wasm: Add DOM accessors functions through NativeInterface

Expose document and clientArea emscripten objects through
NativeInterface.
This is required by WebView implementation for wasm platform.

Task-number: QTBUG-75183
Change-Id: I6f2f084a9dbceb80d2186c7395c008f268a91e39
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Mikołaj Boc <Mikolaj.Boc@qt.io>

src/gui/CMakeLists.txt

@@ -371,6 +371,11 @@ qt_internal_extend_target(Gui CONDITION MACOS
         ${FWAppKit}
 )
 
+qt_internal_extend_target(Gui CONDITION WASM
+    SOURCES
+        platform/wasm/qwasmnativeinterface.cpp
+)
+
 qt_internal_extend_target(Gui CONDITION APPLE
     SOURCES
         image/qimage_darwin.mm

src/gui/kernel/qplatformwindow_p.h

@@ -41,6 +41,15 @@ public:
 
 namespace QNativeInterface::Private {
 
+#if defined(Q_OS_WASM) || defined(Q_QDOC)
+struct Q_GUI_EXPORT QWasmWindow
+{
+    QT_DECLARE_NATIVE_INTERFACE(QWasmWindow, 1, QWindow)
+    virtual emscripten::val document() const = 0;
+    virtual emscripten::val clientArea() const = 0;
+};
+#endif
+
 #if defined(Q_OS_MACOS) || defined(Q_QDOC)
 struct Q_GUI_EXPORT QCocoaWindow
 {

src/gui/kernel/qwindow.cpp

@@ -3065,6 +3065,10 @@ void *QWindow::resolveInterface(const char *name, int revision) const
     QT_NATIVE_INTERFACE_RETURN_IF(QWaylandWindow, platformWindow);
 #endif
 
+#if defined(Q_OS_WASM)
+    QT_NATIVE_INTERFACE_RETURN_IF(QWasmWindow, platformWindow);
+#endif
+
     return nullptr;
 }
 

src/gui/platform/wasm/qwasmnativeinterface.cpp

@@ -0,0 +1,17 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+
+
+#include <QtGui/private/qguiapplication_p.h>
+#include <qpa/qplatformintegration.h>
+#include <qpa/qplatformwindow_p.h>
+
+
+QT_BEGIN_NAMESPACE
+
+using namespace QNativeInterface::Private;
+
+QT_DEFINE_PRIVATE_NATIVE_INTERFACE(QWasmWindow);
+
+QT_END_NAMESPACE

src/plugins/platforms/wasm/qwasmwindow.h

@@ -6,6 +6,7 @@
 
 #include "qwasmintegration.h"
 #include <qpa/qplatformwindow.h>
+#include <qpa/qplatformwindow_p.h>
 #include <emscripten/html5.h>
 #include "qwasmbackingstore.h"
 #include "qwasmscreen.h"
@@ -37,7 +38,7 @@ struct PointerEvent;
 class QWasmDeadKeySupport;
 struct WheelEvent;
 
-class QWasmWindow final : public QPlatformWindow
+class QWasmWindow final : public QPlatformWindow, public QNativeInterface::Private::QWasmWindow
 {
 public:
     QWasmWindow(QWindow *w, QWasmDeadKeySupport *deadKeySupport, QWasmCompositor *compositor,
@@ -91,6 +92,10 @@ public:
     emscripten::val a11yContainer() const { return m_a11yContainer; }
     emscripten::val inputHandlerElement() const { return m_windowContents; }
 
+    // QNativeInterface::Private::QWasmWindow
+    emscripten::val document() const override { return m_document; }
+    emscripten::val clientArea() const override { return m_qtWindow; }
+
 private:
     friend class QWasmScreen;
     static constexpr auto minSizeForRegularWindows = 100;