107 lines
2.6 KiB
Lua
107 lines
2.6 KiB
Lua
-- helper function, simulates PHP's array_fill function
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local array_fill = function(vbegin, vend, value)
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local t = {}
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for i=vbegin, vend do
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t[i] = value
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end
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return t
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end
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Bitmap = {}
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Bitmap.__index = Bitmap
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function Bitmap.new(width, height)
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local self = {}
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setmetatable(self, Bitmap)
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local white = array_fill(0, width, {255, 255, 255})
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self.data = array_fill(0, height, white)
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self.width = width
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self.height = height
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return self
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end
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function Bitmap:writeRawPixel(file, c)
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local dt
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dt = string.format("%c", c)
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file:write(dt)
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end
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function Bitmap:writeComment(fh, ...)
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local strings = {...}
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local str = ""
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local result
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for _, s in pairs(strings) do
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str = str .. tostring(s)
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end
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result = string.format("# %s\n", str)
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fh:write(result)
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end
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function Bitmap:writeP6(filename)
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local fh = io.open(filename, 'w')
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if not fh then
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error(string.format("failed to open %q for writing", filename))
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else
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fh:write(string.format("P6 %d %d 255\n", self.width, self.height))
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self:writeComment(fh, "automatically generated at ", os.date())
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for _, row in pairs(self.data) do
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for _, pixel in pairs(row) do
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self:writeRawPixel(fh, pixel[1])
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self:writeRawPixel(fh, pixel[2])
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self:writeRawPixel(fh, pixel[3])
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end
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end
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end
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end
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function Bitmap:fill(x, y, width, height, color)
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width = (width == nil) and self.width or width
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height = (height == nil) and self.height or height
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width = width + x
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height = height + y
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for i=y, height do
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for j=x, width do
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self:setPixel(j, i, color)
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end
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end
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end
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function Bitmap:setPixel(x, y, color)
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if x >= self.width then
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--error("x is bigger than self.width!")
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return false
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elseif x < 0 then
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--error("x is smaller than 0!")
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return false
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elseif y >= self.height then
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--error("y is bigger than self.height!")
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return false
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elseif y < 0 then
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--error("y is smaller than 0!")
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return false
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end
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self.data[y][x] = color
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return true
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end
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function example_colorful_stripes()
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local w = 260*2
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local h = 260*2
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local b = Bitmap.new(w, h)
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--b:fill(2, 2, 18, 18, {240,240,240})
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b:setPixel(0, 15, {255,68,0})
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for i=1, w do
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for j=1, h do
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b:setPixel(i, j, {
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(i + j * 8) % 256,
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(j + (255 * i)) % 256,
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(i * j) % 256
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}
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);
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end
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end
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return b
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end
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example_colorful_stripes():writeP6('p6.ppm')
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