Classes and Overriding Functions

ruxpin

I have been working on my own SceneManager class for fun and to learn more about Gideros and Lua. I come from using Obj-C and am used to many of its conventions.

I have a class "SceneManager" and a class "Layer". SceneManager and Layer are derived from a Sprite with Core.class(Sprite) and this works great. The problem is that I want to make a new class using Layer as a base and to override its functions. The problem is that Layer functions are not being overridden and are still being called. I assume this is because I am using events or something. Is there a way to call an eventlistener on the base class Layer and only use the functions in the subclass MenuScene?

layer.lua

Layer = Core.class(Sprite)   function Layer:init() self:addEventListener(Event.ADDED_TO_STAGE, self.onAdd, self) self:addEventListener(Event.ENTER_FRAME, self.onUpdate, self) self:addEventListener(Event.REMOVED_FROM_STAGE, self.onRemove, self)   self.paused = false end   function Layer:onUpdate(event) print("LAYER_ONUPDATE") end   function Layer:onAdd(event) print("LAYER_ONADD") end   function Layer:onRemove(event) print("LAYER_ONREMOVE") end

menuscene.lua

MenuScene = Core.class(Layer)   function MenuScene:init() local background = Bitmap.new(Texture.new("gfx/background.png")) self:addChild(background)   local OptionsButton = Button.new( Bitmap.new(Texture.new("gfx/button_up.png")) , Bitmap.new(Texture.new("gfx/button_down.png")) ) OptionsButton:addEventListener("click", self.onOptionsButtonClicked, self) self:addChild(OptionsButton) end   function MenuScene:onUpdate(event) print("MENUSCENE_ONUPDATE") end   function MenuScene:onAdd(event) self:removeEventListener(Event.ADDED_TO_STAGE, self.onAdd, self) end   function MenuScene.onRemove(event) --self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame, self) end   --Handle Button Functions function MenuScene:onOptionsButtonClicked(event) scene = PauseScene:new() sceneManager:push(scene) end

ar2rsawseen

I guess thats an expected behavior, when you call extended classes method, it automatically call's parent's classes method. At least for constructors.
But about adding event listeners, it is better to add them inside extended classes:
http://www.giderosmobile.com/forum/discussion/1234/accessing-children-from-parent-class#Item_13

gorkem

This is a bug. Fixed already and will be ready for next release.

ruxpin

Sweet! Any updates on a release timeframe? I check the blog every day, but have been sad for almost a month now! ha ha

gorkem

The week after next week most probably. Oh yes the blog have to take care of it.

Summer times..

ruxpin

Okay another question regarding events. I am working on the ability to push and pop scenes off a stack and want to be able to pause the scenes underneath from updating. The problem is that if the Pause Scene doesn't take up the whole screen than the scenes underneath can still receive touches. Is there a way to pause a Sprite from receiving events?

Scouser

@ruxpin: I assume set some flag when you pause a scene / layer. Can you not just check the status of the flag in your event handler and ignore events if the layer / scene is paused? Or have the scene / layer stop propagation of events after the layer has done it's processes so layers below don't receive them.

ruxpin

@Sciyser I assume your first solution is to simply set up something like

function Layer:onUpdate(event) if self.paused then return end end

but for every function? That seems like a nice easy idea, but it seems like it is asking for me to constantly forget something.


I am not sure what you mean by your second solution. How do you stop the propagation of events?

Scouser

I wrote the last comment on my tablet, so now I'm on my desktop machine, I'll try and be a little clearer.

In your touch event handler for your object do something like this

function Object:onMouseDown(event) -- check to see if the touch event is for this object if self:hitTestPoint(event.x, event.y) then -- yes it is so let's process for the button self.focus = true self:updateVisualState(true) -- Stop this event from affecting any objects further up the heirarchy event:stopPropagation() end end

techdojo

I'd also consider adding a full-screen semi trans shape behind the pause screen, you could then add a mouse listener to that and use that to capture the events, its also visually more of an acknowledgement to the user as to why the buttons behind (or to the side of) the pause menu aren't working

ruxpin

Awesome ideas! I will probably wind up using both of them!