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local M = {}
local hex_digits = {
"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"
}
function M.new()
return setmetatable({}, M)
end
function M:__newindex(k, v)
error("assignment to framebuffer object", 2)
end
function M:__index(k)
if type(k) == "number" and math.floor(k) == k then
rawset(self, k, {})
return rawget(self, k)
else
return M[k]
end
end
function M:clear()
for k in pairs(self) do
if type(k) == "number" then
self[k] = nil
end
end
end
local function round(x, y)
return math.floor(x + 0.5), math.floor(y + 0.5)
end
function M:plot(x, y, r, g, b)
local x, y = round(x, y)
self[x][y] = colors.packRGB(r, g, b)
end
function M:get(x, y)
local x, y = round(x, y)
if self[x][y] then
return colors.unpackRGB(self[x][y])
end
end
function M:rect(x1, y1, x2, y2, r, g, b)
for x = x1, x2 do
for y = y1, y2 do
self:plot(x, y, r, g, b)
end
end
end
function M:get_size()
return #self, #(self[1] or {})
end
function M:ppm(data, x, y)
if type(data) ~= "string" then
local f = data
data = assert(f.readAll())
f.close()
end
local x, y = round(x or 1, y or 1)
local w, h, depth, data = data:match "^P6\n(%d+) (%d+)\n(%d+)\n(.+)"
assert(w and h and depth, "invalid format; binary PPM (P6) requried")
for dy = 1, h do
for dx = 1, w do
local i = (((dy - 1) * w + dx) - 1) * 3
local r, g, b =
data:byte(i + 1) / depth,
data:byte(i + 2) / depth,
data:byte(i + 3) / depth
self:plot(dx + x - 1, dy + y - 1, r, g, b)
end
end
end
-- determine a palette for a set of colors
local function median_cut(cols, nbuckets)
local max, min = {}, {}
for _, color in ipairs(cols) do
for ch, v in ipairs(color) do
if not max[ch] or v > max[ch] then max[ch] = v end
if not min[ch] or v < min[ch] then min[ch] = v end
end
end
local max_variance, max_variant
for ch in ipairs(max) do
local variance = max[ch] - min[ch]
if not max_variance or variance > max_variance then
max_variance = variance
max_variant = ch
end
end
table.sort(cols, function(a, b) return a[max_variant] <= b[max_variant] end)
local partitions = {{}, {}}
local half = math.floor(#cols / 2)
for i = 1, half do
table.insert(partitions[1], cols[i])
end
for i = half + 1, #cols do
table.insert(partitions[2], cols[i])
end
local palette, map = {}, {}
if nbuckets <= 2 then
for n, part in ipairs(partitions) do
local avg = {0, 0, 0}
for _, color in ipairs(part) do
for ch, v in ipairs(color) do
avg[ch] = avg[ch] + v
end
map[colors.packRGB(unpack(color))] = n
end
for ch, v in ipairs(avg) do
avg[ch] = avg[ch] / #part
end
palette[n] = colors.packRGB(unpack(avg))
end
else
local palette1, map1 = median_cut(partitions[1], nbuckets / 2)
local palette2, map2 = median_cut(partitions[2], nbuckets / 2)
for b, m in pairs {[palette1] = map1, [palette2] = map2} do
local offs = #palette
for i, b in ipairs(b) do
palette[i + offs] = b
end
for c, i in pairs(m) do
map[c] = i + offs
end
end
end
return palette, map
end
local function get_char(fb, x, y)
local cols = {}
local pixels = {}
for y = y, y + 2 do
for x = x, x + 1 do
local color = {fb:get(x, y)}
if color[1] then
table.insert(cols, color)
table.insert(pixels, colors.packRGB(unpack(color)))
else
table.insert(pixels, 0)
end
end
end
if #cols == 0 then
return string.char(0x80)
end
local palette, map = median_cut(cols, 2)
local char = 0x80
-- TODO: document this
local p6 = map[pixels[6]] or 1
for i = 1, 5 do
if (map[pixels[i]] or 1) ~= p6 then
char = char + 2^(i - 1)
end
end
local fg, bg
if map[pixels[6]] == 2 then
fg, bg = palette[1], palette[2]
else
fg, bg = palette[2], palette[1]
end
return string.char(char), fg, bg
end
function M.resolution(mon)
local w, h = mon.getSize()
return w * 2, h * 3
end
function M:present(mon, offsx, offsy)
print("PrESENT")
offsx, offsy = offsx or 0, offsy or 0
local w, h = mon.getSize()
local pw, ph = M.resolution(mon)
local cols = {}
local chars = {}
-- print("","1")
for y = offsy + 1, offsy + ph, 3 do
for x = offsx + 1, offsx + pw, 2 do
local char, fg, bg = get_char(self, x, y)
table.insert(chars, {char, fg, bg})
if fg and bg then
table.insert(cols, {colors.unpackRGB(fg)})
table.insert(cols, {colors.unpackRGB(bg)})
end
end
end
-- print("","2")
local palette, map = median_cut(cols, 16)
for i, color in ipairs(palette) do
mon.setPaletteColor(2^(i - 1), color)
end
-- print("","3")
for i = 1, w * h, w do
mon.setCursorPos(1, (i - 1) / w)
local blit_char, blit_fg, blit_bg = {}, {}, {}
for i = i, i + w - 1 do
local char, fg, bg = unpack(chars[i])
table.insert(blit_char, char)
table.insert(blit_fg, fg and hex_digits[map[fg]] or "1")
table.insert(blit_bg, bg and hex_digits[map[bg]] or "1")
end
mon.blit(
table.concat(blit_char),
table.concat(blit_fg),
table.concat(blit_bg))
end
end
return M
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