module Prawn::Graphics

Implements the drawing facilities for Prawn::Document. Use this to draw the most beautiful imaginable things.

This file lifts and modifies several of PDF::Writer's graphics functions ruby-pdf.rubyforge.org

Constants

KAPPA

This constant is used to approximate a symmetrical arc using a cubic Bezier curve.

Public Instance Methods

circle(center, radius) click to toggle source

Draws a circle of radius radius with the centre-point at point as a complete subpath. The drawing point will be moved to the centre-point upon completion of the drawing the circle.

pdf.circle [100,100], 25
# File lib/prawn/graphics.rb, line 194
def circle(center, radius)
  ellipse(center, radius, radius)
end
close_and_stroke() { || ... } click to toggle source

Closes and strokes the current path. If a block is provided, yields to the block before closing the path. See Graphics::Color for color details.

# File lib/prawn/graphics.rb, line 285
def close_and_stroke
  yield if block_given?
  renderer.add_content "s"
end
close_path() click to toggle source

Closes the current path.

# File lib/prawn/graphics.rb, line 386
def close_path
  renderer.add_content "h"
end
curve(origin, dest, options = {}) click to toggle source

Draws a Bezier curve between two points, bounded by two additional points

pdf.curve [50,100], [100,100], :bounds => [[90,90],[75,75]]
# File lib/prawn/graphics.rb, line 178
def curve(origin, dest, options = {})
  move_to(*origin)
  curve_to(dest, options)
end
curve_to(dest, options = {}) click to toggle source

Draws a Bezier curve from the current drawing position to the specified point, bounded by two additional points.

pdf.curve_to [100,100], :bounds => [[90,90],[75,75]]
# File lib/prawn/graphics.rb, line 67
def curve_to(dest, options = {})
  options[:bounds] or fail Prawn::Errors::InvalidGraphicsPath,
                           "Bounding points for bezier curve must be specified " \
                           "as :bounds => [[x1,y1],[x2,y2]]"

  curve_points = PDF::Core.real_params(
    (options[:bounds] << dest).flat_map { |e| map_to_absolute(e) }
  )

  renderer.add_content("#{curve_points} c")
end
ellipse(point, r1, r2 = r1) click to toggle source

Draws an ellipse of x radius r1 and y radius r2 with the centre-point at point as a complete subpath. The drawing point will be moved to the centre-point upon completion of the drawing the ellipse.

# draws an ellipse with x-radius 25 and y-radius 50
pdf.ellipse [100,100], 25, 50
# File lib/prawn/graphics.rb, line 206
def ellipse(point, r1, r2 = r1)
  x, y = point
  l1 = r1 * KAPPA
  l2 = r2 * KAPPA

  move_to(x + r1, y)

  # Upper right hand corner
  curve_to [x,  y + r2],
           :bounds => [[x + r1, y + l2], [x + l1, y + r2]]

  # Upper left hand corner
  curve_to [x - r1, y],
           :bounds => [[x - l1, y + r2], [x - r1, y + l2]]

  # Lower left hand corner
  curve_to [x, y - r2],
           :bounds => [[x - r1, y - l2], [x - l1, y - r2]]

  # Lower right hand corner
  curve_to [x + r1, y],
           :bounds => [[x + l1, y - r2], [x + r1, y - l2]]

  move_to(x, y)
end
fill(options = {}) { || ... } click to toggle source

Closes and fills the current path. See Graphics::Color for color details.

If the option :fill_rule => :even_odd is specified, Prawn will use the even-odd rule to fill the path. Otherwise, the nonzero winding number rule will be used. See the PDF reference, “Graphics -> Path Construction and Painting -> Clipping Path Operators” for details on the difference.

# File lib/prawn/graphics.rb, line 365
def fill(options = {})
  yield if block_given?
  renderer.add_content(options[:fill_rule] == :even_odd ? "f*" : "f")
end
fill_and_stroke(options = {}) { || ... } click to toggle source

Closes, fills, and strokes the current path. If a block is provided, yields to the block before closing the path. See Graphics::Color for color details.

If the option :fill_rule => :even_odd is specified, Prawn will use the even-odd rule to fill the path. Otherwise, the nonzero winding number rule will be used. See the PDF reference, “Graphics -> Path Construction and Painting -> Clipping Path Operators” for details on the difference.

# File lib/prawn/graphics.rb, line 379
def fill_and_stroke(options = {})
  yield if block_given?
  renderer.add_content(options[:fill_rule] == :even_odd ? "b*" : "b")
end
fill_and_stroke_circle(center,radius) click to toggle source

Draws, strokes, and fills a circle of radius radius with the centre-point at point.

# File lib/prawn/graphics.rb, line 518
    
fill_and_stroke_ellipse(point, r1, r2 = r1) click to toggle source

Draws, strokes, and fills an ellipse of x radius r1 and y radius r2 with the centre-point at point.

# File lib/prawn/graphics.rb, line 545
    
fill_and_stroke_polygon(*points) click to toggle source

Draws, strokes, and fills a polygon from the specified points.

# File lib/prawn/graphics.rb, line 569
    
fill_and_stroke_rectangle(point,width,height) click to toggle source

Draws, fills, and strokes a rectangle given point, width and height. The rectangle is bounded by its upper-left corner.

# File lib/prawn/graphics.rb, line 417
    
fill_and_stroke_rounded_polygon(radius, *points) click to toggle source

Draws, strokes, and fills a rounded polygon from specified points, using radius to define Bezier curves.

# File lib/prawn/graphics.rb, line 596
ops    = %w{fill stroke fill_and_stroke}
fill_circle(center,radius) click to toggle source

Draws and fills a circle of radius radius with the centre-point at point.

# File lib/prawn/graphics.rb, line 509
    
fill_ellipse(point, r1, r2 = r1) click to toggle source

Draws and fills an ellipse of x radius r1 and y radius r2 with the centre-point at point.

# File lib/prawn/graphics.rb, line 536
    
fill_polygon(*points) click to toggle source

Draws and fills a polygon from the specified points.

# File lib/prawn/graphics.rb, line 561
    
fill_rectangle(point,width,height) click to toggle source

Draws and fills ills a rectangle given point, width and height. The rectangle is bounded by its upper-left corner.

# File lib/prawn/graphics.rb, line 408
    
fill_rounded_polygon(radius, *points) click to toggle source

Draws and fills a rounded polygon from specified points, using radius to define Bezier curves.

# File lib/prawn/graphics.rb, line 587
    
fill_rounded_rectangle(point,width,height,radius) click to toggle source

Draws and fills a rounded rectangle given point, width and height and radius for the rounded corner. The rectangle is bounded by its upper-left corner.

# File lib/prawn/graphics.rb, line 437
    
horizontal_line(x1, x2, options = {}) click to toggle source

Draws a horizontal line from x1 to x2 at the current y position, or the position specified by the :at option.

# draw a line from [25, 75] to [100, 75]
horizontal_line 25, 100, :at => 75
# File lib/prawn/graphics.rb, line 147
def horizontal_line(x1, x2, options = {})
  if options[:at]
    y1 = options[:at]
  else
    y1 = y - bounds.absolute_bottom
  end

  line(x1, y1, x2, y1)
end
horizontal_rule() click to toggle source

Draws a horizontal line from the left border to the right border of the bounding box at the current y position.

# File lib/prawn/graphics.rb, line 160
def horizontal_rule
  horizontal_line(bounds.left, bounds.right)
end
line(*points) click to toggle source

Draws a line from one point to another. Points may be specified as tuples or flattened argument list:

pdf.line [100,100], [200,250]
pdf.line(100,100,200,250)
# File lib/prawn/graphics.rb, line 135
def line(*points)
  x0, y0, x1, y1 = points.flatten
  move_to(x0, y0)
  line_to(x1, y1)
end
line_to(*point) click to toggle source

Draws a line from the current drawing position to the specified point. The destination may be described as a tuple or a flattened list:

pdf.line_to [50,50]
pdf.line_to(50,50)
# File lib/prawn/graphics.rb, line 57
def line_to(*point)
  xy = PDF::Core.real_params(map_to_absolute(point))
  renderer.add_content("#{xy} l")
end
line_width(width = nil) click to toggle source

When called without an argument, returns the current line thickness. When called with an argument, sets the line thickness to the specified value (in PDF points)

pdf.line_width #=> 1
pdf.line_width(5)
pdf.line_width #=> 5
# File lib/prawn/graphics.rb, line 121
def line_width(width = nil)
  if width
    self.line_width = width
  else
    current_line_width
  end
end
line_width=(width) click to toggle source

Sets line thickness to the width specified.

# File lib/prawn/graphics.rb, line 108
def line_width=(width)
  self.current_line_width = width
  write_line_width
end
move_to(*point) click to toggle source

Moves the drawing position to a given point. The point can be specified as a tuple or a flattened argument list

pdf.move_to [100,50]
pdf.move_to(100,50)
# File lib/prawn/graphics.rb, line 46
def move_to(*point)
  xy = PDF::Core.real_params(map_to_absolute(point))
  renderer.add_content("#{xy} m")
end
polygon(*points) click to toggle source

Draws a polygon from the specified points.

# draws a snazzy triangle
pdf.polygon [100,100], [100,200], [200,200]
# File lib/prawn/graphics.rb, line 237
def polygon(*points)
  move_to points[0]
  (points[1..-1] << points[0]).each do |point|
    line_to(*point)
  end
  # close the path
  renderer.add_content "h"
end
rectangle(point, width, height) click to toggle source

Draws a rectangle given point, width and height. The rectangle is bounded by its upper-left corner.

pdf.rectangle [300,300], 100, 200
# File lib/prawn/graphics.rb, line 84
def rectangle(point, width, height)
  x, y = map_to_absolute(point)
  box = PDF::Core.real_params([x, y - height, width, height])

  renderer.add_content("#{box} re")
end
rounded_polygon(radius, *points) click to toggle source

Draws a rounded polygon from specified points using the radius to define bezier curves

# draws a rounded filled in polygon
 pdf.fill_and_stroke_rounded_polygon(10, [100, 250], [200, 300], [300, 250],
               [300, 150], [200, 100], [100, 150])
# File lib/prawn/graphics.rb, line 251
def rounded_polygon(radius, *points)
  move_to point_on_line(radius, points[1], points[0])
  sides = points.size
  points << points[0] << points[1]
  (sides).times do |i|
    rounded_vertex(radius, points[i], points[i + 1], points[i + 2])
  end
  # close the path
  renderer.add_content "h"
end
rounded_rectangle(point, width, height, radius) click to toggle source

Draws a rounded rectangle given point, width and height and radius for the rounded corner. The rectangle is bounded by its upper-left corner.

pdf.rounded_rectangle [300,300], 100, 200, 10
# File lib/prawn/graphics.rb, line 97
def rounded_rectangle(point, width, height, radius)
  x, y = point
  rounded_polygon(radius, point, [x + width, y], [x + width, y - height], [x, y - height])
end
rounded_vertex(radius, *points) click to toggle source

Creates a rounded vertex for a line segment used for building a rounded polygon requires a radius to define bezier curve and three points. The first two points define the line segment and the third point helps define the curve for the vertex.

# File lib/prawn/graphics.rb, line 265
def rounded_vertex(radius, *points)
  radial_point_1 = point_on_line(radius, points[0], points[1])
  bezier_point_1 = point_on_line((radius - radius * KAPPA), points[0], points[1])
  radial_point_2 = point_on_line(radius, points[2], points[1])
  bezier_point_2 = point_on_line((radius - radius * KAPPA), points[2], points[1])
  line_to(radial_point_1)
  curve_to(radial_point_2, :bounds => [bezier_point_1, bezier_point_2])
end
stroke() { || ... } click to toggle source

Strokes the current path. If a block is provided, yields to the block before closing the path. See Graphics::Color for color details.

# File lib/prawn/graphics.rb, line 277
def stroke
  yield if block_given?
  renderer.add_content "S"
end
stroke_and_fill_rounded_rectangle(point,width,height,radius) click to toggle source

Draws, fills, and strokes a rounded rectangle given point, width and height and radius for the rounded corner. The rectangle is bounded by its upper-left corner.

# File lib/prawn/graphics.rb, line 447
    
stroke_axis(options = {}) click to toggle source

Draws and strokes X and Y axes rulers beginning at the current bounding box origin (or at a custom location).

Options

:at

Origin of the X and Y axes (default: [0, 0] = origin of the bounding box)

:width

Length of the X axis (default: width of the bounding box)

:height

Length of the Y axis (default: height of the bounding box)

:step_length

Length of the step between markers (default: 100)

:negative_axes_length

Length of the negative parts of the axes (default: 20)

:color:

The color of the axes and the text.
# File lib/prawn/graphics.rb, line 320
def stroke_axis(options = {})
  options = {
    :at => [0, 0],
    :height => bounds.height.to_i - (options[:at] || [0, 0])[1],
    :width => bounds.width.to_i - (options[:at] || [0, 0])[0],
    :step_length => 100,
    :negative_axes_length => 20,
    :color => "000000"
  }.merge(options)

  Prawn.verify_options([:at, :width, :height, :step_length,
                        :negative_axes_length, :color], options)

  save_graphics_state do
    fill_color(options[:color])
    stroke_color(options[:color])

    dash(1, :space => 4)
    stroke_horizontal_line(options[:at][0] - options[:negative_axes_length],
                           options[:at][0] + options[:width], :at => options[:at][1])
    stroke_vertical_line(options[:at][1] - options[:negative_axes_length],
                         options[:at][1] + options[:height], :at => options[:at][0])
    undash

    fill_circle(options[:at], 1)

    (options[:step_length]..options[:width]).step(options[:step_length]) do |point|
      fill_circle([options[:at][0] + point, options[:at][1]], 1)
      draw_text(point, :at => [options[:at][0] + point - 5, options[:at][1] - 10], :size => 7)
    end

    (options[:step_length]..options[:height]).step(options[:step_length]) do |point|
      fill_circle([options[:at][0], options[:at][1] + point], 1)
      draw_text(point, :at => [options[:at][0] - 17, options[:at][1] + point - 2], :size => 7)
    end
  end
end
stroke_bounds() click to toggle source

Draws and strokes a rectangle represented by the current bounding box

# File lib/prawn/graphics.rb, line 292
def stroke_bounds
  stroke_rectangle bounds.top_left, bounds.width, bounds.height
end
stroke_circle(center,radius) click to toggle source

Draws and strokes a circle of radius radius with the centre-point at point.

# File lib/prawn/graphics.rb, line 500
    
stroke_curve(origin,dest,options={}) click to toggle source

Strokes a Bezier curve between two points, bounded by two additional points.

# File lib/prawn/graphics.rb, line 491
    
stroke_ellipse(point, r1, r2 = r1) click to toggle source

Draws and strokes an ellipse of x radius r1 and y radius r2 with the centre-point at point.

# File lib/prawn/graphics.rb, line 527
    
stroke_horizontal_line(x1,x2,options={}) click to toggle source

Strokes a horizontal line from x1 to x2 at the current y position, or the position specified by the :at option.

# File lib/prawn/graphics.rb, line 465
    
stroke_horizontal_rule click to toggle source

Strokes a horizontal line from the left border to the right border of the bounding box at the current y position.

# File lib/prawn/graphics.rb, line 474
    
stroke_line(*points) click to toggle source

Strokes a line from one point to another. Points may be specified as tuples or flattened argument list.

# File lib/prawn/graphics.rb, line 456
    
stroke_polygon(*points) click to toggle source

Draws and strokes a polygon from the specified points.

# File lib/prawn/graphics.rb, line 553
    
stroke_rectangle(point,width,height) click to toggle source

Draws and strokes a rectangle given point, width and height. The rectangle is bounded by its upper-left corner.

# File lib/prawn/graphics.rb, line 399
    
stroke_rounded_polygon(radius, *points) click to toggle source

Draws and strokes a rounded polygon from specified points, using radius to define Bezier curves.

# File lib/prawn/graphics.rb, line 578
    
stroke_rounded_rectangle(point,width,height,radius) click to toggle source

Draws and strokes a rounded rectangle given point, width and height and radius for the rounded corner. The rectangle is bounded by its upper-left corner.

# File lib/prawn/graphics.rb, line 427
    
stroke_vertical_line(y1,y2,params) click to toggle source

Strokes a vertical line at the x coordinate given by :at from y1 to y2.

# File lib/prawn/graphics.rb, line 482
    
vertical_line(y1, y2, params) click to toggle source

Draws a vertical line at the x cooordinate given by :at from y1 to y2.

# draw a line from [25, 100] to [25, 300]
vertical_line 100, 300, :at => 25
# File lib/prawn/graphics.rb, line 169
def vertical_line(y1, y2, params)
  line(params[:at], y1, params[:at], y2)
end

Private Instance Methods

current_line_width() click to toggle source
# File lib/prawn/graphics.rb, line 606
def current_line_width
  graphic_state.line_width
end
current_line_width=(width) click to toggle source
# File lib/prawn/graphics.rb, line 610
def current_line_width=(width)
  graphic_state.line_width = width
end
degree_to_rad(angle) click to toggle source
# File lib/prawn/graphics.rb, line 627
def degree_to_rad(angle)
  angle * Math::PI / 180
end
map_to_absolute(*point) click to toggle source
# File lib/prawn/graphics.rb, line 618
def map_to_absolute(*point)
  x, y = point.flatten
  [@bounding_box.absolute_left + x, @bounding_box.absolute_bottom + y]
end
map_to_absolute!(point) click to toggle source
# File lib/prawn/graphics.rb, line 623
def map_to_absolute!(point)
  point.replace(map_to_absolute(point))
end
point_on_line(distance_from_end, *points) click to toggle source

Returns the coordinates for a point on a line that is a given distance away from the second point defining the line segement

# File lib/prawn/graphics.rb, line 633
def point_on_line(distance_from_end, *points)
  x0, y0, x1, y1 = points.flatten
  length = Math.sqrt((x1 - x0)**2 + (y1 - y0)**2)
  p = (length - distance_from_end) / length
  xr = x0 + p * (x1 - x0)
  yr = y0 + p * (y1 - y0)
  [xr, yr]
end
write_line_width() click to toggle source
# File lib/prawn/graphics.rb, line 614
def write_line_width
  renderer.add_content("#{current_line_width} w")
end