screenAPI.lua

-- This program is meant to give a variety of options to illustrate using the computercraft screen.





function wrapMon() --if there is a monitor, wraps it and returns true, otherwise returns the termAPI and returns false
    if peripheral.find('monitor') then
        monitor = peripheral.find('monitor')
        isMonitor = true
    else
        monitor = _G.term
        isMonitor = false
    end
    return monitor, isMonitor
end

function middle() --returns the middle of the screen in coordinates x, y.
    width, height = monitor.getSize()
    x = math.floor(width/2)
    y = math.floor(height/2)
    return x, y
end

function drawBox(x1, y1, x2, y2, color, char) -- draws a box given the coordinates of two points
    local colorTable = {}
    local xinc, yinc = 1, 1
    if x1 < x2 then
        xinc = 1
    else
        xinc = -1
    end
    if y1 < y2 then
        yinc = 1
    else
        yinc = -1
    end
    for i = x1, x2, xinc do
        colorTable[i] = {}
        for k = y1, y2, yinc do
            colorTable[i][k] = color
            drawDot(i, k, color, char)
        end
    end
    return colorTable
end

function drawDot(x, y, color, char)
    if not char then
        char = ' '
    end
    monitor.setCursorPos(x, y)
    monitor.setBackgroundColor(color)
    monitor.write(char)
    monitor.setBackgroundColor(colors.black)
    return x, y, color, char
end

function drawLine(x1, y1, x2, y2, color) --returns table with x and y position of each pixel with the color, ie table[x][y]
    local colorTable={}
    local x = x2 - x1
    local y = y2 - y1
    if x < 0 then
        xinc = -1
    else
        xinc = 1
    end
    if y < 0 then
        yinc = -1
    else
        yinc = 1
    end
    if math.abs(y/x)>1 then --if the gradient is more than 1, goes through the y values and finds the corresponding x value through a mathematical line approximation equation. This avoids making thick lines by forcing only one pixel per row, essentially giving 1 pixel thick lines.
        for i = x1, x2, xinc do
            colorTable[i] = {}
        end
        for i = y1, y2, yinc do
            local xpos = math.floor((x1 + (x/y)*(i-y1)+0.5))
            drawDot(xpos, i, color)
            colorTable[xpos][i] = color
        end
    elseif math.abs(y/x)<1 then --Works in a similr principle except forces one pixel per column
        for i = x1, x2, xinc do
            local ypos = math.floor((y1+(y/x)*(i-x1))+0.5)
            drawDot(i, ypos, color)
            colorTable[i] = {}
            colorTable[i][ypos] = color
        end
    else
        for i = x1, x2, xinc do --in the case the line goes down 45 degrees the math is much simpler
            local ypos = y1+(y/x)*(i-x1)
            drawDot(i, ypos, color)
            colorTable[i] = {}
            colorTable[i][ypos] = color
        end
    end
    return colorTable
end