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

Instance Methods



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# File 'lib/mini_magick.rb', line 43

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

  # Ensure that the file is an image
  run_command("identify", @path)
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 135

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/mini_magick.rb', line 15

def output
  @output
end

#path ⇒ Object (readonly)

Returns the value of attribute path.



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

def path
  @path
end

#tempfile ⇒ Object (readonly)

Returns the value of attribute tempfile.



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# File 'lib/mini_magick.rb', line 14

def tempfile
  @tempfile
end

Class Method Details

.from_blob(blob, extension = nil) ⇒ Object 



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# File 'lib/mini_magick.rb', line 20

def from_blob(blob, extension=nil)
  begin
    tempfile = ImageTempFile.new("minimagick#{extension}")
    tempfile.binmode
    tempfile.write(blob)
  ensure
    tempfile.close
  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/mini_magick.rb', line 33

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

#[](value) ⇒ Object

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



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# File 'lib/mini_magick.rb', line 52

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"
    dimensions = run_command("identify", "-format", format_option("%w %h"), @path).split("\n")[0].split(" ")
    { :width => dimensions[0].to_i, :height => dimensions[1].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
    run_command('identify', '-format', "\"%[#{value}]\"", @path).chop
  else
    run_command('identify', '-format', "\"#{value}\"", @path).split("\n")[0]
  end
end

#combine_options(&block) ⇒ Object

You can use multiple commands together using this method



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# File 'lib/mini_magick.rb', line 142

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

#crop_resized(width, height, gravity = "Center") ⇒ Object

Scale an image down and crop away any extra to achieve a certain size. This is handy for creating thumbnails of the same dimensions without changing the aspect ratio.



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# File 'lib/mini_magick.rb', line 92

def crop_resized(width, height, gravity = "Center")
  width = width.to_i
  height = height.to_i

  # Grab the width and height of the current image in one go.
  dimensions = self[:dimensions]

  # Only do anything if needs be. Who knows, maybe it's already the exact
  # dimensions we're looking for.
  if(width != dimensions[:width] && height != dimensions[:height])
    combine_options do |c|
      # Scale the image down to the widest dimension.
      if(width != dimensions[:width] || height != dimensions[:height])
        scale = [width / dimensions[:width].to_f, height / dimensions[:height].to_f].max * 100
        c.resize("#{scale}%")
      end

      # Align how things will be cropped.
      c.gravity(gravity)

      # Crop the image to size.
      c.crop("#{width}x#{height}+0+0")
    end
  end
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/mini_magick.rb', line 80

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

  @path.sub!(/(\.\w+)?$/, ".#{format}")
  @path.sub!(".#{format}", "-#{page}.#{format}") unless File.exists?(@path)

  raise "Unable to format to #{format}" unless File.exists?(@path)
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 154

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

#run_command(command, *args) ⇒ Object 



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# File 'lib/mini_magick.rb', line 158

def run_command(command, *args)
  args.collect! do |arg|
    arg = arg.to_s
    arg = %|"#{arg}"| unless arg[0] == ?- # values quoted because they can contain characters like '>', but don't quote switches          
    arg
  end

  @output = `#{command} #{args.join(' ')}`

  if $? != 0
    raise MiniMagickError, "ImageMagick command (#{command} #{args.join(' ')}) failed: Error Given #{$?}"
  else
    @output
  end
end

#to_blob ⇒ Object

Give you raw data back



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# File 'lib/mini_magick.rb', line 125

def to_blob
  f = File.new @path
  f.binmode
  f.read
ensure
  f.close
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 149

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 119

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