110 lines
2.2 KiB
Lua
110 lines
2.2 KiB
Lua
tga_encoder = {}
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local LUA_ARGS_LIMIT = 1000
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local image = setmetatable({}, {
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__call = function(self, ...)
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local t = setmetatable({}, {__index = self})
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t:constructor(...)
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return t
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end,
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})
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function image:constructor(pixels)
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self.bytes = {}
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self.chunks = {self.bytes}
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self.pixels = pixels
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self.width = #pixels[1]
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self.height = #pixels
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self:encode()
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end
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function image:insert(byte)
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table.insert(self.bytes, byte)
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if #self.bytes == LUA_ARGS_LIMIT then
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self.bytes = {}
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table.insert(self.chunks, self.bytes)
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end
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end
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function image:littleendian(size, value)
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for i = 1, size do
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local byte = value % 256
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value = value - byte
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value = value / 256
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self:insert(byte)
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end
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end
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function image:encode_colormap_spec()
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-- first entry index
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self:littleendian(2, 0)
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-- number of entries
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self:littleendian(2, 0)
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-- number of bits per pixel
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self:insert(0)
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end
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function image:encode_image_spec()
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-- X- and Y- origin
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self:littleendian(2, 0)
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self:littleendian(2, 0)
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-- width and height
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self:littleendian(2, self.width)
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self:littleendian(2, self.height)
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-- pixel depth
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self:insert(24)
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-- image descriptor
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self:insert(0)
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end
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function image:encode_header()
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-- id length
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self:insert(0) -- no image id info
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-- color map type
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self:insert(0) -- no color map
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-- image type
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self:insert(2) -- uncompressed true-color image
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-- color map specification
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self:encode_colormap_spec()
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-- image specification
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self:encode_image_spec()
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end
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function image:encode_data()
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for _, row in ipairs(self.pixels) do
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for _, pixel in ipairs(row) do
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self:insert(pixel[3])
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self:insert(pixel[2])
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self:insert(pixel[1])
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end
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end
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end
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function image:encode()
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-- encode header
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self:encode_header()
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-- no color map and image id data
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-- encode data
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self:encode_data()
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-- no extension area
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end
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function image:get_data()
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local data = ""
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for _, bytes in ipairs(self.chunks) do
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data = data .. string.char(unpack(bytes))
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end
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return data .. string.char(0, 0, 0, 0) .. string.char(0, 0, 0, 0) .. "TRUEVISION-XFILE." .. string.char(0)
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end
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function image:save(filename)
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self.data = self.data or self:get_data()
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local f = assert(io.open(filename, "w"))
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f:write(self.data)
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f:close()
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end
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tga_encoder.image = image
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