transition.to(object,params}
transition.pause(object)    
transition.resume(object)

-- A very Simple Pausable Transition
-- Author: Satheesh
-- Release date: 2011-11-27
-- Version: 1.0
-- License: MIT
-- Web: http:www.timeplusq.com
--
-- USAGE:
--      Import the module :
--              require "simple_transition_pausing_from_Satheesh"
--
--      Create transitions as usual
--              transition.to(object,params}
--
--              transition.pause(object)     pauses all transitions of object
--              transition.resume(object)    resumes all transitions of object
--
--
--
-- PROS
--      No extra code. Just use transitions as you used before
--
-- CONS 
--      Delta transitions,easing not supported
--           (to be frank, i have no idea what they do :P)
--      May have minor bugs, since i haven't tested completely.
--           (works fine for my requirements though.. if you find any bug please let me know)
 
 
 
 
 
--The transition.to and transiion.cancel functions are duplicated
local transitionToCopy = transition.to
local transitionCancelCopy = transition.cancel
 
--I override transition.to function with my function myTransitionFunction
--the duplicate i create is used to call the transition
local myTransitionFunction = function(object,params)
        if not object.destination then
                object.destination = {}
        end
        if not object.startTime then
                object.startTime = {}
        end
        if not object.transition then
                object.transition = {}
        end
                
 
        --object.destination - table storing transition parameters of each transition of the object
        
        local transitionNo = #object.destination+1
        object.destination      [transitionNo] = {}
        
        local destination = object.destination[transitionNo]
                        
        destination.x = params.x
        destination.y = params.y
        destination.xScale = params.xScale
        destination.yScale = params.yScale
        destination.time = params.time
        destination.delay = params.delay
        destination.onComplete = params.onComplete
        destination.onStart = params.onStart
        destination.alpha = params.alpha
        destination.width = params.width
        destination.height = params.height
        destination.rotation = params.rotation
        destination.xOrigin = params.xOrigin
        destination.yOrigin = params.yOrigin
        destination.maskX = params.maskX
        destination.maskY = params.maskY
        destination.maskScaleX = params.maskScaleX
        destination.maskScaleY = params.maskScaleY
        destination.maskRotation = params.maskRotation
        destination.xReference = params.xReference
        destination.yReference = params.yReference
        
        if destination.delay== nil then
                destination.delay=0
        end
        
        
        --on transition complete, deletes the corresponding table values for that particular transition 
        --and calls the onComplete function which was specified by the user
        
        local onComplete = params.onComplete
        params.onComplete = function(obj)       
                local localDestination = object.destination
                for i =1,#localDestination do   
                        if localDestination[i]==destination then
                                table.remove(object.destination,i)
                                table.remove(object.startTime,i)
                                table.remove(object.transition,i)
                                break
                        end
                end             
                if onComplete then
                        onComplete(obj)
                end
        end
        
        
        --object.startTime  - table storing starting times of each transition of the object
        --object.transition - table storing transition handles of each transition of the object
        
        object.transition[transitionNo] = transitionToCopy(object,params)
        object.transition[transitionNo].object = object
        object.startTime[transitionNo] = system.getTimer()
        
        return object.transition[transitionNo] 
 
end
 
 
--Function that pauses all transitions of an object
 
local pause = function(object)
 
        --object.pausedDestination - table storing transition parameters of each transition with time and delay adjusted after pause
        object.pauedDestination = {}
        
        --for each transition
        for i =1,#object.startTime do
                local object = object
                local destination = object.destination[i]
                local objTransition = object.transition[i]
                local startTime = object.startTime[i]
                
                object.pauedDestination[i] = destination
                local pauedDestination = object.pauedDestination[i]
                
                                
                local currentTime = system.getTimer()
                local delay = destination.delay
                
                --time and delay adjustment
                if (startTime+delay) > currentTime then
                        pauedDestination.delay = (startTime+delay)-currentTime                  
                else
                        local timeRemaining = (startTime+delay+destination.time) - currentTime
                        pauedDestination.delay = nil
                        pauedDestination.time = timeRemaining
                end
                
                --cancel transition             
                transitionCancelCopy(objTransition)
        end
        
        --remove all transition properties of the object from the respective tables
        object.destination = nil
        object.objTransition = nil
        object.startTime = nil
end
        
--resumes all paused transitions of the object
local resume = function(object)
 
        --pausedDestination holds all transition parameters with adjustments for time and delay
        local pauedDestination = object.pauedDestination
        for i =1,#pauedDestination do
                myTransitionFunction(object,pauedDestination[i])
        end
end
 
--I override transition.cancel function with my function cancel
--the duplicate i created is used to cencel the transition
local cancel = function(transition)
        local object = transition.object
        local localTransition= object.transition
        for i =1,#localTransition do    
                if localTransition[i]==transition then
                        table.remove(object.destination,i)
                        table.remove(object.startTime,i)
                        table.remove(object.transition,i)
                        break
                end
        end     
        transitionCancelCopy(transition)
end
 
--overriding transition.to and transition.cancel
--assigning transition.pause and transition.resume
transition.to=myTransitionFunction
transition.pause = pause
transition.resume = resume
transition.cancel = cancel