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Size: 1.54 KB
Versions: 5
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Contents
# encoding: utf-8
#
# transparency.rb : Implements transparency
#
# Copyright October 2009, Daniel Nelson. All Rights Reserved.
#
# This is free software. Please see the LICENSE and COPYING files for details.
#
module Prawn
module Graphics
module Transparency
def transparent(opacity, stroke_opacity=opacity, &block)
min_version(1.4)
key = "#{opacity}_#{stroke_opacity}"
if opacity_dictionary_registry[key]
opacity_dictionary = opacity_dictionary_registry[key][:obj]
opacity_dictionary_name = opacity_dictionary_registry[key][:name]
else
opacity_dictionary = ref!(:Type => :ExtGState,
:CA => stroke_opacity,
:ca => opacity
)
opacity_dictionary_name = "Tr#{next_opacity_dictionary_id}"
opacity_dictionary_registry[key] = { :name => opacity_dictionary_name,
:obj => opacity_dictionary }
end
page_ext_gstates.merge!(opacity_dictionary_name => opacity_dictionary)
# push a new graphics context onto the graphics context stack
add_content "q"
add_content "/#{opacity_dictionary_name} gs"
yield if block_given?
add_content "Q"
end
private
def opacity_dictionary_registry
@opacity_dictionary_registry ||= {}
end
def next_opacity_dictionary_id
opacity_dictionary_registry.length + 1
end
end
end
end
Version data entries
5 entries across 5 versions & 2 rubygems