elem

Logitech Battery Level Tray Indicator

Show your wireless Logitech devices battery levels in your system tray.

The name comes from the Hungarian word for battery: elem.

Usage

Installing from crates.io

To install from crates.io you must have Rust installed.

cargo install elem --force

Downloading a Prebuilt Binary

To start using elem, download and execute the latest executable from the releases page: Fuwn/elem/releases/latest.

Building Yourself

To build elem, you must have Rust and Git installed on your system.

1. Clone this repository: git clone https://github.com/Fuwn/elem.git
2. Navigate into your local repository: cd elem
3. Build elem: cargo build elem --release
4. elems executable will be located at target/release/elem

Notes

Update Frequency

By default, elem fetches the selected devices battery level every minute. This should be more than enough for most people considering how well Logitech devices conserve power.

If you would like to increase -- or decrease -- the update frequency, you can launch elem from the command-line and pass a value in milliseconds which will be your new update frequency.

$ ./elem 60000  # Updates every 60 seconds (60000ms / 1000ms = 60s)
$ ./elem 1000   # Updates every second (1000ms = 1s)
$ ./elem 120000 # Updates every two minutes (120000ms / 1000ms = 120s)

Frozen?

If elem seems frozen, it isn't. It's just waiting for watchman (battery level fetcher) to return a value.

Solution

Writing this project was actually pretty interesting.

The main problem I had to solve was how I was displaying the battery level from just the number. My first thought was just downloading a bunch of icons and bundling them together with the program. Soon I realized that it's actually not that easy to find royalty free icons that don't look terrible. On top of that, do you really want to carry around 100+ icons with you just to display a number? I ditched that and started going down the procedural route. I tried to locate a Rust crate that generated images from text, but surprisingly, I couldn't find any. Just numbers to text? Still, nope. This lead me to my next item to solve: generating images from numbers.

My first idea which I ended up using is generating ASCII art from numbers. Once again, to my surprise, I couldn't find a crate that did this. (Side note; I actually ended up finding a crate that somewhat accomplished this, but by the time I did, I had already finished my own implementation. I actually prefer my implementation to the crate as this gives me a lot more control over the final result.) Using Patrick Gillespie's Text to ASCII Art Generator (TAAG), I was able to extract a few important ASCII art pieces: numbers zero through nine; and eventually, I ended up needing a set of ellipsis, a question mark, and a smiley face.

Using these fundamental pieces, I was able to write a set of functions to generate ASCII art any number combination I wanted. The great thing about this is that it's all ASCII characters, meaning that I can easily iterate over the lines and characters and convert it into a ad-hoc pixel art. In just a few simple steps, I could take any ASCII pixel art and convert it into a RGBA image using these steps:

1. Find the width of the ASCII art
2. Strip the newline characters so that the entire ASCII art is on one line
3. Iterate over each character in the ASCII art, writing the corresponding pixel value to an image buffer: 0 0 0 0 for an empty pixel and 255 255 255 255 for a filled pixel (red, green, blue, alpha).
4. Save the image buffer to memory and use it as the icon for the tray indicator. :)

Pretty cool, right?

In the future, I'll see if I can optimize this process a bit more, but since the main bottleneck is Logitech G HUBs API, it's not that big of a deal.

License

This project is licensed with the GNU General Public License v3.0.