module Magick

Describes the image formats supported by ImageMagick. If the optional block is present, calls the block once for each image format. The first argument, k, is the format name. The second argument, v, is the properties string described below.

• B is “*” if the format has native blob support, or “ ” otherwise.

• R is “r” if ImageMagick can read that format, or “-” otherwise.

• W is “w” if ImageMagick can write that format, or “-” otherwise.

• A is “+” if the format supports multi-image files, or “-” otherwise.

@overload formats

@return [Hash] the formats hash

@overload formats

@yield [k, v]
@yieldparam k [String] the format name
@yieldparam v [String] the properties string
@return [Magick]

@example

p Magick.formats
=> {"3FR"=>" r-+", "3G2"=>" r-+", "3GP"=>" r-+", "A"=>"*rw+",
...

# File lib/rmagick_internal.rb, line 55
def formats
  @formats ||= init_formats

  if block_given?
    @formats.each { |k, v| yield k, v }
    self
  else
    @formats
  end
end

If the Magick module attribute trace_proc is set to a Proc object, RMagick calls the proc whenever an image is created or destroyed.

You can use this proc to keep track of which images your program has created and which have been destroyed.

@param p [Proc] The proc object.

The following value will be passed into the proc object.
- +which+ - A symbol that indicates which operation the proc is being called for.
  If the proc is called for an image creation, the value is +:c+.
  If called for an image destruction, the value is +:d+.
- +description+ - A string describing the image. This is the same string that
  would be returned by calling the image's inspect method.
- +id+ - A unique identifier for the image. This identifier is not the same as the object's +object_id+.
- +method+ - The name of the method responsible for creating or destroying the image.

@example

Magick.trace_proc = proc do |which, description, id, method|
  ...
end

# File lib/rmagick_internal.rb, line 86
def trace_proc=(p)
  m = Mutex.new
  m.synchronize do
    if @trace_proc.nil? && !p.nil? && !@exit_block_set_up
      at_exit { @trace_proc = nil }
      @exit_block_set_up = true
    end

    @trace_proc = p
  end
end