discourse/lib/letter_avatar.rb

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class LetterAvatar
class Identity
attr_accessor :color, :letter
def self.from_username(username)
identity = new
identity.color = LetterAvatar::COLORS[
Digest::MD5.hexdigest(username)[0...15].to_i(16) % LetterAvatar::COLORS.length
]
identity.letter = username[0].upcase
identity
end
end
# BUMP UP if avatar algorithm changes
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VERSION = 5
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# CHANGE these values to support more pixel ratios
FULLSIZE = 120 * 3
POINTSIZE = 280
class << self
def version
"#{VERSION}_#{image_magick_version}"
end
def cache_path
"tmp/letter_avatars/#{version}"
end
def generate(username, size, opts = nil)
DistributedMutex.synchronize("letter_avatar_#{version}_#{username}") do
identity = (opts && opts[:identity]) || LetterAvatar::Identity.from_username(username)
cache = true
cache = false if opts && opts[:cache] == false
size = FULLSIZE if size > FULLSIZE
filename = cached_path(identity, size)
return filename if cache && File.exists?(filename)
fullsize = fullsize_path(identity)
generate_fullsize(identity) if !cache || !File.exists?(fullsize)
# Optimizing here is dubious, it can save up to 2x for large images (eg 359px)
# BUT... we are talking 2400 bytes down to 1200 bytes, both fit in one packet
# The cost of this is huge, its a 40% perf hit
OptimizedImage.resize(fullsize, filename, size, size)
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filename
end
end
def cached_path(identity, size)
dir = "#{cache_path}/#{identity.letter}/#{identity.color.join("_")}"
FileUtils.mkdir_p(dir)
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File.expand_path "#{dir}/#{size}.png"
end
def fullsize_path(identity)
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File.expand_path cached_path(identity, FULLSIZE)
end
def generate_fullsize(identity)
color = identity.color
letter = identity.letter
filename = fullsize_path(identity)
instructions = %W{
-size #{FULLSIZE}x#{FULLSIZE}
xc:#{to_rgb(color)}
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-pointsize #{POINTSIZE}
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-fill #FFFFFFCC
-font Helvetica
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-gravity Center
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-annotate -0+26 #{letter}
-depth 8
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#{filename}
}
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Discourse::Utils.execute_command('convert', *instructions)
## do not optimize image, it will end up larger than original
filename
end
def to_rgb(color)
r,g,b = color
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"rgb(#{r},#{g},#{b})"
end
def image_magick_version
@image_magick_version ||=
begin
Thread.new do
sleep 2
cleanup_old
end
Digest::MD5.hexdigest(`convert --version` << `convert -list font`)
end
end
def cleanup_old
skip = File.basename(cache_path)
parent_path = File.dirname(cache_path)
Dir.entries(parent_path).each do |path|
unless ['.','..'].include?(path) || path == skip
FileUtils.rm_rf(parent_path + "/" + path)
end
end
end
end
# palette of optimally disctinct colors
# cf. http://tools.medialab.sciences-po.fr/iwanthue/index.php
# parameters used:
# - H: 0 - 360
# - C: 0 - 2
# - L: 0.75 - 1.5
COLORS = [[198,125,40],
[61,155,243],
[74,243,75],
[238,89,166],
[52,240,224],
[177,156,155],
[240,120,145],
[111,154,78],
[237,179,245],
[237,101,95],
[89,239,155],
[43,254,70],
[163,212,245],
[65,152,142],
[165,135,246],
[181,166,38],
[187,229,206],
[77,164,25],
[179,246,101],
[234,93,37],
[225,155,115],
[142,140,188],
[223,120,140],
[249,174,27],
[244,117,225],
[137,141,102],
[75,191,146],
[188,239,142],
[164,199,145],
[173,120,149],
[59,195,89],
[222,198,220],
[68,145,187],
[236,204,179],
[159,195,72],
[188,121,189],
[166,160,85],
[181,233,37],
[236,177,85],
[121,147,160],
[234,218,110],
[241,157,191],
[62,200,234],
[133,243,34],
[88,149,110],
[59,228,248],
[183,119,118],
[251,195,45],
[113,196,122],
[197,115,70],
[80,175,187],
[103,231,238],
[240,72,133],
[228,149,241],
[180,188,159],
[172,132,85],
[180,135,251],
[236,194,58],
[217,176,109],
[88,244,199],
[186,157,239],
[113,230,96],
[206,115,165],
[244,178,163],
[230,139,26],
[241,125,89],
[83,160,66],
[107,190,166],
[197,161,210],
[198,203,245],
[238,117,19],
[228,119,116],
[131,156,41],
[145,178,168],
[139,170,220],
[233,95,125],
[87,178,230],
[157,200,119],
[237,140,76],
[229,185,186],
[144,206,212],
[236,209,158],
[185,189,79],
[34,208,66],
[84,238,129],
[133,140,134],
[67,157,94],
[168,179,25],
[140,145,240],
[151,241,125],
[67,162,107],
[200,156,21],
[169,173,189],
[226,116,189],
[133,231,191],
[194,161,63],
[241,77,99],
[241,217,53],
[123,204,105],
[210,201,119],
[229,108,155],
[240,91,72],
[187,115,210],
[240,163,100],
[178,217,57],
[179,135,116],
[204,211,24],
[186,135,57],
[223,176,135],
[204,148,151],
[116,223,50],
[95,195,46],
[123,160,236],
[181,172,131],
[142,220,202],
[240,140,112],
[172,145,164],
[228,124,45],
[135,151,243],
[42,205,125],
[192,233,116],
[119,170,114],
[158,138,26],
[73,190,183],
[185,229,243],
[227,107,55],
[196,205,202],
[132,143,60],
[233,192,237],
[62,150,220],
[205,201,141],
[106,140,190],
[161,131,205],
[135,134,158],
[198,139,81],
[115,171,32],
[101,181,67],
[149,137,119],
[37,142,183],
[183,130,175],
[168,125,133],
[124,142,87],
[236,156,171],
[232,194,91],
[219,200,69],
[144,219,34],
[219,95,187],
[145,154,217],
[165,185,100],
[127,238,163],
[224,178,198],
[119,153,120],
[124,212,92],
[172,161,105],
[231,155,135],
[157,132,101],
[122,185,146],
[53,166,51],
[70,163,90],
[150,190,213],
[210,107,60],
[166,152,185],
[159,194,159],
[39,141,222],
[202,176,161],
[95,140,229],
[168,142,87],
[93,170,203],
[159,142,54],
[14,168,39],
[94,150,149],
[187,206,136],
[157,224,166],
[235,158,208],
[109,232,216],
[141,201,87],
[208,124,118],
[142,125,214],
[19,237,174],
[72,219,41],
[234,102,111],
[168,142,79],
[188,135,35],
[95,155,143],
[148,173,116],
[223,112,95],
[228,128,236],
[206,114,54],
[195,119,88],
[235,140,94],
[235,202,125],
[233,155,153],
[214,214,238],
[246,200,35],
[151,125,171],
[132,145,172],
[131,142,118],
[199,126,150],
[61,162,123],
[58,176,151],
[215,141,69],
[225,154,220],
[220,77,167],
[233,161,64],
[130,221,137],
[81,191,129],
[169,162,140],
[174,177,222],
[236,174,47],
[233,188,180],
[69,222,172],
[71,232,93],
[118,211,238],
[157,224,83],
[218,105,73],
[126,169,36]]
end