examples: add an example of a qml_singleton

Related to KDAB#25

Author: ahayzen-kdab

examples/qml_features/CMakeLists.txt

@@ -80,6 +80,7 @@ copy_qml_test(nested_qobjects)
 copy_qml_test(properties)
 copy_qml_test(serialisation)
 copy_qml_test(signals)
+copy_qml_test(singleton)
 copy_qml_test(threading)
 copy_qml_test(types)
 

examples/qml_features/qml/main.qml

@@ -46,6 +46,7 @@ ApplicationWindow {
 
         readonly property alias currentItem: drawerView.currentItem
 
+        clip: true
         height: window.height - header.height
         width: Math.min(window.width * 0.66, 200)
         y: header.height
@@ -107,6 +108,10 @@ ApplicationWindow {
                     name: "Nested QObjects"
                     source: "qrc:/pages/NestedQObjectsPage.qml"
                 }
+                ListElement {
+                    name: "Singleton"
+                    source: "qrc:/pages/SingletonPage.qml"
+                }
             }
         }
     }

examples/qml_features/qml/pages/SingletonPage.qml

@@ -0,0 +1,54 @@
+// SPDX-FileCopyrightText: 2023 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// SPDX-FileContributor: Andrew Hayzen <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+import QtQuick 2.12
+import QtQuick.Controls 2.12
+import QtQuick.Layouts 1.12
+
+import com.kdab.cxx_qt.demo 1.0
+
+Page {
+    header: ToolBar {
+        RowLayout {
+            anchors.fill: parent
+
+            ToolButton {
+                text: qsTr("Increment")
+
+                onClicked: RustSingleton.increment()
+            }
+
+            Item {
+                Layout.fillWidth: true
+            }
+        }
+    }
+
+    ColumnLayout {
+        anchors.left: parent.left
+        anchors.right: parent.right
+        anchors.verticalCenter: parent.verticalCenter
+
+        Label {
+            Layout.fillWidth: true
+            horizontalAlignment: Text.AlignHCenter
+            text: qsTr("Singletons can be used from Rust to store state across the session of the application as normal.")
+            wrapMode: Text.Wrap
+        }
+
+        Label {
+            Layout.fillWidth: true
+            horizontalAlignment: Text.AlignHCenter
+            text: qsTr("In this demo increment this value will persist, even after switching pages.")
+            wrapMode: Text.Wrap
+        }
+
+        Label {
+            Layout.fillWidth: true
+            horizontalAlignment: Text.AlignHCenter
+            text: RustSingleton.persistentValue
+            wrapMode: Text.Wrap
+        }
+    }
+}

examples/qml_features/qml/qml.qrc

@@ -17,6 +17,7 @@ SPDX-License-Identifier: MIT OR Apache-2.0
         <file>pages/PropertiesPage.qml</file>
         <file>pages/SerialisationPage.qml</file>
         <file>pages/SignalsPage.qml</file>
+        <file>pages/SingletonPage.qml</file>
         <file>pages/ThreadingPage.qml</file>
         <file>pages/TypesPage.qml</file>
     </qresource>

examples/qml_features/rust/build.rs

@@ -16,6 +16,7 @@ fn main() {
         .file("src/nested_qobjects.rs")
         .file("src/serialisation.rs")
         .file("src/signals.rs")
+        .file("src/singleton.rs")
         .file("src/properties.rs")
         .file("src/threading.rs")
         .file("src/types.rs")

examples/qml_features/rust/src/lib.rs

@@ -12,5 +12,6 @@ mod nested_qobjects;
 mod properties;
 mod serialisation;
 mod signals;
+mod singleton;
 mod threading;
 mod types;

examples/qml_features/rust/src/singleton.rs

@@ -0,0 +1,23 @@
+// SPDX-FileCopyrightText: 2023 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// SPDX-FileContributor: Andrew Hayzen <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+// ANCHOR: book_macro_code
+#[cxx_qt::bridge(cxx_file_stem = "rust_singleton")]
+pub mod ffi {
+    #[cxx_qt::qobject(qml_uri = "com.kdab.cxx_qt.demo", qml_version = "1.0", qml_singleton)]
+    #[derive(Default)]
+    pub struct RustSingleton {
+        #[qproperty]
+        persistent_value: i32,
+    }
+
+    impl qobject::RustSingleton {
+        #[qinvokable]
+        pub fn increment(self: Pin<&mut Self>) {
+            let new_value = self.persistent_value() + 1;
+            self.set_persistent_value(new_value);
+        }
+    }
+}

examples/qml_features/tests/tst_singleton.qml

@@ -0,0 +1,18 @@
+// SPDX-FileCopyrightText: 2023 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// SPDX-FileContributor: Andrew Hayzen <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+import QtQuick 2.12
+import QtTest 1.12
+
+import com.kdab.cxx_qt.demo 1.0
+
+TestCase {
+    name: "SingletonTests"
+
+    function test_increment() {
+        compare(RustSingleton.persistentValue, 0);
+        RustSingleton.increment();
+        compare(RustSingleton.persistentValue, 1);
+    }
+}