imgui-rs/imgui-sys/build.rs

#![allow(dead_code)]

use std::fs;
use std::io;

const DEFINES: &[(&str, Option<&str>)] = &[
    // Rust `char` is a unicode scalar value, e.g. 32 bits.
    ("IMGUI_USE_WCHAR32", None),
    // Disabled due to linking issues
    ("CIMGUI_NO_EXPORT", None),
    ("IMGUI_DISABLE_WIN32_FUNCTIONS", None),
    ("IMGUI_DISABLE_OSX_FUNCTIONS", None),
];

fn main() -> io::Result<()> {
    // Output define args for compiler
    for (key, value) in DEFINES.iter() {
        println!("cargo:DEFINE_{}={}", key, value.unwrap_or(""));
    }

    // Feature flags - no extra dependencies, so these are queried as
    // env-vars to avoid recompilation of build.rs
    let docking_enabled = std::env::var_os("CARGO_FEATURE_DOCKING").is_some();
    let wasm_enabled = std::env::var_os("CARGO_FEATURE_WASM").is_none();

    // If we aren't building WASM output, bunch of extra stuff to do
    if !wasm_enabled {
        // C++ compiler
        let mut build = cc::Build::new();
        build.cpp(true);

        // Set defines for compiler
        for (key, value) in DEFINES.iter() {
            build.define(key, *value);
        }

        // Freetype font rasterizer feature
        #[cfg(feature = "freetype")]
        {
            // Find library
            let freetype = pkg_config::Config::new().find("freetype2").unwrap();
            for include in freetype.include_paths.iter() {
                build.include(include);
            }
            // Set flag for dear imgui
            build.define("IMGUI_ENABLE_FREETYPE", None);
            println!("cargo:DEFINE_IMGUI_ENABLE_FREETYPE=");

            // imgui_freetype.cpp needs access to `#include "imgui.h"`
            let manifest_dir = std::path::Path::new(env!("CARGO_MANIFEST_DIR"));
            if docking_enabled {
                build.include(manifest_dir.join("third-party/imgui-docking/imgui"));
            } else {
                build.include(manifest_dir.join("third-party/imgui-master/imgui"));
            }
        }

        // Which "all imgui" file to use
        let imgui_cpp = if docking_enabled {
             "include_imgui_docking.cpp"
        } else {
            "include_imgui_master.cpp"
        };

        // Set up compiler
        let compiler = build.get_compiler();

        // Avoid the if-supported flag functions for easy cases, as they're
        // kinda costly.
        if compiler.is_like_gnu() || compiler.is_like_clang() {
            build.flag("-fno-exceptions").flag("-fno-rtti");
        }

        // Build imgui lib, suppressing warnings.
        // TODO: disable linking C++ stdlib? Not sure if it's allowed.
        build.warnings(false).file(imgui_cpp).compile("libcimgui.a");
    }
    Ok(())
}