How to detect the center (x,y) of a pressed object

Solar2D Lua Language
#1

Dear all,

I want to click something then print the center x, y of that object (say, some image)

local image = display. new image (“1.png”)

image:setReferencePoint( display.TopLeftReferencePoint )

imagex, imagey = image:localToContent(0,0)

print(imagex…imagey) – up here it works

function click (object, event)

contentx, contenty = object: localToContent(0,0)

print (contentx…contenty) --it doesn’t work and return nil for localToContent

end

image:addEventListener(“tap”,click)

I have also tried to use object.x, object.y

but it end up return the x,y of where I have clicked.

Thanks!

#2

Did you try it with event.target instead of object?

[LUA]

local function click (event)

   local target = event.target

   contentx, contenty = target.x, target.y

end

[/LUA]

Also you can try to attach the function to the object.

[LUA]

local object = display.newImage(“1.png”)

function object:tap(event)

   contentx, contenty = self.x, self.y

end

object:addEventListener(“tap”)

[/LUA]

I hope one of those helps you out.

#3

Thanks!

I have changed the (object) to (event) and it works now @@

actually, what is the different between them?

sometimes i think “event” stands for the (x,y) where a event happen,

sometimes I think “object” stands for the object that have event happened,

but at other timing they are not lol.

#4

I’m glad the soultion works for you.

About the event thing, let me explain: Every time an eventListener notices an event and calls the related function, he sends a table with the event information. depending on the event these information can be very different.

In short and incomplete:

Tap event -> (target, numTap, x, y …)

Touch event -> (target, phase, x, y …)

Collision event -> (self, other, x, y, selfElment, otherElement …)

So it depends which properties you can use.

#5

Did you try it with event.target instead of object?

[LUA]

local function click (event)

   local target = event.target

   contentx, contenty = target.x, target.y

end

[/LUA]

Also you can try to attach the function to the object.

[LUA]

local object = display.newImage(“1.png”)

function object:tap(event)

   contentx, contenty = self.x, self.y

end

object:addEventListener(“tap”)

[/LUA]

I hope one of those helps you out.

#6

Thanks!

I have changed the (object) to (event) and it works now @@

actually, what is the different between them?

sometimes i think “event” stands for the (x,y) where a event happen,

sometimes I think “object” stands for the object that have event happened,

but at other timing they are not lol.

#7

I’m glad the soultion works for you.

About the event thing, let me explain: Every time an eventListener notices an event and calls the related function, he sends a table with the event information. depending on the event these information can be very different.

In short and incomplete:

Tap event -> (target, numTap, x, y …)

Touch event -> (target, phase, x, y …)

Collision event -> (self, other, x, y, selfElment, otherElement …)

So it depends which properties you can use.