Class: Postsvg::Interpreter

Inherits:
Object
  • Object
show all
Defined in:
lib/postsvg/interpreter.rb

Overview

Stack-based PostScript interpreter

Constant Summary collapse

FILL_ONLY = 
{ stroke: false, fill: true }.freeze
STROKE_ONLY = 
{ stroke: true, fill: false }.freeze
FILL_AND_STROKE = 
{ stroke: true, fill: true }.freeze
DEFAULT_IMAGE = 
"data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy" \
"53My5vcmcvMjAwMC9zdmciIHdpZHRoPSI1MTIiIGhlaWdodD0iNTEyIj4KICA" \
"8dGV4dCB4PSIyNCIgeT0iMTk4IiBmaWxsPSJ3aGl0ZSIgZm9udC1zaXplPSIxM" \
"jgiPkltYWdlbTwvdGV4dD4KICA8dGV4dCB4PSIyNCIgeT0iMjk4IiBmaWxsPSJ" \
"3aGl0ZSIgZm9udC1zaXplPSIxMjgiPk5vdDwvdGV4dD4KICA8dGV4dCB4PSIyN" \
"CIgeT0iMzk4IiBmaWxsPSJ3aGl0ZSIgZm9udC1zaXplPSIxMjgiPkZvdW5kPC9" \
"0ZXh0Pgo8L3N2Zz4K"
PATH_TERMINATORS = 
%w[stroke fill show moveto newpath].freeze
PATH_CONTINUATORS = 
%w[lineto curveto rlineto rcurveto].freeze
STATE_MODIFIERS = 
%w[
  setrgbcolor setgray setcmykcolor setlinewidth setlinecap
  setlinejoin setdash translate scale rotate
].freeze

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Interpreter

Returns a new instance of Interpreter.



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# File 'lib/postsvg/interpreter.rb', line 30

def initialize
  @stack = []
  @g_stack = []
  @g_state = default_graphics_state
  @path = PathBuilder.new
  @current_x = 0
  @current_y = 0
  @id_counter = 0
  @svg_out = { defs: [], element_shapes: [], element_texts: [] }
  @global_dict = {}
  @dict_stack = [@global_dict]

  # Initialize path with correct transform mode
  update_path_transform_mode
end

Instance Method Details

#interpret(tokens, _bounding_box = nil) ⇒ Object 



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# File 'lib/postsvg/interpreter.rb', line 46

def interpret(tokens, _bounding_box = nil)
  i = 0
  while i < tokens.length
    token = tokens[i]

    case token.type
    when "number"
      @stack << token.value.to_f
    when "string", "hexstring", "name"
      @stack << token.value
    when "brace"
      if token.value == "{"
        proc_result = parse_procedure(tokens, i + 1)
        @stack << { type: "procedure", body: proc_result[:procedure] }
        i = proc_result[:next_index] - 1
      end
    when "bracket"
      if token.value == "["
        array_result = parse_array(tokens, i + 1)
        @stack << array_result[:array]
        i = array_result[:next_index] - 1
      end
    when "dict"
      if token.value == "<<"
        dict_result = parse_dict(tokens, i + 1)
        @stack << dict_result[:dict]
        i = dict_result[:next_index] - 1
      end
    when "operator"
      execute_operator(token.value, tokens, i)
    end

    i += 1
  end

  # Flush remaining path
  flush_path(STROKE_ONLY) if @path.length.positive?

  @svg_out
end