Class: Graphomaton::Exporters::Png

Inherits:
Object
  • Object
show all
Includes:
Graphomaton::ExporterIntrospection
Defined in:
lib/graphomaton/exporters/png.rb

Defined Under Namespace

Classes: ConversionError

Constant Summary collapse

PNG_SIGNATURE = 
"\x89PNG\r\n\x1A\n".b.freeze
DEFAULT_SCALE = 
1.0
DEFAULT_CONVERTER = 
:auto
DEFAULT_TIMEOUT = 
ProcessRunner::DEFAULT_TIMEOUT
DEFAULT_MAX_OUTPUT_BYTES = 
ProcessRunner::DEFAULT_MAX_STDOUT_BYTES
CONVERTER_COMMANDS = 
{
  rsvg: ['rsvg-convert', '--format', 'png', '-'],
  magick: ['magick', 'svg:-', 'png:-'],
  convert: ['convert', 'svg:-', 'png:-']
}.freeze
CONVERTER_OPTIONS = 
([:auto] + CONVERTER_COMMANDS.keys).freeze

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Graphomaton::ExporterIntrospection

#capabilities, #losses_for

Constructor Details

#initialize(automaton) ⇒ Png

Returns a new instance of Png.



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# File 'lib/graphomaton/exporters/png.rb', line 38

def initialize(automaton)
  @automaton = automaton
end

Class Method Details

.available?(converter: DEFAULT_CONVERTER) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/graphomaton/exporters/png.rb', line 26

def self.available?(converter: DEFAULT_CONVERTER)
  !available_command(converter: converter).nil?
end

.available_command(converter: DEFAULT_CONVERTER) ⇒ Object 



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# File 'lib/graphomaton/exporters/png.rb', line 30

def self.available_command(converter: DEFAULT_CONVERTER)
  resolved_converter = resolve_converter(converter)
  return CONVERTER_COMMANDS[resolved_converter] if resolved_converter != :auto && executable?(CONVERTER_COMMANDS[resolved_converter].first)
  return nil if resolved_converter != :auto

  CONVERTER_COMMANDS.values.find { |command| executable?(command.first) }
end

.executable?(command) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/graphomaton/exporters/png.rb', line 98

def self.executable?(command)
  !ProcessRunner.which(command).nil?
end

.resolve_converter(converter) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/graphomaton/exporters/png.rb', line 102

def self.resolve_converter(converter)
  resolved = converter.to_sym
  return resolved if CONVERTER_OPTIONS.include?(resolved)

  raise ArgumentError, "Unknown PNG converter: #{converter.inspect}. Available converters: #{CONVERTER_OPTIONS.join(', ')}"
end

Instance Method Details

#export(width = 800, height = 600, theme: Svg::DEFAULT_THEME, scale: DEFAULT_SCALE, converter: DEFAULT_CONVERTER, timeout: DEFAULT_TIMEOUT, max_output_bytes: DEFAULT_MAX_OUTPUT_BYTES, **svg_options) ⇒ Object 



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# File 'lib/graphomaton/exporters/png.rb', line 42

def export(width = 800, height = 600, theme: Svg::DEFAULT_THEME, scale: DEFAULT_SCALE, converter: DEFAULT_CONVERTER,
           timeout: DEFAULT_TIMEOUT, max_output_bytes: DEFAULT_MAX_OUTPUT_BYTES, **svg_options)
  export_result(
    width,
    height,
    theme: theme,
    scale: scale,
    converter: converter,
    timeout: timeout,
    max_output_bytes: max_output_bytes,
    **svg_options
  ).output
end

#export_result(width = 800, height = 600, theme: Svg::DEFAULT_THEME, scale: DEFAULT_SCALE, converter: DEFAULT_CONVERTER, timeout: DEFAULT_TIMEOUT, max_output_bytes: DEFAULT_MAX_OUTPUT_BYTES, **svg_options) ⇒ Object 



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# File 'lib/graphomaton/exporters/png.rb', line 56

def export_result(width = 800, height = 600, theme: Svg::DEFAULT_THEME, scale: DEFAULT_SCALE, converter: DEFAULT_CONVERTER,
                  timeout: DEFAULT_TIMEOUT, max_output_bytes: DEFAULT_MAX_OUTPUT_BYTES, **svg_options)
  command = available_command(converter: converter)
  raise ConversionError, missing_converter_message(converter) unless command

  resolved_scale = resolve_scale(scale)
  svg_result = Svg.new(@automaton).export_result(width, height, theme: theme, **svg_options)
  svg = scale_svg_dimensions(svg_result.output, resolved_scale)
  png, error, status = ProcessRunner.capture3(
    *command,
    stdin_data: svg,
    binmode: true,
    timeout: timeout,
    max_stdout_bytes: max_output_bytes
  )
  png = png.b

  if status.success? && png.start_with?(PNG_SIGNATURE)
    return RenderResult.new(
      output: png.freeze,
      diagnostics: svg_result.diagnostics,
      bounds: svg_result.bounds,
      layout: svg_result.layout
    )
  end
  raise ConversionError, invalid_png_message(command, error) if status.success?

  raise ConversionError, failed_conversion_message(command, error)
rescue ProcessRunner::Error => e
  raise ConversionError, failed_conversion_message(command, e.message)
end