How to force all objects to be create with anchor point (0.5, 0.5)

plicatibu · January 2020

I know that I can add new methods for existing classes in init.lua.

But how do I make that all objects be created with anchor point (0.5, 0.5) ?

I thought in overwrite the Sprite:init method in order to make it call Sprite:setAnchorPosition(0.5, 0.5) but I'm not finding the script Lua that contains Sprite definition.

Note: If you have better idea on how to do it, please let me know.

Thanks.

hgy29 · January 2020

There isn't any lua script for it, Sprite is a native class written in C, like most of Gideros classes.
However you can still do it by overriding 'new' method:

Sprite.old_new=Sprite.new
function Sprite.new(...)
 local instance=Sprite.old_new(...)
 instance:setAnchorPoint0.5,0.5)
 return instance
end

But it won't work as you expect because native subclasses creation is done in C++, completely by passing any lua overrides.
Anyway setAnchorPoint in Sprite is a shorthand for setAnchorPoisition(width*ratio,height*ratio), and since width and height would have been 0 at that time, this wouldn't done anything useful...

EDIT: There may be a way using postInit method. if postInit exists on an object, thehn it is called right after the object is contructed/initialized. So doing:

function Sprite:postInit(...)
 self:setAnchorPoint0.5,0.5)
end

may well work!

plicatibu · January 2020

hgy29 said:
There may be a way using postInit method. if postInit exists on an object, thehn it is called right after the object is contructed/initialized. So doing:
function Sprite:postInit(...)
 self:setAnchorPoint0.5,0.5)
end
may well work!

I see. Just a question: is it save to create the postInit() in Sprite? I mean, won't it overwrite and postInit() function in a derived class?

I think probably no Sprite's derived class have postInit() but its safer to ask.

Thank you.

oleg · January 2020

@plicatibu You can simply create your class with the parameters you need, just like you create a "button class", but you will need to update the anchor position - after each bitmap is added

hgy29 · January 2020

IIRC postInit is used for leak tests by bhleaky.lua, Gideros don't use it internally but calls it if it exists.

plicatibu · January 2020

@oleg I didn't want to do this because it would give me more work.

I think its better changing code in a specific point that applies to all classes.

@hgy29 Thanks for clarification. I'll add the postInit(...) to Sprite class in init.lua.

Regards.

plicatibu · January 2020

@hgy29 It worked like a charm.

Thanks again.

SinisterSoft · January 2020

Useful to know too - should be in the official docs.

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