Remove widget from Gtk viewport / scrolled window in dynamic GUI

Question

I am building a GUI (Python binding of GTK3) where one Gtk Scrolled Window (from Glade) can contain different treeviews. The program launches with an empty window and the first time around everything works with:

 self.scrolled_window.add_with_viewport(treeview)
 self.main_window.show_all()

Edit: Picture of the test program (see source below):

The second time around I get the following error:

(main.py:15905): Gtk-CRITICAL **: gtk_scrolled_window_add_with_viewport: assertion 'gtk_bin_get_child (GTK_BIN (child_widget)) == NULL' failed

I think that I might need to empty the viewport or scrolled window first, but don't know how that is done and can't find any documentation for it.

Edit: When using self.scrolled_window.remove(self.scrolled_window.get_child()) I don't see the dataset at the start up and error messages appear when switching layers.

Edit: I updated the code once more so the example data is there right from the start.

The glade file (test_project.glade):

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.16.1 -->
<interface>
  <requires lib="gtk+" version="3.10"/>
  <object class="GtkWindow" id="window1">
    <property name="can_focus">False</property>
    <property name="default_width">440</property>
    <property name="default_height">250</property>
    <signal name="destroy" handler="on_window1_destroy" swapped="no"/>
    <child>
      <object class="GtkBox" id="box1">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkScrolledWindow" id="scrolledwindow1">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="shadow_type">in</property>
            <child>
              <placeholder/>
            </child>
          </object>
          <packing>
            <property name="expand">True</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkScrolledWindow" id="scrolledwindow2">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="shadow_type">in</property>
            <child>
              <placeholder/>
            </child>
          </object>
          <packing>
            <property name="expand">True</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
        <child>
          <object class="GtkBox" id="box2">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <child>
              <object class="GtkButton" id="add_layer">
                <property name="label" translatable="yes">add layer</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <signal name="clicked" handler="on_add_layer_clicked" swapped="no"/>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">True</property>
                <property name="position">0</property>
              </packing>
            </child>
            <child>
              <object class="GtkButton" id="add_data">
                <property name="label" translatable="yes">add data</property>
                <property name="name">add_data</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <signal name="clicked" handler="on_add_data_clicked" swapped="no"/>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">True</property>
                <property name="position">1</property>
              </packing>
            </child>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">2</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>

The python code:

#!/usr/bin/python3

from gi.repository import Gtk
import random

class BottomTreeView(Gtk.TreeView):
    def __init__(self, store):
        Gtk.TreeView.__init__(store)
        self.store = store

        renderer = Gtk.CellRendererText()
        column = Gtk.TreeViewColumn("Dataset", renderer, text=0)
        self.append_column(column)

        for x in range(10):
            self.store.append(None, [str(random.random())])

class MainWindow(object):
    def __init__(self, builder):
        self.main_window = builder.get_object("window1")
        self.sw1 = builder.get_object("scrolledwindow1")
        self.sw2 = builder.get_object("scrolledwindow2")
        self.layernumber = 0

        self.topstore = Gtk.TreeStore(str, object)
        self.topview = Gtk.TreeView(self.topstore)
        renderer1 = Gtk.CellRendererText()
        column1 = Gtk.TreeViewColumn("Name", renderer1, text=0)
        self.topview.append_column(column1)
        self.sw1.add_with_viewport(self.topview)

        #Adding test data in a dumb way
        self.store1 = Gtk.TreeStore(str)
        for x in range(10):
            self.store1.append(None, [str(random.random())])
        self.view1 = Gtk.TreeView(self.store1)
        self.rend1 = Gtk.CellRendererText()
        self.col1 = Gtk.TreeViewColumn("Dataset", self.rend1, text=0)
        self.view1.append_column(self.col1)
        self.sw2.add_with_viewport(self.view1)
        self.topstore.append(None, ["Layer 1", self.view1])

        self.store2 = Gtk.TreeStore(str)
        for x in range(10):
            self.store2.append(None, [str(random.random())])
        self.view2 = Gtk.TreeView(self.store2)
        self.rend2 = Gtk.CellRendererText()
        self.col2 = Gtk.TreeViewColumn("Dataset", self.rend2, text=0)
        self.view2.append_column(self.col2)
        self.topstore.append(None, ["Layer 2", self.view2])

        self.select = self.topview.get_selection()
        self.select.connect("changed", self.on_tree_selection_changed)
        self.main_window.show_all()

    def on_add_layer_clicked(self, widget):
        self.layernumber += 1
        store = Gtk.TreeStore(str)
        bottom = BottomTreeView(store)
        self.topstore.append(None, [str(self.layernumber), bottom])

    def on_add_data_clicked(self, widget):
        self.selection = self.topview.get_selection()
        model, treeiter = self.selection.get_selected()
        print("Adding data to {0}".format(model[treeiter][0]))
        datasheet = model[treeiter][1]
        datasheet.store.append(None, [str(random.random())])

    def on_window1_destroy(self, widget):
        Gtk.main_quit()

    def on_tree_selection_changed(self, selection):
        print("\n>>> Selection changed")
        model, treeiter = selection.get_selected()
        print(">>> Model: {0}, Treeiter: {1}".format(model, treeiter))
        if treeiter != None:
             print(">>> You selected Layer {0}.".format(model[treeiter][1]))
             tree_obj = model[treeiter][1]
             #The following lines mess up the program from the startup
             #self.sw2.remove(self.sw2.get_child())
             #self.sw2.add_with_viewport(tree_obj)
             #self.main_window.show_all()

def main():
    builder = Gtk.Builder()
    objects = builder.add_objects_from_file("test_project.glade",
         ("window1", ""))

    window_instance = MainWindow(builder)
    builder.connect_signals(window_instance)
    Gtk.main()

if __name__ == "__main__":
     main()

Taraxacum

Funny how they left Gtk.ScrolledWindow() out of the examples: python-gtk-3-tutorial.readthedocs.io..? – Cunnilingus

Answer 1

To clear out the scrolled window, do this:

self.scrolled_window.remove(self.scrolled_window.get_child())

Anesthetize

This works fine for switching through the widgets once. The second time a widget is called the program crashes: "Warning: g_object_freeze_notify: assertion 'G_IS_OBJECT (object)' failed". I will try to include an example program in my question. – Taraxacum

Made some progress. Might be able to answer it myself. Need another hour :) – Taraxacum

Answer 2

After the answer by ptomato I realized that I was adding the TreeViews by using:

  self.scrolled_window.add_with_viewport(some_treeview)

For some reason the scrolled_window.remove() function does not like viewports. Instead one should use:

  self.scrolled_window.add(some_treeview)

It probably makes sense because the documentation states that:

If a widget has native scrolling abilities, such as Gtk.TextView, Gtk.TreeView or Gtk.IconView, it can be added to a Gtk.ScrolledWindow with Gtk.Container.add (). If a widget does not, you must first add the widget to a Gtk.Viewport, then add the viewport to the scrolled window.

(Source: https://lazka.github.io/pgi-docs/Gtk-3.0/classes/Viewport.html)

So because a Gtk.TreeView is already scrollable it should not go into a separate Gtk.Viewport widget.

Working example

I cleaned up the example from above and it is now fully functioning:

Glade file

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.16.1 -->
<interface>
  <requires lib="gtk+" version="3.10"/>
  <object class="GtkWindow" id="window1">
    <property name="can_focus">False</property>
    <property name="default_width">800</property>
    <property name="default_height">600</property>
    <signal name="destroy" handler="on_window1_destroy" swapped="no"/>
    <child>
      <object class="GtkBox" id="box1">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkBox" id="box2">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <child>
              <object class="GtkScrolledWindow" id="scrolledwindow1">
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="shadow_type">in</property>
                <child>
                  <placeholder/>
                </child>
              </object>
              <packing>
                <property name="expand">True</property>
                <property name="fill">True</property>
                <property name="position">0</property>
              </packing>
            </child>
            <child>
              <object class="GtkScrolledWindow" id="scrolledwindow2">
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="shadow_type">in</property>
                <child>
                  <placeholder/>
                </child>
              </object>
              <packing>
                <property name="expand">True</property>
                <property name="fill">True</property>
                <property name="position">1</property>
              </packing>
            </child>
          </object>
          <packing>
            <property name="expand">True</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkBox" id="box3">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <child>
              <object class="GtkButton" id="add_layer">
                <property name="label" translatable="yes">add layer</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <signal name="clicked" handler="on_add_layer_clicked" swapped="no"/>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">True</property>
                <property name="position">0</property>
              </packing>
            </child>
            <child>
              <object class="GtkButton" id="add_data">
                <property name="label" translatable="yes">add data</property>
                <property name="name">add_data</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <signal name="clicked" handler="on_add_data_clicked" swapped="no"/>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">True</property>
                <property name="position">1</property>
              </packing>
            </child>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>

Python file

#!/usr/bin/python3

from gi.repository import Gtk
import random

class LayerTreeView(Gtk.TreeView):
    def __init__(self, store):
        Gtk.TreeView.__init__(self, store)
        renderer = Gtk.CellRendererText()
        column = Gtk.TreeViewColumn("Name", renderer, text=0)
        self.append_column(column)

class DataTreeView(Gtk.TreeView):
    def __init__(self, store):
        Gtk.TreeView.__init__(self, store)
        self.store = store
        renderer = Gtk.CellRendererText()
        column = Gtk.TreeViewColumn("Dataset", renderer, text=0)
        self.append_column(column)

        for x in range(10):
            self.store.append(None, [str(random.random())])

class MainWindow(object):
    def __init__(self, builder):
        self.main_window = builder.get_object("window1")
        self.sw1 = builder.get_object("scrolledwindow1")
        self.sw2 = builder.get_object("scrolledwindow2")
        self.layernumber = 1

        #Initializing top TreeStore and TreeView
        #First object is the store, second is the view of the bottom data-view
        self.topstore = Gtk.TreeStore(str, object, object)
        self.topview = LayerTreeView(self.topstore)
        self.sw1.add(self.topview)

        #Adding some testdata
        for x in range(3):
            datastore = Gtk.TreeStore(str)
            dataview = DataTreeView(datastore)
            layername = "Layer {0}".format(self.layernumber)
            self.layernumber += 1
            self.topstore.append(None, [layername, datastore, dataview])

        self.select = self.topview.get_selection()
        self.select.connect("changed", self.on_tree_selection_changed)
        self.main_window.show_all()

    def on_add_layer_clicked(self, widget):
        datastore = Gtk.TreeStore(str)
        dataview = DataTreeView(datastore)
        layername = "Layer {0}".format(self.layernumber)
        self.layernumber += 1
        self.topstore.append(None, [layername, datastore, dataview])

    def on_add_data_clicked(self, widget):
        self.selection = self.topview.get_selection()
        model, treeiter = self.selection.get_selected()
        if treeiter != None:
            data_object = model[treeiter][1]
            data_object.append(None, [str(random.random())])

    def on_window1_destroy(self, widget):
        Gtk.main_quit()

    def on_tree_selection_changed(self, selection):
        model, treeiter = selection.get_selected()
        if treeiter != None:
            treeview_object = model[treeiter][2]
            child = self.sw2.get_child()
            if child != None:
                self.sw2.remove(self.sw2.get_child())
            self.sw2.add(treeview_object)
            self.main_window.show_all()

def main():
    builder = Gtk.Builder()
    objects = builder.add_objects_from_file("treeview_switcher.glade",
         ("window1", ""))

    window_instance = MainWindow(builder)
    builder.connect_signals(window_instance)
    Gtk.main()

if __name__ == "__main__":
     main()

Taraxacum

"If a widget has native scrolling abilities, such as Gtk.TextView, Gtk.TreeView or Gtk.IconView, it can be added to a Gtk.ScrolledWindow with Gtk.Container.add (). If a widget does not, you must first add the widget to a Gtk.Viewport, then add the viewport to the scrolled window." This is, put simply, untrue. A Gtk.TreeView does NOT have "native scrolling abilities"'. There is a HUGE problem with Gtk+3 documentation, specially (but not limited to) the Gtk.ScrolledWindow. – Cunnilingus