Assertion 'GDK_IS_SCREEN (screen)' fails in frozen app

[mherrmann]

Firstly, thanks for sharing this library. The concept is very elegant and useful.

I want to look up the icon for a directory (/home/michael in the code below):

import pgi
pgi.install_as_gi()
import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk,Gio

file_path = '/home/michael'

f = Gio.file_new_for_path(file_path)
file_info = f.query_info('standard::icon', 0, None)
icon_name = file_info.get_icon().get_names()[0]
icon_theme = Gtk.IconTheme.get_default()
icon_filename = icon_theme.lookup_icon(icon_name, 32, 0)
print(icon_filename.get_filename())

This works fine when I do it in my Python shell. However, when I freeze the above code with PyInstaller, I get:

(process:15580): Gtk-CRITICAL **: gtk_icon_theme_get_for_screen: assertion 'GDK_IS_SCREEN (screen)' failed
Traceback (most recent call last):
  File "main.py", line 13, in <module>
AttributeError: 'NoneType' object has no attribute 'lookup_icon'
Failed to execute script main

The main problem seems to be the failing assertion GDK_IS_SCREEN. Googling for this assertion, I found that it may be related to the environment variables DISPLAY and XDG_CURRENT_DESKTOP. Unfortunately, that doesn't seem to be it as they are both set correctly (to :0 and Unity, respectively).

Do you happen to know what else could cause the assertion GDK_IS_SCREEN to fail, in a frozen app?

[lazka]

Looks like gtk init failed (you can check the return of Gtk.init_check(None)). no idea why.

I'd try to get things working with pygobject instead to rule out any missing pgi features.

[mherrmann]

Wow, that was a quick response. Thanks!

I've been having trouble getting pygobject installed in my virtualenv. Why would you recommend pygobject over pgi in this case?

[lazka]

try virtualenv --system-site-packages venv

Why would you recommend pygobject over pgi in this case?

Because pgi is currently so far away from feature complete that you can't run any reasonable sized/useful application with it.

[mherrmann]

The above code would be all I need so I was hoping that if it works from the shell then I may also be able to use it when my app is frozen. But I'll follow your advice. Thanks again!

[lazka]

Oh ok. just wanted to mention that I've only seen the above error when DISPLAY was missing, as you suspected. Not sure how "freezing" could affect that..

[mherrmann]

One difference I could see is that PyInstaller doesn't seem to ship dependencies as .py files but somehow encodes them inside a binary. It must then use some import hook to load them. I saw that pgi also uses import hooks. Could it be that the two clash somehow?

[lazka]

Yeah, that might be a problem and prevent python overrides from loading (this isn't tested at least).Try calling Gtk.init(sys.argv) right after import.

[mherrmann]

You're a genius. Calling Gtk.init(sys.argv) right after import fixes the problem!

[lazka]

I've opened #39 for this. Thanks.