Eugen Rochko
2 years ago
committed by
GitHub
GitHub
16 changed files with 283 additions and 242 deletions
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# frozen_string_literal: true |
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require 'mime/types/columnar' |
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module Paperclip |
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class ColorExtractor < Paperclip::Processor |
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MIN_CONTRAST = 3.0 |
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FREQUENCY_THRESHOLD = 0.01 |
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def make |
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depth = 8 |
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# Determine background palette by getting colors close to the image's edge only |
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background_palette = palette_from_histogram(convert(':source -alpha set -gravity Center -region 75%x75% -fill None -colorize 100% -alpha transparent +region -format %c -colors :quantity -depth :depth histogram:info:', source: File.expand_path(@file.path), quantity: 10, depth: depth), 10) |
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# Determine foreground palette from the whole image |
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foreground_palette = palette_from_histogram(convert(':source -format %c -colors :quantity -depth :depth histogram:info:', source: File.expand_path(@file.path), quantity: 10, depth: depth), 10) |
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background_color = background_palette.first || foreground_palette.first |
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foreground_colors = [] |
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return @file if background_color.nil? |
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max_distance = 0 |
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max_distance_color = nil |
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foreground_palette.each do |color| |
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distance = ColorDiff.between(background_color, color) |
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if distance > max_distance |
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max_distance = distance |
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max_distance_color = color |
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end |
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end |
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foreground_colors << max_distance_color unless max_distance_color.nil? |
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max_distance = 0 |
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max_distance_color = nil |
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foreground_palette.each do |color| |
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distance = ColorDiff.between(background_color, color) |
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contrast = w3c_contrast(background_color, color) |
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if distance > max_distance && contrast >= MIN_CONTRAST && !foreground_colors.include?(color) |
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max_distance = distance |
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max_distance_color = color |
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end |
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end |
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foreground_colors << max_distance_color unless max_distance_color.nil? |
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# If we don't have enough colors for accent and foreground, generate |
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# new ones by manipulating the background color |
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(2 - foreground_colors.size).times do |i| |
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foreground_colors << lighten_or_darken(background_color, 35 + (15 * i)) |
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end |
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# We want the color with the highest contrast to background to be the foreground one, |
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# and the one with the highest saturation to be the accent one |
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foreground_color = foreground_colors.max_by { |rgb| w3c_contrast(background_color, rgb) } |
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accent_color = foreground_colors.max_by { |rgb| rgb_to_hsl(rgb.r, rgb.g, rgb.b)[1] } |
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meta = { |
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colors: { |
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background: rgb_to_hex(background_color), |
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foreground: rgb_to_hex(foreground_color), |
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accent: rgb_to_hex(accent_color), |
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}, |
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} |
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attachment.instance.file.instance_write(:meta, (attachment.instance.file.instance_read(:meta) || {}).merge(meta)) |
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@file |
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end |
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private |
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def w3c_contrast(color1, color2) |
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luminance1 = (0.2126 * color1.r + 0.7152 * color1.g + 0.0722 * color1.b) + 0.05 |
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luminance2 = (0.2126 * color2.r + 0.7152 * color2.g + 0.0722 * color2.b) + 0.05 |
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if luminance1 > luminance2 |
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luminance1 / luminance2 |
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else |
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luminance2 / luminance1 |
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end |
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end |
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# rubocop:disable Style/MethodParameterName |
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def rgb_to_hsl(r, g, b) |
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r /= 255.0 |
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g /= 255.0 |
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b /= 255.0 |
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max = [r, g, b].max |
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min = [r, g, b].min |
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h = (max + min) / 2.0 |
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s = (max + min) / 2.0 |
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l = (max + min) / 2.0 |
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if max == min |
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h = 0 |
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s = 0 # achromatic |
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else |
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d = max - min |
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s = l >= 0.5 ? d / (2.0 - max - min) : d / (max + min) |
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case max |
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when r |
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h = (g - b) / d + (g < b ? 6.0 : 0) |
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when g |
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h = (b - r) / d + 2.0 |
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when b |
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h = (r - g) / d + 4.0 |
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end |
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h /= 6.0 |
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end |
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[(h * 360).round, (s * 100).round, (l * 100).round] |
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end |
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def hue_to_rgb(p, q, t) |
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t += 1 if t.negative? |
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t -= 1 if t > 1 |
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return (p + (q - p) * 6 * t) if t < 1 / 6.0 |
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return q if t < 1 / 2.0 |
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return (p + (q - p) * (2 / 3.0 - t) * 6) if t < 2 / 3.0 |
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p |
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end |
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def hsl_to_rgb(h, s, l) |
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h /= 360.0 |
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s /= 100.0 |
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l /= 100.0 |
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r = 0.0 |
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g = 0.0 |
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b = 0.0 |
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if s == 0.0 |
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r = l.to_f |
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g = l.to_f |
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b = l.to_f # achromatic |
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else |
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q = l < 0.5 ? l * (1 + s) : l + s - l * s |
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p = 2 * l - q |
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r = hue_to_rgb(p, q, h + 1 / 3.0) |
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g = hue_to_rgb(p, q, h) |
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b = hue_to_rgb(p, q, h - 1 / 3.0) |
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end |
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[(r * 255).round, (g * 255).round, (b * 255).round] |
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end |
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# rubocop:enable Style/MethodParameterName |
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def lighten_or_darken(color, by) |
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hue, saturation, light = rgb_to_hsl(color.r, color.g, color.b) |
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light = begin |
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if light < 50 |
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[100, light + by].min |
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else |
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[0, light - by].max |
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end |
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end |
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ColorDiff::Color::RGB.new(*hsl_to_rgb(hue, saturation, light)) |
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end |
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def palette_from_histogram(result, quantity) |
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frequencies = result.scan(/([0-9]+)\:/).flatten.map(&:to_f) |
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hex_values = result.scan(/\#([0-9A-Fa-f]{6,8})/).flatten |
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total_frequencies = frequencies.reduce(&:+).to_f |
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frequencies.map.with_index { |f, i| [f / total_frequencies, hex_values[i]] } |
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.sort_by { |r| -r[0] } |
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.reject { |r| r[1].size == 8 && r[1].end_with?('00') } |
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.map { |r| ColorDiff::Color::RGB.new(*r[1][0..5].scan(/../).map { |c| c.to_i(16) }) } |
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.slice(0, quantity) |
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end |
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def rgb_to_hex(rgb) |
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'#%02x%02x%02x' % [rgb.r, rgb.g, rgb.b] |
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end |
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end |
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end |
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@ -0,0 +1,14 @@ |
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# frozen_string_literal: true |
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module Paperclip |
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module TranscoderExtensions |
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# Prevent the transcoder from modifying our meta hash |
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def initialize(file, options = {}, attachment = nil) |
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meta_value = attachment&.instance_read(:meta) |
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super |
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attachment&.instance_write(:meta, meta_value) |
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end |
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end |
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end |
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Paperclip::Transcoder.prepend(Paperclip::TranscoderExtensions) |
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