Ansca Corona 102

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www.anscamobile.com

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Whats Corona

A simple, yet powerful framework allowing rapid mobile cross platform application development.


Corona 102 Functions &

EventListeners


Corona framework based on Lua


Corona Lua resources

http://ww.lua.orghttp://www.lua.org/lua-l.htmlhttp://developer.anscamobile.com/http://en.wikipedia.org/wiki/Lua_


Corona Without functions

local text = display.newText("hello",100,200,"Helvetica",24);textObj:setTextColor(r,g,b);

Disadvantages:

When program begins to get too big, difficult to manage codereusing code becomes hard to break apartdebugging becomes a nightmareno sense of where program starts


Corona With Functions:local function STextColor(textObj, r,g,b) textObj:setTextColor(r,g,b);end

local function main()local text = display.newText("hello",100,200,"Helvetica",24);STxtColor(text,255,0,0);end

main()

Advantages:

easier to manage codeeasier to re-use code on other programs as welleasier to debug since you can narrow down where error occursa sense of where program starts


Corona Functions:

First-class values.Passed by value.Stored in tables.Returned from functions.Global and local.called from other packages


Corona Function Definitions:function name(args) body return [values]endGlobal Function

local function name(args) body return [values]endfunction local to file scope

f = function (args) body return [values]endAnonymous function

function ( ... ) bodyreturn values]

end(...) indicates variable args and {...} places them in a table where they processed in standard way.


Corona More function definitions:

function obj:name(args) body return [values]endObject function getting extra args and self


Corona Calling functions:foo(args)simple call. returning zero or more values.

t.f(args) calling function store in field f of table t

local function f(mode, value) body

endlocal function with two arguments

r = f { value =3.14159, mode=auto}Calling a function with table, args can be passed by name.

function f(t)body

endarguments accessed as t.value, t.mode


Corona EventListeners:

Coronas event listeners are part of the Corona framework and not part of the Luaprogramming language.

http://developer.anscamobile.com/content/events-and-listeners



Event listeners allow Coronas display objectsand program scope to register for specific events to respond to.




To setup an event listener you must

attach an addEventListener.register a function to listen to the event.Optional, remove the event listener after use.




There are two types of event listeners

Runtime dispatched by the systemDisplay-object self-explanatory.



Corona Runtime Event Listeners:

local function onEnterFrame(event) print (event.name)end

Runtime:addEventListener(enterFrame,onEnterFrame)



Corona Display Object Event Listeners:

local button = display.newImage(button.png,15,25);

local function button:touch(event) print (event.name)end

button:addEventListener(touch,button)



Listeners

local listener = function(event)print( event.name, event.time )

end

Runtime:addEventListener("enterFrame", listener)


Event Types

enterFrame system orientation accelerometer GPS heading touch timer ...


Touch + Multitouch

x y xStart yStart phase id time


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Corona SDKCode Less. Play More.

Documents

Ansca Corona 102