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# frozen_string_literal: true
module PDF
module Core
# Graphics state saving and restoring
class GraphicStateStack
# Graphic state stack
attr_accessor :stack
# @param previous_state [GraphicState, nil]
def initialize(previous_state = nil)
self.stack = [GraphicState.new(previous_state)]
end
# Pushes graphic state onto stack
#
# @param graphic_state [GraphicState, nil]
# @return [void]
def save_graphic_state(graphic_state = nil)
stack.push(GraphicState.new(graphic_state || current_state))
end
# Restores previous graphic state
#
# @return [void]
def restore_graphic_state
if stack.empty?
raise PDF::Core::Errors::EmptyGraphicStateStack,
"\n You have reached the end of the graphic state stack"
end
stack.pop
end
# Current graphic state
#
# @return [GraphicState]
def current_state
stack.last
end
# Tells whether there are any saved graphic states
#
# @return [Boolean]
# @see #empty?
def present?
!stack.empty?
end
# Tells whether there are no saved graphic states
#
# @return [Boolean]
# @see #present?
def empty?
stack.empty?
end
end
# Graphics state.
# It's a *partial* represenation of PDF graphics state. Only the parts
# implemented in Prawn are present here.
#
# NOTE: This class may be a good candidate for a copy-on-write hash.
class GraphicState
# Color space
# @return [Hash]
attr_accessor :color_space
# Dash
# @return [Hash<[:dash, :space, :phase], [nil, Numeric]>]
attr_accessor :dash
# Line cap
# @return [Symbol]
attr_accessor :cap_style
# Line Join
# @return [Symbol]
attr_accessor :join_style
# Line width
# @return [Numberic]
attr_accessor :line_width
# Fill color
# @return [String]
attr_accessor :fill_color
# Stroke color
attr_accessor :stroke_color
# @param previous_state [GraphicState, nil]
def initialize(previous_state = nil)
if previous_state
initialize_copy(previous_state)
else
@color_space = {}
@fill_color = '000000'
@stroke_color = '000000'
@dash = { dash: nil, space: nil, phase: 0 }
@cap_style = :butt
@join_style = :miter
@line_width = 1
end
end
# PDF representation of dash settings
#
# @return [String]
def dash_setting
return '[] 0 d' unless @dash[:dash]
array =
if @dash[:dash].is_a?(Array)
@dash[:dash]
else
[@dash[:dash], @dash[:space]]
end
"[#{PDF::Core.real_params(array)}] #{PDF::Core.real(@dash[:phase])} d"
end
private
def initialize_copy(other)
# mutable state
@color_space = other.color_space.dup
@fill_color = other.fill_color.dup
@stroke_color = other.stroke_color.dup
@dash = other.dash.dup
# immutable state that doesn't need to be duped
@cap_style = other.cap_style
@join_style = other.join_style
@line_width = other.line_width
end
end
end
end
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