Class: MiniMagick::Image

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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(input_path, tempfile = nil) ⇒ Image

TODO:

Allow this to accept a block that can pass off to Image#combine_options

Create a new MiniMagick::Image object

DANGER: The file location passed in here is the *working copy*. That is, it gets modified. you can either copy it yourself or use the MiniMagick::Image.open(path) method which creates a temporary file for you and protects your original!

Parameters:

  • input_path (String) —

    The location of an image file



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

def initialize(input_path, tempfile = nil)
  @path = input_path
  @tempfile = tempfile # ensures that the tempfile will stick around until this image is garbage collected.
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/mini_magick.rb', line 320

def method_missing(symbol, *args)
  combine_options do |c|
    c.method_missing(symbol, *args)
  end
end

Instance Attribute Details

#path ⇒ String

Returns The location of the current working file.

Returns:

  • (String) —

    The location of the current working file



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# File 'lib/mini_magick.rb', line 32

def path
  @path
end

Class Method Details

.create(ext = nil, validate = true) {|IOStream| ... } ⇒ Image

Used to create a new Image object data-copy. Not used to “paint” or that kind of thing.

Takes an extension in a block and can be used to build a new Image object. Used by both #open and #read to create a new object! Ensures we have a good tempfile!

Parameters:

  • ext (String) (defaults to: nil) —

    Specify the extension you want to read it as

  • validate (Boolean) (defaults to: true) —

    If false, skips validation of the created image. Defaults to true.

Yields:

  • (IOStream) —

    You can #write bits to this object to create the new Image

Returns:

  • (Image) —

    The created image



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# File 'lib/mini_magick.rb', line 134

def create(ext = nil, validate = true, &block)
  begin
    tempfile = Tempfile.new(['mini_magick', ext.to_s.downcase])
    tempfile.binmode
    block.call(tempfile)
    tempfile.close

    image = self.new(tempfile.path, tempfile)

    if validate and !image.valid?
      raise MiniMagick::Invalid
    end
    return image
  ensure
    tempfile.close if tempfile
  end
end

.from_blob(blob, ext = nil) ⇒ Object

Deprecated.

Please use Image.read instead!



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# File 'lib/mini_magick.rb', line 61

def from_blob(blob, ext = nil)
  warn "Warning: MiniMagick::Image.from_blob method is deprecated. Instead, please use Image.read"
  create(ext) { |f| f.write(blob) }
end

.from_file(file, ext = nil) ⇒ Object

Deprecated.

Please use MiniMagick::Image.open(file_or_url) now



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# File 'lib/mini_magick.rb', line 120

def from_file(file, ext = nil)
  warn "Warning: MiniMagick::Image.from_file is now deprecated. Please use Image.open"
  open(file, ext)
end

.import_pixels(blob, columns, rows, depth, map, format = "png") ⇒ Object

Creates an image object from a binary string blob which contains raw pixel data (i.e. no header data).

Returns

  • Image

    The loaded image.

Parameters

  • blob

    String – Binary string blob containing raw pixel data.

  • columns

    Integer – Number of columns.

  • rows

    Integer – Number of rows.

  • depth

    Integer – Bit depth of the encoded pixel data.

  • map

    String – A code for the mapping of the pixel data. Example: ‘gray’ or ‘rgb’.

  • format

    String – The file extension of the image format to be used when creating the image object. Defaults to ‘png’.



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# File 'lib/mini_magick.rb', line 81

def import_pixels(blob, columns, rows, depth, map, format="png")
  # Create an image object with the raw pixel data string:
  image = create(".dat", validate = false) { |f| f.write(blob) }
  # Use ImageMagick to convert the raw data file to an image file of the desired format:
  converted_image_path = image.path[0..-4] + format
  argument = "-size #{columns}x#{rows} -depth #{depth} #{map}:#{image.path} #{converted_image_path}"
  cmd = CommandBuilder.new("convert", argument) #Example: convert -size 256x256 -depth 16 gray:blob.dat blob.png
  image.run(cmd)
  # Update the image instance with the path of the properly formatted image, and return:
  image.path = converted_image_path
  image
end

.open(file_or_url, ext = nil) ⇒ Image

Opens a specific image file either on the local file system or at a URI.

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

Extension is either guessed from the path or you can specify it as a second parameter.

If you pass in what looks like a URL, we require ‘open-uri’ before opening it.

Parameters:

  • file_or_url (String) —

    Either a local file path or a URL that open-uri can read

  • ext (String) (defaults to: nil) —

    Specify the extension you want to read it as

Returns:

  • (Image) —

    The loaded image



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# File 'lib/mini_magick.rb', line 105

def open(file_or_url, ext = nil)
  file_or_url = file_or_url.to_s # Force it to be a String... hell or highwater
  if file_or_url.include?("://")
    require 'open-uri'
    ext ||= File.extname(URI.parse(file_or_url).path)
    self.read(Kernel::open(file_or_url), ext)
  else
    ext ||= File.extname(file_or_url)
    File.open(file_or_url, "rb") do |f|
      self.read(f, ext)
    end
  end
end

.read(stream, ext = nil) ⇒ Image

This is the primary loading method used by all of the other class methods.

Use this to pass in a stream object. Must respond to Object#read(size) or be a binary string object (BLOBBBB)

As a change from the old API, please try and use IOStream objects. They are much, much better and more efficient!

Probably easier to use the #open method if you want to open a file or a URL.

Parameters:

  • stream (IOStream, String) —

    Some kind of stream object that needs to be read or is a binary String blob!

  • ext (String) (defaults to: nil) —

    A manual extension to use for reading the file. Not required, but if you are having issues, give this a try.

Returns:



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# File 'lib/mini_magick.rb', line 48

def read(stream, ext = nil)
  if stream.is_a?(String)
    stream = StringIO.new(stream)
  end

  create(ext) do |f|
    while chunk = stream.read(8192)
      f.write(chunk)
    end
  end
end

Instance Method Details

#<<(*args) ⇒ String

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

Remember, we are always acting on this instance of the Image when messing with this.

Returns:

  • (String) —

    Whatever the result from the command line is. May not be terribly useful.



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# File 'lib/mini_magick.rb', line 235

def <<(*args)
  run_command("mogrify", *args << escaped_path)
end

#[](value) ⇒ String, ...

A rather low-level way to interact with the “identify” command. No nice API here, just the crazy stuff you find in ImageMagick. See the examples listed!

Examples:

image["format"]      #=> "TIFF"
image["height"]      #=> 41 (pixels)
image["width"]       #=> 50 (pixels)
image["colorspace"]  #=> "DirectClassRGB"
image["dimensions"]  #=> [50, 41]
image["size"]        #=> 2050 (bits)
image["original_at"] #=> 2005-02-23 23:17:24 +0000 (Read from Exif data)
image["EXIF:ExifVersion"] #=> "0220" (Can read anything from Exif)

Parameters:

  • format (String) —

    A format for the “identify” command

Returns:

  • (String, Numeric, Array, Time, Object) —

    Depends on the method called! Defaults to String for unknown commands

See Also:

  • reference see http://www.imagemagick.org/script/command-line-options.php#format


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# File 'lib/mini_magick.rb', line 200

def [](value)
  # Why do I go to the trouble of putting in newlines? Because otherwise animated gifs screw everything up
  case value.to_s
  when "colorspace"
    run_command("identify", "-format", format_option("%r"), escaped_path).split("\n")[0]
  when "format"
    run_command("identify", "-format", format_option("%m"), escaped_path).split("\n")[0]
  when "height"
    run_command("identify", "-format", format_option("%h"), escaped_path).split("\n")[0].to_i
  when "width"
    run_command("identify", "-format", format_option("%w"), escaped_path).split("\n")[0].to_i
  when "dimensions"
    run_command("identify", "-format", format_option("%w %h"), escaped_path).split("\n")[0].split.map{|v|v.to_i}
  when "size"
    File.size(@path) # Do this because calling identify -format "%b" on an animated gif fails!
  when "original_at"
    # Get the EXIF original capture as a Time object
    Time.local(*self["EXIF:DateTimeOriginal"].split(/:|\s+/)) rescue nil
  when /^EXIF\:/i
    result = run_command('identify', '-format', "\"%[#{value}]\"", escaped_path).chop
    if result.include?(",")
      read_character_data(result)
    else
      result
    end
  else
    run_command('identify', '-format', "\"#{value}\"", escaped_path).split("\n")[0]
  end
end

#collapse! ⇒ Object

Collapse images with sequences to the first frame (ie. animated gifs) and preserve quality



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# File 'lib/mini_magick.rb', line 278

def collapse!
  run_command("mogrify", "-quality", "100", "#{path}[0]")
end

#combine_options {|command| ... } ⇒ Object

You can use multiple commands together using this method. Very easy to use!

Examples:

image.combine_options do |c|
  c.draw "image Over 0,0 10,10 '#{MINUS_IMAGE_PATH}'"
  c.thumbnail "300x500>"
  c.background background
end

Yield Parameters:



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# File 'lib/mini_magick.rb', line 336

def combine_options(&block)
  c = CommandBuilder.new('mogrify')
  block.call(c)
  c << @path
  run(c)
end

#composite(other_image, output_extension = 'jpg', &block) ⇒ Object 



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# File 'lib/mini_magick.rb', line 348

def composite(other_image, output_extension = 'jpg', &block)
  begin
    second_tempfile = Tempfile.new(output_extension)
    second_tempfile.binmode
  ensure
    second_tempfile.close
  end

  command = CommandBuilder.new("composite")
  block.call(command) if block
  command.push(other_image.path)
  command.push(self.path)
  command.push(second_tempfile.path)

  run(command)
  return Image.new(second_tempfile.path, second_tempfile)
end

#destroy! ⇒ Object 



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# File 'lib/mini_magick.rb', line 402

def destroy!
  return if @tempfile.nil?
  File.unlink(@tempfile.path)
  @tempfile = nil
end

#escaped_path ⇒ Object 



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# File 'lib/mini_magick.rb', line 166

def escaped_path
  Pathname.new(@path).to_s.inspect
end

#format(format, page = 0) ⇒ nil

This is used to change the format of the image. That is, from “tiff to jpg” or something like that. Once you run it, the instance is pointing to a new file with a new extension!

DANGER: This renames the file that the instance is pointing to. So, if you manually opened the file with Image.new(file_path)… then that file is DELETED! If you used Image.open(file) then you are ok. The original file will still be there. But, any changes to it might not be…

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.

Parameters:

  • format (String) —

    The target format… like ‘jpg’, ‘gif’, ‘tiff’, etc.

  • page (Integer) (defaults to: 0) —

    If this is an animated gif, say which ‘page’ you want with an integer. Leave as default if you don’t care.

Returns:

  • (nil) 


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# File 'lib/mini_magick.rb', line 253

def format(format, page = 0)
  c = CommandBuilder.new('mogrify', '-format', format)
  yield c if block_given?
  c << @path
  run(c)

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

  unless File.exists?(@path)
    begin
      FileUtils.copy_file(@path.sub(".#{format}", "-#{page}.#{format}"), @path)
    rescue => ex
      raise MiniMagick::Error, "Unable to format to #{format}; #{ex}" 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/mini_magick.rb', line 367

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

#mime_type ⇒ Object 



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# File 'lib/mini_magick.rb', line 313

def mime_type
  format = self[:format]
  "image/"+format.downcase
end

#run(command_builder) ⇒ Object 



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# File 'lib/mini_magick.rb', line 380

def run(command_builder)
  command = command_builder.command

  sub = Subexec.run(command, :timeout => MiniMagick.timeout)

  if sub.exitstatus != 0
    # Clean up after ourselves in case of an error
    destroy!

    # Raise the appropriate error
    if sub.output =~ /no decode delegate/i || sub.output =~ /did not return an image/i
      raise Invalid, sub.output
    else
      # TODO: should we do something different if the command times out ...?
      # its definitely better for logging.. otherwise we dont really know
      raise Error, "Command (#{command.inspect.gsub("\\", "")}) failed: #{{:status_code => sub.exitstatus, :output => sub.output}.inspect}"
    end
  else
    sub.output
  end
end

#run_command(command, *args) ⇒ Object 



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# File 'lib/mini_magick.rb', line 371

def run_command(command, *args)
  # -ping "efficiently determine image characteristics."
  if command == 'identify'
    args.unshift '-ping'
  end

  run(CommandBuilder.new(command, *args))
end

#to_blob ⇒ String

Gives you raw image data back

Returns:

  • (String) —

    binary string



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# File 'lib/mini_magick.rb', line 305

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

#valid? ⇒ Boolean

Checks to make sure that MiniMagick can read the file and understand it.

This uses the ‘identify’ command line utility to check the file. If you are having issues with this, then please work directly with the ‘identify’ command and see if you can figure out what the issue is.

Returns:

  • (Boolean) 


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# File 'lib/mini_magick.rb', line 177

def valid?
  run_command("identify", @path)
  true
rescue MiniMagick::Invalid
  false
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/mini_magick.rb', line 344

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

#write(output_to) ⇒ IOStream, Boolean

Writes the temporary file out to either a file location (by passing in a String) or by passing in a Stream that you can #write(chunk) to repeatedly

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

Parameters:

  • output_to (IOStream, String) —

    Some kind of stream object that needs to be read or a file path as a String

Returns:

  • (IOStream, Boolean) —

    If you pass in a file location [String] then you get a success boolean. If its a stream, you get it back.



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# File 'lib/mini_magick.rb', line 288

def write(output_to)
  if output_to.kind_of?(String) || !output_to.respond_to?(:write)
    FileUtils.copy_file @path, output_to
    run_command "identify", output_to.to_s.inspect # Verify that we have a good image
  else # stream
    File.open(@path, "rb") do |f|
      f.binmode
      while chunk = f.read(8192)
        output_to.write(chunk)
      end
    end
    output_to
  end
end