Here is a simple demo of data-binding to user-interface elements in Corona SDK. The purpose is to update variables so that UI elements (textfields in this demo) are updated automatically.
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-- UI data binding demo for Corona SDK -- -- Update variables and UI elements (textfields in this demo) are updated automatically -- -- Created by: Dave Yang / Quantumwave Interactive Inc. -- Version: 1.00 -- place variables inside UIdata local UIdata = { sum = 0, rand = -1, } -- create the UI elements local sumTxt = display.newText( UIdata.sum, 150, 125, native.systemFont, 24 ) local randTxt = display.newText( UIdata.rand, 150, 250, native.systemFont, 24 ) -- bind the data to the UI elements local UIdataBinding = { sum = sumTxt, rand = randTxt, } --------------------------------------------------------------------------- -- reference to the original UIdata table local _uidata = UIdata -- empty UIdata to make it work with the metatable below UIdata = {} -- the metatable defines what to do with access and change to data in UIdata local UIdataMT = { __index = function(t,k) return _uidata[k] end, __newindex = function(t,k,v) -- changes to the data is updated in the textfield; other UI elements can be applied according to type UIdataBinding[tostring(k)].text = v -- update the original data _uidata[k] = v end } setmetatable(UIdata, UIdataMT) -- single line if you prefer to replace the lines above starting from 'local UIdataMT = {' --setmetatable(UIdata, {__index=function(t,k) return _uidata[k] end, __newindex=function(t,k,v) UIdataBinding[tostring(k)].text=v;_uidata[k]=v end}) --------------------------------------------------------------------------- -- change and access data UIdata.sum = 42 print(UIdata.sum) UIdata.rand = math.random(99) print(UIdata.rand) |
The latest updates can be found at github.