How to Cross-Compile a Slint Application with Qt Backend in Rust

[Alarak-Alex]

How to Cross-Compile a Slint Application with Qt Backend in Rust

I'm developing an application using Slint and Rust, and I want to use Qt as the backend for rendering the UI. I need to cross-compile this application to different target platforms.

Current Environment

• Using Rust (edition 2021)
• Slint version: 1.10.0
• The current project is a Slint-based desktop application

Goals

1. Use Qt as the backend for Slint
2. Cross-compile the application to other platforms (e.g., from macOS to Linux or Windows)

What I've Tried

I've already added Slint as a dependency in Cargo.toml, but I'm not sure how to specify Qt as the backend and properly set up the cross-compilation environment.

Specific Questions

1. How do I specify Qt as the backend for Slint in Cargo.toml?
2. What Qt dependencies need to be installed for cross-compilation?
3. What are the recommended cross-compilation toolchain configurations?
4. Are there any specific build flags that need to be set?

Thank you for your help!

[Alarak-Alex]

I'm uncertain whether I need to download the corresponding version of Qt for the target platform on my local machine.

[ogoffart]

I have never done it so I can't help, but you can specify the QT_INCLUDE_PATH and QT_LIBRARY_PATH env variables when compiling.
https://docs.rs/qttypes/latest/qttypes/#finding-qt

[Alarak-Alex]

I'm using the cargo-cross tool for cross-platform compilation, and I have a question about the suggestion to set Qt environment variables (QT_INCLUDE_PATH and QT_LIBRARY_PATH). Since I'm using cargo-cross for compilation, do I still need to set these environment variables on my local machine? Shouldn't cargo-cross automatically handle these cross-platform dependencies?

[tronical]

do I still need to set these environment variables on my local machine?

If you're using cross then you need these to be set inside the docker container. You can set the from the outside and use passthrough in [build.env] in your Cross.toml. The paths they'd be referring to are local to the container though.

How do you install Qt for your target architecture inside the cross container?