SOLVED Invoke Parent Function inside / outside class (TreeView)

Dear developers,

My topic seems a bit cryptic, but I am lacking the proper chargon to be more precise.

I have my TreeViewFunctions with a list of objects with values.
I want a button to activate and the sum selected and the sum of values of the object calculated outside the Treeview Gui hence I want to display it outside (my thinking might not be correct route to success) , when the user check marks an element.

I've read about the Python "super()" thing but could not implement anything remotely working in my case. I once read in the documentation about passing gui to parents but can't find its any more. Anyway I tried a lot ... I know this is a broad OOP question but hence its tied to the treeview I try my luck here anyway.

The use-case is:
Users selects elements -> display value on the fly -> let user interact (in my case import)

2022-02-26-Window_000060.jpg

My Helper -> def calc_selected(self):

Thanks in advance.
Mogh

"""
Adapted from:
    https://plugincafe.maxon.net/topic/10654/14102_using-customgui-listview/2
"""
import c4d
import random
 
# Be sure to use a unique ID obtained from http://www.plugincafe.com/.
PLUGIN_ID = 1000010  # TEST ID ONLY
 
# TreeView Column IDs.
ID_CHECKBOX = 1
ID_NAME = 2
ID_OTHER = 3
ID_LONGFILENAME = 4
MY_BUTON = 5
HOW_MANY = 6
ID_FILESIZE = 7
HOW_MANY_MB = 8
MY_CALC = 9

TREEVIEW = 99

# A tuple of characters to select from (a-z).
CHARACTERS = tuple( chr ( n) for n in range(97, 122))


class TextureObject(object):
    """
    Class which represent a texture, aka an Item in our list
    """
    def __init__(self):
        self.texturePath = TextureObject.RandomString(5, 10)
        self.otherData = TextureObject.RandomString(5, 20)
        self.longfilename = "-"
        self._selected = False
        self.filesize = TextureObject.RandomNumber()

    @staticmethod
    def RandomString(minLength, maxLength):
        """Returns a string of random characters with a length between 
        #minLength and #maxLength.

        The characters are taken from the 97 (a) to 122 (z) ASCII range.
        """
        return "".join(
            (random.choice(CHARACTERS) for _ in range(minLength, maxLength)))

    @staticmethod
    def RandomNumber():
        return random.randrange(1, 99)

    @property
    def IsSelected(self):
        return self._selected
 
    def Select(self):
        self._selected = True
 
    def Deselect(self):
        self._selected = False

    def __repr__(self):
        return str(self)
 
    def __str__(self):
        return self.texturePath
 
 
class ListView(c4d.gui.TreeViewFunctions):
 
    def __init__(self):
        """
        """
        # Add ten mock data texture objects.
        self.listOfTexture = [TextureObject() for _ in range(10)]

    def IsResizeColAllowed(self, root, userdata, lColID):
        return True
 
    def IsTristate(self, root, userdata):
        return False
 
    def GetColumnWidth(self, root, userdata, obj, col, area):
        """Measures the width of cells.

        Although this function is called #GetColumnWidth and has a #col, it is
        not only executed by column but by cell. So, when there is a column
        with items requiring the width 5, 10, and 15, then there is no need
        for evaluating all items. Each item can return its ideal width and
        Cinema 4D will then pick the largest value.

        Args:
            root (any): The root node of the tree view.
            userdata (any): The user data of the tree view.
            obj (any): The item for the current cell.
            col (int): The index of the column #obj is contained in.
            area (GeUserArea): An already initialized GeUserArea to measure
             the width of strings.
        
        Returns:
            TYPE: Description
        """
        # The default width of a column is 80 units.
        width = 80
        # Replace the width with the text width. area is a prepopulated
        # user area which has already setup all the font stuff, we can
        # measure right away.

        if col == ID_NAME:
            return area.DrawGetTextWidth(obj.texturePath) + 5
        if col == ID_OTHER:
            return area.DrawGetTextWidth(obj.otherData) + 5
        if col == ID_LONGFILENAME:
            return area.DrawGetTextWidth(obj.longfilename) + 5
            
        return width

    def IsMoveColAllowed(self, root, userdata, lColID):
        # The user is allowed to move all columns.
        # TREEVIEW_MOVE_COLUMN must be set in the container of AddCustomGui.
        return True
 
    def GetFirst(self, root, userdata):
        """
        Return the first element in the hierarchy, or None if there is no element.
        """
        rValue = None if not self.listOfTexture else self.listOfTexture[0]
        return rValue
 
    def GetDown(self, root, userdata, obj):
        """
        Return a child of a node, since we only want a list, we return None everytime
        """
        return None
 
    def GetNext(self, root, userdata, obj):
        """
        Returns the next Object to display after arg:'obj'
        """
        rValue = None
        currentObjIndex = self.listOfTexture.index(obj)
        nextIndex = currentObjIndex + 1
        if nextIndex < len(self.listOfTexture):
            rValue = self.listOfTexture[nextIndex]
 
        return rValue
 
    def GetPred(self, root, userdata, obj):
        """
        Returns the previous Object to display before arg:'obj'
        """
        rValue = None
        currentObjIndex = self.listOfTexture.index(obj)
        predIndex = currentObjIndex - 1
        if 0 <= predIndex < len(self.listOfTexture):
            rValue = self.listOfTexture[predIndex]
 
        return rValue
 
    def GetId(self, root, userdata, obj):
        """
        Return a unique ID for the element in the TreeView.
        """
        return hash(obj)
 
    def Select(self, root, userdata, obj, mode):
        """
        Called when the user selects an element.
        """
        # I only use the checkbox to select list elemenmts
        """
        if mode == c4d.SELECTION_NEW:
            for tex in self.listOfTexture:
                tex.Deselect()
            obj.Select()
        elif mode == c4d.SELECTION_ADD:
            obj.Select()
        elif mode == c4d.SELECTION_SUB:
            obj.Deselect()
        """

    def IsSelected(self, root, userdata, obj):
        """
        Returns: True if *obj* is selected, False if not.
        """
        return obj.IsSelected
 
    def SetCheck(self, root, userdata, obj, column, checked, msg):
        """
        Called when the user clicks on a checkbox for an object in a
        `c4d.LV_CHECKBOX` column.
        """
        if checked:
            obj.Select()
        else:
            obj.Deselect()
 
    def IsChecked(self, root, userdata, obj, column):
        """
        Returns: (int): Status of the checkbox in the specified *column* for *obj*.
        """
        if obj.IsSelected:
            return c4d.LV_CHECKBOX_CHECKED | c4d.LV_CHECKBOX_ENABLED
        else:
            return c4d.LV_CHECKBOX_ENABLED
 
    def GetName(self, root, userdata, obj):
        """
        Returns the name to display for arg:'obj', only called for column of type LV_TREE
        """
        return str(obj)  # Or obj.texturePath
 
    def DrawCell(self, root, userdata, obj, col, drawinfo, bgColor):
        """
        Draw into a Cell, only called for column of type LV_USER
        """
        if col in (ID_OTHER, ID_LONGFILENAME):
            text = obj.otherData if col == ID_OTHER else obj.longfilename
            canvas = drawinfo["frame"]
            textWidth = canvas.DrawGetTextWidth(text)
            textHeight = canvas.DrawGetFontHeight()
            xpos = drawinfo["xpos"]
            ypos = drawinfo["ypos"] + drawinfo["height"]

            if (drawinfo["width"] < textWidth):
                while (drawinfo["width"] < textWidth):
                    if len(text) <= 4:
                        text = "..."
                        break
                    text = text[:-4] + "..."
                    textWidth = canvas.DrawGetTextWidth(text)

            textWidth = canvas.DrawGetTextWidth(text)
            drawinfo["frame"].DrawText(text, xpos, ypos - int(textHeight * 1.1))

        if col == ID_FILESIZE:
            text = obj.filesize
            canvas = drawinfo["frame"]
            # w = geUserArea.DrawGetTextWidth(name)
            h = canvas.DrawGetFontHeight()
            # xpos = drawinfo["xpos"] + 10
            xpos = drawinfo["xpos"] + drawinfo["width"] - canvas.DrawGetTextWidth(text)
            ypos = drawinfo["ypos"] + drawinfo["height"]
            drawinfo["frame"].DrawText(text, xpos, ypos - int(h * 1.1))

    def DoubleClick(self, root, userdata, obj, col, mouseinfo):
        """
        Called when the user double-clicks on an entry in the TreeView.
 
        Returns:
          (bool): True if the double-click was handled, False if the
            default action should kick in. The default action will invoke
            the rename procedure for the object, causing `SetName()` to be
            called.
        """
        c4d.gui.MessageDialog("You clicked on " + str(obj))
        return True
 
    def DeletePressed(self, root, userdata):
        "Called when a delete event is received."
        for tex in reversed(self.listOfTexture):
            if tex.IsSelected:
                self.listOfTexture.remove(tex)


class TestDialog(c4d.gui.GeDialog):
    _treegui = None  # Our CustomGui TreeView
    _listView = ListView()  # Our Instance of c4d.gui.TreeViewFunctions

    def __init__(self):
        self.overall = len(self._listView.listOfTexture)

    def CreateLayout(self):
        # Create the TreeView GUI.
        customgui = c4d.BaseContainer()
        customgui.SetBool(c4d.TREEVIEW_BORDER, c4d.BORDER_THIN_IN)
        customgui.SetBool(c4d.TREEVIEW_HAS_HEADER, True)  # True if the tree view may have a header line.
        customgui.SetBool(c4d.TREEVIEW_HIDE_LINES, True)  # True if no lines should be drawn.
        customgui.SetBool(c4d.TREEVIEW_MOVE_COLUMN, True)  # True if the user can move the columns.
        customgui.SetBool(c4d.TREEVIEW_RESIZE_HEADER, True)  # True if the column width can be changed by the user.
        customgui.SetBool(c4d.TREEVIEW_FIXED_LAYOUT, True)  # True if all lines have the same height.
        customgui.SetBool(c4d.TREEVIEW_ALTERNATE_BG, True)  # Alternate background per line.
        customgui.SetBool(c4d.TREEVIEW_CURSORKEYS, True)  # True if cursor keys should be processed.
        customgui.SetBool(c4d.TREEVIEW_NOENTERRENAME, False)  # Suppresses the rename popup when the user presses enter.

        if self.GroupBegin(id=1000, flags=c4d.BFH_SCALEFIT | c4d.BFV_SCALEFIT, rows=3, cols=1, groupflags=c4d.BORDER_OUT):
            self.GroupBorderSpace(left=5, top=5, right=5, bottom=5)
            self.GroupBorderNoTitle(borderstyle=c4d.BORDER_NONE)

            if self.GroupBegin(id=1001, flags=c4d.BFH_SCALEFIT | c4d.BFV_SCALEFIT, rows=2, cols=3, groupflags=c4d.BORDER_OUT):
                self.GroupBorderNoTitle(borderstyle=c4d.BORDER_NONE)
                self._treegui = self.AddCustomGui(TREEVIEW, c4d.CUSTOMGUI_TREEVIEW, "", c4d.BFH_SCALEFIT | c4d.BFV_SCALEFIT, minw=430, minh=160, customdata=customgui)
                if not self._treegui:
                    print("[ERROR]: Could not create TreeView")
                    return False
                self.GroupEnd()

            if self.GroupBegin(id=1002, flags=c4d.BFH_FIT | c4d.BFV_FIT, rows=2, cols=4, groupflags=c4d.BORDER_OUT):
                self.GroupBorderNoTitle(borderstyle=c4d.BORDER_NONE)

                self.AddStaticText(HOW_MANY, flags=c4d.BFV_CENTER | c4d.BFV_SCALE | c4d.BFH_LEFT | c4d.BFH_SCALE, name="Selected: 0 / " + str(self.overall))
                self.AddStaticText(HOW_MANY_MB, flags=c4d.BFV_CENTER | c4d.BFV_SCALE | c4d.BFH_LEFT | c4d.BFH_SCALE, name="Filesize Sum: ____")
                self.AddButton(MY_CALC, c4d.BFH_CENTER, name="Calc Manual")
                self.AddButton(MY_BUTON, c4d.BFH_CENTER, name="Enable me by check-boxing")
                self.Enable(MY_BUTON, False)
                self.GroupEnd()

            if self.GroupBegin(id=1002, flags=c4d.BFH_FIT | c4d.BFV_FIT, rows=2, cols=3, groupflags=c4d.BORDER_OUT):
                self.GroupBorderSpace(left=5, top=5, right=5, bottom=5)
                self.GroupBorderNoTitle(c4d.BORDER_ACTIVE_3)
                self.AddStaticText(1003, flags=c4d.BFV_CENTER | c4d.BFV_SCALE | c4d.BFH_CENTER | c4d.BFH_SCALE, name="How do I invoke action from inside the treegui class?")
                self.GroupEnd()
            self.GroupEnd()

        return True

    def calc_selected(self, autoactivate):
        """
        this is a helper to calculate the selected elements and to enable the button
        I do NOT know how to trigger this everytime a user clicks on a checkbox in the treegui class

        :return: # slected and sum of the selecteed filsize
        """
        selected = 0
        filsizesum = 0
        for fileitem in self._listView.listOfTexture:
            if fileitem.IsSelected is True:
                filsizesum += fileitem.filesize
                selected += 1

        if selected > 0 and autoactivate:
            self.Enable(MY_BUTON, True)

        sel_string = "Selected: " + str(selected) + " / " + str(self.overall)
        self.SetString(HOW_MANY, sel_string)

        mb_string = "Filesize Sum: " + str(filsizesum)
        self.SetString(HOW_MANY_MB, mb_string)

        return selected, filsizesum

    def InitValues(self):
        # Initialize the column layout for the TreeView.
        layout = c4d.BaseContainer()
        layout.SetLong(ID_CHECKBOX, c4d.LV_CHECKBOX)
        layout.SetLong(ID_NAME, c4d.LV_TREE)
        layout.SetLong(ID_LONGFILENAME, c4d.LV_USER)
        layout.SetLong(ID_OTHER, c4d.LV_USER)
        layout.SetLong(ID_FILESIZE, c4d.LV_USER)
        self._layout = layout
        self._treegui.SetLayout(5, layout)
 
        # Set the header titles.
        self._treegui.SetHeaderText(ID_CHECKBOX, "Check")
        self._treegui.SetHeaderText(ID_NAME, "Name")
        self._treegui.SetHeaderText(ID_LONGFILENAME, "Long Filename")
        self._treegui.SetHeaderText(ID_OTHER, "Other")
        self._treegui.SetHeaderText(ID_FILESIZE, "Filesize")

        self._treegui.Refresh()
 
        # Set TreeViewFunctions instance used by our CUSTOMGUI_TREEVIEW
        self._treegui.SetRoot(self._treegui, self._listView, None)

        return True
 
    def Command(self, id, msg):
        # Click on button
        if id == MY_BUTON:
            newID = int(len(self._listView.listOfTexture) + 1)
            tex = TextureObject()
            tex.texturePath = "Some new data " + str(newID)
            tex.longfilename = TextureObject.RandomString(20, 40)
            self._listView.listOfTexture.append(tex)
            self._treegui.Refresh()
 
        if id == MY_CALC:
            self.calc_selected(False)
            # print(self.calc_selected(False))

        return True

 
class MenuCommand(c4d.plugins.CommandData):
    dialog = None
 
    def Execute(self, doc):
        if self.dialog is None:
            self.dialog = TestDialog()
        return self.dialog.Open(c4d.DLG_TYPE_ASYNC, PLUGIN_ID, defaulth=300, defaultw=430)
 
    def RestoreLayout(self, sec_ref):
        if self.dialog is None:
            self.dialog = TestDialog()
        return self.dialog.Restore(PLUGIN_ID, secret=sec_ref)
 
 
def main():
    c4d.plugins.RegisterCommandPlugin(
        PLUGIN_ID, "Python TreeView Example", 0, None, "Python TreeView Example", MenuCommand())


if __name__ == "__main__":
    main()


Hey @mogh,

Thank you for reaching us. Since this is a bit abstract question, I will answer it a bit more abstractly.

super()

The super keyword is just a way to invoke the base implementation of a method in many languages. So, when you have this:

class AClass:
    """Some class.
    """
    def MultiplyByTwo (self, value: int) -> int:
        """Multiplies #value by two and returns the result.
        """
        return value * 2

class BClass (AClass):
    """Has AClass as its base.
    """
    def MultiplyByTwo (self, value: int, offset: int) -> int:
        """Calls the base implementation with #value and returns its result plus #offset.
        """
        r = super().MultiplyByTwo(value)
        return r + offset

Then AClass.MultiplyByTwo is being shadowed by BClass.MultiplyByTwo in BClass. With super you can call that shadowed base implementation. super() in Python is a bit confusing, as its syntax has changed from Python 2 to 3 and is also dependent on the context, but its effect is quite simple:

a = AClass()
b = BClass()

# Calls AClass.MultiplyByTwo()
print (a.MultiplyByTwo(2))

# Calls the overloaded base implementation AClass.MultiplyByTwo() with super()
# in BClass.MultiplyByTwo(), to avoid having to write the same code twice.
print (b.MultiplyByTwo(2, 2))
4
6
[Finished in 139ms]

In our API we sometimes recommend to call the base implementation of something, e.g. in a Message method, to ensure that all the background processing Cinema 4D is doing is carried out properly. But from what I can see, super() is not relevant in your case.

I have my TreeViewFunctions with a list of objects with values. I want a button to activate and the sum selected and the sum of values of the object calculated outside the Treeview Gui hence I want to display it outside (my thinking might not be correct route to success) , when the user check marks an element.

I am not 100% sure what your goals are in this case. There are, however, two simple techniques with which you should be able to solve your problem (you will only need one of them, and which one depends on your goals):

Access an Enclosing Entity from a Subordinate Entity

Sometimes you want to have access to a larger enclosing class/interface/data structure from something that is contained within that enclosing entity. Examples would be accessing a GeDialog from a GeUserArea hosted by it or acessing a GeDialog from a TreeViewFunctions utility interface which is attached to tree view hosted by the dialog. The answer is then to either make the enclosing entity available as a global variable (which is a bad idea) or to simply pass a reference for it to the subordinate entity. As a sketch for your case:

class ListView(c4d.gui.TreeViewFunctions):
    """The subordinate entity.
    """ 
 
    def __init__(self, host: c4d.gui.GeDialog):
        """Initializes a ListView with a host.

        Args:
            host (c4d.gui.GeDialog): The hosting dialog.
        """
        if not isinstance(host, c4d.gui.GeDialog):
            raise TypeError(
                f"Expected {c4d.gui.GeDialog} for argument 'host'. Received: {host}")

        self._host = host

    def DoSomethingWithDialog(self, *data):
        """Calls the dialog over the stored reference.
        """
        self._host.Open(*data)


# ...

class TestDialog(c4d.gui.GeDialog):
    """The enclosing entity.
    """
    # I am not quite sure why Maxime then did attach this stuff to the class
    # and not to the instance (which I would consider bad style).
    # In this case, apart from stylistic concerns, we cannot do this 
    # practically, as we must establish a reference between a TestDialog 
    # instance and a ListView instance.

    # _listView = ListView()  # Our Instance of c4d.gui.TreeViewFunctions

    def __init__(self):
        """
        """
        # Create an instance of ListView and give it access to the dialog
        # which carries it.
        self._listView = ListView(host=self)
Extend an Interface

The second, and likely more relevant "pattern" (and pattern is here a bit of an overstatement) is simply to extend the interface that is ListView. While TreeViewFunctions gives you an outline of what the class must be able to do (i.e., it establishes an interface), there is nothing which prevents you from extending that. Again, as a sketch:

class ListView(c4d.gui.TreeViewFunctions):
    """The subordinate entity.
    """ 
 
    def __init__(self, dataToManage: list[SomeFancyType]):
        """Initializes a ListView with a host.

        Args:
            dataToManage: The data manged by the list view.
        """
        # Dome some validation of #dataToManage ...

        self._data = dataToManage

    def CalculateSomePropertySum(self) -> int:
        """Returns the sum of #SomeProperty of all #SomeFancyType managed as
        #data by this instance.
        """
        return sum((item.SomeProperty for item in self._data))


# ...

class TestDialog(c4d.gui.GeDialog):
    """The enclosing entity.
    """
    def __init__(self):
        """
        """
        self._listView = ListView()

    def Command(self, cid, cmsg):
        """Invokes CalculateItemSum() on self._listView which relies on data
        which at least informally is invisible to this TestDialog instance 
        (in practice you can of course access anything in Python, but that
        often makes ugly code).
        
        Args:
            cid (int): The command id.
            cmsg (any): The command id message data.
        
        """
        # ...

        # The user wants to see a summary of SomeProperty of all items in the
        # list view.
        if cid == ID_BUTTON_SHOW_SUMMARY_SOMEPRROPERTY:
            # Get the value by calling the method of the interface.
            value = self._listView.CalculateSomePropertySum()
            # Show a dialog with the result.
            c4d.gui.MessageDialog(
                f"The sum of 'SomeProperty' of all items is: {value}")
            # Or set some gadget in the dialog to that value.
            self.SetInt32(ID_SOMEPRROPERTY_SUM, int(value))

        # ...

I hope this gives you an idea in which direction to sail with your code 🙂 I must also point out that we cannot provide full solutions here, as this is a pure design question.

Cheers,
Ferdinand

Hey @mogh,

Thank you for reaching us. Since this is a bit abstract question, I will answer it a bit more abstractly.

super()

The super keyword is just a way to invoke the base implementation of a method in many languages. So, when you have this:

class AClass:
    """Some class.
    """
    def MultiplyByTwo (self, value: int) -> int:
        """Multiplies #value by two and returns the result.
        """
        return value * 2

class BClass (AClass):
    """Has AClass as its base.
    """
    def MultiplyByTwo (self, value: int, offset: int) -> int:
        """Calls the base implementation with #value and returns its result plus #offset.
        """
        r = super().MultiplyByTwo(value)
        return r + offset

Then AClass.MultiplyByTwo is being shadowed by BClass.MultiplyByTwo in BClass. With super you can call that shadowed base implementation. super() in Python is a bit confusing, as its syntax has changed from Python 2 to 3 and is also dependent on the context, but its effect is quite simple:

a = AClass()
b = BClass()

# Calls AClass.MultiplyByTwo()
print (a.MultiplyByTwo(2))

# Calls the overloaded base implementation AClass.MultiplyByTwo() with super()
# in BClass.MultiplyByTwo(), to avoid having to write the same code twice.
print (b.MultiplyByTwo(2, 2))
4
6
[Finished in 139ms]

In our API we sometimes recommend to call the base implementation of something, e.g. in a Message method, to ensure that all the background processing Cinema 4D is doing is carried out properly. But from what I can see, super() is not relevant in your case.

I have my TreeViewFunctions with a list of objects with values. I want a button to activate and the sum selected and the sum of values of the object calculated outside the Treeview Gui hence I want to display it outside (my thinking might not be correct route to success) , when the user check marks an element.

I am not 100% sure what your goals are in this case. There are, however, two simple techniques with which you should be able to solve your problem (you will only need one of them, and which one depends on your goals):

Access an Enclosing Entity from a Subordinate Entity

Sometimes you want to have access to a larger enclosing class/interface/data structure from something that is contained within that enclosing entity. Examples would be accessing a GeDialog from a GeUserArea hosted by it or acessing a GeDialog from a TreeViewFunctions utility interface which is attached to tree view hosted by the dialog. The answer is then to either make the enclosing entity available as a global variable (which is a bad idea) or to simply pass a reference for it to the subordinate entity. As a sketch for your case:

class ListView(c4d.gui.TreeViewFunctions):
    """The subordinate entity.
    """ 
 
    def __init__(self, host: c4d.gui.GeDialog):
        """Initializes a ListView with a host.

        Args:
            host (c4d.gui.GeDialog): The hosting dialog.
        """
        if not isinstance(host, c4d.gui.GeDialog):
            raise TypeError(
                f"Expected {c4d.gui.GeDialog} for argument 'host'. Received: {host}")

        self._host = host

    def DoSomethingWithDialog(self, *data):
        """Calls the dialog over the stored reference.
        """
        self._host.Open(*data)


# ...

class TestDialog(c4d.gui.GeDialog):
    """The enclosing entity.
    """
    # I am not quite sure why Maxime then did attach this stuff to the class
    # and not to the instance (which I would consider bad style).
    # In this case, apart from stylistic concerns, we cannot do this 
    # practically, as we must establish a reference between a TestDialog 
    # instance and a ListView instance.

    # _listView = ListView()  # Our Instance of c4d.gui.TreeViewFunctions

    def __init__(self):
        """
        """
        # Create an instance of ListView and give it access to the dialog
        # which carries it.
        self._listView = ListView(host=self)
Extend an Interface

The second, and likely more relevant "pattern" (and pattern is here a bit of an overstatement) is simply to extend the interface that is ListView. While TreeViewFunctions gives you an outline of what the class must be able to do (i.e., it establishes an interface), there is nothing which prevents you from extending that. Again, as a sketch:

class ListView(c4d.gui.TreeViewFunctions):
    """The subordinate entity.
    """ 
 
    def __init__(self, dataToManage: list[SomeFancyType]):
        """Initializes a ListView with a host.

        Args:
            dataToManage: The data manged by the list view.
        """
        # Dome some validation of #dataToManage ...

        self._data = dataToManage

    def CalculateSomePropertySum(self) -> int:
        """Returns the sum of #SomeProperty of all #SomeFancyType managed as
        #data by this instance.
        """
        return sum((item.SomeProperty for item in self._data))


# ...

class TestDialog(c4d.gui.GeDialog):
    """The enclosing entity.
    """
    def __init__(self):
        """
        """
        self._listView = ListView()

    def Command(self, cid, cmsg):
        """Invokes CalculateItemSum() on self._listView which relies on data
        which at least informally is invisible to this TestDialog instance 
        (in practice you can of course access anything in Python, but that
        often makes ugly code).
        
        Args:
            cid (int): The command id.
            cmsg (any): The command id message data.
        
        """
        # ...

        # The user wants to see a summary of SomeProperty of all items in the
        # list view.
        if cid == ID_BUTTON_SHOW_SUMMARY_SOMEPRROPERTY:
            # Get the value by calling the method of the interface.
            value = self._listView.CalculateSomePropertySum()
            # Show a dialog with the result.
            c4d.gui.MessageDialog(
                f"The sum of 'SomeProperty' of all items is: {value}")
            # Or set some gadget in the dialog to that value.
            self.SetInt32(ID_SOMEPRROPERTY_SUM, int(value))

        # ...

I hope this gives you an idea in which direction to sail with your code 🙂 I must also point out that we cannot provide full solutions here, as this is a pure design question.

Cheers,
Ferdinand

🙇 👏 💃 😌 Thank You @ferdinand

Access an Enclosing Entity from a Subordinate Entity, was the solution I was searching for hence I needed to alter the GeDialog from inside the TreeViewFunctions. This seems to be the only solution hence these checkboxes belong to the treeview ?!?

Anyway its working and I am very happy 🙂

User sets checkbox -> Sum is calculated -> button is activated.

I updated the example code (and removed the now unnecessary button to prevent further confusion) with the desired behavior for future readers.

kind regards
mogh

"""
Adapted from:
    https://plugincafe.maxon.net/topic/10654/14102_using-customgui-listview/2
"""
import c4d
import random
 
# Be sure to use a unique ID obtained from http://www.plugincafe.com/.
PLUGIN_ID = 1000010  # TEST ID ONLY
 
# TreeView Column IDs.
ID_CHECKBOX = 1
ID_NAME = 2
ID_OTHER = 3
ID_LONGFILENAME = 4
MY_BUTON = 5
HOW_MANY = 6
ID_FILESIZE = 7
HOW_MANY_MB = 8
MY_CALC = 9

TREEVIEW = 99

# A tuple of characters to select from (a-z).
CHARACTERS = tuple( chr ( n) for n in range(97, 122))


class TextureObject(object):
    """
    Class which represent a texture, aka an Item in our list
    """
    def __init__(self):
        self.texturePath = TextureObject.RandomString(5, 10)
        self.otherData = TextureObject.RandomString(5, 20)
        self.longfilename = "-"
        self._selected = False
        self.filesize = TextureObject.RandomNumber()

    @staticmethod
    def RandomString(minLength, maxLength):
        """Returns a string of random characters with a length between 
        #minLength and #maxLength.

        The characters are taken from the 97 (a) to 122 (z) ASCII range.
        """
        return "".join(
            (random.choice(CHARACTERS) for _ in range(minLength, maxLength)))

    @staticmethod
    def RandomNumber():
        return random.randrange(1, 99)

    @property
    def IsSelected(self):
        return self._selected
 
    def Select(self):
        self._selected = True
 
    def Deselect(self):
        self._selected = False

    def __repr__(self):
        return str(self)
 
    def __str__(self):
        return self.texturePath
 
 
class ListView(c4d.gui.TreeViewFunctions):
 
    def __init__(self, host):
        """Initializes a ListView with a host.

        Args:
            host (c4d.gui.GeDialog): The hosting dialog.
        """
        # Add ten mock data texture objects.
        self.listOfTexture = [TextureObject() for _ in range(10)]
        if not isinstance(host, c4d.gui.GeDialog):
            raise TypeError("Expected {} for argument 'host'. Received: {}".format(c4d.gui.GeDialog, host))
        else:
            self._host = host

    def DoSomethingWithDialog(self):
        """Calls the dialog over the stored reference.
        """
        self._host.calc_selected()

    def IsResizeColAllowed(self, root, userdata, lColID):
        return True
 
    def IsTristate(self, root, userdata):
        return False
 
    def GetColumnWidth(self, root, userdata, obj, col, area):
        """Measures the width of cells.

        Although this function is called #GetColumnWidth and has a #col, it is
        not only executed by column but by cell. So, when there is a column
        with items requiring the width 5, 10, and 15, then there is no need
        for evaluating all items. Each item can return its ideal width and
        Cinema 4D will then pick the largest value.

        Args:
            root (any): The root node of the tree view.
            userdata (any): The user data of the tree view.
            obj (any): The item for the current cell.
            col (int): The index of the column #obj is contained in.
            area (GeUserArea): An already initialized GeUserArea to measure
             the width of strings.
        
        Returns:
            TYPE: Description
        """
        # The default width of a column is 80 units.
        width = 80
        # Replace the width with the text width. area is a prepopulated
        # user area which has already setup all the font stuff, we can
        # measure right away.

        if col == ID_NAME:
            return area.DrawGetTextWidth(obj.texturePath) + 5
        if col == ID_OTHER:
            return area.DrawGetTextWidth(obj.otherData) + 5
        if col == ID_LONGFILENAME:
            return area.DrawGetTextWidth(obj.longfilename) + 5
            
        return width

    def IsMoveColAllowed(self, root, userdata, lColID):
        # The user is allowed to move all columns.
        # TREEVIEW_MOVE_COLUMN must be set in the container of AddCustomGui.
        return True
 
    def GetFirst(self, root, userdata):
        """
        Return the first element in the hierarchy, or None if there is no element.
        """
        rValue = None if not self.listOfTexture else self.listOfTexture[0]
        return rValue
 
    def GetDown(self, root, userdata, obj):
        """
        Return a child of a node, since we only want a list, we return None everytime
        """
        return None
 
    def GetNext(self, root, userdata, obj):
        """
        Returns the next Object to display after arg:'obj'
        """
        rValue = None
        currentObjIndex = self.listOfTexture.index(obj)
        nextIndex = currentObjIndex + 1
        if nextIndex < len(self.listOfTexture):
            rValue = self.listOfTexture[nextIndex]
 
        return rValue
 
    def GetPred(self, root, userdata, obj):
        """
        Returns the previous Object to display before arg:'obj'
        """
        rValue = None
        currentObjIndex = self.listOfTexture.index(obj)
        predIndex = currentObjIndex - 1
        if 0 <= predIndex < len(self.listOfTexture):
            rValue = self.listOfTexture[predIndex]
 
        return rValue
 
    def GetId(self, root, userdata, obj):
        """
        Return a unique ID for the element in the TreeView.
        """
        return hash(obj)
 
    def Select(self, root, userdata, obj, mode):
        """
        Called when the user selects an element.
        """
        # I only use the checkbox to select list elemenmts
        """
        if mode == c4d.SELECTION_NEW:
            for tex in self.listOfTexture:
                tex.Deselect()
            obj.Select()
        elif mode == c4d.SELECTION_ADD:
            obj.Select()
        elif mode == c4d.SELECTION_SUB:
            obj.Deselect()
        """

    def IsSelected(self, root, userdata, obj):
        """
        Returns: True if *obj* is selected, False if not.
        """
        return obj.IsSelected
 
    def SetCheck(self, root, userdata, obj, column, checked, msg):
        """
        Called when the user clicks on a checkbox for an object in a
        `c4d.LV_CHECKBOX` column.
        """
        if checked:
            obj.Select()
        else:
            obj.Deselect()

        self.DoSomethingWithDialog()

 
    def IsChecked(self, root, userdata, obj, column):
        """
        Returns: (int): Status of the checkbox in the specified *column* for *obj*.
        """
        if obj.IsSelected:
            return c4d.LV_CHECKBOX_CHECKED | c4d.LV_CHECKBOX_ENABLED
        else:
            return c4d.LV_CHECKBOX_ENABLED
 
    def GetName(self, root, userdata, obj):
        """
        Returns the name to display for arg:'obj', only called for column of type LV_TREE
        """
        return str(obj)  # Or obj.texturePath
 
    def DrawCell(self, root, userdata, obj, col, drawinfo, bgColor):
        """
        Draw into a Cell, only called for column of type LV_USER
        """
        if col in (ID_OTHER, ID_LONGFILENAME):
            text = obj.otherData if col == ID_OTHER else obj.longfilename
            canvas = drawinfo["frame"]
            textWidth = canvas.DrawGetTextWidth(text)
            textHeight = canvas.DrawGetFontHeight()
            xpos = drawinfo["xpos"]
            ypos = drawinfo["ypos"] + drawinfo["height"]

            if (drawinfo["width"] < textWidth):
                while (drawinfo["width"] < textWidth):
                    if len(text) <= 4:
                        text = "..."
                        break
                    text = text[:-4] + "..."
                    textWidth = canvas.DrawGetTextWidth(text)

            textWidth = canvas.DrawGetTextWidth(text)
            drawinfo["frame"].DrawText(text, xpos, ypos - int(textHeight * 1.1))

        if col == ID_FILESIZE:
            text = obj.filesize
            canvas = drawinfo["frame"]
            # w = geUserArea.DrawGetTextWidth(name)
            h = canvas.DrawGetFontHeight()
            # xpos = drawinfo["xpos"] + 10
            xpos = drawinfo["xpos"] + drawinfo["width"] - canvas.DrawGetTextWidth(text)
            ypos = drawinfo["ypos"] + drawinfo["height"]
            drawinfo["frame"].DrawText(text, xpos, ypos - int(h * 1.1))

    def DoubleClick(self, root, userdata, obj, col, mouseinfo):
        """
        Called when the user double-clicks on an entry in the TreeView.
 
        Returns:
          (bool): True if the double-click was handled, False if the
            default action should kick in. The default action will invoke
            the rename procedure for the object, causing `SetName()` to be
            called.
        """
        c4d.gui.MessageDialog("You clicked on " + str(obj))
        return True
 
    def DeletePressed(self, root, userdata):
        "Called when a delete event is received."
        for tex in reversed(self.listOfTexture):
            if tex.IsSelected:
                self.listOfTexture.remove(tex)


class TestDialog(c4d.gui.GeDialog):
    _treegui = None  # Our CustomGui TreeView
    # _listView = ListView()  # Our Instance of c4d.gui.TreeViewFunctions

    def __init__(self):
        """
        """
        # Create an instance of ListView and give it access to the dialog
        # which carries it.
        self._listView = ListView(host=self)
        self.overall = len(self._listView.listOfTexture)

    def CreateLayout(self):
        # Create the TreeView GUI.
        customgui = c4d.BaseContainer()
        customgui.SetBool(c4d.TREEVIEW_BORDER, c4d.BORDER_THIN_IN)
        customgui.SetBool(c4d.TREEVIEW_HAS_HEADER, True)  # True if the tree view may have a header line.
        customgui.SetBool(c4d.TREEVIEW_HIDE_LINES, True)  # True if no lines should be drawn.
        customgui.SetBool(c4d.TREEVIEW_MOVE_COLUMN, True)  # True if the user can move the columns.
        customgui.SetBool(c4d.TREEVIEW_RESIZE_HEADER, True)  # True if the column width can be changed by the user.
        customgui.SetBool(c4d.TREEVIEW_FIXED_LAYOUT, True)  # True if all lines have the same height.
        customgui.SetBool(c4d.TREEVIEW_ALTERNATE_BG, True)  # Alternate background per line.
        customgui.SetBool(c4d.TREEVIEW_CURSORKEYS, True)  # True if cursor keys should be processed.
        customgui.SetBool(c4d.TREEVIEW_NOENTERRENAME, False)  # Suppresses the rename popup when the user presses enter.

        if self.GroupBegin(id=1000, flags=c4d.BFH_SCALEFIT | c4d.BFV_SCALEFIT, rows=2, cols=1, groupflags=c4d.BORDER_OUT):
            self.GroupBorderSpace(left=5, top=5, right=5, bottom=5)
            self.GroupBorderNoTitle(borderstyle=c4d.BORDER_NONE)

            if self.GroupBegin(id=1001, flags=c4d.BFH_SCALEFIT | c4d.BFV_SCALEFIT, rows=2, cols=3, groupflags=c4d.BORDER_OUT):
                self.GroupBorderNoTitle(borderstyle=c4d.BORDER_NONE)
                self._treegui = self.AddCustomGui(TREEVIEW, c4d.CUSTOMGUI_TREEVIEW, "", c4d.BFH_SCALEFIT | c4d.BFV_SCALEFIT, minw=430, minh=160, customdata=customgui)
                if not self._treegui:
                    print("[ERROR]: Could not create TreeView")
                    return False
                self.GroupEnd()

            if self.GroupBegin(id=1002, flags=c4d.BFH_FIT | c4d.BFV_FIT, rows=2, cols=3, groupflags=c4d.BORDER_OUT):
                self.GroupBorderNoTitle(borderstyle=c4d.BORDER_NONE)

                self.AddStaticText(HOW_MANY, flags=c4d.BFV_CENTER | c4d.BFV_SCALE | c4d.BFH_LEFT | c4d.BFH_SCALE, name="Selected: 0 / " + str(self.overall))
                self.AddStaticText(HOW_MANY_MB, flags=c4d.BFV_CENTER | c4d.BFV_SCALE | c4d.BFH_LEFT | c4d.BFH_SCALE, name="Filesize Sum: __________")
                self.AddButton(MY_BUTON, c4d.BFH_CENTER, name="Enable me by check-boxing")
                self.Enable(MY_BUTON, False)
                self.GroupEnd()

            self.GroupEnd()

        return True

    def calc_selected(self):
        """this is a helper to calculate the selected elements and to enable the button

        :return: # slected and sum of the selecteed filsize
        """
        selected = 0
        filsizesum = 0
        self.overall = len(self._listView.listOfTexture)  # update our count

        for fileitem in self._listView.listOfTexture:
            if fileitem.IsSelected is True:
                filsizesum += fileitem.filesize
                selected += 1

        if selected > 0:
            self.Enable(MY_BUTON, True)
        else:
            self.Enable(MY_BUTON, False)

        sel_string = "Selected: " + str(selected) + " / " + str(self.overall)
        self.SetString(HOW_MANY, sel_string)

        mb_string = "Filesize Sum: " + str(filsizesum)
        self.SetString(HOW_MANY_MB, mb_string)

        return selected, filsizesum

    def InitValues(self):
        # Initialize the column layout for the TreeView.
        layout = c4d.BaseContainer()
        layout.SetLong(ID_CHECKBOX, c4d.LV_CHECKBOX)
        layout.SetLong(ID_NAME, c4d.LV_TREE)
        layout.SetLong(ID_LONGFILENAME, c4d.LV_USER)
        layout.SetLong(ID_OTHER, c4d.LV_USER)
        layout.SetLong(ID_FILESIZE, c4d.LV_USER)
        self._layout = layout
        self._treegui.SetLayout(5, layout)
 
        # Set the header titles.
        self._treegui.SetHeaderText(ID_CHECKBOX, "Check")
        self._treegui.SetHeaderText(ID_NAME, "Name")
        self._treegui.SetHeaderText(ID_LONGFILENAME, "Long Filename")
        self._treegui.SetHeaderText(ID_OTHER, "Other")
        self._treegui.SetHeaderText(ID_FILESIZE, "Filesize")

        self._treegui.Refresh()
 
        # Set TreeViewFunctions instance used by our CUSTOMGUI_TREEVIEW
        self._treegui.SetRoot(self._treegui, self._listView, None)

        return True
 
    def Command(self, id, msg):
        # Click on button
        if id == MY_BUTON:
            newID = int(len(self._listView.listOfTexture) + 1)
            tex = TextureObject()
            tex.texturePath = "Some new data " + str(newID)
            tex.longfilename = TextureObject.RandomString(20, 40)
            self._listView.listOfTexture.append(tex)
            self.calc_selected()
            self._treegui.Refresh()

        return True

 
class MenuCommand(c4d.plugins.CommandData):
    dialog = None
 
    def Execute(self, doc):
        if self.dialog is None:
            self.dialog = TestDialog()
        return self.dialog.Open(c4d.DLG_TYPE_ASYNC, PLUGIN_ID, defaulth=300, defaultw=430)
 
    def RestoreLayout(self, sec_ref):
        if self.dialog is None:
            self.dialog = TestDialog()
        return self.dialog.Restore(PLUGIN_ID, secret=sec_ref)
 
 
def main():
    c4d.plugins.RegisterCommandPlugin(
        PLUGIN_ID, "Python TreeView Example", 0, None, "Python TreeView Example", MenuCommand())


if __name__ == "__main__":
    main()