezier.gif')

require 'RMagick'

canvas = Magick::Image.new(240, 300,
              Magick::HatchFill.new('white','lightcyan2'))
gc = Magick::Draw.new

gc.fill('red')
gc.stroke('blue')
gc.stroke_width(2)
gc.path('M120,150 h-75 a75,75 0 1, 0 75,-75 z')
gc.fill('yellow')
gc.path('M108.5,138.5 v-75 a75,75 0 0,0 -75,75 z')
gc.draw(canvas)

canvas.write('path.gif')

require 'RMagick'

canvas = Magick::Image.new(240, 300,
              Magick::HatchFill.new('white','lightcyan2'))
gc = Magick::Draw.new

gc.stroke('#001aff')
gc.stroke_width(3)
gc.fill('#00ff00')

x = 120
y = 32.5
gc.polygon(x,    y,     x+29, y+86,  x+109, y+86,
           x+47, y+140, x+73, y+226, x,     y+175,
           x-73, y+226, x-47, y+140, x-109, y+86,
           x-29, y+86)

gc.draw(canvas)
canvas.write('polygon.gif')