Glade - Invalid object type 'WebKitWebView' when loading from file. works on Glade Application

问题

I am building a python GTK application and I used Glade to define the interface. (using the Glade Interface Designer).

Everything look good on Glade but when I try to create the GUI from my Python program it gives a error loading Webkit related views:

Glade - Invalid object type 'WebKitWebView'

It works fine in Glade Designer and also if I create the widgets manually, but the Builder doesn't like it.

I am building the ui like this:

GtkBuilder = Gtk.Builder.new_from_file("glade/main.glade")
GtkBuilder.connect_signals(self)

My .glade file:

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.22.0 -->
<interface>
  <requires lib="gtk+" version="3.12"/>
  <requires lib="webkit2gtk" version="4.0"/>
  <object class="GtkPopover" id="popover1">
    <property name="can_focus">False</property>
    <child>
      <placeholder/>
    </child>
  </object>
  <object class="WebKitSettings" id="wv_settings">
    <property name="enable_developer_extras">True</property>
    <property name="enable_dns_prefetching">True</property>
    <property name="enable_webaudio">True</property>
    <property name="enable_webgl">True</property>
    <property name="user_agent">Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/11.0 Safari/605.1.15</property>
    <property name="enable_smooth_scrolling">True</property>
    <property name="enable_accelerated_2d_canvas">True</property>
    <property name="enable_media_stream">True</property>
    <property name="enable_mediasource">True</property>
    <property name="enable_encrypted_media">True</property>
  </object>
  <object class="GtkApplicationWindow" id="MainWindow">
    <property name="can_focus">False</property>
    <property name="window_position">center</property>
    <property name="default_width">440</property>
    <property name="default_height">250</property>
    <property name="deletable">False</property>
    <child>
      <object class="WebKitWebView" id="webview">
        <property name="visible">True</property>
        <property name="can_focus">True</property>
        <property name="settings">wv_settings</property>
        <property name="is_ephemeral">True</property>
        <signal name="decide-policy" handler="on_webview_decide_policy" swapped="no"/>
        <signal name="load-changed" handler="on_webview_load_changed" swapped="no"/>
        <child>
          <placeholder/>
        </child>
      </object>
    </child>
    <child type="titlebar">
      <object class="GtkHeaderBar" id="header">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <child>
          <object class="GtkButton" id="btn_back">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="receives_default">True</property>
            <signal name="clicked" handler="on_back_btn_clicked" swapped="no"/>
            <child>
              <object class="GtkImage">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="stock">gtk-go-back</property>
              </object>
            </child>
          </object>
        </child>
        <child>
          <object class="GtkButton" id="btn_forward">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="receives_default">True</property>
            <signal name="clicked" handler="on_btn_forward_clicked" swapped="no"/>
            <child>
              <object class="GtkImage">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="stock">gtk-go-forward</property>
              </object>
            </child>
          </object>
          <packing>
            <property name="position">1</property>
          </packing>
        </child>
        <child>
          <object class="GtkButton" id="btn_refresh">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="receives_default">True</property>
            <signal name="clicked" handler="on_btn_refresh_clicked" swapped="no"/>
            <child>
              <object class="GtkImage">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="stock">gtk-refresh</property>
              </object>
            </child>
          </object>
          <packing>
            <property name="position">2</property>
          </packing>
        </child>
        <child type="title">
          <object class="GtkEntry">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="width_chars">30</property>
            <property name="caps_lock_warning">False</property>
            <property name="input_purpose">url</property>
            <signal name="activate" handler="on_search_input" swapped="no"/>
          </object>
          <packing>
            <property name="position">3</property>
          </packing>
        </child>
        <child>
          <object class="GtkButton" id="btn_close">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="receives_default">True</property>
            <signal name="clicked" handler="on_btn_close_clicked" swapped="no"/>
            <child>
              <object class="GtkImage">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="stock">gtk-close</property>
              </object>
            </child>
          </object>
          <packing>
            <property name="pack_type">end</property>
            <property name="position">2</property>
          </packing>
        </child>
        <child>
          <object class="GtkButton" id="btn_settings">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="receives_default">True</property>
            <signal name="clicked" handler="on_btn_settings_clicked" swapped="no"/>
            <child>
              <object class="GtkImage">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="stock">gtk-preferences</property>
              </object>
            </child>
          </object>
          <packing>
            <property name="pack_type">end</property>
            <property name="position">5</property>
          </packing>
        </child>
        <child>
          <object class="GtkMenuButton" id="menu">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="receives_default">True</property>
            <property name="popover">popover1</property>
            <child>
              <object class="GtkImage">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="stock">gtk-index</property>
              </object>
            </child>
          </object>
          <packing>
            <property name="pack_type">end</property>
            <property name="position">5</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>

Any ideas what I am doing wrong?

Thank you.

回答1:

The widget needs to have been instantiated once before you use it, I guess it's just the case for non-GTK+ widgets.

The code below is Vala, but you get the point:

namespace MyApp {
    using WebKit;

    [GtkTemplate (ui = "/org/gnome/MyApp/window.ui")]
    public class Window : Gtk.ApplicationWindow {
        public Window (Gtk.Application app) {
            WebView webview = new WebView();

            Object (application: app);          
        }
    }
}

回答2:

Instead of instantiated it like @mrzapp, you should use following code

typeof(WebKit.WebView).ensure();

Ensures that the indicated type has been registered with the type system, and its _class_init method has been run.

https://valadoc.org/gobject-2.0/GLib.Type.ensure.html

来源：https://stackoverflow.com/questions/51010820/glade-invalid-object-type-webkitwebview-when-loading-from-file-works-on-gla