Not able to understand what's going

Solar2D General Questions/Discussion
#1

Hello everyone,

When I press back key the Runtime:enterFrame should stop and on pressing the back key again after 1 sec the Runtime:enterFrame should start, but in that one sec time if I keep on tapping back key again and again something weird starts happening the object start to move fast and fast, the below is my code

coal=0 local ball=display.newCircle( 100, 100, 50 ) function move( ) ball.x=ball.x+1 end Runtime:addEventListener("enterFrame",move) local function onKeyEvent( event ) if ( event.keyName == "back" ) then if ( system.getInfo("platform") == "android" ) then if event.phase=="up" then coal=coal+1 if coal%2~=0 then Runtime:removeEventListener("enterFrame",move) else timer.performWithDelay(1000,function() Runtime:addEventListener( "enterFrame", move ) end,1) end end return true end end end Runtime:addEventListener( "key", onKeyEvent )

Help from everyone is welcome.

Thanks and Regards,

Swanand Thakur.

#2

The timer thing is playing a trick on you, they need to be handled with a variable and if called prematurely, cancelled, or you’ll end up with multiple calls.

Something like this:

coal=0 local ball=display.newCircle( 100, 100, 50 ) function move( ) ball.x=ball.x+1 end Runtime:addEventListener("enterFrame",move) local myTimer local function onKeyEvent( event ) if ( event.keyName == "back" ) then if ( system.getInfo("platform") == "android" ) then if event.phase=="up" then coal=coal+1 if coal%2~=0 then Runtime:removeEventListener("enterFrame",move) else if myTimer then timer.cancel(myTimer) end myTimer=timer.performWithDelay(1000,function() Runtime:addEventListener( "enterFrame", move ) end,1) end end return true end end end Runtime:addEventListener( "key", onKeyEvent )

This will prevent it from getting called multiple times.

Hope it helps and have a great day!

anaqim

#3

Hello brother @Anaqim,

Your solution is working well, but only in case if I choose delay time equivalent to 1 sec or greater than it if I choose time equal to 500ms then its malfunctioning as before.

Regards,

Swanand Thakur.

#4

May contain typos:

local coal = 0 -- local ball = display.newCircle( 100, 100, 50 ) -- ball.finalize = function( self ) if( self.\_lastTimer ) then timer.cancel( self.\_lastTimer ) self.\_lastTimer = nil end if( self.enterFrame ) then Runtime:removeEventListener( "enterFrame", self ) self.enterFrame = nil end end; ball:addEventListener( "finalize" ) -- local function ballMover( self ) self.x = self.x + 1 end -- ball.enterFrame = ballMover Runtime:addEventListener( "enterFrame", ball ) -- ball.timer = function( self ) self.enterFrame = ballMover Runtime:addEventListener( "enterFrame", self ) self.\_lastTimer = nil end -- ball.key = function( self, event ) if ( event.keyName == "back" ) then if ( system.getInfo("platform") == "android" ) then if event.phase=="up" then coal = coal + 1 if coal % 2 ~= 0 then Runtime:removeEventListener( "enterFrame", self ) self.enterFrame = nil elseif( self.\_lastTimer == nil ) then self.\_lastTimer = timer.performWithDelay( 1000, self ) end end return true end end end Runtime:addEventListener( "key", ball)
#5

I worry, that this entire construct  is over-complicated and therefore subject to error.

Can you describe in a couple of short sentences of a bullet list what you want to do here? i.e. What is the over-arching mechanic?

#6

Updated my code post to prevent multiple ongoing timers.

Again, this whole thing is way too complicated.  Tell us what you want to achieve and I’ll see if there is a simpler option.

#7

self.enterFrame = nil

it is possible to reference events directly from objects like that?

it should be in the documentation, its pretty vital stuff

would that mean its possible to say:

if self.enterFrame then …

then?

#8
  1. It is documented.  They are called table listeners:  

https://docs.coronalabs.com/guide/events/detectEvents/index.html#function-and-table-listeners

 
 
2. What I’m doing is clearing the variable that points to the function as a bookkeeping thing for my code.
 
Elsewhere I check to be sure obj.enterFrame is present before removing the listener.
 
If I don’t do this, it will crash.
 
Ex: This would crash:
 

function obj.enterFrame(self) end Runtime:addEventListener( "enterFrame", obj ) local function cancelIt() Runtime:removeEventListener( "enterFrame", obj ) obj.enterFrame = nil end cancelIt() ... later cancelIt()-- CRASH

This logic prevents the issue:
 

function obj.enterFrame(self) end Runtime:addEventListener( "enterFrame", obj ) local function cancelIt() if( not obj.enterFrame ) then return end Runtime:removeEventListener( "enterFrame", obj ) obj.enterFrame = nil end cancelIt() ... later cancelIt()
#9

@anaqim,

Here are the docs on table listeners:
https://docs.coronalabs.com/guide/events/detectEvents/index.html#function-and-table-listeners

#10

@swan…,

Correct me if I’m wrong but essentially this is what you want:

  • Track coal as counter
  • A ‘ball’ that moves automatically from left to right, except in certain cases (below)
  • Allow the user to click the ‘back’ button to increment coal counter
  • When the coal counter is incremented and found to be a multiple of 2, you want to stop the ball from moving for one second.
  • At the end of a one-second stop you want the ball to resume moving.

If that is correct, this is how I would do it:

local getTimer = system.getTimer local isAndroid = (system.getInfo("platform") == "android") local coal = 0 local pauseDuration = 1000 local ball = display.newCircle( 100, 100, 50 ) ball.\_waitTill = getTimer() - pauseDuration -- Ensure it can move immediately function ball.finalize( self ) Runtime:removeEventListener( "enterFrame", self ) end; ball:addEventListener( "finalize" ) function ball.enterFrame( self ) if( getTimer() \< self.\_waitTill ) then return end -- self.x = self.x + 1 end;Runtime:addEventListener( "enterFrame", ball ) if( isAndroid ) then ball.key = function( self, event ) if( event.keyName == "back" and event.phase=="up" ) then coal = coal + 1 if( coal % 2 ~= 0 ) then self.\_waitTill = getTimer() + pauseDuration end end return true end; Runtime:addEventListener( "key", ball ) end
#11

Thanks for the info RG

I’ll be studying it  :slight_smile:

#12

Sir @roaminggamer,

Your first three steps are correct I am correcting your 4th step

  • If counter is a multiple of two, ball should resume after one second and if its not a multiple of two then it should stop.
  • On the first click it should stop and on the second click it should start moving after one second.
#13

https://github.com/roaminggamer/RG_FreeStuff/raw/master/AskEd/2018/04/coalBall.zip

local getTimer = system.getTimer local isAndroid = (system.getInfo("platform") == "android") local debugEn = true local coal = 0 local pauseDuration = 1000 local ball = display.newCircle( 100, 100, 50 ) ball.\_waitTill = getTimer() - pauseDuration -- Ensure it can move immediately ball.isMoving = true ball.allowResume = false function ball.finalize( self ) Runtime:removeEventListener( "enterFrame", self ) end; ball:addEventListener( "finalize" ) function ball.enterFrame( self ) print( self.isMoving, self.allowResume ) if( self.isMoving == false ) then if( self.allowResume == false ) then return false end if( getTimer() \< self.\_waitTill ) then return false end end -- self.x = self.x + 1 end; Runtime:addEventListener("enterFrame", ball) local coalLabel = display.newText( coal, 300, 300 ) if( isAndroid or debugEn ) then ball.key = function( self, event ) for k,v in pairs(event) do print(k,v) end if( event.phase=="up" and ( event.keyName == "back" or event.keyName == "space") ) then coal = coal + 1 coalLabel.text = coal .. " : " .. tostring(coal % 2) if( coal % 2 == 0 ) then self.isMoving = false self.allowResume = true self.\_waitTill = getTimer() + pauseDuration else self.isMoving = false self.allowResume = false end end return true end; Runtime:addEventListener( "key", ball ) end
#14

Sir @roaminggamer,

Lots of thanks for this solution, it worked well. It has also taught some really helpful concepts which will surely help me in future. Thanks once again.

Regards,

Swanand Thakur

#15

The timer thing is playing a trick on you, they need to be handled with a variable and if called prematurely, cancelled, or you’ll end up with multiple calls.

Something like this:

coal=0 local ball=display.newCircle( 100, 100, 50 ) function move( ) ball.x=ball.x+1 end Runtime:addEventListener("enterFrame",move) local myTimer local function onKeyEvent( event ) if ( event.keyName == "back" ) then if ( system.getInfo("platform") == "android" ) then if event.phase=="up" then coal=coal+1 if coal%2~=0 then Runtime:removeEventListener("enterFrame",move) else if myTimer then timer.cancel(myTimer) end myTimer=timer.performWithDelay(1000,function() Runtime:addEventListener( "enterFrame", move ) end,1) end end return true end end end Runtime:addEventListener( "key", onKeyEvent )

This will prevent it from getting called multiple times.

Hope it helps and have a great day!

anaqim

#16

Hello brother @Anaqim,

Your solution is working well, but only in case if I choose delay time equivalent to 1 sec or greater than it if I choose time equal to 500ms then its malfunctioning as before.

Regards,

Swanand Thakur.

#17

May contain typos:

local coal = 0 -- local ball = display.newCircle( 100, 100, 50 ) -- ball.finalize = function( self ) if( self.\_lastTimer ) then timer.cancel( self.\_lastTimer ) self.\_lastTimer = nil end if( self.enterFrame ) then Runtime:removeEventListener( "enterFrame", self ) self.enterFrame = nil end end; ball:addEventListener( "finalize" ) -- local function ballMover( self ) self.x = self.x + 1 end -- ball.enterFrame = ballMover Runtime:addEventListener( "enterFrame", ball ) -- ball.timer = function( self ) self.enterFrame = ballMover Runtime:addEventListener( "enterFrame", self ) self.\_lastTimer = nil end -- ball.key = function( self, event ) if ( event.keyName == "back" ) then if ( system.getInfo("platform") == "android" ) then if event.phase=="up" then coal = coal + 1 if coal % 2 ~= 0 then Runtime:removeEventListener( "enterFrame", self ) self.enterFrame = nil elseif( self.\_lastTimer == nil ) then self.\_lastTimer = timer.performWithDelay( 1000, self ) end end return true end end end Runtime:addEventListener( "key", ball)
#18

I worry, that this entire construct  is over-complicated and therefore subject to error.

Can you describe in a couple of short sentences of a bullet list what you want to do here? i.e. What is the over-arching mechanic?

#19

Updated my code post to prevent multiple ongoing timers.

Again, this whole thing is way too complicated.  Tell us what you want to achieve and I’ll see if there is a simpler option.

#20

self.enterFrame = nil

it is possible to reference events directly from objects like that?

it should be in the documentation, its pretty vital stuff

would that mean its possible to say:

if self.enterFrame then …

then?