Add Cargo.toml and build.rs for Bazel workspaces

This commit introduces Cargo.toml files for the detector, tracker, and
examples workspaces to enable Rust tooling and standalone Cargo builds.

- detector/Cargo.toml: Defines the 'rtmo' library, which includes C++
  interoperability via the 'cxx' crate.
- detector/build.rs: Configured to compile the C++ sources (engine.cpp,
  rtmo.cpp) and link against dependencies like CUDA, TensorRT, and
  CVCUDA, mirroring the Bazel setup.
- tracker/Cargo.toml: Defines the 'tracker' library with its Rust
  dependencies and a path dependency on the 'rtmo' library.
- examples/Cargo.toml: Defines the 'image_demo' and 'video_demo'
  binaries, with path dependencies on 'rtmo' and 'tracker', along with
  other necessary crates.

These additions facilitate the use of standard Rust development tools and
workflows alongside the existing Bazel build system.

Author: google-labs-jules[bot]

detector/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "rtmo"
+version = "0.1.0" # Default version, can be adjusted
+edition = "2021"  # From MODULE.bazel (rust.toolchain)
+authors = ["Your Name <you@example.com>"] # Placeholder
+
+[lib]
+name = "rtmo"
+path = "src/lib.rs"
+
+[dependencies]
+cxx = "1.0.149"
+
+# For handling the C++ compilation and linking:
+[build-dependencies]
+cxx-build = "1.0.149" # Or a suitable build script helper if available via rules_rust
+
+# Potentially, if rtmo.rs is a separate module for the bridge
+# [[bin]]
+# name = "rtmo_bridge_bin" # Example if it were a binary
+# path = "src/rtmo.rs"

detector/build.rs

@@ -0,0 +1,76 @@
+use std::path::PathBuf;
+
+fn main() {
+    println!("cargo:rerun-if-changed=src/rtmo.rs");
+    println!("cargo:rerun-if-changed=src/engine.cpp");
+    println!("cargo:rerun-if-changed=src/engine.hpp");
+    println!("cargo:rerun-if-changed=src/rtmo.cpp");
+    println!("cargo:rerun-if-changed=src/rtmo.hpp");
+
+    let manifest_dir = PathBuf::from(std::env::var("CARGO_MANIFEST_DIR").unwrap());
+    let workspace_root = manifest_dir.parent().unwrap_or(&manifest_dir); // Assuming detector is one level down from workspace root
+
+    // --- CUDA ---
+    // These are common paths. Adjust if your CUDA installation is different.
+    let cuda_include_path = PathBuf::from("/usr/local/cuda/include");
+    let cuda_lib_path = PathBuf::from("/usr/local/cuda/lib64");
+    println!("cargo:rustc-link-search=native={}", cuda_lib_path.display());
+    println!("cargo:rustc-link-lib=dylib=cudart"); // Link against CUDA runtime
+
+    // --- TensorRT ---
+    // Path relative to workspace root.
+    let tensorrt_base_path = workspace_root.join("repositories/tensorrt");
+    let tensorrt_include_path = tensorrt_base_path.join("include/x86_64-linux-gnu");
+    let tensorrt_lib_path = tensorrt_base_path.join("lib/x86_64-linux-gnu");
+
+    println!("cargo:rustc-link-search=native={}", tensorrt_lib_path.display());
+    println!("cargo:rustc-link-lib=dylib=nvinfer");
+    println!("cargo:rustc-link-lib=dylib=nvinfer_plugin");
+
+    // --- CVCUDA ---
+    // Path relative to workspace root.
+    let cvcuda_base_path = workspace_root.join("repositories/cvcuda");
+    let cvcuda_include_path = cvcuda_base_path.join("include");
+    let cvcuda_lib_path = cvcuda_base_path.join("lib");
+
+    println!("cargo:rustc-link-search=native={}", cvcuda_lib_path.display());
+    println!("cargo:rustc-link-lib=dylib=cvcuda");
+    println!("cargo:rustc-link-lib=dylib=nvcv_types");
+
+
+    // --- Build C++ files using cxx_build ---
+    let mut build = cxx_build::bridge("src/rtmo.rs"); // Path to the Rust file with CXX bridge
+    build
+        .file("src/engine.cpp")
+        .file("src/rtmo.cpp")
+        .include(&manifest_dir.join("src")) // for engine.hpp, rtmo.hpp
+        .include(&cuda_include_path)
+        .include(&tensorrt_include_path)
+        .include(&cvcuda_include_path)
+        .flag_if_supported("-std=c++17") // Assuming C++17, adjust if necessary
+        .flag_if_supported("-pthread"); // For TensorRT plugins
+
+    // Add any other necessary compiler flags or definitions
+    // e.g., .define("SOME_MACRO", "value")
+
+    // Linker arguments for specific libraries if needed (beyond simple -l flags)
+    // For TensorRT plugin, Bazel had: linkopts = ["-lpthread", "-Wl,--no-as-needed -ldl -lrt -Wl,--as-needed"]
+    // The -lpthread is covered by cargo:rustc-link-lib=pthread if cc crate doesn't add it.
+    // The cc crate usually handles pthread implicitly if specified with .flag("-pthread") for compiler and linker.
+    // Let's ensure pthread is linked.
+    println!("cargo:rustc-link-lib=dylib=pthread");
+    // For dlsym, rt_timer related symbols which might be needed by TensorRT
+    println!("cargo:rustc-link-lib=dylib=dl");
+    println!("cargo:rustc-link-lib=dylib=rt");
+
+
+    build.compile("rtmo_cpp_bridge");
+
+    println!("cargo:warning=This build.rs attempts to compile C++ dependencies. Ensure CUDA, TensorRT, and CVCUDA are correctly installed and paths are configured if issues arise.");
+    println!("cargo:warning=CUDA include path: {}", cuda_include_path.display());
+    println!("cargo:warning=CUDA lib path: {}", cuda_lib_path.display());
+    println!("cargo:warning=TensorRT include path: {}", tensorrt_include_path.display());
+    println!("cargo:warning=TensorRT lib path: {}", tensorrt_lib_path.display());
+    println!("cargo:warning=CVCUDA include path: {}", cvcuda_include_path.display());
+    println!("cargo:warning=CVCUDA lib path: {}", cvcuda_lib_path.display());
+}

examples/Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "examples"
+version = "0.1.0"
+edition = "2021" # From MODULE.bazel (rust.toolchain)
+authors = ["Your Name <you@example.com>"] # Placeholder
+publish = false # Examples are typically not published
+
+[[bin]]
+name = "image_demo"
+path = "src/image_demo.rs"
+
+[[bin]]
+name = "video_demo"
+path = "src/video_demo.rs"
+
+[dependencies]
+rtmo = { path = "../detector" }
+tracker = { path = "../tracker" } # Needed by video_demo
+
+cxx = "1.0.149"
+image = "0.25.0"
+ab_glyph = "0.2.29"
+imageproc = "0.25.0"
+minifb = "0.28.0"
+video-rs = { version = "0.10.3", features = ["ndarray"] }
+
+# Note: Since image_demo does not use tracker, ab_glyph, imageproc, minifb, video-rs,
+# these will still be compiled if you do `cargo build --bin image_demo` because
+# they are listed as common dependencies. For example crates, this is often acceptable.
+# If strict separation is needed, they would need to be separate Cargo packages.

tracker/Cargo.toml

@@ -0,0 +1,31 @@
+[package]
+name = "tracker"
+version = "0.1.0"
+edition = "2021" # From MODULE.bazel (rust.toolchain)
+authors = ["Your Name <you@example.com>"] # Placeholder
+
+[lib]
+name = "tracker"
+path = "src/lib.rs"
+
+[dependencies]
+rtmo = { path = "../detector" }
+nalgebra = "0.33.2"
+num = "0.4.3"
+thiserror = "2.0.12"
+
+[dev-dependencies]
+# rtmo = { path = "../detector" } # Already in [dependencies]
+# nalgebra = "0.33.2" # Already in [dependencies]
+# num = "0.4.3" # Already in [dependencies]
+# thiserror = "2.0.12" # Already in [dependencies]
+nearly_eq = "0.2.4"
+quickcheck = "1.0.3"
+rand = "0.8.5"
+
+# The tracker_test in BUILD.bazel uses srcs = glob(["src/*.rs"]),
+# which suggests tests might be inline or in files picked up by Cargo's
+# default test discovery (e.g. src/tests/some_test.rs or tests/integration_test.rs).
+# If tests are embedded within lib.rs or other src/*.rs files (like src/test_byte_tracker.rs),
+# Cargo will pick them up automatically. No specific [[test]] section is needed
+# unless there's a non-standard test file name or location.