Class: MiniMagick::Image

Inherits:
Object
  • Object
show all
Defined in:
lib/mini_magick/image.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/image.rb', line 158

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 mogrify program Look here to find all the commands (www.imagemagick.org/script/mogrify.php)



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# File 'lib/mini_magick/image.rb', line 314

def method_missing(symbol, *args)
  combine_options do |c|
    c.send(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/image.rb', line 4

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/image.rb', line 131

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/image.rb', line 56

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/image.rb', line 117

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/image.rb', line 76

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
  arguments = ["-size", "#{columns}x#{rows}", "-depth", "#{depth}", "#{map}:#{image.path}", "#{converted_image_path}"]
  cmd = CommandBuilder.new("convert", *arguments) #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/image.rb', line 100

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)
    Kernel::open(file_or_url) do |f|
      self.read(f, ext)
    end
  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/image.rb', line 35

def read(stream, ext = nil)
  if stream.is_a?(String)
    stream = StringIO.new(stream)
  elsif stream.is_a?(StringIO)
    # Do nothing, we want a StringIO-object
  elsif stream.respond_to? :path
    if File.respond_to?(:binread)
      stream = StringIO.new File.binread(stream.path.to_s)
    else
      stream = StringIO.new File.open(stream.path.to_s,"rb") { |f| f.read }
    end
  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/image.rb', line 228

def <<(*args)
  run_command("mogrify", *args << 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/image.rb', line 193

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", '%r\n', path).split("\n")[0].strip
  when "format"
    run_command("identify", "-format", '%m\n', path).split("\n")[0]
  when "height"
    run_command("identify", "-format", '%h\n', path).split("\n")[0].to_i
  when "width"
    run_command("identify", "-format", '%w\n', path).split("\n")[0].to_i
  when "dimensions"
    run_command("identify", "-format", MiniMagick::Utilities.windows? ? '"%w %h\n"' : '%w %h\n', 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}]", path).chomp
    if result.include?(",")
      read_character_data(result)
    else
      result
    end
  else
    run_command('identify', '-format', value, 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/image.rb', line 272

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

#combine_options(tool = "mogrify") {|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/image.rb', line 330

def combine_options(tool = "mogrify", &block)
  c = CommandBuilder.new(tool)

  c << path if tool.to_s == "convert"
  block.call(c)
  c << path
  run(c)
end

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



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# File 'lib/mini_magick/image.rb', line 339

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/image.rb', line 388

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

#format(format, page = 0) {|c| ... } ⇒ 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.

If you would like to convert between animated formats, pass nil as your page and ImageMagick will copy all of the pages.

with an integer. Default 0 will convert only the first page; ‘nil’ will convert all pages.

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

Yields:

  • (c)

Returns:

  • (nil) 


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# File 'lib/mini_magick/image.rb', line 251

def format(format, page = 0)
  c = CommandBuilder.new('mogrify', '-format', format)
  yield c if block_given?
  if page
    c << "#{path}[#{page}]"
  else
    c << path
  end
  run(c)

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

  unless File.exists?(path)
    raise MiniMagick::Error, "Unable to format to #{format}"
  end
end

#mime_type ⇒ Object 



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# File 'lib/mini_magick/image.rb', line 307

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

#path_for_windows_quote_space(path) ⇒ Object 



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# File 'lib/mini_magick/image.rb', line 6

def path_for_windows_quote_space(path)
  path = Pathname.new(@path).to_s
  # For Windows, if a path contains space char, you need to quote it, otherwise you SHOULD NOT quote it.
  # If you quote a path that does not contains space, it will not work.
  @path.include?(' ') ? path.inspect : path
end

#run(command_builder) ⇒ Object 



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# File 'lib/mini_magick/image.rb', line 366

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/image.rb', line 357

def run_command(command, *args)
  if command == 'identify'
    args.unshift '-ping'  # -ping "efficiently determine image characteristics."
    args.unshift '-quiet' if MiniMagick.mogrify? # graphicsmagick has no -quiet option.
  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/image.rb', line 299

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/image.rb', line 170

def valid?
  run_command("identify", path)
  true
rescue MiniMagick::Invalid
  false
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/image.rb', line 282

def write(output_to)
  if output_to.kind_of?(String) || !output_to.respond_to?(:write)
    FileUtils.copy_file path, output_to
    run_command "identify", MiniMagick::Utilities.windows? ? path_for_windows_quote_space(output_to.to_s) :  output_to.to_s # 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