Re: Actor signals

[Lionel Landwerlin <llandwerlin gmail com>]

On 30/10/12 01:37, Patrick Shirkey wrote:
> On Tue, October 30, 2012 12:27 pm, Lionel Landwerlin wrote:
> > On 30/10/12 01:19, Patrick Shirkey wrote:
> > > Thanks for your advice.
> > >
> > > This is the pick method:
> > >
> > >       def do_pick (self, pick_color):
> > >           if self.should_pick_paint() == False:
> > >               return
> > >
> > >           box = self.get_allocation_box()
> > >           self.__draw_shape(box.x2 - box.x1, box.y2 - box.y1, pick_color)
> > >
> > >
> > >
> > > There's not much to it so I am not sure why it is doing something weird
> > > or
> > > how to fix it.
> > Are you sure the __draw_shape() method doesn't alterate the picking
> > color when drawing? (opacity? mask?)
> The opacity is being explicitly set in the button-press-event handler.
>
>      if(status == 0): # button-press-event
>          opacity = 200
>      else: # button-release-event/button-leave-event
>          opacity = 255
>
>      set_opacity(opacity)
>
>
> The __draw_shape function doesn't appear to have anything that would cause
> trouble. Also the code works for the top layer but not the bottom layer.
> The issue appears to be that the id of the actor is not found for the
> bottom layer but I am not sure why it would be unable to find it's own id
> especially when the top layer doesn't have this problem.
>
>
> Here's the __draw_shape methods:
>
>      def do_draw_shape(self, width, height):
>          pass
>
>      def __draw_shape(self, width, height, color=None, texture=None):
>          tmp_alpha = self.get_paint_opacity() * color.alpha / 255
>          if texture:
>              Cogl.set_source_texture(texture)
>          else:
>              Cogl.set_source_color4ub(color.red, color.green, color.blue,
> tmp_alpha)
>          self.do_draw_shape(width, height)
>          Cogl.path_fill()

Well that's the problem.
When the pick function is called, it should ONLY draw with given color. 
Nothing else.
No opacity.

Clutter does picking (aka finding the actor underneath you pointer) by 
rendering each object of the scene with a different color.
Then reading the value of the color at a given position in the rendered 
scene.

If you change the opacity when doing the picking you're using a color 
that isn't known by Clutter, therefore leading to the warning you've seen.

You should add an opacity argument to __draw_shape() and pass :

self.get_paint_opacity() * color.alpha / 255

when called from do_draw_shape() and pass

color.alpha

when called from do_pick()

-Lionel