From 38d28085ab9274d132d5ed301ce95551c6ba11de Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Morten=20S=C3=B8rvig?= <morten.sorvig@qt.io>
Date: Wed, 20 Mar 2024 13:23:53 +0100
Subject: [PATCH] Add example which demonstrates app cleanup
Don't call exec(), instead allocate objects on the
heap and then delete at quit() time.
---
examples/application_exit/CMakeLists.txt | 22 +++++++++
examples/application_exit/Main.qml | 22 +++++++++
examples/application_exit/main.cpp | 57 ++++++++++++++++++++++++
3 files changed, 101 insertions(+)
create mode 100644 examples/application_exit/CMakeLists.txt
create mode 100644 examples/application_exit/Main.qml
create mode 100644 examples/application_exit/main.cpp
diff --git a/examples/application_exit/CMakeLists.txt b/examples/application_exit/CMakeLists.txt
new file mode 100644
index 0000000..cd7380c
--- /dev/null
+++ b/examples/application_exit/CMakeLists.txt
@@ -0,0 +1,22 @@
+cmake_minimum_required(VERSION 3.16)
+
+project(application_exit)
+
+find_package(Qt6 REQUIRED COMPONENTS Quick)
+
+qt_standard_project_setup(REQUIRES 6.6)
+
+qt_add_executable(application_exit
+ main.cpp
+)
+
+qt_add_qml_module(application_exit
+ URI applicationexit
+ VERSION 1.0
+ QML_FILES Main.qml
+)
+
+target_link_libraries(application_exit
+ PRIVATE Qt6::Quick
+)
+
diff --git a/examples/application_exit/Main.qml b/examples/application_exit/Main.qml
new file mode 100644
index 0000000..ecc308d
--- /dev/null
+++ b/examples/application_exit/Main.qml
@@ -0,0 +1,22 @@
+import QtQuick
+import QtQuick.Window
+
+Window {
+ width: 640
+ height: 480
+ visible: true
+
+ Text {
+ text: "Click To Quit"
+ anchors.fill: parent
+ horizontalAlignment: Text.AlignHCenter
+ verticalAlignment: Text.AlignVCenter
+ }
+
+ MouseArea {
+ anchors.fill: parent
+ onClicked: {
+ deleter.quit();
+ }
+ }
+}
diff --git a/examples/application_exit/main.cpp b/examples/application_exit/main.cpp
new file mode 100644
index 0000000..15d029a
--- /dev/null
+++ b/examples/application_exit/main.cpp
@@ -0,0 +1,57 @@
+#include <QGuiApplication>
+#include <QQmlApplicationEngine>
+#include <QQmlContext>
+
+#include <emscripten.h>
+
+class Deleter;
+
+QGuiApplication *g_app = nullptr;
+QQmlApplicationEngine *g_engine = nullptr;
+
+class Deleter : public QObject
+{
+ Q_OBJECT
+public:
+ explicit Deleter(QObject *parent = nullptr)
+ : QObject(parent) {}
+
+ Q_INVOKABLE void quit() {
+
+ // QCoreApplication does not support deleting itself from inside
+ // an event callback. Make a native zero-timer callback to make sure
+ // we are deleting without Qt on the stack.
+ emscripten_async_call([](void *deleter){
+
+ // Delete self
+ delete static_cast<Deleter *>(deleter);
+
+ // Delete the QQmlApplicationEngine and QGuiApplication instances.
+ delete g_engine; g_engine = nullptr;
+ delete g_app; g_app = nullptr;
+
+ // Optinally trigger runtime exit as well.
+ emscripten_force_exit(0);
+ }, this, 0);
+ }
+};
+
+int main(int argc, char *argv[])
+{
+ // This example demonstrates how to cleanly exit a Qt application.
+ //
+ // This is done by creating the QML application engine and Qt application
+ // on the heap, and then returning from main() without calling exec().
+ //
+ // Qt for WebAssembly supports omitting the exec() call, since the native
+ // event loop is already running by the time main() is called. Emscripten
+ // supports returning from main() without exiting the runtime, see the
+ // EXIT_RUNTIME linker option.
+
+ g_app = new QGuiApplication(argc, argv);
+ g_engine = new QQmlApplicationEngine();
+ g_engine->loadFromModule("applicationexit", "Main");
+ g_engine->rootContext()->setContextProperty("deleter", new Deleter);
+}
+
+#include "main.moc"
--
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