FileNotFoundError on fonts due to Windows Font Blocking policy

[wedgef5]

I have a PySide6 application using QtAwesome which has worked fine on every machine I have installed it on up until now. On this new machine, the application fails to start with a FileNotFoundError on fontawesome4-webfont-4.7.ttf. I have created a small test application, which exhibits the same problem...

import sys
import qtawesome as qta
from PySide6.QtWidgets import (QApplication, QWidget, QGridLayout,
                               QToolButton, QLabel)

app = QApplication(sys.argv)

window = QWidget()
layout = QGridLayout(window)
names = ['fa5s.grip-horizontal', 'fa5s.file-export', 'fa5s.file-import']
for i, name in enumerate(names):
    qicon = qta.icon(name, scale_factor=1.3)
    btn = QToolButton()
    btn.setIcon(qicon)
    btn.setIconSize(QSize(32, 32))
    layout.addWidget(btn, i, 0)
    layout.addWidget(QLabel(name), i, 1)
window.show()

sys.exit(app.exec_())

The error I get is this...

Traceback (most recent call last):
  File "C:\...\pydev\qta_test\qta_test.py", line 12, in <module>
    qicon = qta.icon(name, scale_factor=1.3)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\...\pydev\qta_test\.venv\Lib\site-packages\qtawesome\__init__.py", line 234, in icon
    return _instance().icon(*names, **kwargs)
           ^^^^^^^^^^^
  File "C:\...\pydev\qta_test\.venv\Lib\site-packages\qtawesome\__init__.py", line 130, in _instance
    _resource['iconic'] = IconicFont(*_BUNDLED_FONTS)
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\...\pydev\qta_test\.venv\Lib\site-packages\qtawesome\iconic_font.py", line 337, in __init__
    self.load_font(*fargs)
  File "C:\...\pydev\qta_test\.venv\Lib\site-packages\qtawesome\iconic_font.py", line 377, in load_font
    with open(os.path.join(directory, ttf_filename), 'rb') as font_data:
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: 'C:\\...\\AppData\\Local\\Microsoft\\Windows\\Fonts\\fontawesome4-webfont-4.7.ttf'

I'm using a venv, which works on every other machine I've installed on. The fontawesome4-webfont-4.7.ttf file is not present on any of the machines in the AppData path in the traceback. It IS in .venv\Lib\site-packages\qtawesome\fonts on every machine, including the one on which the error is occurring.

This is on Windows 11 and Python 3.12.5 installed from the python.org installer.

[wedgef5]

Update...

The virtual environment doesn't matter. The same error occurs with PySide6 and QtAwesome installed in the base Python's site-packages and the venv deactivated.

[ccordoba12]

Hey @wedgef5, thanks for reporting. Do you have permissions to write to this directory?

C:\\...\\AppData\\Local\\Microsoft\\Windows\\Fonts\\

[wedgef5]

@ccordoba12 Yes. It is within my home directory. I also tried doing the entire install from an elevated CMD window, and it made no difference. None of the machines that I have installed on (including all of those that are working correctly) have the fonts in that path.

[wedgef5]

One other factor worth noting: the machine where I'm having this problem is my work computer, and it is controlled by group policy from above. That said, I typically have great freedom within my own home directory and I do have admin access on the local machine. I have checked the "trusted fonts" setting as noted in #167 but that is not enabled on my machine. I do not know of any other setting that would cause the fonts to not be read from site-packages\qtawesome\fonts.

[wedgef5]

I have determined that this issue is being caused by the Windows "untrusted font blocking" policy. In my case, however, it appears to be slightly different than what was addressed in #167. The Group Policy on my machine seems to not allow ANY fonts to be installed at all. I have some administrator access on my local machine, and I still can't do it. Even after copying the ttf files to %SystemRoot%\Fonts (which is supposed to be the location to put "trusted" fonts), the Install button in File Explorer is grayed out. If I try to right-click, Install, I get a message about the file not being a "valid" font file. My Windows Event Viewer is full of messages about the font installation being blocked.

I think the reason I was getting the FileNotFoundException is due to this section of iconic_font.py in IconicFont._install_fonts()

                if os.path.splitext(filename)[-1] == '.ttf':
                    # Load the font in the current session
                    if not gdi32.AddFontResourceW(dst_path):
                        try:
                            os.remove(dst_path)
                        except OSError:
                            # Possible permission error when trying to remove
                            # a font which potentially is already in use
                            # See spyder-ide/qtawesome#236
                            continue

When gdi32.AddFontResourceW() fails (due to the blocking policy), it returns zero. That causes the file to be removed from the user Font directory, then load_font() tries to open it.

Should a separate issue be opened to more gracefully handle this case of font-blocking or perhaps just rename this issue?

[dalthviz]

Thank you for the extra info @wedgef5 ! I think renaming this issue should be enough 👍 Also, do you have any suggestion regarding how we could improve the font-blocking case? Let us know!

[wedgef5]

I have edited the subject of the bug to be a bit more descriptive. There are two possibilities I can think of to try and address this. In my case, I believe the font installation failed silently, so I had no idea what was going on, and I spent a lot of time trying to diagnose why I was getting the FileNotFoundError. Is there some way that a simple test could be added to the installation process such that the user would be alerted to this possibility?

In my case, I can see no easy way to use the TTF files. I have started working on migrating the font usage in my application to use SVG files instead. Is there any appetite for including SVG versions of the fonts as a fallback?

[dalthviz]

Is there some way that a simple test could be added to the installation process such that the user would be alerted to this possibility?

We will need to check into that, but maybe improving the check that can end up removing the font file by querying the available fonts with something like https://stackoverflow.com/a/51259162/15954282 and then raising a FontError in case we are able to determine that the font was unable to be added/installed? 🤔

In my case, I can see no easy way to use the TTF files. I have started working on migrating the font usage in my application to use SVG files instead. Is there any appetite for including SVG versions of the fonts as a fallback?

I think a fallback is something that we have discussed before (#175) but using an icon in the font itself 🤔 Having the ability to use icons from SVG could make sense what do you think @ccordoba12 ?