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>

1 files changed, 22 insertions, 0 deletions

diff --git a/src/plugins/platforms/wasm/qwasmintegration.cpp b/src/plugins/platforms/wasm/qwasmintegration.cpp
index e601d553f2..703b0fde0b 100644
--- a/src/plugins/platforms/wasm/qwasmintegration.cpp
+++ b/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