add example application built entirely with Cargo

.github/workflows/github-cxx-qt-tests.yml

@@ -155,10 +155,13 @@ jobs:
       # Ubuntu 22.04 uses GCC 11 by default. Somehow when using that compiler,
       # GNU ld fails to link, though lld works. To test a full GNU toolchain,
       # use GCC 12 (with the default GNU ld).
+      #
+      # mold (or lld) is required for qml-minimal-no-cmake to link.
       run: >-
         sudo apt-get update &&
         sudo apt-get install -y
         gcc-12
+        mold
         ninja-build
         clang-format-12
         libssl-dev

Cargo.toml

@@ -11,6 +11,7 @@ members = [
     "cxx-qt-lib",
     "cxx-qt-lib-headers",
 
+    "examples/cargo_without_cmake",
     "examples/demo_threading",
     "examples/qml_extension_plugin/core",
     "examples/qml_features",

cxx-qt-build/src/lib.rs

@@ -237,6 +237,7 @@ fn generate_cxxqt_cpp_files(
 pub struct CxxQtBuilder {
     rust_sources: Vec<PathBuf>,
     qobject_headers: Vec<PathBuf>,
+    qrc_files: Vec<PathBuf>,
     qt_modules: HashSet<String>,
     cc_builder: cc::Build,
 }
@@ -250,6 +251,7 @@ impl CxxQtBuilder {
         Self {
             rust_sources: vec![],
             qobject_headers: vec![],
+            qrc_files: vec![],
             qt_modules,
             cc_builder: cc::Build::new(),
         }
@@ -264,6 +266,33 @@ impl CxxQtBuilder {
         self
     }
 
+    /// Generate C++ files from [Qt resource .qrc files](https://doc.qt.io/qt-6/resources.html).
+    /// The generated file needs to be `#include`d in another .cpp file. For example:
+    /// ```no_run
+    /// # use cxx_qt_build::CxxQtBuilder;
+    /// CxxQtBuilder::new()
+    ///     .file("src/cxxqt_module.rs")
+    ///     .qrc("src/my_resources.qrc")
+    ///     .cc_builder(|cc| {
+    ///         cc.file("file_with_include.cpp");
+    ///     })
+    ///     .build();
+    /// ```
+    ///
+    /// In `file_with_include.cpp`:
+    /// ```C++
+    /// #include "my_resources.qrc.cpp"
+    /// ```
+    ///
+    /// You also need to [explicitly load](https://doc.qt.io/qt-6/resources.html#explicit-loading-and-unloading-of-embedded-resources)
+    /// the resources in your .cpp file by calling `qInitResources()` once before starting your application.
+    pub fn qrc(mut self, qrc_file: impl AsRef<Path>) -> Self {
+        let qrc_file = qrc_file.as_ref();
+        self.qrc_files.push(qrc_file.to_path_buf());
+        println!("cargo:rerun-if-changed={}", qrc_file.display());
+        self
+    }
+
     /// Link additional [Qt modules](https://doc.qt.io/qt-6/qtmodules.html).
     /// Specify their names without the `Qt` prefix, for example `"Widgets"`.
     /// The Core and Gui modules are linked automatically; there is no need to specify them.
@@ -356,6 +385,12 @@ impl CxxQtBuilder {
             self.cc_builder.file(qtbuild.moc(&qobject_header));
         }
 
+        // Generate code from .qrc files, but do not compile it. Instead, the user needs to #include them
+        // in a .cpp file. Otherwise, MSVC won't link if the generated C++ is built separately.
+        for qrc_file in self.qrc_files {
+            qtbuild.qrc(&qrc_file);
+        }
+
         self.cc_builder.compile("cxx-qt-gen");
     }
 }

examples/CMakeLists.txt

@@ -4,6 +4,7 @@
 #
 # SPDX-License-Identifier: MIT OR Apache-2.0
 
+add_subdirectory(cargo_without_cmake)
 add_subdirectory(qml_extension_plugin)
 add_subdirectory(qml_features)
 add_subdirectory(qml_minimal)

examples/cargo_without_cmake/CMakeLists.txt

@@ -0,0 +1,47 @@
+# SPDX-FileCopyrightText: 2022 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+# SPDX-FileContributor: Be Wilson <[email protected]>
+#
+# SPDX-License-Identifier: MIT OR Apache-2.0
+
+# This CMakeLists.txt does not build any C++ directly. It is only here to integrate building
+# this crate into the larger CMake build of this repository. For development and testing, you
+# can run
+#
+# cargo build -p qml-minimal-no-cmake
+#
+# from any directory in this repository to build this crate without using CMake at all.
+
+find_package(QT NAMES Qt6 Qt5 COMPONENTS Core Gui Qml QuickControls2 QmlImportScanner REQUIRED)
+find_package(Qt${QT_VERSION_MAJOR} COMPONENTS Core Gui Qml QuickControls2 QmlImportScanner REQUIRED)
+get_target_property(QMAKE Qt${QT_VERSION_MAJOR}::qmake IMPORTED_LOCATION)
+
+# Use Corrosion to create a target for the crate that can be built without CMake.
+# This allows it to share built dependencies with the other crates in the workspace.
+find_package(Corrosion QUIET)
+if(NOT Corrosion_FOUND)
+    include(FetchContent)
+    FetchContent_Declare(
+        Corrosion
+        GIT_REPOSITORY https://github.com/corrosion-rs/corrosion.git
+        GIT_TAG v0.2.1
+    )
+
+    FetchContent_MakeAvailable(Corrosion)
+endif()
+
+set(CRATE qml-minimal-no-cmake)
+corrosion_import_crate(MANIFEST_PATH Cargo.toml CRATES ${CRATE})
+corrosion_set_env_vars(${CRATE} "QMAKE=${QMAKE}")
+if(UNIX AND NOT APPLE)
+    find_program(MOLD_EXECUTABLE mold)
+    if(MOLD_EXECUTABLE)
+        corrosion_add_target_rustflags(${CRATE} "-Clink-arg=-fuse-ld=mold")
+    else()
+        find_program(LLD_EXECUTABLE lld)
+        if(LLD_EXECUTABLE)
+            corrosion_add_target_rustflags(${CRATE} "-Clink-arg=-fuse-ld=lld")
+        else()
+            message(WARNING "Neither mold nor lld linkers were found. ${CRATE} will likely fail to link without using one of these.")
+        endif()
+    endif()
+endif()

examples/cargo_without_cmake/Cargo.toml

@@ -0,0 +1,24 @@
+# SPDX-FileCopyrightText: 2022 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+# SPDX-FileContributor: Andrew Hayzen <[email protected]>
+# SPDX-FileContributor: Gerhard de Clercq <[email protected]>
+#
+# SPDX-License-Identifier: MIT OR Apache-2.0
+[package]
+name = "qml-minimal-no-cmake"
+version = "0.3.0"
+authors = [
+  "Andrew Hayzen <[email protected]>",
+  "Be Wilson <[email protected]>",
+  "Gerhard de Clercq <[email protected]>",
+  "Leon Matthes <[email protected]>"
+]
+edition = "2018"
+license = "MIT OR Apache-2.0"
+
+[dependencies]
+cxx = "1.0"
+cxx-qt = { path = "../../cxx-qt" }
+cxx-qt-lib = { path = "../../cxx-qt-lib" }
+
+[build-dependencies]
+cxx-qt-build = { path = "../../cxx-qt-build" }

examples/cargo_without_cmake/build.rs

@@ -0,0 +1,18 @@
+// SPDX-FileCopyrightText: 2022 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// SPDX-FileContributor: Be Wilson <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+use cxx_qt_build::CxxQtBuilder;
+
+fn main() {
+    CxxQtBuilder::new()
+        .qt_modules(&["Qml", "Network"])
+        .file("src/cxxqt_object.rs")
+        .qrc("src/qml.qrc")
+        .cc_builder(|cc| {
+            cc.file("src/run.cpp");
+            println!("cargo:rerun-if-changed=src/run.cpp");
+        })
+        .build();
+}

examples/cargo_without_cmake/src/cxxqt_object.rs

@@ -0,0 +1,47 @@
+// SPDX-FileCopyrightText: 2022 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// SPDX-FileContributor: Be Wilson <[email protected]>
+// SPDX-FileContributor: Andrew Hayzen <[email protected]>
+// SPDX-FileContributor: Gerhard de Clercq <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+#[cxx_qt::bridge]
+mod ffi {
+    unsafe extern "C++" {
+        include!("cxx-qt-lib/include/qt_types.h");
+        type QString = cxx_qt_lib::QString;
+    }
+
+    pub struct Data {
+        number: i32,
+        string: UniquePtr<QString>,
+    }
+
+    impl Default for Data {
+        fn default() -> Self {
+            Self {
+                number: 0,
+                string: QString::from_str(""),
+            }
+        }
+    }
+
+    #[cxx_qt::qobject]
+    #[derive(Default)]
+    pub struct MyObject;
+    impl cxx_qt::QObject<MyObject> {
+        #[qinvokable]
+        pub fn increment_number(self: Pin<&mut Self>) {
+            let previous = self.as_ref().number();
+            self.set_number(previous + 1);
+        }
+
+        #[qinvokable]
+        pub fn say_hi(&self, string: &QString, number: i32) {
+            println!(
+                "Hi from Rust! String is '{}' and number is {}",
+                string, number
+            );
+        }
+    }
+}

examples/cargo_without_cmake/src/main.qml

@@ -0,0 +1,50 @@
+// SPDX-FileCopyrightText: 2022 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// SPDX-FileContributor: Andrew Hayzen <[email protected]>
+// SPDX-FileContributor: Gerhard de Clercq <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+import QtQuick 2.12
+import QtQuick.Controls 2.12
+import QtQuick.Window 2.12
+
+import com.kdab.cxx_qt.demo 1.0
+
+Window {
+    height: 480
+    title: qsTr("Hello World")
+    visible: true
+    width: 640
+
+    MyObject {
+        id: myObject
+        number: 1
+        string: "My String with my number: " + myObject.number
+    }
+
+    Column {
+        anchors.fill: parent
+        anchors.margins: 10
+        spacing: 10
+
+        Label {
+            text: "Number: " + myObject.number
+        }
+
+        Label {
+            text: "String: " + myObject.string
+        }
+
+        Button {
+            text: "Increment Number"
+
+            onClicked: myObject.incrementNumber()
+        }
+
+        Button {
+            text: "Say Hi!"
+
+            onClicked: myObject.sayHi(myObject.string, myObject.number)
+        }
+    }
+}

examples/cargo_without_cmake/src/main.rs

@@ -0,0 +1,39 @@
+// SPDX-FileCopyrightText: 2022 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// SPDX-FileContributor: Be Wilson <[email protected]>
+// SPDX-FileContributor: Andrew Hayzen <[email protected]>
+// SPDX-FileContributor: Gerhard de Clercq <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+mod cxxqt_object;
+
+use std::{convert::TryInto, ffi::CString, os::raw::c_char, os::raw::c_int, ptr};
+
+extern "C" {
+    fn run_cpp(argc: c_int, argv: *const *const c_char) -> c_int;
+}
+
+fn main() {
+    let args: Vec<CString> = std::env::args_os()
+        .map(|string| {
+            // Unix OsStrings can be directly converted to CStrings.
+            #[cfg(unix)]
+            use std::os::unix::ffi::OsStrExt;
+
+            // Windows OsStrings are WTF-8 encoded, so they need to be
+            // converted to UTF-8 Strings before being converted to CStrings.
+            // https://simonsapin.github.io/wtf-8/
+            #[cfg(windows)]
+            let string = string.to_string_lossy();
+
+            CString::new(string.as_bytes()).unwrap()
+        })
+        .collect();
+
+    let mut c_args: Vec<*const c_char> = args.iter().map(|arg| arg.as_ptr()).collect();
+    c_args.push(ptr::null());
+
+    unsafe {
+        run_cpp(args.len().try_into().unwrap(), c_args.as_ptr());
+    }
+}

examples/cargo_without_cmake/src/qml.qrc

@@ -0,0 +1,13 @@
+<!DOCTYPE RCC>
+<!--
+SPDX-FileCopyrightText: 2022 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+SPDX-FileContributor: Andrew Hayzen <[email protected]>
+SPDX-FileContributor: Gerhard de Clercq <[email protected]>
+
+SPDX-License-Identifier: MIT OR Apache-2.0
+-->
+<RCC version="1.0">
+    <qresource prefix="/">
+        <file>main.qml</file>
+    </qresource>
+</RCC>

examples/cargo_without_cmake/src/run.cpp

@@ -0,0 +1,48 @@
+// clang-format off
+// SPDX-FileCopyrightText: 2022 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// clang-format on
+// SPDX-FileContributor: Be Wilson <[email protected]>
+// SPDX-FileContributor: Andrew Hayzen <[email protected]>
+// SPDX-FileContributor: Gerhard de Clercq <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+#include <QtGui/QGuiApplication>
+#include <QtQml/QQmlApplicationEngine>
+
+#include "cxx-qt-gen/include/my_object.cxxqt.h"
+
+// Include the C++ code generated by rcc from the .qrc file
+#include "qml.qrc.cpp"
+
+extern "C" int
+run_cpp(int argc, char* argv[])
+{
+  // Normally in a C++ program, global variables for the Qt Resource System are
+  // initialized before the C++ main function runs. However, when building a
+  // Rust executable with Cargo, the Qt Resource System needs to be initialized
+  // manually.
+  // https://doc.qt.io/qt-6/resources.html#explicit-loading-and-unloading-of-embedded-resources
+  qInitResources();
+
+  QGuiApplication app(argc, argv);
+
+  QQmlApplicationEngine engine;
+
+  const QUrl url(QStringLiteral("qrc:/main.qml"));
+  QObject::connect(
+    &engine,
+    &QQmlApplicationEngine::objectCreated,
+    &app,
+    [url](QObject* obj, const QUrl& objUrl) {
+      if (!obj && url == objUrl)
+        QCoreApplication::exit(-1);
+    },
+    Qt::QueuedConnection);
+
+  qmlRegisterType<MyObject>("com.kdab.cxx_qt.demo", 1, 0, "MyObject");
+
+  engine.load(url);
+
+  return app.exec();
+}