Expert needed: object:addEventListener with tables objects

Solar2D General Questions/Discussion
#1

I try to activate a function (funct02, see below) when objects are “tapped”.

These objects, images in fact, are issued from a random process (funct01) and store in a table.
Funct01 is ok but I can’t activate funct02 when I “tap” objects.
Help would be very much appreciated. What’s wrong?

[lua] local ui = require(“ui”)

local bigTable = { { “s1.png”,“s2.png” } }

local smallTable = { } --store result of random process
local randomImage1 --variable for the first image (random process)
local randomImage2 --for 2nd image

local funct01 = function ( event ) --when btn1 pressed, smallTable is filled

for i = 1, 2 do
local tir1 = math.random( 1, 2 )
smallTable[#smallTable+1] = tir1
end

randomImage1 = bigTable[1] [smallTable[1] ]
img1 = display.newImage ( randomImage1 )
img1.x = 160; img1.y = 200

randomImage2 = bigTable[1] [smallTable[2] ]
img2 = display.newImage ( randomImage2 )
img2.x = 200; img2.y = 200

end

–Btn1
local btn1 = ui.newButton{
default = “btn1.png”,
over = “btn1_over.png”,
onRelease = funct01
}
btn1.x = 160; btn1.y = 240

local funct02 = function ( event ) --when randomImage1 or randomImage2 “tap”
–do something
end

randomImage1:addEventListener ( “tap”, funct02 ) --DOESN’T WORK, WHY?, idem img1 or img2[/lua]
[import]uid: 8970 topic_id: 5289 reply_id: 305289[/import]

#2

randomImage1 is equal to the string “s1.png” or “s1.png” and is not a display object. Add the event listener to img1 [import]uid: 12405 topic_id: 5289 reply_id: 17554[/import]

#3

you’re trying to assign your event to a .png filename not a display object!

you need to put local img1, img2 at the top of your file then do

[lua]img1.addEventListener(“tap”, funct02)
img2.addEventListener(“tap”, funct02)[/lua]
etc
[import]uid: 6645 topic_id: 5289 reply_id: 17556[/import]

#4

Thanks for quick responses. You’re right… I can see on terminal with a “print” command that randomImage1 is a filename!
But img1:addEventListener (“tap”, funct02) nor img2 doesn’t work… It seems it’s like if they are values table… I hope I missed nothing in your responses.
And a question: img1 and img2 are globale variable, why to declare as local at the top of file (I understand: outside of funct01)? [import]uid: 8970 topic_id: 5289 reply_id: 17607[/import]

#5

I try to do a new example and to simplify to understand what’s wrong…
(summary: I try to generate a random image when a button is pressed; then I want to activate a function when this image is “tapped”).

“img1” is not “add:EventListener” sensitive! If you can point my mistake, thanks.
[lua] local ui = require(“ui”)

local bigTable = { { “s1.png”,“s2.png” } }

local tirage1 = 1 --to initialize with a value

local image1 = bigTable[1] [tirage1] --to initialize

local img1 = display.newImage ( image1 ) --to initialize
img1.x = 160; img1.y = 200
img1.alpha = 0

–function to generate a new image
local funct01 = function ( event )
tirage1 = math.random (1,2)

image1 = bigTable[1] [tirage1]
img1 = display.newImage ( image1 )
img1.x = 160; img1.y = 200
img1.alpha = 1
end

local funct02 = function (event)
print (“OK”) --not the case at the moment!!
end

–Button to activate function01
local btn1 = ui.newButton{
default = “btn1.png”,
over = “btn1_over.png”,
onRelease = funct01
}
btn1.x = 160; btn1.y = 240

img1:addEventListener ( “tap”, funct02 ) --DOESN’T WORK, WHY?[/lua] [import]uid: 8970 topic_id: 5289 reply_id: 17804[/import]

#6

when this first runs you’re creating img1 and adding a tap listener to it. if you were to set alpha to 1 instead of 0, you’ll see your tap function on this button should work

when you then click btn1 to create a *new* img1, my guess is it is overwriting your original img1, and therefore that eventListener no longer exists for img1, since you just changed it to point to a different object.

try this
[lua]local ui = require(“ui”)

local bigTable = { { “s1.png”,“s2.png” } }

local tirage1 = 1 --to initialize with a value

local funct02 = function (event)
print (“OK”)
end

–function to generate a new image
local funct01 = function ( event )
tirage1 = math.random (1,2)

image1 = bigTable[1] [tirage1]

– create a new image
local another_img = display.newImage ( image1 )
another_img.x = math.random(160); another_img.y = math.random(200)
another_img:addEventListener(“tap”,funct02)
end

–Button to activate function01
local btn1 = ui.newButton{
default = “btn1.png”,
over = “btn1_over.png”,
onRelease = funct01
}
btn1.x = 160; btn1.y = 240
[/lua]

what are you actually trying to do though? [import]uid: 6645 topic_id: 5289 reply_id: 17817[/import]

#7

Well done with “object:addEventListener” inside the function!
Thanks a lot @jmp909. [import]uid: 8970 topic_id: 5289 reply_id: 17905[/import]