wasm: install one browser window resize handler

Install one browser window resize handler instead of
per-canvas resize handlers, which avoids having to
uninstall on QScreen destruction.

Task-number: QTBUG-75463
Change-Id: I8345262a906ed735f8e9e146f1e963f515cf0d25
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>

src/plugins/platforms/wasm/qwasmeventtranslator.cpp

@@ -375,9 +375,6 @@ void QWasmEventTranslator::initEventHandlers()
     emscripten_set_touchend_callback(canvasId, (void *)this, 1, &touchCallback);
     emscripten_set_touchmove_callback(canvasId, (void *)this, 1, &touchCallback);
     emscripten_set_touchcancel_callback(canvasId, (void *)this, 1, &touchCallback);
-
-    emscripten_set_resize_callback(nullptr, (void *)this, 1, uiEvent_cb); // Note: handles browser window resize
-
 }
 
 template <typename Event>
@@ -909,19 +906,4 @@ bool QWasmEventTranslator::processKeyboard(int eventType, const EmscriptenKeyboa
     return accepted;
 }
 
-int QWasmEventTranslator::uiEvent_cb(int eventType, const EmscriptenUiEvent *e, void *userData)
-{
-    Q_UNUSED(e)
-    QWasmEventTranslator *eventTranslator = static_cast<QWasmEventTranslator *>(userData);
-
-    if (eventType == EMSCRIPTEN_EVENT_RESIZE) {
-        // This resize event is called when the HTML window is resized. Depending
-        // on the page layout the the canvas might also have been resized, so we
-        // update the Qt screen size (and canvas render size).
-        eventTranslator->screen()->updateQScreenAndCanvasRenderSize();
-    }
-
-    return 0;
-}
-
 QT_END_NAMESPACE

src/plugins/platforms/wasm/qwasmeventtranslator.h

@@ -57,8 +57,6 @@ public:
 
     static int touchCallback(int eventType, const EmscriptenTouchEvent *ev, void *userData);
 
-    static int uiEvent_cb(int eventType, const EmscriptenUiEvent *e, void *userData);
-
     void processEvents();
     void initEventHandlers();
     int handleTouch(int eventType, const EmscriptenTouchEvent *touchEvent);

src/plugins/platforms/wasm/qwasmintegration.cpp

@@ -115,6 +115,21 @@ QWasmIntegration::QWasmIntegration()
     }
 
     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);
+        Q_UNUSED(e);
+        Q_UNUSED(userData);
+
+        // This resize event is called when the HTML window is resized. Depending
+        // on the page layout the the canvas(es) might also have been resized, so we
+        // update the Qt screen sizes (and canvas render sizes).
+        if (QWasmIntegration *integration = QWasmIntegration::get())
+            integration->resizeAllScreens();
+        return 0;
+    };
+    emscripten_set_resize_callback(nullptr, nullptr, 1, onWindowResize);
 }
 
 QWasmIntegration::~QWasmIntegration()
@@ -245,4 +260,11 @@ void QWasmIntegration::resizeScreen(const QString &canvasId)
     m_screens.value(canvasId)->updateQScreenAndCanvasRenderSize();
 }
 
+void QWasmIntegration::resizeAllScreens()
+{
+    qDebug() << "resizeAllScreens";
+    for (QWasmScreen *screen : m_screens)
+        screen->updateQScreenAndCanvasRenderSize();
+}
+
 QT_END_NAMESPACE

src/plugins/platforms/wasm/qwasmintegration.h

@@ -81,6 +81,7 @@ public:
     void addScreen(const QString &canvasId);
     void removeScreen(const QString &canvasId);
     void resizeScreen(const QString &canvasId);
+    void resizeAllScreens();
 
 private:
     mutable QWasmFontDatabase *m_fontDb;