Screen documentation

Introductions

NEET Computers offer self-contained screen objects to aid in and facilitate computer graphics, With all computers starting with a base object at "screen" or "_G.screen". This master screen object is special only in that it provides a draw function to update the visible graphics of a computer from itself, colored screen peripherals also use these objects and have a comparable function.

Screen objects can create other screen objects, not sharing any special functionality of their parent, and these objects will support every useful graphical operation. If you desire to take advantage of a screen objects speed optimizations, it's wise to avoid alpha values other than 255, and to use write/read data functions to draw objects instead of manually using drawPixel or drawLine.

Lookup table

getSize() Gets the size of the screen
createLayer(sizeX, sizeY) Creates a blank screen object without rendering capabilities
clone(x1, y1, x2, y2) Clones the given sector of the screen onto a new screen object without rendering capabilities
substitute(srcR, srcG, srcB, destR, destG, destB) Swaps the color src with the color dest, doesn't support alpha values
writeData(x, y, buffer, width) Writes binary data to the screen (examples below)
readData(x1, y1, x2, y2) Reads the given sector as a block of writeData compatible binary data
writePixel(x, y, R, G, B, A = 255) Sets the pixel to the given color
readPixel(x, y) Reads the color of one pixel
writeLine(x1, y1, x2, y2, R, G, B, A = 255) Draws a line between and including two points
fill(x1, y1, x2, y2, R, G, B, A = 255) Sets the given sector of the screen to one color
set(R, G, B, A = 255) Sets the entirety of the screen to one color
set() Sets the entirety of the screen to black
draw() Updates the screen if its rendering compatible

Functions in detail

getSize()

Gets the size of the screen object.

Parameters: None Returns: int, int

createLayer(sizeX, sizeY)

Creates a black screen object of the given size, the object will not possess a draw function.

Parameters: sizeX[Integer], sizeY[Integer] Returns: Object

clone(x1, y1, x2, y2)

Clones the given region to a new screen object without a draw function, the new objects contents will be identical to the data of the original region.

Parameters: x1[Integer], y1[Integer], x2[Integer], y2[Integer] Returns: Object

substitute(srcR, srcG, srcB, destR, destG, destB)

Replaces the color described with the src arguments for the color described with the dest arguments, this operation does not support alpha values, if your trying to replace a color drawn with transparency, you will have to know what RGB color was generated when it was blended with the screen.

Parameters: srcR[Integer], srcG[Integer], srcB[Integer], destR[Integer], destG[Integer], destB[Integer] Returns: None

writeData(x, y, buffer, width)

Efficiently and quickly write a block of data to the screen. this block will be drawn at xy, and will be drawn to width, the height of the block is determined by the blocks size compared against its width.
The buffers length must be dividable by width * 4, and it constructed with alternating bytes for R, G, B, and A with this pattern repeating for each pixel drawn left to right, and the buffer object should be one single string of bytes.
Lua example below 

local chunks = {}
for py = 1, height do
    for px = 1, width do
        -- string.char packs one pixel's R,G,B,A into a 4-byte chunk
        chunks[#chunks + 1] = string.char(r, g, b, a)
    end
end
local buffer = table.concat(chunks) --merges all chunks together in one pass for optimal speed

screen.writeData(0, 0, buffer, width)
Parameters: x[Integer], y[Integer], buffer[Bytes], width[Integer] Returns: None

readData(x1, y1, x2, y2)

Reads the full given area as a block of bytes, formatted the same way writeData accepts data. It is indeed possible to pass the output of readData to writeData, or preform other operations of it, it is noteworthy that the alpha values of the output block are always 255 or fully opaque, the output of any transparent operations already blended with the screen.

Parameters: x1[Integer], y1[Integer], x2[Integer], y2[Integer] Returns: Bytes

writePixel(x, y, R, G, B, A = 255)

Sets the single pixel at xy to the provided color.

Parameters: x[Integer], y[Integer], R[Integer], G[Integer], B[Integer], A[Integer] Returns: None

readPixel(x, y)

Reads the RGB color values of the given pixel, not including a alpha value which is assumed 255 or fully opaque.
Lua example below 

R, G, B = readPixel(x, y)
Parameters: x[Integer], y[Integer] Returns: Integer, Integer, Integer

writeLine(x1, y1, x2, y2, R, G, B, A = 255)

Draws a line between and including the two points.

Parameters: x1[Integer], y1[Integer], x2[Integer], y2[Integer], R[Integer], G[Integer], B[Integer], A[Integer] Returns: None

fill(x1, y1, x2, y2, R, G, B, A = 255)

Fills the area between and including the two points with the color.

Parameters: x1[Integer], y1[Integer], x2[Integer], y2[Integer], R[Integer], G[Integer], B[Integer], A[Integer] Returns: None

set(R, G, B, A = 255)

Sets the entire screen to the provided color.

Parameters: R[Integer], G[Integer], B[Integer], A[Integer] Returns: None

set()

Sets the entire screen to the black.

Parameters: None Returns: None

draw()

If the screen object has rendering capabilities, this function updates the renderer, and is required to display changes to the screen object.

Parameters: None Returns: None