Class: EventedMagick::Image

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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(input_path, tempfile = nil) ⇒ Image

Instance Methods



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# File 'lib/evented_magick.rb', line 41

def initialize(input_path, tempfile=nil)
  @path = input_path
  @tempfile = tempfile # ensures that the tempfile will stick around until this image is garbage collected.
  @method = defined?(::EM) && EM.reactor_running? ? :evented_execute : :blocking_execute

  # Ensure that the file is an image
  output = run_command("identify", "-format", format_option("%m %w %h"), @path)
  (format, width, height) = output.split
  @values = { 'format' => format, 'width' => width.to_i, 'height' => height.to_i, 'dimensions' => [width.to_i, height.to_i] }
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(symbol, *args) ⇒ Object

If an unknown method is called then it is sent through the morgrify program Look here to find all the commands (www.imagemagick.org/script/mogrify.php)



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# File 'lib/evented_magick.rb', line 109

def method_missing(symbol, *args)
  args.push(@path) # push the path onto the end
  run_command("mogrify", "-#{symbol}", *args)
  self
end

Instance Attribute Details

#output ⇒ Object (readonly)

Returns the value of attribute output.



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# File 'lib/evented_magick.rb', line 13

def output
  @output
end

#path ⇒ Object (readonly)

Returns the value of attribute path.



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# File 'lib/evented_magick.rb', line 11

def path
  @path
end

#tempfile ⇒ Object (readonly)

Returns the value of attribute tempfile.



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# File 'lib/evented_magick.rb', line 12

def tempfile
  @tempfile
end

Class Method Details

.from_blob(blob, ext = nil) ⇒ Object 



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# File 'lib/evented_magick.rb', line 18

def from_blob(blob, ext = nil)
  begin
    tempfile = Tempfile.new(['evented_magick', ext.to_s])
    tempfile.binmode
    tempfile.write(blob)
  ensure
    tempfile.close if tempfile
  end

  return self.new(tempfile.path, tempfile)
end

.open(image_path) ⇒ Object Also known as: from_file

Use this if you don’t want to overwrite the image file



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# File 'lib/evented_magick.rb', line 31

def open(image_path)
  File.open(image_path, "rb") do |f|
    self.from_blob(f.read, File.extname(image_path))
  end
end

Instance Method Details

#<<(*args) ⇒ Object

Sends raw commands to imagemagick’s mogrify command. The image path is automatically appended to the command



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# File 'lib/evented_magick.rb', line 64

def <<(*args)
  run_command("mogrify", *args << @path)
end

#[](value) ⇒ Object

For reference see www.imagemagick.org/script/command-line-options.php#format



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# File 'lib/evented_magick.rb', line 53

def [](value)
  key = value.to_s
  return @values[key] if %w(format width height dimensions).include? key
  if key == "size"
    File.size(@path)
  else
    run_command('identify', '-format', "\"#{key}\"", @path).split("\n")[0]
  end
end

#blocking_execute(cmd) ⇒ Object 



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# File 'lib/evented_magick.rb', line 161

def blocking_execute(cmd)
  output = `#{cmd}`
  [output, $?]
end

#combine_options(&block) ⇒ Object

You can use multiple commands together using this method



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# File 'lib/evented_magick.rb', line 116

def combine_options(&block)
  c = CommandBuilder.new
  block.call c
  run_command("mogrify", *c.args << @path)
end

#evented_execute(cmd) ⇒ Object 



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# File 'lib/evented_magick.rb', line 152

def evented_execute(cmd)
  fiber = Fiber.current
  EM::system(cmd) do |output, status|
    fiber.resume([output, status])
  end
  
  Fiber.yield
end

#format(format, page = 0) ⇒ Object

This is a ‘special’ command because it needs to change @path to reflect the new extension Formatting an animation into a non-animated type will result in ImageMagick creating multiple pages (starting with 0). You can choose which page you want to manipulate. We default to the first page.



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# File 'lib/evented_magick.rb', line 72

def format(format, page=0)
  run_command("mogrify", "-format", format, @path)

  old_path = @path.dup
  @path.sub!(/(\.\w+)?$/, ".#{format}")
  File.delete(old_path) unless old_path == @path

  unless File.exists?(@path)
    begin
      FileUtils.copy_file(@path.sub(".#{format}", "-#{page}.#{format}"), @path)
    rescue e
      raise MiniMagickError, "Unable to format to #{format}; #{e}" unless File.exist?(@path)
    end
  end
ensure
  Dir[@path.sub(/(\.\w+)?$/, "-[0-9]*.#{format}")].each do |fname|
    File.unlink(fname)
  end
end

#format_option(format) ⇒ Object

Outputs a carriage-return delimited format string for Unix and Windows



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# File 'lib/evented_magick.rb', line 128

def format_option(format)
  windows? ? "#{format}\\n" : "#{format}\\\\n"
end

#run_command(command, *args) ⇒ Object 



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# File 'lib/evented_magick.rb', line 132

def run_command(command, *args)
  full_args = args.collect do |arg|        
    # args can contain characters like '>' so we must escape them, but don't quote switches
    if arg !~ /^[\+\-]/
      "\"#{arg}\""
    else
      arg.to_s
    end
  end.join(' ')

  full_cmd = "#{command} #{full_args}"
  (output, status) = send(@method, full_cmd)

  if status.exitstatus == 0
    output
  else
    raise MiniMagickError, "ImageMagick command (#{full_cmd.inspect}) failed: #{{:status_code => status, :output => output}.inspect}"
  end
end

#to_blob ⇒ Object

Give you raw data back



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# File 'lib/evented_magick.rb', line 99

def to_blob
  f = File.new @path
  f.binmode
  f.read
ensure
  f.close if f
end

#windows? ⇒ Boolean

Check to see if we are running on win32 – we need to escape things differently

Returns:

  • (Boolean) 


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# File 'lib/evented_magick.rb', line 123

def windows?
  !(RUBY_PLATFORM =~ /win32/).nil?
end

#write(output_path) ⇒ Object

Writes the temporary image that we are using for processing to the output path



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# File 'lib/evented_magick.rb', line 93

def write(output_path)
  FileUtils.copy_file @path, output_path
  run_command "identify", output_path # Verify that we have a good image
end