Granularize ui-sys building.

It's now possible to pull and build (default), build from the current
sources without pulling (--features="build"), or not build at all, in
which case a copy of `libui.so` must exist in ui-sys/lib or be available
in a standard shared library search location.

Closes #8

Author: NoraCodes

README.md

@@ -89,6 +89,16 @@ fn main() {
 }
 ```
 
+## Building ui-sys
+
+`ui-sys` includes `libui` as a sub-module and allows it to be built on-the-fly with the
+default features `fetch` and `build. With `fetch disabled, it will simply build the
+existing sources without updating them, and with `build` disabled it will build nothing,
+assuming either a system or local (in `./lib/`) version of `libui` is available.
+
+Note that _most of the time_, building `libui` on the fly is what you want. It does however
+require a copy of cmake, essential build tools, et cetera.
+
 ## Testing Note
 Travis does not connect video devices to their testing environments, so the tests cannot be run. Therefore, the "tests" only check compilation.
 

ui-sys/.gitignore

@@ -0,0 +1 @@
+lib/

ui-sys/Cargo.toml

@@ -2,7 +2,6 @@
 name = "ui-sys"
 version = "0.1.2"
 authors = ["Leo Tindall <[email protected]>", "Patrick Walton <[email protected]>"]
-build = "build.rs"
 license = "MIT"
 description = "Native bindings to the minimalist, cross-platform, widget set `libui`"
 
@@ -28,6 +27,9 @@ keywords = ["windows", "gtk", "gui", "user_interface", "macos"]
 # they must match exactly.
 categories = ["gui", "os::macos-apis", "os::unix-apis", "os::windows-apis"]
 
+links = "ui"
+build = "build.rs"
+
 [badges]
 # Travis CI: `repository` in format "<user>/<project>" is required.
 # `branch` is optional; default is `master`
@@ -41,6 +43,12 @@ is-it-maintained-open-issues = { repository = "LeoTindall/libui-rs" }
 
 maintenance = { status = "actively-developed" }
 
+[features]
+default = ["fetch", "build"]
+
+fetch = []
+build = []
+
 [dependencies]
 libc = "0.2"
 

ui-sys/build.rs

@@ -6,31 +6,52 @@ use std::path::Path;
 use std::process::Command;
 
 fn main() {
-    // Update the submodule with libui if needed
-    if !Path::new("libui/.git").exists() {
-        Command::new("git").args(&["version"]).status().expect("Git does not appear to be installed. Git is required to build ui-sys; install Git or build ui-sys independently. Error");
-        Command::new("git").args(&["submodule", "update", "--init"]).status().expect("Unable to update Git submodules. Error");
-    } else {
-        Command::new("git").args(&["submodule", "update", "--recursive"]).status().expect("Unable to update Git submodules. Error");
+    // Fetch the submodule if needed
+    if cfg!(feature = "fetch") {
+        // Init or update the submodule with libui if needed
+        if !Path::new("libui/.git").exists() {
+            Command::new("git")
+                .args(&["version"])
+                .status()
+                .expect("Git does not appear to be installed. Error");
+            Command::new("git")
+                .args(&["submodule", "update", "--init"])
+                .status()
+                .expect("Unable to init libui submodule. Error");
+        } else {
+            Command::new("git")
+                .args(&["submodule", "update", "--recursive"])
+                .status()
+                .expect("Unable to update libui submodule. Error");
+        }
     }
 
-    let target = env::var("TARGET").unwrap();
-    let msvc = target.contains("msvc");
+    // Build libui if needed. Otherwise, assume it's in lib/
+    let mut dst;
+    let mut msvc = false;
+    if cfg!(feature = "build") {
+        dst = Config::new("libui").build_target("").build();
+        // Deterimine if we're building for MSVC
+        let target = env::var("TARGET").unwrap();
+        msvc = target.contains("msvc");
 
-    let dst = Config::new("libui")
-        .build_target("")
-        .build();
+        let mut postfix = Path::new("build").join("out");
+        if msvc {
+            postfix = postfix.join("Release");
+        }
+        dst = dst.join(&postfix);
+    } else {
+        dst = env::current_dir()
+            .expect("Unable to retrieve current directory location.");
+        dst.push("lib");
+    }
+    println!("cargo:rustc-link-search=native={}", dst.display());
 
-    let mut postfix = Path::new("build").join("out");
     let libname;
-    if msvc {
-        postfix = postfix.join("Release");
+     if msvc {
         libname = "libui";
     } else {
         libname = "ui";
     }
-    let dst = dst.join(&postfix);
-
     println!("cargo:rustc-link-lib={}", libname);
-    println!("cargo:rustc-link-search=native={}", dst.display());
 }