Codea in Codea with built in examples

--# Buffer
Buffer = class()

function Buffer:init()
    self.buffer = {}

    self.font = "Inconsolata"
    self.fontSize = 20

    -- x = line, y = pos
    self.cursor = vec2(1,1)

    self.t = 0
    self.cursorBlink = 0
end

function Buffer:setStyle()
    textMode(CORNER)
    font( self.font )
    fill(255)
    fontSize( self.fontSize )
    textWrapWidth(10000)
end

function Buffer:cursorToScreen(c)
    -- Get a subset of the buffer
    local lines = table_slice( self.buffer, 1, c.x )
    local l = self.buffer[c.x]

    local upToStr = self:bufferToString(lines)
    local lstr = nil

    if l then
        lstr = table.concat(l)
    end

    pushStyle()

    self:setStyle()

    local lw = 0
    local _,lh = textSize("A")
    local emptyLine = true

    if lstr and lstr ~= "" then
        lw,lh = textSize(string.sub(lstr,1,c.y - 1))
        emptyLine = false
    end

    local pw,ph = textSize(upToStr)

    if emptyLine then
        ph = ph + lh
    end

    popStyle()

    return lw,(ph - lh/2)
end

function Buffer:bufferToString(b)
    local bstrings = {}
    for k,v in pairs(b) do
        table.insert(bstrings, table.concat( b[k] ) )
    end

    return table.concat( bstrings, "\n" )
end

function Buffer:moveCursor(o)
    self.cursor = self.cursor + o

    self.cursor.x = math.max(1, math.min(self.cursor.x, #self.buffer))

    local l = self.buffer[self.cursor.x]
    local y = self.cursor.y

    y = math.max(1, math.min(y, #l + 1))
    self.cursor.y = y
end

function Buffer:insertCharacter(c)
    local l = self.buffer[self.cursor.x]

    if l == nil then
        l = {}
        self.buffer[self.cursor.x] = l
    end

    if c == "\n" then
        local start = table_slice(l,1,self.cursor.y)
        local tail = table_slice(l,self.cursor.y+1,#l)

        table[self.cursor.x] = start
        table.insert(self.buffer, self.cursor.x+1, tail)

        self.cursor = vec2( self.cursor.x + 1, 1 )
    elseif c == BACKSPACE then
        if self.cursor.y == 1 then
            -- delete line
            local prevLine = self.buffer[self.cursor.x - 1]

            table.remove(self.buffer, self.cursor.x)

            if prevLine then
                self.cursor = vec2(self.cursor.x - 1, #prevLine + 1)
                table_append( prevLine, l )
            end
        else
            -- delete character
            table.remove(l, self.cursor.y - 1 )
            self.cursor = vec2(self.cursor.x, self.cursor.y - 1 )
        end
    else
        table.insert(l, self.cursor.y, c)

        self.cursor = vec2( self.cursor.x, self.cursor.y + 1 )
    end
end

function Buffer:draw()
    self.t = self.t + 8 * DeltaTime
    self.cursorBlink = (math.sin(self.t) + 1) * 128

    pushStyle()

    self:setStyle()

    local str = self:toString()
    local w,h = textSize(str)

    pushMatrix()
    translate( 40, -40 )

    text(str, 0, HEIGHT - h)

    -- Draw cursor
    -- Cursor pos x,y
    local cpx,cpy = self:cursorToScreen(self.cursor)
    fill(0, 87, 255, self.cursorBlink)
    rectMode(CENTER)
    rect(cpx,HEIGHT - cpy,5,22)

    popMatrix()
    popStyle()
end

function Buffer:clear()
    self.cursor = vec2(1,1)
    self.buffer = {}
end

function Buffer:load(code)
    self:clear()
    local i
    for i = 1,string.len(code) do
        self:insertCharacter(string.sub(code,i,i))
    end
end

function Buffer:toString()
    return self:bufferToString(self.buffer)
end

function Buffer:toStringWithoutActiveLine()
    local bstrings = {}
    for k,v in pairs(self.buffer) do
        if k ~= self.cursor.x then
            table.insert(bstrings, table.concat( self.buffer[k] ) )
        end
    end

    return table.concat( bstrings, "\n" )
end

--# Embutton
-- Emoji Button
EmButton = class()

function EmButton:init(pos,txt)
    -- you can accept and set parameters here
    self.pos = pos
    self.text = txt
    self.action = nil
    self.highlight = false
    self.color = color(255,255,255,255)
end

function EmButton:size()
    pushStyle()
    self:setStyle()

    local w,h = textSize(self.text)

    popStyle()

    return w,h
end

function EmButton:hitTest(lp)
    local w,h = self:size()

    local left,right = self.pos.x - w/2, self.pos.x + w/2
    local top,bottom = self.pos.y + h/2, self.pos.y - h/2

    if lp.x > left and lp.x < right and
       lp.y > bottom and lp.y < top then
        return true
    end

    return false
end

function EmButton:setStyle()
    fill(self.color)
    noStroke()
    textMode(CENTER)
    fontSize(50)
    font("AppleColorEmoji")
end

function EmButton:draw()
    pushMatrix()

    translate(self.pos.x,self.pos.y)

    pushStyle()
    self:setStyle()

    text(self.text,0,0)

    popStyle()

    popMatrix()
end

function EmButton:touched(touch)
    if touch.state == ENDED then
        -- Tapped
        if self:hitTest( vec2(touch.x,touch.y) ) then
            if self.action then self.action() end
        end
    end
end
--# Main
supportedOrientations(PORTRAIT)
function keyHeight()
    if CurrentOrientation == LANDSCAPE_LEFT or
       CurrentOrientation == LANDSCAPE_RIGHT then
        return 350
    else
        return 260
    end
end

function layoutAndDrawKeys()
    local start = WIDTH
    local keySz = 30
    local height = keyHeight()
    for i = #keys,1,-1 do
        local k = keys[i]

        k.pos = vec2( start - keySz, height + keySz )

        start = start - 2*keySz

        k:draw()
    end

    trash.pos = vec2(WIDTH - keySz - 10, HEIGHT - keySz - 20)
    trash:draw()
end

function setup()
    showKeyboard()

    displayMode(FULLSCREEN_NO_BUTTONS)

    buffer = Buffer()

    s = Samples()

    local closeKey = EmButton(vec2(0,0), "◀")
    closeKey.color = color(255,100,50,255)
    closeKey.action = function() close() end

    local startKey = EmButton(vec2(0,0), "⏪")
    startKey.action = function() buffer:moveCursor(vec2(0,-1000)) end

    local endKey = EmButton(vec2(0,0), "⏩")
    endKey.action = function() buffer:moveCursor(vec2(0,1000)) end

    local leftKey = EmButton(vec2(0,0), "⬅")
    leftKey.action = function() buffer:moveCursor(vec2(0,-1)) end

    local rightKey = EmButton(vec2(0,0), "➡")
    rightKey.action = function() buffer:moveCursor(vec2(0,1)) end

    local upKey = EmButton(vec2(0,0), "⬆")
    upKey.action = function() buffer:moveCursor(vec2(-1,0)) end

    local downKey = EmButton(vec2(0,0), "⬇")
    downKey.action = function() buffer:moveCursor(vec2(1,0)) end

    local keyKey = EmButton(vec2(0,0), "📝")
    keyKey.action = function() showKeyboard() end

    local prevKey = EmButton(vec2(0,0), "◀")
    prevKey.color = color(50,255,100,255)
    prevKey.action = function() buffer:load(s:prev()) end

    local nextKey = EmButton(vec2(0,0), "▶")
    nextKey.color = color(50,255,100,255)
    nextKey.action = function() buffer:load(s:next()) end

    keys = {closeKey,startKey,leftKey,
            rightKey,endKey,upKey,
            downKey,keyKey,prevKey,nextKey}

    trash = EmButton(vec2(0,0), "❌")
    trash.action = function() buffer:clear() end


end

function keyboard(key)
    buffer:insertCharacter(key)
end

function touched(touch)
    for k,v in pairs(keys) do
        v:touched(touch)
    end

    trash:touched(touch)
end

-- This function gets called once every frame
function draw()
    -- This sets a dark background color
    background(40, 40, 50)

    resetStyle()

    local str = buffer:toString()

    local chunk = loadstring(str)

    if chunk then
        chunk()
    else
        str = buffer:toStringWithoutActiveLine()
        chunk = loadstring(str)
        if chunk then chunk() end
    end

    resetStyle()

    fill(0,0,0,50)
    rectMode(CORNER)
    rect(0,0,WIDTH,HEIGHT)

    -- Do your drawing here
    buffer:draw()

    layoutAndDrawKeys()
end
--# Samples
Samples = class()

function Samples:init()
    self.ex = {}
    self.i = 0
    local nl = "\n"
    self.ex[1] = "text(\"Hello World\",300,500)"
    self.ex[2] = "fill(255,0,0)" .. nl
    self.ex[2] = self.ex[2] .. "ellipse(300,500,100,100)"
    self.max = 2
end

function Samples:next()
    if self.i ~= self.max then self.i = self.i + 1 end
    return self.ex[self.i]
end

function Samples:prev()
    if self.i ~= 1 then self.i = self.i - 1 end
    return self.ex[self.i]
end
--# Util
function table_append (t1, t2)
    local t1s = #t1
    for k,v in pairs(t2) do t1[k + t1s] = v end
end

function table_slice (values,i1,i2)
    local res = {}
    local n = #values

    -- default values for range
    i1 = i1 or 1
    i2 = i2 or n
    if i2 < 0 then
        i2 = n + i2 + 1
    elseif i2 > n then
        i2 = n
    end

    if i1 < 1 or i1 > n then
        return {}
    end

    local k = 1

    for i = i1,i2 do
        res[k] = values[i]
        k = k + 1
    end

    return res
end