Recursively check if Sprite is (literally) visible

totebo · September 2016

Is there a way of checking if a Sprite is visible, taking all of its parents into account? Without being able check if the final Sprite has been added to "stage", I can't seem to figure it out.

I want to use this in my Button class to avoid it triggering if it has been added to a Sprite with setVisible(false), or if it hasn't been added to the stage at all.

totebo · September 2016

This seems to work, but feels "dirty". Is there a better/simpler/more efficient way?

function isVisibleRecursive( sprite )
 
	stage.__is_stage = true
 
	local visible = false
 
	repeat
 
		visible = sprite:isVisible() and sprite:getParent() ~= nil
		sprite = sprite:getParent()
 
	until sprite == nil or sprite.__is_stage
 
	return visible
 
end
 
local sprite1 = Sprite.new()
local sprite2 = Sprite.new()
sprite2:addChild( sprite1 )
stage:addChild( sprite2 )
 
print( isVisibleRecursive(sprite1) )

totebo · September 2016

.

pie · September 2016

@totebo try this from GiderosCodingEasy by ar2rsawseen

function Sprite:isVisibleDeeply()
	-- Answer true only if the sprite and all it's a parents are visible. Normally, isVisible() will
	-- return true even if a sprite is actually not visible on screen by wont of one of it's parents
	-- being made invisible.
	--
	local try=self
	while (try) do
		if  not(try:isVisible() and try:getAlpha()>0) then
			return false
		end
		try = try:getParent()
	end
	return true
end

https://github.com/ar2rsawseen/GiderosCodingEasy/blob/master/GiderosCodingEasy.lua#L687

totebo · September 2016

Thanks @pie!

I think that solition only checks for isVisible, and would return true even if the Sprite is not added to the stage (and thus not actually visible)?

keszegh · September 2016

for that part use
stage:contains(mysprite)

http://docs.giderosmobile.com/reference/gideros/Sprite/contains

totebo · September 2016

Fantastic, thanks! Had missed that one.

totebo · September 2016

This is the final method, for reference:

function isVisibleRecursive( sprite )
 
	local visible = false
 
	repeat
 
		visible = sprite:isVisible() and stage:contains(sprite)
		sprite = sprite:getParent()
 
	until sprite == nil or visible == false
 
	return visible
 
end
 
local sprite1 = Sprite.new()
local sprite2 = Sprite.new()
sprite2:addChild( sprite1 )
stage:addChild( sprite2 )
 
print( isVisibleRecursive(sprite1) )

keszegh · September 2016

i don't know if it would be faster to check at the beginning
local visible=false
if not stage:contains(sprite) then return visible end

as this is maybe native and so perhaps faster then checking one by one all levels of the hierarchy for containment.

totebo · September 2016

Yeah, edited the post, check it out. It should break as soon as sprite is not visible, or stage does not contain it. If the first sprite isVisible() == false or not contained by stage, it's game over.

n1cke · September 2016

function Sprite:isVisibleRecursive()
	if self.__parent then return self:isVisible() and self.__parent:isVisibleRecursive()
	else return self:isVisible() and stage:contains(self) end
end

keszegh · September 2016

yes, but contains needs to be called only for the initial sprite, like:

function isVisibleRecursive( sprite )
 
	local visible = false
 if not stage:contains(sprite) then return visible end
	repeat
 
		visible = sprite:isVisible()
		sprite = sprite:getParent()
 
	until sprite == nil or visible == false
 
	return visible
 
end
 
local sprite1 = Sprite.new()
local sprite2 = Sprite.new()
sprite2:addChild( sprite1 )
stage:addChild( sprite2 )
 
print( isVisibleRecursive(sprite1) )

totebo · September 2016

Wow, that is neat. And beyond my level of efficient coding. Nice one @n1cke!

keszegh · September 2016

@n1cke, that's neat, although my version still contains less calls to contains.

n1cke · September 2016

@keszegh: only one "contains" call is performed here because it is last condition to check.

keszegh · September 2016

@n1cke, you are right, my mistake. your code is most efficient.

at the end it depends also on if one tends to set sprites to not visible. if this is less likely (like in my case), then it still may be more efficient to start with a stage:contains and then proceed with the visibility checks.

hgy29 · September 2016

@totebo,
I don't know if it will work for you but you may want to try:

 function isReallyVisible(sprite)
 local gx,gy=sprite:localToGlobal(0,0) --Assuming 0,0 is actually within the sprite
 return sprite:hitTestPoint(gx,gy,true) -- Check inside taking clip/visibility into account
 end

totebo · September 2016

That's a cool and different solution!

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