This houses the RLE-like image format decoder for progressive animation of the Oro logo in constrained environments, such as kernels and embedded devices.

A singular, concrete, non-generic iterator type is exposed (OroLogo) that, when iterated, gives an endless stream of cursor commands useful for continuously updating a persistent buffer of pixel information.

The format supports up to 4 lightness levels (0..=3) that can be used for a primitive amount of anti-aliasing, and are supported by many OLED/LCD displays alike.

The iterator itself performs a single base draw on the first frame, followed by an endless looping stream of update frames that modify the previously drawn frame directly. This includes the frame that 'wraps around' to the first frame, avoiding expensive redraws when the animation loops (however there is still a small decompression cost upon looping).

The library is optimized for cases where individual pixel updates are expensive (e.g. direct-to-framebuffer rasterizer implementations, such as those found in the Oro kernel, or bus-issued pixel updates, such as those over SPI or I²C lines).

The entire logo animation for the 256x256 variant, as of June 20, 2023, fits in about 23KiB of static storage.

Usage

You can see a (mostly cross-platform) in-terminal example by running

cargo run --example terminal

You may also dump raw greyscale frame data using dump:

cargo run --example dump > /tmp/oro-logo.bin
# using ImageMagick's `convert` utility...
convert -delay 4 -loop 0 -size 256x256 -depth 8 gray:/tmp/oro-logo.bin /tmp/oro-logo.gif

Implementing the decoder for a buffer of 256x256 linear pixels should be as simple as the following:

use oro_logo_rle::{
	OroLogo, Command, OroLogoData,

	// with feature `oro-logo-1024`
	OroLogo1024x1024,
	// with feature `oro-logo-512`
	OroLogo512x512,
	// with feature `oro-logo-256`
	OroLogo256x256,
	// with feature `oro-logo-64`
	OroLogo64x64,
	// with feature `oro-logo-32`
	OroLogo32x32,
};

type OroLogoSized = OroLogo::<OroLogo256x256>;
let mut iter = OroLogoSized::new();

// (uses fictional `Color` type)
let mut buffer = [Color; OroLogoSized::WIDTH * OroLogoSized::Height];

loop {
	let mut off = 0usize;

	match iter.next() {
		None => panic!("Oro logo exhausted commands (shouldn't happen)"),

		Some(Command::End) => break,

		Some(Command::Draw(count, lightness)) => {
			let color = match lightness {
				0 => Color::Black,
				1 => Color::DarkGray,
				2 => Color::Gray,
				3 => Color::White,
				_ => unreachable!(),
			};

			for i in 0..count {
				buffer[off + (i as usize)] = color;
			}

			off += count as usize;
		}

		Some(Command::Skip(count)) => {
			off += count as usize;
		}
	}

	// (fictional per-frame operations)
	preset(&buffer);
	sleep_ms(1000 / ORO_LOGO_FPS);
}

After Effects Project

The After Effects project contains all of the assets necessary to re-create the logo, and is located in after-effects.

License

Copyright © 2023, Joshua Lee Junon.

A license is to be determined. Please do not use code or assets in this repository in any fashion until one is issued.