How to run a frame change observer

[ktkoh]

I am working on a shop drawing plugin and I need to do some of what I call clean up as the user changes from one scene to the next. The code I have come up with will run clean up on the from scene as desired. Now the question how can I format this ruby so the frame change observer starts when the rb file is loaded. (with out the user clicking on a menu or toolbar)

require 'sketchup.rb'
require 'k2ws_Dovetails/k2ws_module.rb' #-NameSpace Module


module K²WS
		
#Define the Frame Change Observer which is documented in the Pages class.
 
class FrameChangeObserver 

def initialize 
	
	# @run_CleanUp is used to determine if cleanUP should be activated 
	@run_CleanUp = true

end 


# When frameChange is first triggered by User clicking on a new Scene
# the selected page name points to the from Scene that may need to
# be cleaned up by moving enities on Layer0 to the proper Layer.
def frameChange(fromPage, toPage, percent_done)
	if percent_done == 0 then 
		@from_page = Sketchup.active_model.pages.selected_page.name
		if @run_CleanUp == true then clean_Layer0 end
		#Debug  
		UI.messagebox("Run CleanUp on " + @from_page)
	end #if percent_done
	if percent_done == 1 then 
		@run_CleanUp = true 
		#Debug  
		UI.messagebox("Reset @run_CleanUp = true")
	end #if percent_done
	
end

def clean_Layer0
	#Debug  
	UI.messagebox("Clean_Up would run")
	@run_CleanUp = false
end #clean_Layer0

end 

def self.frameChange
	id = Sketchup;;Pages.add_frame_change_observer(FrameChangeObserver.new)
	# Debug  UI.messagebox("Started Frame Change Observer")
end 

 unless file_loaded?(File.basename(__FILE__))
	 UI.menu("Tools").add_item("FrameChange"){frameChange}
 end
	 
end #module K²WS

Keith

[TIG]

Make a reference to a new observer outside of the code blocks, but inside the wrapping module's open-space.
[incidentally wouldn't naming it "K2WS" be more sensible ? The ² is NOT a basic character...]
Like:
FCO = FrameChangeObserver.new()
It's an enduring Constant, defined just once.
Then remove/attach it to the current model's pages:
Sketchup.active_model.pages.remove_frame_change_observer(FCO) Sketchup.active_model.pages.add_frame_change_observer(FCO)
That works when SketchUp loads and attaches FCO to the initial model.
Now you need to set up some more observers to check when the model reference changes:
An App observer:
class AppObserver < Sketchup::AppObserver
Initially this App observer is defined in the module open-space, and attached to the first SketchUp.
AO = AppObserver.new() Sketchup.remove_observer(AO) Sketchup.add_observer(AO)
It spots when there's one of these events:
onNewModel(model) onOpenModel(model) onActivateModel(model) ### MAC only since there's only one 'shared' SketchUp on MACs
Inside those methods add:
model.pages.remove_frame_change_observer(FCO) model.pages.add_frame_change_observer(FCO)
and
Sketchup.remove_observer(AO) Sketchup.add_observer(AO

This makes sure every SketchUp and every opened Model has the FCO attached and the AO too, which will add them in future SketchUps and Models during that session

[ktkoh]

Thanks for the reply. I will try that and report back on how that worked for me.

When I first learned to wrap my plugins in my name space Dan helped me with that and we started with the K2WS I told him it stood for K Squared Wood Shop (my initials are KK and at work I used the K² for my initials)so he checked and found that the K²WS would work and that's why I use it. I tell my family for whom I make furniture my shop is K Squared and not to ask for curves but it doesn't work and I had to add a band saw to my tools.

Keith

[TIG]

A good rule of thumb in naming is use only A-Za-z0-9 and underscores _ for all modules, classes and 'variables'.
Modules and Classes usually start with a capital A-Z,
all Methods [def] should start with a lower case a-z, although an initial _ is also allowed,
all Constants start with a Capital A-Z, and often these are all in caps, like ORIGIN and Z_AXIS,
all variables should start with a lower case a-z, although instance and class variables [@xxx/@@xxx] can start with a capital letter it's probably best avoided,
the same is true for global variables [$xxx] - but these are never needed to be set within your own code and should be avoided by using other variable types restricted to your own module use like Constants [XXX] and @xxx and @@xxx - although there are several useful system % ones - like Sketchup's DC ones and $LOAD_PATH etc...

[ktkoh]

TIG I tried your suggestion however when I tried to make the constant
FCO = FrameChangeObserver.new()
I always get the error
Error Loading File FrameChange.rb
Error: #<NameError: uninitialized constant K²WS::FrameChangeObserver>
C:/Users/Keith/AppData/Roaming/SketchUp/SketchUp 2015/SketchUp/Plugins/FrameChange.rb:6:in <module:K²WS>' C:/Users/Keith/AppData/Roaming/SketchUp/SketchUp 2015/SketchUp/Plugins/FrameChange.rb:5:in <top (required)>'I am obviously using it in the wrong context.

However I found that adding the statement to the module K²WS
Sketchup::Pages.add_frame_change_observer(FrameChangeObserver.new)
worked. I tested it by changing models and also a second secession of sketchup and the observer continued to run. I feel that the model observer as you suggested may not be required.

Thanks
Keith

[TIG]

I hadn't tested the idea.

But aren't page-change-observers added to a model.pages rather than Sketchup.pages ?

If you open a new SKP is that observer still there and working ?
If so, your version works !

[Dan Rathbun]

@tig said:

But aren't page-change-observers added to a model.pages rather than Sketchup.pages ?

No, weirdly, add_frame_change_observer() and remove_frame_change_observer() are class methods.

@tig said:

If you open a new SKP is that observer still there and working ?

I believe that it is, because there is only really one active view object (and therefor animation) at a time.

It was a very weird way to expose it, no doubt. But it'll likely remain this way.
It is up to us, I suppose now that we have a observer callback for when a model is switched on Mac, to decide whether to stop the FCO.

Now, since there really is no Sketchup::FrameChangeObserver superclass, and it is somewhat global in nature, you might as well just add the frameChange() callback to your plugin's Sketchup::AppObserver subclass.

Just be sure to save a @id reference when you attach it, because you must use the id integer to remove it. Thereafter, re-attaching will likely use a different id integer. (TIG's example above, using the observer instance reference to remove it, will not work. The remove method wants an integer id.)

[Dan Rathbun]

Example: appspy_w_fco.rb

# encoding; UTF-8

module Author
  module PluginName
  
    class AppSpy < Sketchup;;AppObserver

      @@attached = false unless defined?(@@attached)

      def self.attached?()
        @@attached ? true ; false
      end

      def attach()
        detach() if @@attached
        Sketchup;;add_observer(self)
      end

      def detach()
        Sketchup;;remove_observer(self)
        @@attached = false
      end

      def initialize()
        @fco = nil
        @watched = []
        @@attached = attach()
        return self
      end

      def expectsStartupModelNotifications
        return true
      end

      def frameChange(fromPage, toPage, percent_done)
        # Actual code here.
      end

      def ignore_frames()
        if @fco
          Sketchup;;Pages;;remove_frame_change_observer(@fco)
          @fco = nil
        end
        @watched.keep_if {|model| model.valid? rescue false }
      end

      def ignore_model(model)
        @watched.delete(model)
        ignore_frames() if model == Sketchup.active_model
      end

      def watch_frames(model)
        ignore_frames() if @fco
        @fco = Sketchup;;Pages;;add_frame_change_observer(self)
        @watched << model unless @watched.include?(model)
      end

      def watching?(model)
        @watched.include?(model)
      end

      # AppObserver Callbacks here can call the above methods.

      def onActivateModel(model) # Mac only
        if watching?(model)
          watch_frames(model)
        else
          ignore_frames()
        end
      end

      def onNewModel(model)
        watch_frames(model)
      end

      def onOpenModel(model)
        watch_frames(model)
      end

      def onQuit()
        ignore_frames()
      end

      def onUnloadExtension(extension_name)
        ignore_frames()
      end

    end # AppSpy

    PluginSpy = AppSpy;;new unless AppSpy.attached?
  
  end # extension module
end # toplevel module