On 22 nov, 12:15, claudio canepa <[email protected]> wrote:
> ---------- Forwarded message ----------
> From: <[email protected]>
> Date: Tue, Nov 16, 2010 at 10:04 PM
> Subject: Issue 163 in los-cocos: Event order
> To: [email protected]
>
> Status: New
> Owner: ----
>
> New issue 163 by mikejohnwyatt: Event
> orderhttp://code.google.com/p/los-cocos/issues/detail?id=163
>
> What steps will reproduce the problem?
>
> 1. Create a heirarchy of event-handling layers. At least one of the layers
> should have multiple child layers. All layers should handle the same event
> and not return EVENT_HANDLED.
>
> Example:
>
> Scene
> BackgroundLayer (z=0)
> GuiLayer (z=1)
> AlphaButton (z=0)
> BravoButton (z=1)
>
> 2. Run the program and fire the event.
>
> What is the expected output?
>
> I expect the event handlers to be called in the following order:
>
> 1) BravoButton
> 2) AlphaButton
> 3) GuiLayer
> 4) BackgroundLayer
>
> What do you see instead?
>
> In reality, the order is like this:
>
> 1) BackgroundLayer
> 2) AlphaButton
> 3) BravoButton
> 4) GuiLayer
>
> The problem is that the event handlers are simply pushed onto the window in
> order of the layer's children list (which is sorted with the lowest Z values
> first). This results in the handlers being called from back-to-front,
> instead of the documented front-to-back (from \cocos\layer\base_layers.py:
> "Events are propagated to layers (from front to back) until some layer
> catches the event and accepts it.").
>
> I need the order to be front-to-back so I can implement a basic GUI, in
> which events (like a mouse click) can be first caught by a widget (like a
> button) before being optionally passed to the background (i.e. if no button
> was clicked).
>
Front to back order is also sensible for selecting an actor with the
mouse.
And yes, current cocos don't honor the front-to-back.
Fair warning - Redesign opportunity:
Seems that the event propagation code was amidst a change for the
0.3.0 release, and then not ever completed.
By example, Scenes and Layer supposedly inherits code from
scene.EventHandlerMixin, but that code is never executed, and anyway
in that code the line
scene = self.get(Scene)
will traceback any time. ( probably wanted to be scene =
self.get_ancestor(Scene) )
> I have attached a patch file to fix this issue. Basically I just reversed
> the order of pushing child handlers onto the window in the scene and layer's
> push_all_handlers() method.
Reversing the order seems sensible
> I also removed event pushing from the on_enter
> method, since that would otherwise cause events to be registered in order of
> on_enter being called.
What if a program wants to spawn a mouse pickable actor some time
after the scene has been running ?
The basic problem is that the pyglet event dispatcher stores the
listeners in a stack, a linear structure, and we want to walk the tree
in front to back.
Other that implement a cocos dispatcher, when adding a handler to a
running scene we should:
>
> Attachments:
> event order fix.patch 2.4 KB
>
> --
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