rgb2hex & hex2rbg

sslivka · June 2013

function rgb2hex1(r, g, b)
	local rgb, i, m, hex, hexABC = r*65536 + g*256 + b, 0, 0, "", "0123456789ABCDEF"
	while rgb > 0 do
		i = i + 1
		rgb, m = math.floor(rgb/16), math.fmod(rgb, 16) + 1
		hex = string.sub(hexABC, m, m) .. hex
	end
	local switch = {[4] = "00" .. hex, [5] = "0" .. hex, [6] = hex}
	return "0x" .. switch[#hex]
end
 
function rgb2hex2(r, g, b)
	return r*65536 + g*256 + b
end
 
function hex2rbg(hex)
	local rgb, d = {}, {65536, 256, 1}
	for i = 1, 3 do
		rgb[i] = math.floor(hex/d[i])
		hex = math.fmod(hex, d[i])
	end
	return rgb[1], rgb[2], rgb[3]
end
 
print(rgb2hex1(163, 54, 90))
application:setBackgroundColor(rgb2hex2(163, 54, 90))
print(hex2rbg(0xA3365A))

ar2rsawseen · June 2013

@ssilvka cool
Additionally:

local rgb_to_hsl = function(r, g, b)
	r = r/255 
	g = g/255 
	b = b/255
	local max = math.max(r, g, b)
	local min = math.min(r, g, b)
	local h
	local s
	local l = (max + min) / 2
	if(max == min) then
		--achromatic
		h = 0
		s = 0
	else
		local d = max - min
		if(l > 0.5) then
			s = d / (2 - max - min)
		else 
			s = d / (max + min)
		end
 
		if max == r then
			if g < b then
				h = (g - b) / d + 6
			else
				h = (g - b) / d
			end
		elseif max == g then
			h = (b - r) / d + 2
		elseif max == b then
			h = (r - g) / d + 4
		end
		h = h / 6
	end
	return math.floor(h*360 + 0.5), math.floor(s*100 + 0.5), math.floor(l*100 + 0.5)
end
 
local hsl_to_rgb = function(h, s, l)
	h = h/360
	s = s/100
	l = l/100
	local r, g, b
	if(s == 0) then
		--achromatic
		r = 1
		g = 1
		b = l
	else
		local q
		if l < 0.5 then
			q = l * (1 + s)
		else
			q = l + s - l * s
		end
		local p = 2 * l - q
		r = hue_to_rgb(p, q, h + 1/3)
		g = hue_to_rgb(p, q, h)
		b = hue_to_rgb(p, q, h - 1/3)
	end
	return math.floor(r * 255 + 0.5), math.floor(g * 255 + 0.5), math.floor(b * 255 + 0.5)
end
 
local hue_to_rgb = function(p, q, t)
	if(t < 0) then t = t + 1 end
	if(t > 1) then t = t - 1 end
	if(t < 1/6) then return p + (q - p) * 6 * t end
	if(t < 1/2) then return q end
	if(t < 2/3) then return p + (q - p) * (2/3 - t) * 6 end
	return p
end
 
local h, s, l = rgb_to_hsl(35,9,34)
print(h.." "..s.." "..l)

sslivka · June 2013

@ar2rsawseen, maybe you know where I can get Color Picker component for Gideros?

ar2rsawseen · June 2013

you mean like provide selecting a color inside app?
Sorry don't remember seeing anything like that, but if someone would have such component, it would most probably be @OZApps

OZApps · June 2013

you mean like provide selecting a color inside app?
Sorry don't remember seeing anything like that, but if someone would have such component, it would most probably be @OZApps

I had created one long before adopting Gideros, so it was made in BeerSDK and there was a video on one of the sites (now Posterous has taken it down, the problem with free services, you just do not know when they will take it down, like Geocities, etc in the past)

OZApps · June 2013

I managed to get the data from Posterous and I found the link to the color picker video, you can see it here

john26 · June 2013

I've often wondered why Gideros insists on colours being entered as a single number. OpenGL specifies them as (R,G,B) triplets which is also easier for the user. Behind the scenes Gideros must be unpacking to (R,G,B) anyway...?

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