3 files changed, 47 insertions, 2 deletions
diff --git a/src/corelib/kernel/qeventdispatcher_wasm.cpp b/src/corelib/kernel/qeventdispatcher_wasm.cpp
index cc24b5ff7c..aa44158551 100644
--- a/src/corelib/kernel/qeventdispatcher_wasm.cpp
+++ b/src/corelib/kernel/qeventdispatcher_wasm.cpp
@@ -217,6 +217,9 @@ QEventDispatcherWasm::QEventDispatcherWasm()
 #if QT_CONFIG(thread)
         g_mainThread = pthread_self();
 #endif
+        // Call the "onLoaded" JavaScript callback, unless startup tasks
+        // have been registered which should complete first.
+        checkCallQtLoaded();
     } else {
 #if QT_CONFIG(thread)
         std::lock_guard<std::mutex> lock(g_staticDataMutex);
@@ -895,6 +898,45 @@ void QEventDispatcherWasm::socketSelect(int timeout, int socket, bool waitForRea
 }
 
 namespace {
+    int g_startupTasks = 0;
+}
+
+// The following functions manages sending the "qtLoaded" event/callback
+// from qtloader.js on startup, once Qt initialization has been completed
+// and the application is ready to display the first frame. This can be
+// either as soon as the event loop is running, or later, if additional
+// startup tasks (e.g. local font loading) have been registered.
+
+void QEventDispatcherWasm::registerStartupTask()
+{
+    ++g_startupTasks;
+}
+
+void QEventDispatcherWasm::completeStarupTask()
+{
+    --g_startupTasks;
+    checkCallQtLoaded();
+}
+
+void QEventDispatcherWasm::checkCallQtLoaded()
+{
+    if (g_startupTasks > 0)
+        return;
+
+    static bool qtLoadedCalled = false;
+    if (qtLoadedCalled)
+        return;
+    qtLoadedCalled = true;
+
+    QTimer::singleShot(0, [](){
+        emscripten::val qt = emscripten::val::module_property("qt");
+        if (qt.isUndefined())
+            return;
+        qt.call<void>("onLoaded");
+    });
+}
+
+namespace {
     void trampoline(void *context) {
 
         auto async_fn = [](void *context){
diff --git a/src/corelib/kernel/qeventdispatcher_wasm_p.h b/src/corelib/kernel/qeventdispatcher_wasm_p.h
index 564bbffa47..afffc8a813 100644
--- a/src/corelib/kernel/qeventdispatcher_wasm_p.h
+++ b/src/corelib/kernel/qeventdispatcher_wasm_p.h
@@ -56,6 +56,11 @@ public:
     static void runOnMainThreadAsync(std::function<void(void)> fn);
     static void socketSelect(int timeout, int socket, bool waitForRead, bool waitForWrite,
                             bool *selectForRead, bool *selectForWrite, bool *socketDisconnect);
+
+    static void registerStartupTask();
+    static void completeStarupTask();
+    static void checkCallQtLoaded();
+
 protected:
     virtual bool processPostedEvents();
 
diff --git a/src/plugins/platforms/wasm/qtloader.js b/src/plugins/platforms/wasm/qtloader.js
index 7b9288cd30..1789ad70e3 100644
--- a/src/plugins/platforms/wasm/qtloader.js
+++ b/src/plugins/platforms/wasm/qtloader.js
@@ -160,8 +160,6 @@ async function qtLoad(config)
         config.preRun = [];
     config.preRun.push(qtPreRun);
 
-    config.onRuntimeInitialized = () => config.qt.onLoaded?.();
-
     const originalLocateFile = config.locateFile;
     config.locateFile = filename =>
     {