Make these configurable (+ environment variables support)

• bind to 0.0.0.0
• port

I asked for a code-review in the #beginners channel in the Rust discord and I got it

I couldn't find an API yet to convert a DynamicImage from image-rs to stream-able bytes. So, I write to the file system and read the bytes from the file to stream the image.

I am looking for an equivalent of image::load_from_memory(https://docs.rs/image/0.23.0-preview.0/image/fn.load_from_memory.html) for writing. Something like image::write_to_memory.

I tried digging into how save encodes an image and ran into this write_to function. It looks like save finds the file format with a match and encodes it to write to the specified path. Maybe, there is an API to do that to a buffer that I am not aware of.

Related issues:

image-rs/image#982
image-rs/image#834
image-rs/image#827

P.S. This looks like my answer, the write_to that I ran into is actually available on the DynamicImage object.

Originally, I made this for a very specific need of the https://readbot.app project. I just needed to grayscale images (no color on kindle's e-ink display yet) and scale them down to 600 pixels width because I wanted to reduce the size.

But this project can be expaneded to expose image-rs (what a beautiful project 🎉) with a web interface.

This can be done by exposing the image processing functions as GET parameters. I can think if this being the supported API:

Legend:

• ? indicates that I don't know anything about that and can't make a decision yet (If you know, please feel free to change it via a PR).
• Everything else is where I know something, just enough to make a first wild guess. By no means it means that I know a lot about that image processing function.
• (x, y) is a tuple representing multiple get parameters or their types or values

Support image formats other than png

Resources:

• https://www.rust-lang.org/what/wasm
• https://github.com/rustwasm/wasm-bindgen
• https://hacks.mozilla.org/2018/04/javascript-to-rust-and-back-again-a-wasm-bindgen-tale/