Module: Alchemy::Picture::Transformations

Extended by:
ActiveSupport::Concern
Included in:
EssencePicture, Alchemy::Picture
Defined in:
app/models/alchemy/picture/transformations.rb

Overview

This concern can extend classes that expose image_file, image_file_width and image_file_height. It provides methods for cropping and resizing.

Constant Summary collapse

THUMBNAIL_WIDTH = 
160
THUMBNAIL_HEIGHT = 
120

Instance Method Summary collapse

Instance Method Details

#can_be_cropped_to(string, upsample = false) ⇒ Object

An Image smaller than dimensions can not be cropped to given size - unless upsample is true.



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# File 'app/models/alchemy/picture/transformations.rb', line 119

def can_be_cropped_to(string, upsample = false)
  return true if upsample
  is_bigger_than sizes_from_string(string)
end

#crop(size, crop_from = nil, crop_size = nil, upsample = false) ⇒ Object

Returns the rendered cropped image. Tries to use the crop_from and crop_size parameters. When they can’t be parsed, it just crops from the center.



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# File 'app/models/alchemy/picture/transformations.rb', line 50

def crop(size, crop_from = nil, crop_size = nil, upsample = false)
  raise "No size given!" if size.empty?
  render_to = sizes_from_string(size)
  if crop_from && crop_size
    top_left = point_from_string(crop_from)
    crop_dimensions = sizes_from_string(crop_size)
    xy_crop_resize(render_to, top_left, crop_dimensions, upsample)
  else
    center_crop(render_to, upsample)
  end
end

#crop_size? ⇒ Boolean

Returns true if the class we’re included in has a meaningful crop_size attribute

Returns:

  • (Boolean) 


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# File 'app/models/alchemy/picture/transformations.rb', line 132

def crop_size?
  respond_to?(:crop_size) && !crop_size.nil? && !crop_size.empty?
end

#default_mask(mask_arg) ⇒ Object

Returns the default centered image mask for a given size. If the mask is bigger than the image, the mask is scaled down so the largest possible part of the image is visible.



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# File 'app/models/alchemy/picture/transformations.rb', line 17

def default_mask(mask_arg)
  mask = mask_arg.dup
  mask[:width] = image_file_width if mask[:width].zero?
  mask[:height] = image_file_height if mask[:height].zero?

  crop_size = size_when_fitting({width: image_file_width, height: image_file_height}, mask)
  top_left = get_top_left_crop_corner(crop_size)

  point_and_mask_to_points(top_left, crop_size)
end

#image_size ⇒ Object

This function returns the :width and :height of the image file as a Hash



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# File 'app/models/alchemy/picture/transformations.rb', line 109

def image_size
  {
    width: image_file_width,
    height: image_file_height
  }
end

#landscape_format? ⇒ Boolean Also known as: landscape?

Returns true if picture’s width is greater than it’s height

Returns:

  • (Boolean) 


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# File 'app/models/alchemy/picture/transformations.rb', line 88

def landscape_format?
  image_file.landscape?
end

#portrait_format? ⇒ Boolean Also known as: portrait?

Returns true if picture’s width is smaller than it’s height

Returns:

  • (Boolean) 


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# File 'app/models/alchemy/picture/transformations.rb', line 95

def portrait_format?
  image_file.portrait?
end

#render_size? ⇒ Boolean

Returns true if the class we’re included in has a meaningful render_size attribute

Returns:

  • (Boolean) 


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# File 'app/models/alchemy/picture/transformations.rb', line 126

def render_size?
  respond_to?(:render_size) && render_size.present?
end

#resize(size, upsample = false) ⇒ Object

Returns the rendered resized image using imagemagick directly.



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# File 'app/models/alchemy/picture/transformations.rb', line 64

def resize(size, upsample = false)
  image_file.thumb(upsample ? size : "#{size}>")
end

#sizes_from_string(string = "0x0") ⇒ Object

Given a string with an x, this function returns a Hash with point :width and :height.

Raises:

  • (ArgumentError) 


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# File 'app/models/alchemy/picture/transformations.rb', line 71

def sizes_from_string(string = "0x0")
  string = "0x0" if string.nil? || string.empty?

  raise ArgumentError unless string =~ /(\d*x\d*)/

  width, height = string.scan(/(\d*)x(\d*)/)[0].map(&:to_i)

  width = 0 if width.nil?
  height = 0 if height.nil?
  {
    width: width,
    height: height
  }
end

#square_format? ⇒ Boolean Also known as: square?

Returns true if picture’s width and height is equal

Returns:

  • (Boolean) 


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# File 'app/models/alchemy/picture/transformations.rb', line 102

def square_format?
  image_file.aspect_ratio == 1.0
end

#thumbnail_size(size_string = "0x0", crop = false) ⇒ Object

Returns a size value String for the thumbnail used in essence picture editors.



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# File 'app/models/alchemy/picture/transformations.rb', line 30

def thumbnail_size(size_string = "0x0", crop = false)
  size = sizes_from_string(size_string)

  # only if crop is set do we need to actually parse the size string, otherwise
  # we take the base image size.
  if crop
    size[:width] = get_base_dimensions[:width] if size[:width].zero?
    size[:height] = get_base_dimensions[:height] if size[:height].zero?
    size = reduce_to_image(size)
  else
    size = get_base_dimensions
  end

  size = size_when_fitting({width: THUMBNAIL_WIDTH, height: THUMBNAIL_HEIGHT}, size)
  "#{size[:width]}x#{size[:height]}"
end