Class: ActiveStorage::Variation

Inherits:
Object
  • Object
show all
Defined in:
app/models/active_storage/variation.rb

Overview

A set of transformations that can be applied to a blob to create a variant. This class is exposed via the ActiveStorage::Blob#variant method and should rarely be used directly.

In case you do need to use this directly, it's instantiated using a hash of transformations where the key is the command and the value is the arguments. Example:

ActiveStorage::Variation.new(resize: "100x100", monochrome: true, trim: true, rotate: "-90")

You can also combine multiple transformations in one step, e.g. for center-weighted cropping:

ActiveStorage::Variation.new(combine_options: {
  resize: "100x100^",
  gravity: "center",
  crop: "100x100+0+0",
})

A list of all possible transformations is available at www.imagemagick.org/script/mogrify.php.

Defined Under Namespace

Classes: UnsupportedImageProcessingArgument, UnsupportedImageProcessingMethod

Constant Summary collapse

SUPPORTED_IMAGE_PROCESSING_METHODS = 
[
 "adaptive_blur",
 "adaptive_resize",
 "adaptive_sharpen",
 "adjoin",
 "affine",
 "alpha",
 "annotate",
 "antialias",
 "append",
 "apply",
 "attenuate",
 "authenticate",
 "auto_gamma",
 "auto_level",
 "auto_orient",
 "auto_threshold",
 "backdrop",
 "background",
 "bench",
 "bias",
 "bilateral_blur",
 "black_point_compensation",
 "black_threshold",
 "blend",
 "blue_primary",
 "blue_shift",
 "blur",
 "border",
 "bordercolor",
 "borderwidth",
 "brightness_contrast",
 "cache",
 "canny",
 "caption",
 "channel",
 "channel_fx",
 "charcoal",
 "chop",
 "clahe",
 "clamp",
 "clip",
 "clip_path",
 "clone",
 "clut",
 "coalesce",
 "colorize",
 "colormap",
 "color_matrix",
 "colors",
 "colorspace",
 "colourspace",
 "color_threshold",
 "combine",
 "combine_options",
 "comment",
 "compare",
 "complex",
 "compose",
 "composite",
 "compress",
 "connected_components",
 "contrast",
 "contrast_stretch",
 "convert",
 "convolve",
 "copy",
 "crop",
 "cycle",
 "deconstruct",
 "define",
 "delay",
 "delete",
 "density",
 "depth",
 "descend",
 "deskew",
 "despeckle",
 "direction",
 "displace",
 "dispose",
 "dissimilarity_threshold",
 "dissolve",
 "distort",
 "dither",
 "draw",
 "duplicate",
 "edge",
 "emboss",
 "encoding",
 "endian",
 "enhance",
 "equalize",
 "evaluate",
 "evaluate_sequence",
 "extent",
 "extract",
 "family",
 "features",
 "fft",
 "fill",
 "filter",
 "flatten",
 "flip",
 "floodfill",
 "flop",
 "font",
 "foreground",
 "format",
 "frame",
 "function",
 "fuzz",
 "fx",
 "gamma",
 "gaussian_blur",
 "geometry",
 "gravity",
 "grayscale",
 "green_primary",
 "hald_clut",
 "highlight_color",
 "hough_lines",
 "iconGeometry",
 "iconic",
 "identify",
 "ift",
 "illuminant",
 "immutable",
 "implode",
 "insert",
 "intensity",
 "intent",
 "interlace",
 "interline_spacing",
 "interpolate",
 "interpolative_resize",
 "interword_spacing",
 "kerning",
 "kmeans",
 "kuwahara",
 "label",
 "lat",
 "layers",
 "level",
 "level_colors",
 "limit",
 "limits",
 "linear_stretch",
 "linewidth",
 "liquid_rescale",
 "list",
 "loader",
 "log",
 "loop",
 "lowlight_color",
 "magnify",
 "map",
 "mattecolor",
 "median",
 "mean_shift",
 "metric",
 "mode",
 "modulate",
 "moments",
 "monitor",
 "monochrome",
 "morph",
 "morphology",
 "mosaic",
 "motion_blur",
 "name",
 "negate",
 "noise",
 "normalize",
 "opaque",
 "ordered_dither",
 "orient",
 "page",
 "paint",
 "pause",
 "perceptible",
 "ping",
 "pointsize",
 "polaroid",
 "poly",
 "posterize",
 "precision",
 "preview",
 "process",
 "quality",
 "quantize",
 "quiet",
 "radial_blur",
 "raise",
 "random_threshold",
 "range_threshold",
 "red_primary",
 "regard_warnings",
 "region",
 "remote",
 "render",
 "repage",
 "resample",
 "resize",
 "resize_to_fill",
 "resize_to_fit",
 "resize_to_limit",
 "resize_and_pad",
 "respect_parentheses",
 "reverse",
 "roll",
 "rotate",
 "sample",
 "sampling_factor",
 "saver",
 "scale",
 "scene",
 "screen",
 "seed",
 "segment",
 "selective_blur",
 "separate",
 "sepia_tone",
 "shade",
 "shadow",
 "shared_memory",
 "sharpen",
 "shave",
 "shear",
 "sigmoidal_contrast",
 "silent",
 "similarity_threshold",
 "size",
 "sketch",
 "smush",
 "snaps",
 "solarize",
 "sort_pixels",
 "sparse_color",
 "splice",
 "spread",
 "statistic",
 "stegano",
 "stereo",
 "storage_type",
 "stretch",
 "strip",
 "stroke",
 "strokewidth",
 "style",
 "subimage_search",
 "swap",
 "swirl",
 "synchronize",
 "taint",
 "text_font",
 "threshold",
 "thumbnail",
 "tile_offset",
 "tint",
 "title",
 "transform",
 "transparent",
 "transparent_color",
 "transpose",
 "transverse",
 "treedepth",
 "trim",
 "type",
 "undercolor",
 "unique_colors",
 "units",
 "unsharp",
 "update",
 "valid_image",
 "view",
 "vignette",
 "virtual_pixel",
 "visual",
 "watermark",
 "wave",
 "wavelet_denoise",
 "weight",
 "white_balance",
 "white_point",
 "white_threshold",
 "window",
 "window_group",
].concat(ActiveStorage.supported_image_processing_methods)
UNSUPPORTED_IMAGE_PROCESSING_ARGUMENTS = 
ActiveStorage.unsupported_image_processing_arguments

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(transformations) ⇒ Variation

Returns a new instance of Variation.



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# File 'app/models/active_storage/variation.rb', line 345

def initialize(transformations)
  @transformations = transformations
end

Instance Attribute Details

#transformations ⇒ Object (readonly)

Returns the value of attribute transformations.



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# File 'app/models/active_storage/variation.rb', line 21

def transformations
  @transformations
end

Class Method Details

.decode(key) ⇒ Object

Returns a Variation instance with the transformations that were encoded by encode.



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# File 'app/models/active_storage/variation.rb', line 334

def decode(key)
  new ActiveStorage.verifier.verify(key, purpose: :variation)
end

.encode(transformations) ⇒ Object

Returns a signed key for the transformations, which can be used to refer to a specific variation in a URL or combined key (like ActiveStorage::Variant#key).



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# File 'app/models/active_storage/variation.rb', line 340

def encode(transformations)
  ActiveStorage.verifier.generate(transformations, purpose: :variation)
end

.wrap(variator) ⇒ Object

Returns a Variation instance based on the given variator. If the variator is a Variation, it is returned unmodified. If it is a String, it is passed to ActiveStorage::Variation.decode. Otherwise, it is assumed to be a transformations Hash and is passed directly to the constructor.



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# File 'app/models/active_storage/variation.rb', line 322

def wrap(variator)
  case variator
  when self
    variator
  when String
    decode variator
  else
    new variator
  end
end

Instance Method Details

#key ⇒ Object

Returns a signed key for all the transformations that this variation was instantiated with.



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# File 'app/models/active_storage/variation.rb', line 371

def key
  self.class.encode(transformations)
end

#transform(image) ⇒ Object

Accepts an open MiniMagick image instance, like what's returned by MiniMagick::Image.read(io), and performs the transformations against it. The transformed image instance is then returned.



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# File 'app/models/active_storage/variation.rb', line 351

def transform(image)
  ActiveSupport::Notifications.instrument("transform.active_storage") do
    transformations.each do |name, argument_or_subtransformations|
      validate_transformation(name, argument_or_subtransformations)
      image.mogrify do |command|
        if name.to_s == "combine_options"
          argument_or_subtransformations.each do |subtransformation_name, subtransformation_argument|
            validate_transformation(subtransformation_name, subtransformation_argument)
            pass_transform_argument(command, subtransformation_name, subtransformation_argument)
          end
        else
          validate_transformation(name, argument_or_subtransformations)
          pass_transform_argument(command, name, argument_or_subtransformations)
        end
      end
    end
  end
end