Make build flags features (ArtifexSoftware#14)

* build: make build flags features

* build: use pkg-config crate for more robust library handling

* build: revert to inverse handling of HAVE_* flags

* build: remove useless features

Cargo.toml

@@ -11,6 +11,7 @@ repository = "https://github.com/messense/mupdf-rs"
 
 [features]
 default = ["noto-small", "no-cjk", "js", "xps", "svg", "cbz", "img", "html", "epub"]
+sys-lib = ["mupdf-sys/sys-lib"]
 noto-small = ["mupdf-sys/noto-small"]
 no-cjk = ["mupdf-sys/no-cjk"]
 tofu = ["mupdf-sys/tofu"]

mupdf-sys/Cargo.toml

@@ -35,6 +35,7 @@ links="mupdf-wrapper"
 repository = "https://github.com/messense/mupdf-rs"
 
 [features]
+sys-lib = []
 noto-small = []
 no-cjk = []
 tofu = []
@@ -49,5 +50,6 @@ epub = []
 [build-dependencies]
 bindgen = "0.55"
 cc = "1.0.50"
+pkg-config = "0.3"
 
 [dependencies]

mupdf-sys/build.rs

@@ -58,16 +58,29 @@ fn main() {
     })
     .collect::<Vec<String>>()
     .join(" ");
+    let make_flags = vec![
+        "libs".to_owned(),
+        format!("build={}", profile),
+        format!("OUT={}", out_dir),
+        #[cfg(feature = "sys-lib")]
+        "USE_SYSTEM_LIBS=yes".to_owned(),
+        "HAVE_X11=no".to_owned(),
+        "HAVE_GLUT=no".to_owned(),
+        "HAVE_CURL=no".to_owned(),
+        "verbose=yes".to_owned(),
+        format!("XCFLAGS={}", xcflags),
+    ];
+
+    #[cfg(feature = "sys-lib")]
+    for lib in &["freetype2", "zlib", "jbig2dec", "libjpeg", "libopenjp2"] {
+        let _ = pkg_config::probe_library(lib).unwrap_or_else(|e| {
+            eprintln!("{}", e);
+            panic!();
+        });
+    }
+
     let output = Command::new("make")
-        .arg("libs")
-        .arg(format!("build={}", profile))
-        .arg(format!("OUT={}", out_dir))
-        .arg("USE_SYSTEM_LIBS=no")
-        .arg("HAVE_X11=no")
-        .arg("HAVE_GLUT=no")
-        .arg("HAVE_CURL=no")
-        .arg("verbose=yes")
-        .arg(format!("XCFLAGS={}", xcflags))
+        .args(&make_flags)
         .current_dir(mupdf_dir)
         .stdout(Stdio::inherit())
         .stderr(Stdio::inherit())