A Page Controller class for Codea

--# Main
-- Page Controller class for Codea
-- By JakAttak
 
displayMode(FULLSCREEN)
function setup()
    font("HelveticaNeue-UltraLight")
    
    local title = Title("Page Controller")
 
    page = PageController(title, page2, { draw = page3, touched = tpage3 })
end
 
function draw()
    background(255)
    page:draw()
end
 
function touched(t)
    page:touched(t)
end
 
-- Example pages
function page2()
    pBackground(0, (noise(1000+ElapsedTime/100)+1.5)*128, (noise(1000+ElapsedTime/10)+1.5)*128, 255)
    
    fontSize(40) fill(0, 0, 0, 255)
    text("Hey, look, it's Page 2", WIDTH / 2, HEIGHT / 2)
end
 
function page3()
    pBackground(255, 100, 100, 255)
    
    stroke(0, 0, 0, 255) strokeWidth(2) if fillEllipse then fill(stroke()) else noFill() end
    ellipse(WIDTH / 2, HEIGHT / 4, WIDTH / 4)
    
    fontSize(40) fill(255, 255, 255, 255) textAlign(CENTER)
    text("Page 3\n\nDemonstrates passing a table\n\nTry touching the ellipse", WIDTH / 2, HEIGHT / 1.5)
end
 
function tpage3(t)
    if vec2(t.x, t.y):dist(vec2(WIDTH / 2, HEIGHT / 4)) <= WIDTH / 8 and t.state ~= ENDED then
        fillEllipse = true
        
        return true
    else
        fillEllipse = false
    end
end
 
 
 

--# PageController
PageController = class()
 
function PageController:init(...)
    self.pages = { ... }
    self:managePages()
    
    self.toSwitch = WIDTH / 4
    self.timePerPage = 1
    self.indicator = math.max(WIDTH, HEIGHT) / 100
    self.page, self.scroll, self.scrollo, self.locked = 1, 0, 0, false
end
 
function PageController:managePages()
    for i, page in ipairs(self.pages) do
        if typeOf(page) == "table" then
            page.draw = page.draw or function() end
            page.touched = page.touched or function() end
        elseif typeOf(page) == "class" then
            local dfun = page.draw or function() end
            page.draw = function() dfun(page) end
            local tfun = page.touched or function() end
            page.touched = function(touch) tfun(page, touch) end
        elseif typeOf(page) == "function" then
            self.pages[i] = { draw = page, touched = function() end }
        else
            self.pages[i] = nil
        end
    end
end
 
function PageController:draw()
    -- Draw pages that should be shown
    pushMatrix()
    translate(self.scrollo, 0)
    if self.pages[self.page] ~= nil then
        pushStyle()
        self.pages[self.page].draw()
        popStyle()
    end
    
    if self.pages[self.page - 1] ~= nil and self.scroll > 0 then
        pushMatrix()
        translate(-WIDTH, 0)
        pushStyle()
        self.pages[self.page - 1].draw()
        popStyle()
        popMatrix()
    end
    
    if self.pages[self.page + 1] ~= nil and self.scroll < 0 then
        pushMatrix()
        translate(WIDTH, 0)
        pushStyle()
        self.pages[self.page + 1].draw()
        popStyle()
        popMatrix()
    end
    popMatrix()
    
    -- Draw page indicators
    local w = self.indicator * (#self.pages * 2 - 1)
    local x = (WIDTH / 2) - (w / 2) + self.indicator / 2
    for p = 1, #self.pages do
        if p == self.page then fill(255)
        else fill(255, 127) end
        
        ellipse(x, self.indicator, self.indicator)
        
        x = x + self.indicator * 2
    end
end
 
function PageController:closestPage()
    local closest = self.page
    if self.scrollo > self.toSwitch and self.page > 1 then
        closest = self.page - 1
    elseif self.scrollo < -self.toSwitch and self.page < #self.pages then
        closest = self.page + 1
    end
    
    return closest
end
 
function PageController:touched(t)
    -- Handle touching on pages
    if self.scrollo == 0 then
        if self.pages[self.page] ~= nil and self.pages[self.page].touched(t) == true then 
            return -- If touched something then no scrolling
        end
    end
    
    -- No scrolling when locked
    if self.locked then return end
    
    -- Stop tween when dragging
    if self.releasing ~= nil then
        tween.stop(self.releasing)
    end
    
    -- Scroll from drag
    self.scroll = self.scroll + t.deltaX
    
    local min = self.pages[self.page].pcSlideMin or 0
    local off = math.max(0, math.abs(self.scroll) - min)
    self.scrollo = off * math.sign(self.scroll)

    
    -- Tweens to closest page
    if t.state == ENDED then
        local closestPage = self:closestPage()
        local target = (self.page - closestPage) * WIDTH
        
        if closestPage ~= self.page then self.locked = true end
        
        local dur = (math.abs(self.scrollo) / (self.toSwitch)) / ((WIDTH / self.toSwitch) * self.timePerPage)
        self.releasing = tween(dur, self, { scrollo = target, scroll = target }, tween.easing.cubicOut, function()
            self.page = closestPage
            self.scroll = 0
            self.scrollo = 0
            self.releasing = nil
            self.locked = false
        end)
    end
end
 
 
 
-- Helper functions
function typeOf(x)
    -- Extended type function
    if x == nil then 
        return 'nil' 
    end
    if type(x) == 'table' and x.is_a then 
        return('class') 
    end
    
    local txt
    
    if typeTable == nil then
        typeTable = {
            [getmetatable(vec2()).__index ] = 'vec2', 
            [getmetatable(vec3()).__index ] = 'vec3',
            [getmetatable(color()).__index ] = 'color', 
            [getmetatable(image(1,1)).__index ] = 'image', 
            [getmetatable(matrix()).__index] = 'matrix', 
            [getmetatable(mesh()).__index ] = 'mesh' ,
            [getmetatable(physics.body(CIRCLE, 1)).__index] = 'physics body',
        }
    end
    
    local i = getmetatable(x)
    if i then 
        txt = typeTable[i.__index] 
    end    
    if txt then 
        return txt 
    end
    
    txt = type(x)
    return txt
end

math.sign = function(n)
    if n < 0 then 
        return -1
    end
    
    return 1
end
 
function pBackground(...)
    -- Called same as background, draws a rect instead so each page can have individual background
    pushStyle()
    rectMode(CORNERS)
    fill(...)
    rect(-WIDTH / 768, -WIDTH / 768, WIDTH + WIDTH / 768, HEIGHT + WIDTH / 768)
    popStyle()
end
 

--# Title
-- An example of using a class with the Page Controller
Title = class()
 
function Title:init(name)
    fontSize(WIDTH / 10) fill(255, 255, 255, 255)
    local w, h = textSize(name)
    local timg = image(w, h) setContext(timg)
    text(name, w / 2, h / 2)
    setContext()
    
    self.m = mesh()
    self.m.texture = timg
    self.m:addRect(WIDTH / 2, HEIGHT / 2, w, h)
    self.m.shader = shader("Effects:Ripple")
    self.m.shader.freq = 0.08
end
 
function Title:draw()
    pBackground(0, 128, 255)
    
    self.m.shader.time = ElapsedTime
    self.m:draw()
    
    fontSize(WIDTH / 30) fill(255, 255, 255, 255)
    text("(swipe or drag to use)", WIDTH / 2, HEIGHT / 4)
end
 
function Title:touched(touch)
    -- Codea does not automatically call this method
end