Add a background to a PNG file

add_bg_to_png.py

#!/usr/bin/env pip-run
"""Takes a PNG file, adds a white background to it, and copies it to the
clipboard.

Uses `pip-run` to run the script with the required packages installed.

This script is licensed under the MIT License.
Copyright © 2024 Kyle L. Davis
"""
__requires__ = ["Pillow", "pywin32"]

import io
import sys
from pathlib import Path
from typing import TypeAlias
from typing import Union

import win32clipboard
from PIL import Image


PathLike = Union[str, bytes, Path]
RGBA: TypeAlias = tuple[int, int, int, int]


def add_white_bg_to_png(
    png_file: PathLike,
    copy: bool = True,
    open: bool = False,
    background_color: RGBA = (255, 255, 255, 255),
) -> None:
    """Add a white background to a PNG file and copy it to the clipboard."""
    with Image.open(png_file) as img:
        img = img.convert("RGBA")
        bg = Image.new("RGBA", img.size, background_color)
        img = Image.alpha_composite(bg, img)

        # Copy to clipboard
        if copy:
            output = io.BytesIO()
            img.convert("RGB").save(output, "BMP")
            data = output.getvalue()[14:]
            output.close()
            win32clipboard.OpenClipboard()
            win32clipboard.EmptyClipboard()
            win32clipboard.SetClipboardData(win32clipboard.CF_DIB, data)
            win32clipboard.CloseClipboard()

        # Open the image
        if open:
            img.show()
        print("Image copied to clipboard.")


if __name__ == "__main__":
    if len(sys.argv) != 2:
        print(f"Usage: {sys.argv[0]} <png_file>")
        print(
            "Takes a PNG file and adds a white background to it, copying it to the clipboard."
        )
        raise SystemExit(1)

    add_white_bg_to_png(sys.argv[1])