coverflowify.rb

#!/usr/bin/env ruby

# Usage:
# Example command ./coverflowify.rb source.png 30 20 50 true output.png
# 
# The values are:
# * shrink percent - specifies by how much percent to shrink the background images
# * skew percent - specifies how much 3d rotation (inward) to give background images
# * visible percent - specifies how much of background images stick out on left and right
# * add_shadow - if true, adds default shadow, also accepts full shadow spec, like "70x4+5+5"
# * output path - just uses "result.png" if omitted

require 'skeptick'
include Skeptick


original, shrink_percent, skew_percent, visible_percent, add_shadow, result = ARGV
raise 'Must supply filename' unless original

shrink_percent  ||= 20
skew_percent    ||= 30
visible_percent ||= 40
add_shadow      = add_shadow == 'true' ? '30x3+3+3' : add_shadow
result ||= 'result.png'

shrink_percent  = shrink_percent.to_i
skew_percent    = skew_percent.to_i
visible_percent = visible_percent.to_i

def dimensions(path)
  `convert -auto-orient #{path} -format "%[fx:w],%[fx:h]" info:`.
    strip.split(',').map(&:to_i)
end

w, h  = dimensions(original)
ishp  = 100 - shrink_percent
iskp  = 100 - skew_percent
rw    = (w * (ishp / 100.0)).to_i
rh    = (h * (ishp / 100.0)).to_i
pdiff = ((rh - (rh * (iskp / 100.0))) / 2.0).to_i
extp  = (rw * (visible_percent / 100.0)).to_i
result_width = w + extp

left_img = convert do
  clone(0)
  apply :matte
  apply '-virtual-pixel', 'transparent'
  apply :distort
  apply 'Perspective',
    "'0,0 0,0  0,#{rh} 0,#{rh}  #{rw},0 #{rw},#{pdiff}  #{rw},#{rh} #{rw},#{rh - pdiff}'"
  set :background, 'transparent'
  set :gravity, 'west'
  set :extent, "#{result_width}x#{h}"
end

right_img = convert do
  clone(0)
  apply :matte
  apply '-virtual-pixel', 'transparent'
  apply :distort
  apply 'Perspective',
    "'0,0 0,#{pdiff}  0,#{rh} 0,#{rh - pdiff}  #{rw},0 #{rw},0  #{rw},#{rh} #{rw},#{rh}'"
  set :background, 'transparent'
  set :gravity, 'east'
  set :extent, "#{result_width}x#{h}"
end

background_layer = compose(:dst_over) do
  clone(0)
  set :resize, geometry(width: rw, height: rh, exact: true)
  image left_img
  image right_img
  delete(0)
end

source_img = if add_shadow
  compose(:over, original) do
    convert do
      clone
      set :background, 'black'
      set :shadow, add_shadow
    end
    swap
  end
else
  original
end

result = compose(:dst_over, to: result) do
  set '-auto-orient'
  image source_img
  image background_layer
  set '-auto-orient'
  set :gravity, 'center'
  set :extent, "#{result_width}x#{h}"
end

result.build