Added simple-graphics.lua and added documentation.

README.md

@@ -1,2 +1,3 @@
 # cc-simple-graphics
+
 A simple, unopinionated graphics API for Computercraft devices.

simple-graphics.lua

@@ -0,0 +1,64 @@
+--[[
+Simple Graphics: An unopinionated graphics API to make hand-made GUIs easy.
+Author: Andrew Lalis <andrewlalisofficial@gmail.com>
+]]--
+
+local lib = {}
+
+-- Clears a screen or terminal. If c is not nil then the background color will
+-- be set prior to clearing.
+function lib.clear(m, c)
+    if c ~= nil then m.setBackgroundColor(c) end
+    m.clear()
+end
+
+-- Fills a rectangle from the given X and Y coordinates, with a width and
+-- height given by w and h respectively. If c is not nil, then the background
+-- color is set to c.
+function lib.fillRect(m, x, y, w, h, c)
+    if c ~= nil then m.setBackgroundColor(c) end
+    for i = 1, w do
+        for j = 1, h do
+            m.setCursorPos(x+i-1, y+j-1)
+            m.write(" ")
+        end
+    end
+end
+
+-- Draws a horizontal line from x1 to x2 on the given y level.
+function lib.drawXLine(m, x1, x2, y, bg, fg, char)
+    char = char or " "
+    if bg ~= nil then m.setBackgroundColor(bg) end
+    if fg ~= nil then m.setTextColor(fg) end
+    for x = x1, x2 do
+        m.setCursorPos(x, y)
+        m.write(char)
+    end
+end
+
+-- Draws a vertical line from y1 to y2, on the given x level.
+function lib.drawYLine(m, y1, y2, x, bg, fg, char)
+    char = char or " "
+    if bg ~= nil then m.setBackgroundColor(bg) end
+    if fg ~= nil then m.setTextColor(fg) end
+    for y = y1, y2 do
+        m.setCursorPos(x, y)
+        m.write(char)
+    end
+end
+
+-- Draws text starting at the given x y position.
+function lib.drawText(m, x, y, text, fg, bg)
+    if fg ~= nil then m.setTextColor(fg) end
+    if bg ~= nil then m.setBackgroundColor(bg) end
+    m.setCursorPos(x, y)
+    m.write(text)
+end
+
+-- Draws text such that the center of the text is aligned with the given
+-- x and y coordinates.
+function lib.drawTextCenter(m, x, y, text, fg, bg)
+    lib.drawText(m, x-(#text/2)+1, y, text, fg, bg)
+end
+
+return lib