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# encoding: utf-8
# gradient.rb : Implements axial gradient
#
# Contributed by Wojciech Piekutowski. November, 2009
#
# This is free software. Please see the LICENSE and COPYING files for details.
#
module Prawn
module Graphics
module Gradient
# Sets the fill gradient from color1 to color2.
#
# It accepts CMYK and RGB colors, like #fill_color. Both colors must be
# of the same type.
#
# point, width and height define a bounding box in which the gradient
# will be rendered. For example, if you want to have page full of text
# with gradually changing color:
#
# pdf.fill_gradient [0, pdf.bounds.height], pdf.bounds.width,
# pdf.bounds.height, 'FF0000', '0000FF'
# pdf.text 'lots of text'*1000
#
# <tt>:stroke_bounds</tt> - draw gradient bounds
def fill_gradient(point, width, height, color1, color2, options = {})
set_gradient(:fill, point, width, height, color1, color2, options)
end
# Sets the stroke gradient from color1 to color2.
#
# See #fill_gradient for details.
def stroke_gradient(point, width, height, color1, color2, options = {})
set_gradient(:stroke, point, width, height, color1, color2, options)
end
private
def set_gradient(type, point, width, height, color1, color2, options)
if options[:stroke_bounds]
stroke_color 0, 0, 0, 100
stroke_rectangle point, width, height
end
if color_type(color1) != color_type(color2)
raise ArgumentError, 'both colors must be of the same type: RGB or CMYK'
end
process_color color1
process_color color2
shader = ref!({
:FunctionType => 2,
:Domain => [0.0, 1.0],
:C0 => normalize_color(color1),
:C1 => normalize_color(color2),
:N => 1,
})
shading = ref!({
:ShadingType => 2, # axial shading
:ColorSpace => color_type(color1) == :RGB ? :DeviceRGB : :DeviceCMYK,
:Coords => [0.0, 0.0, 1.0, 0.0],
:Function => shader,
:Extend => [true, true],
})
x, y = *point
shading_pattern = ref!({
:PatternType => 2, # shading pattern
:Shading => shading,
:Matrix => [0,-height, -width, 0, x, y],
})
patterns = page.resources[:Pattern] ||= {}
id = patterns.empty? ? 'SP1' : patterns.keys.sort.last.succ
patterns[id] = shading_pattern
set_color type, id, :pattern => true
end
end
end
end
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