Module: Jpegtran

Defined in:
lib/jpegtran.rb

Overview

The jpegtran tool command frontend.

See Also:

Defined Under Namespace

Classes: Result

Constant Summary collapse

COMMAND =

Holds jpegoptim command.

:jpegtran
BOOLEAN_ARGS =

Indicates turn on/off style arguments.

Set::new [
    :optimize, :progressive, :grayscale, :perfect, :transpose, 
    :transverse, :trim, :arithmetic
]
COPY_OPTIONS =

Holds copy values.

Set::new [
    :none, :comments, :all
]
FLIP_OPTIONS =

Holds flip values.

Set::new [
    :horizontal, :vertical
]
ERROR =

Holds output matchers.

/jpegtran:\s*(.*)\s*/

Class Method Summary collapse

Class Method Details

.available? ⇒ Boolean

Checks if jpegtran is available.

Returns:

  • (Boolean) —

    true if it is, false in otherwise



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# File 'lib/jpegtran.rb', line 67

def self.available?
    return Whereis.available? self::COMMAND 
end

.optimize(path, options = { }, &block) ⇒ Struct

Performs optimizations above file. For list of arguments, see reference of jpegtran.

If block is given, runs jpegoptim asynchronously. In that case, em-pipe-run file must be already required.

Parameters:

  • paths (String, Array) —

    file path or array of paths for optimizing

  • options (Hash) (defaults to: { }) —

    options

  • block (Proc) —

    block for giving back the results

Returns:



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# File 'lib/jpegtran.rb', line 84

def self.optimize(path, options = { }, &block)

    # Command
    cmd = CommandBuilder::new(self::COMMAND)
    cmd.separators = ["-", " ", "-", " "]
    
    # Turn on/off arguments
    options.each_pair do |k, v|
        if v.kind_of? TrueClass and self::BOOLEAN_ARGS.include? k 
            cmd << k
        end
    end
    
    # Rotate
    if options[:rotate].kind_of? Integer
        cmd.arg(:rotate, options[:rotate].to_i)
    elsif options.include? :rotate
        raise Exception::new("Invalid value for :rotate option. Integer expected.")
    end
    
    # Rotate
    if options[:restart].kind_of? Integer
        cmd.arg(:restart, options[:restart].to_i)
    elsif options.include? :restart
        raise Exception::new("Invalid value for :restart option. Integer expected.")
    end
    
    # Crop
    if options[:crop].kind_of? String
        cmd.arg(:crop, options[:crop].to_s)
    elsif options.include? :crop
        raise Exception::new("Invalid value for :crop option. Structured string expected. See 'jpegtran' reference.")
    end
    
    # Scans
    if options[:scans].kind_of? String
        cmd.arg(:scans, options[:scans].to_s)
    elsif options.include? :scans
        raise Exception::new("Invalid value for :scans option. String expected.")
    end
            
    # Copy
    if options.include? :copy 
        value = options[:copy].to_sym
        if self::COPY_OPTIONS.include? value
            cmd.arg(:copy, value)
        else
            raise Exception::new("Invalid value for :copy. Expected " << self::COPY_OPTIONS.to_s)
        end
    end 
    
    # Flip
    if options.include? :flip
        value = options[:flip].to_sym
        if self::FLIP_OPTIONS.include? :value
            cmd.arg(:flip, value)
        else
            raise Exception::new("Invalid value for :flip. Expected " << self::FLIP_OPTIONS.to_s)
        end
    end
    
    # Outfile
    if options.include? :outfile
        if options[:outfile].kind_of? String
            value = options[:outfile].to_s
        else
            raise Exception::new("Invalid value for :outfile option. String expected.")
        end
    else
        value = path.to_s
    end
    
    cmd.arg(:outfile, value)
    
    # Runs the command
    cmd << path.to_s
    
    if options[:debug] == true
        STDERR.write cmd.to_s + "\n"
    end
        
    # Blocking
    if block.nil?
        cmd.execute!

    # Non-blocking
    else
        cmd.execute do |output|
            block.call()
        end
    end
    
end