[WIP] register QML modules at build time

This is a prerequisite for using qmlcachegen
KDAB#242

crates/cxx-qt-build/src/lib.rs

@@ -59,6 +59,10 @@ struct QmlModule {
     pub version_major: usize,
     /// The .rs files with #[qml_element] attribute(s)
     pub rust_files: Vec<PathBuf>,
+    /// .qml files included in the module
+    pub qml_files: Vec<PathBuf>,
+    /// Other QRC resources (such as images) included in the module
+    pub qrc_files: Vec<PathBuf>,
 }
 
 impl GeneratedCpp {
@@ -381,6 +385,8 @@ impl CxxQtBuilder {
         version_major: usize,
         version_minor: usize,
         rust_files: &[impl AsRef<Path>],
+        qml_files: &[impl AsRef<Path>],
+        qrc_files: &[impl AsRef<Path>],
     ) -> Self {
         let rust_files: Vec<PathBuf> = rust_files
             .iter()
@@ -391,11 +397,15 @@ impl CxxQtBuilder {
                 panic_duplicate_file_and_qml_module(path, uri, version_major, version_minor);
             }
         }
+        let qml_files: Vec<PathBuf> = qml_files.iter().map(|p| p.as_ref().to_path_buf()).collect();
+        let qrc_files: Vec<PathBuf> = qrc_files.iter().map(|p| p.as_ref().to_path_buf()).collect();
         self.qml_modules.push(QmlModule {
             uri: uri.to_owned(),
             version_major,
             version_minor,
             rust_files,
+            qml_files,
+            qrc_files,
         });
         self
     }
@@ -532,6 +542,8 @@ impl CxxQtBuilder {
 
         let mut cc_builder_whole_archive_files_added = false;
 
+        let lib_name = "cxx-qt-generated";
+
         // Bridges for QML modules are handled separately because
         // the metatypes_json generated by moc needs to be passed to qmltyperegistrar
         for qml_module in self.qml_modules {
@@ -548,16 +560,20 @@ impl CxxQtBuilder {
                 }
             }
 
-            let qml_type_registration_files = qtbuild.register_qml_types(
+            let qml_type_registration_files = qtbuild.register_qml_module(
                 &qml_metatypes_json,
+                &qml_module.qml_files,
+                &qml_module.qrc_files,
                 qml_module.version_major,
                 qml_module.version_minor,
                 &qml_module.uri,
+                lib_name,
             );
             self.cc_builder
                 .file(qml_type_registration_files.qmltyperegistrar);
             self.cc_builder.file(qml_type_registration_files.plugin);
             cc_builder_whole_archive.file(qml_type_registration_files.plugin_init);
+            cc_builder_whole_archive.file(qml_type_registration_files.qrc);
             self.cc_builder.define("QT_STATICPLUGIN", None);
             cc_builder_whole_archive_files_added = true;
         }
@@ -599,6 +615,6 @@ impl CxxQtBuilder {
         if cc_builder_whole_archive_files_added {
             cc_builder_whole_archive.compile("qt-static-initializers");
         }
-        self.cc_builder.compile("cxx-qt-gen");
+        self.cc_builder.compile(lib_name);
     }
 }

crates/qt-build-utils/src/lib.rs

@@ -124,6 +124,8 @@ pub struct QmlTypeRegistrationFiles {
     /// The compiled static library must be linked with [+whole-archive](https://doc.rust-lang.org/rustc/command-line-arguments.html#linking-modifiers-whole-archive)
     /// or the linker will discard the generated static variables because they are not referenced from `main`.
     pub plugin_init: PathBuf,
+    /// File generated by rcc for the QML plugin
+    pub qrc: PathBuf,
 }
 
 /// Helper for build.rs scripts using Qt
@@ -571,12 +573,15 @@ impl QtBuild {
     }
 
     /// Generate C++ files to automatically register a QML element at build time using the JSON output from [moc](Self::moc)
-    pub fn register_qml_types(
+    pub fn register_qml_module<P: AsRef<Path>>(
         &mut self,
         metatypes_json: &[impl AsRef<Path>],
+        qml_files: &[P],
+        qrc_files: &[P],
         major_version: usize,
         minor_version: usize,
         import_name: &str,
+        library_name: &str,
     ) -> QmlTypeRegistrationFiles {
         if self.qmltyperegistrar_executable.is_none() {
             self.qmltyperegistrar_executable = Some(
@@ -585,9 +590,56 @@ impl QtBuild {
             );
         }
 
+        let qml_uri_dirs = import_name.replace('.', "/");
+
         let out_dir = env::var("OUT_DIR").unwrap();
+        let qml_module_dir = format!("{out_dir}/qml_modules/{qml_uri_dirs}");
+        std::fs::create_dir_all(&qml_module_dir).expect("Could not create QML module directory");
 
         let qml_uri_cpp_symbol_safe = import_name.replace('.', "_");
+        let typeinfo_path = format!("{qml_uri_cpp_symbol_safe}.qmltypes");
+        let plugin_class_name = format!("{qml_uri_cpp_symbol_safe}_plugin");
+
+        let mut qmldir =
+            File::create(format!("{qml_module_dir}/qmldir")).expect("Could not create qmldir file");
+        write!(
+            qmldir,
+            "module {import_name}
+optional plugin {library_name}
+classname {plugin_class_name}
+typeinfo {typeinfo_path}
+prefer :/qt/qml/{qml_uri_dirs}/
+"
+        )
+        .expect("Could not write qmldir file");
+
+        let mut qml_files_qrc = String::new();
+        for file_path in qml_files.iter().chain(qrc_files.iter()) {
+            qml_files_qrc.push_str(&format!(
+                "    <file alias=\"{}\">{}</file>\n",
+                file_path.as_ref().display(),
+                std::fs::canonicalize(file_path).unwrap().display()
+            ));
+        }
+
+        let qrc_path = format!("{qml_module_dir}/qml_module_resources.qrc");
+        let mut qrc = File::create(&qrc_path).expect("Could not create qrc file");
+        write!(
+            qrc,
+            r#"<RCC>
+  <qresource prefix="/">
+    <file alias="/qt/qml/{qml_uri_dirs}">{qml_module_dir}</file>
+  </qresource>
+  <qresource prefix="/qt/qml/{qml_uri_dirs}">
+{qml_files_qrc}
+    <file alias="qmldir">{qml_module_dir}/qmldir</file>
+  </qresource>
+</RCC>
+"#
+        )
+        .expect("Could note write qrc file");
+        let qrc_output = self.qrc(&qrc_path);
+
         let output_path = PathBuf::from(&format!(
             "{out_dir}/{qml_uri_cpp_symbol_safe}_qmltyperegistration.cpp"
         ));
@@ -620,7 +672,6 @@ impl QtBuild {
             );
         }
 
-        let plugin_class_name = format!("{qml_uri_cpp_symbol_safe}_plugin");
         // This function is generated by qmltyperegistrar
         let register_types_function = format!("qml_register_types_{qml_uri_cpp_symbol_safe}");
 
@@ -668,6 +719,7 @@ Q_IMPORT_PLUGIN({plugin_class_name});
             qmltyperegistrar: output_path,
             plugin: qml_plugin_cpp_path,
             plugin_init: qml_plugin_init_path,
+            qrc: qrc_output,
         }
     }
 

examples/cargo_without_cmake/build.rs

@@ -14,10 +14,14 @@ fn main() {
         // - Qt Qml is linked by enabling the qt_qml Cargo feature (default).
         // - Qt Qml requires linking Qt Network on macOS
         .qt_module("Network")
-        .qml_module("com.kdab.cxx_qt.demo", 1, 0, &["src/cxxqt_object.rs"])
-        // Generate C++ code from the .qrc file with the rcc tool
-        // https://doc.qt.io/qt-6/resources.html
-        .qrc("qml/qml.qrc")
+        .qml_module(
+            "com.kdab.cxx_qt.demo",
+            1,
+            0,
+            &["src/cxxqt_object.rs"],
+            &["qml/main.qml"],
+            &[] as &[&str; 0],
+        )
         .build();
 }
 // ANCHOR_END: book_cargo_executable_build_rs

examples/cargo_without_cmake/src/main.rs

@@ -25,7 +25,7 @@ fn main() {
 
     // Load the QML path into the engine
     if let Some(engine) = engine.as_mut() {
-        engine.load(&QUrl::from("qrc:/main.qml"));
+        engine.load(&QUrl::from("qrc:/qt/qml/com/kdab/cxx_qt/demo/qml/main.qml"));
     }
 
     // Start the app