#@gimp Graduated color accent : gimp_gca, gimp_gca_preview
#@gimp : Reference color = color(255,255,255)
#@gimp : Amplitude = float(1,0,5)
#@gimp : Max value = choice("From input","From reference color","Maximum allowed")
#@gimp : Channel = choice(0,"Saturation","Lightness")
#@gimp : sep = separator(), Preview type = choice("Full","Forward horizontal","Forward vertical","Backward horizontal","Backward vertical","Duplicate horizontal","Duplicate vertical")
#@gimp : sep = separator(), note = note("<small>Author: <i>David Tschumperl&#233;</i>.      Latest update: <i>07/15/2015</i>.</small>")
gimp_gca :
  channel={1+$6}
  -repeat $! -l[$>] -to_color -split_opacity -l[0]
    --fc $1,$2,$3
    --[1] [0] -norm[1] -/[1] {1e-6+iM} -*[1] -1 -+[1] 1 -pow[1] $4
    -rgb2hsl[0] -s[0] c
    -if {$5==0} -*[$channel,-1]
    -elif {$5==1} ($1^$2^$3) -rgb2hsl[-1] -*[$channel] {i[$channel]} -rm[-2,-1]
    -else -rv[$channel,-1] -rm[-1]
    -endif
    -a c -hsl2rgb
  -endl -a c -endl -done

gimp_gca_preview :
  -gimp_split_preview "-gimp_gca $*",$-1