Python-Logo-Widgets

Python Logo Widgets — Architecture

Seventy lines of implementation, and two details that make it work.

python_logo_widgets/
├── widgets.py    three tk.Frame subclasses
├── _compat.py    the original function API, wrapping the classes
├── _demo.py      the standalone demo
├── __main__.py   python -m entry
└── imgs/         logo.gif, length.gif, width.gif

The widgets

All three are the same shape:

class LogoWidget(tk.Frame):
    def __init__(self, parent, bg="black", **kwargs):
        super().__init__(parent, **kwargs)
        self._image = tk.PhotoImage(file=_load_image("logo.gif"))
        self._label = tk.Label(self, image=self._image, bg=bg)
        self._label.pack(fill=tk.BOTH, expand=True)

Subclassing Frame rather than exposing a function is what makes them embeddable — the caller places them like any other widget, in any geometry manager, inside any container.

Detail one: finding the images

from importlib.resources import files

def _load_image(image_name):
    return str(files("python_logo_widgets.imgs").joinpath(image_name))

Resolved through the package, not by a path relative to the source file or the working directory. That is why the widgets work identically from a source checkout, a wheel install, and someone else’s application — the three ways a bundled resource usually gets lost.

imgs/__init__.py exists to make the directory an importable package so files() can address it.

One limitation: str() on the result assumes the resource has a real filesystem path, which is true for a normal pip install and not for a zipped package. importlib.resources.as_file() is the supported idiom. See internal/known-issues.md.

Detail two: keeping the images alive

self._image = tk.PhotoImage(...)

Tkinter holds no Python reference to a PhotoImage. An image assigned only to a local would be garbage-collected when __init__ returns, and the label would render blank with no error — the single most common Tkinter bug, and one that looks like a missing file.

Binding it to the instance ties the image’s lifetime to the widget’s, which is exactly right.

_compat.py

The original API was three functions that each opened a window:

def logo_widget():
    root = tk.Tk()
    root.title("Python Logo Widget")
    LogoWidget(root).pack()
    root.mainloop()

They are kept, implemented in terms of the new classes rather than duplicating them, so old code keeps working and there is one implementation. Underscore-prefixed to signal they are not the recommended API.

_demo.py and __main__.py

The demo window shown by python-logo-widgets and python -m python_logo_widgets. Separate from the library so importing the package opens nothing.

Why GIF

Tkinter’s PhotoImage reads GIF and PNG only. PNG would work; GIF is what is bundled. Anything else — JPEG, SVG, WebP — needs Pillow, and a widget package that pulled in an imaging library to show three static badges would not be worth depending on.

What is not here

No scaling, no theming beyond bg, no state, no I/O. The package loads three images and draws them, and its correctness is entirely in the two details above.

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