Change plugin variables within Undo

[maricanis]

Hi,

In my plugin I define undoable operation with start_operation and commit_operation around my code.
Operation does next:

• check some flag value
• based on flag changes materials of multiple surfaces in the model
• sets new value to the flag

If I use undo, after performing operation - materials are changed back correctly, but my internal flag variable is not, so next time I try to run operation staring flag value is wrong.

Question:
Is there some way to define which function Sketchup should call when Edit->Undo is clicked?

I've looked Transaction observers, but it seems like they will trigger for every step of my operation (for each surface's material change), which is not the thing I need.

I've tried to find similar question on the forum, and also browsed through API documentation, but haven't found solution.

Thanks in advance,
Marija

[tt_su]

Do you have a reproducible snippet of code?

By flag, I assume you mean attribute or variable?

[maricanis]

Hi,

Here is example of code.
I have global variable @@dl_materials_changed which enables toggling on-off of faces materials in the model.
Each time user press UI button this function onToggleMaterial is called.

So with this code Undo correctly switches materials back, but @@dl_materials_changed flag is not changed, so next time I press button in UI it doesn't have correct value.

def onToggleMaterial()
    Sketchup.active_model.start_operation("toggle materials")
    showFCMaterials()
    Sketchup.active_model.commit_operation()
end

def showFCMaterials()
    #load all faces in @faces varialbe
    @faces = getFaces(Sketchup.active_model.entities)  

    #Set materials if flag is true
    if @@dl_materials_changed
        @faces.each {|face|
            material_name = face.get_attribute("faceData","material_name","")
            if material_name != ""
                 face.material = materials[material_name]
            else
                 face.material = nil
            end
        }
        @@dl_materials_changed = false
    else
         @faces.each_value {|face|
            face.material = nil
        }
        @@dl_materials_changed = true
    end
end

[danielbowring]

you could store the value/flag on the model instead, then it would also change with the undo steps

model = Sketchup.active_model
model.set_attribute('maricanis', 'dl_materials_changed', true)
#...
model.get_attribute('maricanis', 'dl_materials_changed', false)