From Python Code to a Bootable Graphics OS

#osdev #aetherix #python #opensource

One of the classic milestones in hobby operating system development is switching from text mode to graphics mode. In this example, Aetherix boots into VGA Mode 13h, plays a loading animation, renders a full-screen background, and composites a logo all from Python code that builds a bootable disk image.

Highlights

🎞️ Loading animation
🎨 VGA Mode 13h graphics
🖼️ Full-screen background rendering
🪟 Logo compositing
💾 Bootable disk image generation
🐍 Written in Python with Aetherix

The example preprocesses images at build time, generating a shared VGA palette for the background and logo. When the system boots, the kernel simply renders the prepared pixel data, resulting in a fast graphical startup.

Source code

from os import system as s
from pathlib import Path

from aetherix import Project, imaging
from aetherix.drivers import graphics

ASSETS_DIR = Path(__file__).resolve().parent / "assets"

# -- Prepare assets at build time (resizing/quantizing happens here, not
#    at boot -- the kernel only ever handles already-prepared bytes) --
loading_frames = [
    imaging.load_image(ASSETS_DIR / f"loading_{i}.png") for i in range(6)
]

# background and logo will be on screen AT THE SAME TIME, so they must
# share one 256-color palette -- VGA Mode 13h has a single palette for the
# whole screen, not one per image (see imaging.load_images_shared_palette).
background, logo = imaging.load_images_shared_palette([
    (ASSETS_DIR / "background.png", graphics.GFX_WIDTH, graphics.GFX_HEIGHT, True),
    (ASSETS_DIR / "logo.png", 64, 64, False),
])

LOGO_X = (graphics.GFX_WIDTH - logo.width) // 2
LOGO_Y = (graphics.GFX_HEIGHT - logo.height) // 2

with Project("GraphicsOS", graphics_mode=graphics.MODE_13H) as os_:

    @os_.kernel_entry
    def main(prog, drivers):
        # 1. Loading animation -- plays once, then falls through.
        drivers.graphics.play_frames(prog, loading_frames, delay_iterations=3_000_000, loop=False)

        # 2. Home screen -- background, then a logo composited on top.
        drivers.graphics.show_image(prog, background, x=0, y=0)
        drivers.graphics.show_image(prog, logo, x=LOGO_X, y=LOGO_Y)

        prog.hlt()

    out = os_.build(str("graphics_os.img"))
    print(f"Built: {out} ({out.stat().st_size} bytes)")
    print(f"Kernel sectors: {(len(os_.kernel.assemble()) + 511) // 512}")
    print("Boot it with: qemu-system-i386 -drive file=graphics_os.img,format=raw")
    s("qemu-system-i386 -drive file=graphics_os.img,format=raw")