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 120

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 250

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

Instance Attribute Details

#path ⇒ String (readonly)

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 18

def path
  @path
end

Class Method Details

.create(ext = nil) {|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

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 93

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

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

    if !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 47

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 80

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

.open(file_or_url, ext = File.extname(file_or_url)) ⇒ 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 will see if Kernel#open exists. If it doesn’t then we require ‘open-uri’. That way, if you have a work-alike library, we won’t demolish it. Open-uri never gets required unless you pass in something with “://” in it.

Parameters:

  • file_or_url (String) —

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

  • ext (String) (defaults to: File.extname(file_or_url)) —

    Specify the extension you want to read it as

Returns:

  • (Image) —

    The loaded image



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# File 'lib/mini_magick.rb', line 65

def open(file_or_url, ext = File.extname(file_or_url))
  file_or_url = file_or_url.to_s # Force it to be a String... hell or highwater
  if file_or_url.include?("://")
    if !Kernel.respond_to?("open")
      require 'open-uri'
    end
    self.read(Kernel::open(file_or_url), ext)
  else
    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 34

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 188

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["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 155

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 "format"
    run_command("identify", "-format", format_option("%m"), @path).split("\n")[0]
  when "height"
    run_command("identify", "-format", format_option("%h"), @path).split("\n")[0].to_i
  when "width"
    run_command("identify", "-format", format_option("%w"), @path).split("\n")[0].to_i
  when "dimensions"
    run_command("identify", "-format", format_option("%w %h"), @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).chop
    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.rb', line 228

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 266

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 278

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 327

def destroy!
  return if @tempfile.nil?
  File.unlink(@tempfile.path)
  @tempfile = nil
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 206

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

  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 MiniMagickError, "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 297

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

#run(command_builder) ⇒ Object 



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

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 301

def run_command(command, *args)
  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 240

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 133

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 274

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/mini_magick.rb', line 233

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