wasm: do not quit() on beforeunload()

This is the wrong event: exiting the app here it is not
compatible with the back/forward cache for instance. See the
the MDN docs for the “Window: unload” event.

Instead, make the Qt default be that we assume the
app process will live “forever” until the browser
terminates it, much like modern process handling on
e.g. iOS.

We may want to come back to app lifecycle handling
at a later point. This might require changes to application
code: implementing main() in such that it supports
clean shutdowns and auditing showdown code to make
sure it is web-compatible.

Change-Id: I0f32026a3af76c9cc79e3aab31e8aaed7b8f8023
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>

2 files changed, 0 insertions, 15 deletions

diff --git a/src/plugins/platforms/wasm/qwasmintegration.cpp b/src/plugins/platforms/wasm/qwasmintegration.cpp
index 2f2524737d..470deb6d70 100644
--- a/src/plugins/platforms/wasm/qwasmintegration.cpp
+++ b/src/plugins/platforms/wasm/qwasmintegration.cpp
@@ -62,11 +62,6 @@
 using namespace emscripten;
 QT_BEGIN_NAMESPACE
 
-static void browserBeforeUnload(emscripten::val)
-{
-    QWasmIntegration::QWasmBrowserExit();
-}
-
 static void addCanvasElement(emscripten::val canvas)
 {
     QWasmIntegration::get()->addScreen(canvas);
@@ -95,7 +90,6 @@ static void resizeAllScreens(emscripten::val event)
 
 EMSCRIPTEN_BINDINGS(qtQWasmIntegraton)
 {
-    function("qtBrowserBeforeUnload", &browserBeforeUnload);
     function("qtAddCanvasElement", &addCanvasElement);
     function("qtRemoveCanvasElement", &removeCanvasElement);
     function("qtResizeCanvasElement", &resizeCanvasElement);
@@ -127,8 +121,6 @@ QWasmIntegration::QWasmIntegration()
         addScreen(canvas);
     }
 
-    emscripten::val::global("window").set("onbeforeunload", val::module_property("qtBrowserBeforeUnload"));
-
     // install browser window resize handler
     auto onWindowResize = [](int eventType, const EmscriptenUiEvent *e, void *userData) -> int {
         Q_UNUSED(eventType);
@@ -172,12 +164,6 @@ QWasmIntegration::~QWasmIntegration()
     s_instance = nullptr;
 }
 
-void QWasmIntegration::QWasmBrowserExit()
-{
-    QCoreApplication *app = QCoreApplication::instance();
-    app->quit();
-}
-
 bool QWasmIntegration::hasCapability(QPlatformIntegration::Capability cap) const
 {
     switch (cap) {
diff --git a/src/plugins/platforms/wasm/qwasmintegration.h b/src/plugins/platforms/wasm/qwasmintegration.h
index f527053489..16c48e1ea1 100644
--- a/src/plugins/platforms/wasm/qwasmintegration.h
+++ b/src/plugins/platforms/wasm/qwasmintegration.h
@@ -82,7 +82,6 @@ public:
     QWasmClipboard *getWasmClipboard() { return m_clipboard; }
 
     static QWasmIntegration *get() { return s_instance; }
-    static void QWasmBrowserExit();
 
     void addScreen(const emscripten::val &canvas);
     void removeScreen(const emscripten::val &canvas);