Springboard for Corona SDK, based on widget.scrollView

main.lua

local springboard = require("springboard")

local group = display.newGroup() -- root display group
local pageTotal = 3
local board -- springboard instance
local pageDots = {} -- dots at the top

local function animatePageDot() -- called each time the springboard changes page
	local currentPage = board.page
	-- reset all pagedots
	for i=1, pageTotal do
		local dot=pageDots[i]
		dot.xScale=1; dot.yScale=1
	end
	-- enlarge dot for current page
	transition.to(pageDots[currentPage], {time=30, xScale=1.4, yScale=1.4})
end

-- creat page dots
local dotGroup=display.newGroup(); dotGroup.anchorX=.5; dotGroup.anchorChildren=true
dotGroup.x = 0.5*display.contentWidth; dotGroup.y = 30

for i=1, pageTotal do
	local dot = display.newCircle((i-1)*50, 0, 10); dotGroup:insert(dot) -- in a real app you would use a smooth dot image, circles of this size look pixellated
	pageDots[i]=dot
end

-- create springboard
local boardGroup = display.newGroup(); group:insert(boardGroup)
board = springboard.new(boardGroup, 300, 400, pageTotal, animatePageDot, {backgroundColor={.8,.8,1}, time=200})

boardGroup.x = 10
boardGroup.y = 50

-- fill the springboard with content
for i=1, pageTotal do
	local rect = display.newRect((i-1)*300 + 10, 50, 280, 200); rect.anchorX = 0; rect.anchorY = 0; rect:setFillColor(.2*i, .1*i, .3*i)
	board.view:insert(rect) -- insert into springboard
end

-- flip to initial page (default on page 1)
board:goToPage(2, 0) -- time = 0 for instant page switch (no transition)

scrollview.lua

module(..., package.seeall)

local widget = require( "widget" )

local math_abs = math.abs
local math_floor = math.floor
local system_getTimer = system.getTimer

local springboard = { }
local springboard_mt = { __index = springboard }


function springboard.new(group, pageWidth, pageHeight, pages, onScrollComplete, params)
	local touchTime, scrollView
	local obj = {pageWidth=pageWidth, pageHeight=pageHeight, pages=pages, page=1, onScrollComplete=onScrollComplete}
	obj.backgroundColor=(params and params.backgroundColor) or nil
	obj.time=(params and params.time) or nil
	
	local function scrollListener(event)
		local phase = event.phase
		if phase == "began" then
			touchTime = event.time
		elseif phase == "moved" and not touchTime then -- no began phase when focus is explicetly transferred to springboard with takeFocus
			touchTime = event.time
		elseif phase == "ended" or phase == "off" or phase == "cancelled" then
			touchTime = touchTime or system_getTimer()
			local motionTime = system_getTimer() - touchTime
			local dist = event.xStart - event.x; local swipeDist = math_abs(dist); local nextPage
			-- calculate next page index (negative or 0)
			if (motionTime <= 300 and swipeDist >= 30) then
				-- fast page flip
				nextPage = obj.page + dist/swipeDist
			else
				-- slow controlled drag
				local x, y = scrollView:getContentPosition()
				nextPage = math_floor(-x/pageWidth) + ((-x%pageWidth > 0.5*pageWidth and 1) or 0) + 1
			end
			-- move to page
			if nextPage >= 1 and nextPage <= pages then
				-- snap to next page
				scrollView:scrollToPosition({x=-(nextPage-1)*pageWidth, onComplete=onScrollComplete, time=obj.time})
				obj.page = nextPage
			else
				-- out of bounds
				scrollView:scrollToPosition({x=-(obj.page-1)*pageWidth, onComplete=onScrollComplete, time=obj.time}) 
			end
		end
		return true
	end
	
	
	scrollView = widget.newScrollView
	{
		top = 0,
		left = 0,
		width = pageWidth,
		height = pageHeight,
		scrollWidth = pageWidth * pages,
		scrollHeight = pageHeight,
		listener = scrollListener,
		backgroundColor = obj.backgroundColor,
		hideBackground = not obj.backgroundColor,
		verticalScrollDisabled = true,
		hideScrollBar = true,
	}
	group:insert(scrollView)
	obj.view = scrollView
	
	return setmetatable(obj, springboard_mt)
end
 
 
 function springboard:goToPage(page, time)
	local options = {x = -(page-1)*self.pageWidth, onComplete = self.onScrollComplete, time=(time or self.time)}
	self.view:scrollToPosition(options) 
	self.page = page
end


return springboard