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 196
def circle(center, radius)
  ellipse(center, radius, radius)
end
circle_at(point, options) click to toggle source

DEPRECATED: Please use circle instead.

# File lib/prawn/graphics.rb, line 184
def circle_at(point, options)
  warn "[DEPRECATION] 'circle_at' is deprecated in favor of 'circle'. " +
       "'circle_at' will be removed in release 1.1"
  circle(point, options[: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 296
def close_and_stroke
  yield if block_given?
  add_content "s"
end
close_path() click to toggle source

Closes the current path.

# File lib/prawn/graphics.rb, line 325
def close_path
  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 173
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 65
def curve_to(dest,options={})
   options[:bounds] or raise Prawn::Errors::InvalidGraphicsPath,
     "Bounding points for bezier curve must be specified "+
     "as :bounds => [[x1,y1],[x2,y2]]"

   curve_points = (options[:bounds] << dest).map { |e| map_to_absolute(e) }
   add_content("%.3f %.3f %.3f %.3f %.3f %.3f c" %
                 curve_points.flatten )
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 215
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 + l1], [x + l2, y + r2]]

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

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

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

  move_to(x, y)
end
ellipse_at(point, r1, r2=r1) click to toggle source

DEPRECATED: Please use ellipse instead.

# File lib/prawn/graphics.rb, line 201
def ellipse_at(point, r1, r2=r1)
  warn "[DEPRECATION] 'ellipse_at' is deprecated in favor of 'ellipse'. " +
       "'ellipse_at' will be removed in release 1.1"
  ellipse(point, r1, r2)
end
fill() click to toggle source

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

# File lib/prawn/graphics.rb, line 309
def fill
  yield if block_given?
  add_content "f"
end
fill_and_stroke() 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.

# File lib/prawn/graphics.rb, line 318
def fill_and_stroke
  yield if block_given?
  add_content "b"
end
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 142
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 155
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 130
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 55
def line_to(*point)
  x,y = map_to_absolute(point)
  add_content("%.3f %.3f l" % [ x, y ])
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 116
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 103
def line_width=(width)
  self.current_line_width = width
  write_line_width
end
method_missing(id,*args,&block) click to toggle source

Provides the following shortcuts:

stroke_some_method(*args) #=> some_method(*args); stroke
fill_some_method(*args) #=> some_method(*args); fill
fill_and_stroke_some_method(*args) #=> some_method(*args); fill_and_stroke
# File lib/prawn/graphics.rb, line 335
def method_missing(id,*args,&block)
  case(id.to_s)
  when /^fill_and_stroke_(.*)/
    send($1,*args,&block); fill_and_stroke
  when /^stroke_(.*)/
    send($1,*args,&block); stroke
  when /^fill_(.*)/
    send($1,*args,&block); fill
  else
    super
  end
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 44
def move_to(*point)
  x,y = map_to_absolute(point)
  add_content("%.3f %.3f m" % [ x, y ])
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 246
def polygon(*points)
  move_to points[0]
  (points[1..-1] << points[0]).each do |point|
    line_to(*point)
  end
  # close the path
  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 80
def rectangle(point,width,height)
  x,y = map_to_absolute(point)
  add_content("%.3f %.3f %.3f %.3f re" % [ x, y - height, width, height ])
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 260
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
  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 91
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 275
def rounded_vertex(radius, *points)
  x0,y0,x1,y1,x2,y2 = points.flatten
  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 288
def stroke
  yield if block_given?
  add_content "S"
end
stroke_bounds() click to toggle source

Draws and strokes a rectangle represented by the current bounding box

# File lib/prawn/graphics.rb, line 303
def stroke_bounds
  stroke_rectangle bounds.top_left, bounds.width, bounds.height
end
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 164
def vertical_line(y1,y2,params)
  line(params[:at],y1,params[:at],y2)
end

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