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[RFC] support color256 decoding, "fixes" color256 encoding #62

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[RFC] support color256 decoding, "fixes" color256 encoding #62

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283 changes: 278 additions & 5 deletions AsciiPixel/src/colorant2ansi.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -28,16 +28,289 @@ function (enc::TermColor256)(c::AbstractRGB)
r, g, b = clamp01nan(red(c)), clamp01nan(green(c)), clamp01nan(blue(c))
r24, g24, b24 = map(c->round(Int, c * 23), (r, g, b))
if r24 == g24 == b24
# Use grayscales because of higher resolution
# This way even grayscale RGB images look good.
# RGB scale color code
r24 == 0 && return 17 # 0x000000
r24 == 9 && return 60 # 0x5f5f5f
r24 == 12 && return 103 # 0x878787
r24 == 16 && return 146 # 0xafafaf
r24 == 19 && return 189 # 0xd7d7d7
r24 == 23 && return 232 # 0xffffff
# gray scale color code
232 + r24
else
r6, g6, b6 = map(c->round(Int, c * 5), (r, g, b))
16 + 36 * r6 + 6 * g6 + b6
r6, g6, b6 = map(c->floor(Int, c * 5), (r, g, b))
17 + 36 * r6 + 6 * g6 + b6
end
end
(enc::TermColor256)(c::AbstractGray) = round(Int, 232 + clamp01nan(real(c)) * 23)
function (enc::TermColor256)(c::AbstractGray)
val = round(Int, clamp01nan(gray(c)) * 26)
val == 0 && return 17 # 0x000000
val > 24 && return 232 # 0xffffff
return 232 + val
Comment on lines +46 to +49
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@johnnychen94 johnnychen94 Jan 3, 2022

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This can be implemented wrong here; just that this version passes the enc(enc(c)) = c test for those 256 colors.

end
@inline (enc::TermColor256)(idx::Integer) = RGB(reinterpret(ARGB32, TERMCOLOR256_LOOKUP[idx]))

# https://www.ditig.com/256-colors-cheat-sheet
const TERMCOLOR256_LOOKUP = [
# 8-bit, RGB hex

# Primary 3-bit (8 colors)
0x000000, 0x800000, 0x008000, 0x808000, 0x000080, 0x800080, 0x008080, 0xc0c0c0,

# Equivalent "bright" versions of original 8 colors.
0x808080,
0xff0000,
0x00ff00,
0xffff00,
0x0000ff,
0xff00ff,
0x00ffff,
0xffffff,

# Strictly ascending.
0x000000,
0x00005f,
0x000087,
0x0000af,
0x0000d7,
0x0000ff,
0x005f00,
0x005f5f,
0x005f87,
0x005faf,
0x005fd7,
0x005fff,
0x008700,
0x00875f,
0x008787,
0x0087af,
0x0087d7,
0x0087ff,
0x00af00,
0x00af5f,
0x00af87,
0x00afaf,
0x00afd7,
0x00afff,
0x00d700,
0x00d75f,
0x00d787,
0x00d7af,
0x00d7d7,
0x00d7ff,
0x00ff00,
0x00ff5f,
0x00ff87,
0x00ffaf,
0x00ffd7,
0x00ffff,
0x5f0000,
0x5f005f,
0x5f0087,
0x5f00af,
0x5f00d7,
0x5f00ff,
0x5f5f00,
0x5f5f5f,
0x5f5f87,
0x5f5faf,
0x5f5fd7,
0x5f5fff,
0x5f8700,
0x5f875f,
0x5f8787,
0x5f87af,
0x5f87d7,
0x5f87ff,
0x5faf00,
0x5faf5f,
0x5faf87,
0x5fafaf,
0x5fafd7,
0x5fafff,
0x5fd700,
0x5fd75f,
0x5fd787,
0x5fd7af,
0x5fd7d7,
0x5fd7ff,
0x5fff00,
0x5fff5f,
0x5fff87,
0x5fffaf,
0x5fffd7,
0x5fffff,
0x870000,
0x87005f,
0x870087,
0x8700af,
0x8700d7,
0x8700ff,
0x875f00,
0x875f5f,
0x875f87,
0x875faf,
0x875fd7,
0x875fff,
0x878700,
0x87875f,
0x878787,
0x8787af,
0x8787d7,
0x8787ff,
0x87af00,
0x87af5f,
0x87af87,
0x87afaf,
0x87afd7,
0x87afff,
0x87d700,
0x87d75f,
0x87d787,
0x87d7af,
0x87d7d7,
0x87d7ff,
0x87ff00,
0x87ff5f,
0x87ff87,
0x87ffaf,
0x87ffd7,
0x87ffff,
0xaf0000,
0xaf005f,
0xaf0087,
0xaf00af,
0xaf00d7,
0xaf00ff,
0xaf5f00,
0xaf5f5f,
0xaf5f87,
0xaf5faf,
0xaf5fd7,
0xaf5fff,
0xaf8700,
0xaf875f,
0xaf8787,
0xaf87af,
0xaf87d7,
0xaf87ff,
0xafaf00,
0xafaf5f,
0xafaf87,
0xafafaf,
0xafafd7,
0xafafff,
0xafd700,
0xafd75f,
0xafd787,
0xafd7af,
0xafd7d7,
0xafd7ff,
0xafff00,
0xafff5f,
0xafff87,
0xafffaf,
0xafffd7,
0xafffff,
0xd70000,
0xd7005f,
0xd70087,
0xd700af,
0xd700d7,
0xd700ff,
0xd75f00,
0xd75f5f,
0xd75f87,
0xd75faf,
0xd75fd7,
0xd75fff,
0xd78700,
0xd7875f,
0xd78787,
0xd787af,
0xd787d7,
0xd787ff,
0xd7af00,
0xd7af5f,
0xd7af87,
0xd7afaf,
0xd7afd7,
0xd7afff,
0xd7d700,
0xd7d75f,
0xd7d787,
0xd7d7af,
0xd7d7d7,
0xd7d7ff,
0xd7ff00,
0xd7ff5f,
0xd7ff87,
0xd7ffaf,
0xd7ffd7,
0xd7ffff,
0xff0000,
0xff005f,
0xff0087,
0xff00af,
0xff00d7,
0xff00ff,
0xff5f00,
0xff5f5f,
0xff5f87,
0xff5faf,
0xff5fd7,
0xff5fff,
0xff8700,
0xff875f,
0xff8787,
0xff87af,
0xff87d7,
0xff87ff,
0xffaf00,
0xffaf5f,
0xffaf87,
0xffafaf,
0xffafd7,
0xffafff,
0xffd700,
0xffd75f,
0xffd787,
0xffd7af,
0xffd7d7,
0xffd7ff,
0xffff00,
0xffff5f,
0xffff87,
0xffffaf,
0xffffd7,
0xffffff,

# Gray-scale range.
0x080808,
0x121212,
0x1c1c1c,
0x262626,
0x303030,
0x3a3a3a,
0x444444,
0x4e4e4e,
0x585858,
0x626262,
0x6c6c6c,
0x767676,
0x808080,
0x8a8a8a,
0x949494,
0x9e9e9e,
0xa8a8a8,
0xb2b2b2,
0xbcbcbc,
0xc6c6c6,
0xd0d0d0,
0xdadada,
0xe4e4e4,
0xeeeeee,
]

"""
TermColor24bit()
Expand Down
44 changes: 40 additions & 4 deletions AsciiPixel/test/colorant2ansi.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -5,13 +5,29 @@
# This tests if the mapping from RGB to the
# 256 ansi color codes is correct
@testset "256 colors" begin
# reference functions to compare against
#reference functions to compare against
function _ref_col2ansi(r,g,b)
r6, g6, b6 = map(c->round(Int, 5c), (r, g, b))
16 + 36 * r6 + 6 * g6 + b6
r24, g24, b24 = map(c->round(Int, c * 23), (r, g, b))
if r24 == g24 == b24
# RGB scale color code
r24 == 0 && return 17 # 0x000000
r24 == 9 && return 60 # 0x5f5f5f
r24 == 12 && return 103 # 0x878787
r24 == 16 && return 146 # 0xafafaf
r24 == 19 && return 189 # 0xd7d7d7
r24 == 23 && return 232 # 0xffffff
# gray scale color code
232 + r24
else
r6, g6, b6 = map(c->floor(Int, c * 5), (r, g, b))
17 + 36 * r6 + 6 * g6 + b6
end
end
function _ref_col2ansi(gr)
round(Int, 232 + gr * 23)
val = round(Int, clamp01nan(gr) * 26)
val == 0 && return 17 # 0x000000
val > 24 && return 232 # 0xffffff
return 232 + val
end
@testset "RGB" begin
enc = TermColor256()
Expand All @@ -32,6 +48,26 @@
@test enc(col) === _ref_col2ansi(r)
end
end

@testset "decoder" begin
enc = TermColor256()

@testset "RGB scale" begin
for idx in 17:232
ccode = AsciiPixel.TERMCOLOR256_LOOKUP[idx]
c = RGB(reinterpret(ARGB32, ccode))
@test enc(c) == idx
end
end

@testset "Gray scale" begin
for idx in 232:256
ccode = AsciiPixel.TERMCOLOR256_LOOKUP[idx]
c = Gray(red(RGB(reinterpret(ARGB32, ccode))))
@test enc(c) == idx
end
end
end
end

# This tests if the mapping from RGB to the 24 bit r g b tuples
Expand Down