Attaching an icon resource to a Rust application

Question

How do you attach an icon resource to a Rust application? I've seen how it's done in C but I'm not clear on how it works in Rust. This would be on Windows. I know that Linux and OS X work differently. If anyone has any tips on this for OS X that would be great too.

Answer 1

Windows

An easy way to set the icon for your .exe file is with the winres crate. First, add winres as a build dependency in your Cargo.toml:

[target.'cfg(windows)'.build-dependencies]
winres = "0.1"

Then, add a build script (a file named build.rs next to your Cargo.toml):

use std::io;
#[cfg(windows)] use winres::WindowsResource;

fn main() -> io::Result<()> {
    #[cfg(windows)] {
        WindowsResource::new()
            // This path can be absolute, or relative to your crate root.
            .set_icon("assets/icon.ico")
            .compile()?;
    }
    Ok(())
}

Note that this does not update the icon shown in the taskbar or title bar. Setting that must be done via your GUI framework, e.g. iced recently added a way to configure this.

macOS

To set the icon on macOS, you need to bundle the executable into an .app. An .app is actually a directory, not a file. It looks something like this:

• My App.app
  • Contents
    • Info.plist — This XML file includes information about your app, including the name of the binary and the location of the icon file:

      <key>CFBundleExecutable</key>
      <string>myapp</string>
      <key>CFBundleIconFile</key>
      <string>AppIcon.icns</string>
      

    • MacOS
      • myapp — The binary from target/release
    • Resources
      • AppIcon.icns

macOS apps are typically distributed as .dmg files. A release script could build the binary, bundle it into an .app, and then bundle that into a .dmg, along with a symlink to /Applications to make it easier for the user to “install” the app by moving it there.

Here are sample .dmg contents, and the corresponding release script.