Add support for FAP icons

[dcoles]

Discussed in #20

^{Originally posted by GitCat3 December 7, 2022}
So I notice that there seems to be no way to create an icon for the .fap in the flipper zero, is this planned or is there a way to do this and i'm just dumb?

[dcoles]

This isn't currently supported by the manifest! macro, but support can definitely be added.

I think the only real "trick" is converting an image to the format expected by the Flipper Zero. The two options would be:

• Have the user pre-build the icon and just include it in the binary (what we do in the images example)
• Use build.rs or a proc macro to process the image when creating the manifest

I'm probably learning towards the later, since it would make a better experience for developers.

[dcoles]

As of flipperzero-rt-0.4.1 it's now possible to set a custom icon for your application! 🥳

From examples/hello-rust:

// Define the FAP Manifest for this application
manifest!(
    name = "Hello, Rust!",
    has_icon = true,
    // See `docs/icons.md` for icon format
    icon = "rustacean-10x10.icon"
);

Icons can be created from any 10x10 px monochrome image. However they need to be converted to the Flipper Zero's custom icon format before they can be used.