Android: Add classes to embed QML into native Android

Add classes that make it possible to add QML as a View into
a native Android app:

QtView: Base class for QtQuickView, handles non-Quick dependent
operations. In essence a Java ViewGroup class which loads a
QWindow and embeds it into itself.

QtEmbeddedLoader: Extends QtLoader for embedded case, creates the
embedded version of QtActivityDelegate and provides an embedded-specific
path to loading Qt libraries (Mostly just allows users to set the name
of the main lib)

QtAndroidWindowEmbedding namespace: Deals with calls from
QtEmbeddedDelegate to create/destroy QWindow and from QtView to
show the window.

Take the QtEmbeddedDelegate introduced in an earlier commit
into use, and add functionality for loading QWindows for
QtViews and managing QtViews into it.

Add a factory for creating instances of QtEmbeddedDelegate.
The factory holds a map of QtEmbeddedDelegate objects and
creates them, with the Activity as the key. This is to make
it so that the same delegate can be used by multiple views
which share the same Context.

Known issues left:
* keyboard focus not working, as with other child windows

Pick-to: 6.7
Task-number: QTBUG-118872
Change-Id: I94a5f9b4f904c05cc6368cf20f273fcf10d31f17
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>

4 files changed, 124 insertions, 9 deletions

diff --git a/src/plugins/platforms/android/CMakeLists.txt b/src/plugins/platforms/android/CMakeLists.txt
index a3344bfd71..d5a275a76c 100644
--- a/src/plugins/platforms/android/CMakeLists.txt
+++ b/src/plugins/platforms/android/CMakeLists.txt
@@ -40,6 +40,7 @@ qt_internal_add_plugin(QAndroidIntegrationPlugin
         qandroidplatformtheme.cpp qandroidplatformtheme.h
         qandroidplatformwindow.cpp qandroidplatformwindow.h
         qandroidsystemlocale.cpp qandroidsystemlocale.h
+        androidwindowembedding.cpp androidwindowembedding.h
     NO_UNITY_BUILD_SOURCES
         # Conflicting symbols and macros with androidjnimain.cpp
         # TODO: Unify the usage of FIND_AND_CHECK_CLASS, and similar
diff --git a/src/plugins/platforms/android/androidjnimain.cpp b/src/plugins/platforms/android/androidjnimain.cpp
index bf15213b66..206bbd03d6 100644
--- a/src/plugins/platforms/android/androidjnimain.cpp
+++ b/src/plugins/platforms/android/androidjnimain.cpp
@@ -13,6 +13,7 @@
 #include "androidjniinput.h"
 #include "androidjnimain.h"
 #include "androidjnimenu.h"
+#include "androidwindowembedding.h"
 #include "qandroidassetsfileenginehandler.h"
 #include "qandroideventdispatcher.h"
 #include "qandroidplatformdialoghelpers.h"
@@ -92,6 +93,8 @@ static const char m_methodErrorMsg[] = "Can't find method \"%s%s\"";
 
 Q_CONSTINIT static QBasicAtomicInt startQtAndroidPluginCalled = Q_BASIC_ATOMIC_INITIALIZER(0);
 
+Q_DECLARE_JNI_CLASS(QtEmbeddedDelegateFactory, "org/qtproject/qt/android/QtEmbeddedDelegateFactory")
+
 namespace QtAndroid
 {
     QBasicMutex *platformInterfaceMutex()
@@ -187,10 +190,17 @@ namespace QtAndroid
     // FIXME: avoid direct access to QtActivityDelegate
     QtJniTypes::QtActivityDelegateBase qtActivityDelegate()
     {
+        using namespace QtJniTypes;
         if (!m_activityDelegate.isValid()) {
-            auto activity = QtAndroidPrivate::activity();
-            m_activityDelegate = activity.callMethod<QtJniTypes::QtActivityDelegateBase>(
-                    "getActivityDelegate");
+            if (isQtApplication()) {
+                auto context = QtAndroidPrivate::activity();
+                m_activityDelegate = context.callMethod<QtActivityDelegateBase>("getActivityDelegate");
+            } else {
+                m_activityDelegate = QJniObject::callStaticMethod<QtActivityDelegateBase>(
+                                                    Traits<QtEmbeddedDelegateFactory>::className(),
+                                                    "getActivityDelegate",
+                                                    QtAndroidPrivate::activity());
+            }
         }
 
         return m_activityDelegate;
@@ -213,11 +223,15 @@ namespace QtAndroid
         // embedded into a native Android app, where the Activity/Service is created
         // by the user, outside of Qt, and Qt content is added as a view.
         JNIEnv *env = QJniEnvironment::getJniEnv();
-        static const jint isQtActivity = env->IsInstanceOf(QtAndroidPrivate::activity().object(),
-                                                           m_qtActivityClass);
-        static const jint isQtService = env->IsInstanceOf(QtAndroidPrivate::service().object(),
-                                                          m_qtServiceClass);
-        return isQtActivity || isQtService;
+        auto activity = QtAndroidPrivate::activity();
+        if (activity.isValid())
+            return env->IsInstanceOf(activity.object(), m_qtActivityClass);
+        auto service = QtAndroidPrivate::service();
+        if (service.isValid())
+            return env->IsInstanceOf(QtAndroidPrivate::service().object(), m_qtServiceClass);
+        // return true as default as Qt application is our default use case.
+        // famous last words: we should not end up here
+        return true;
     }
 
     void notifyAccessibilityLocationChange(uint accessibilityObjectId)
@@ -870,7 +884,8 @@ Q_DECL_EXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void */*reserved*/)
             || !QtAndroidAccessibility::registerNatives(env)
             || !QtAndroidDialogHelpers::registerNatives(env)
             || !QAndroidPlatformClipboard::registerNatives(env)
-            || !QAndroidPlatformWindow::registerNatives(env)) {
+            || !QAndroidPlatformWindow::registerNatives(env)
+            || !QtAndroidWindowEmbedding::registerNatives(env)) {
         __android_log_print(ANDROID_LOG_FATAL, "Qt", "registerNatives failed");
         return -1;
     }
diff --git a/src/plugins/platforms/android/androidwindowembedding.cpp b/src/plugins/platforms/android/androidwindowembedding.cpp
new file mode 100644
index 0000000000..7d82ac6d87
--- /dev/null
+++ b/src/plugins/platforms/android/androidwindowembedding.cpp
@@ -0,0 +1,61 @@
+// 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 "androidwindowembedding.h"
+
+#include <QtCore/qcoreapplication.h>
+#include <QtCore/qjnienvironment.h>
+#include <QtCore/qjniobject.h>
+#include <QtCore/qjnitypes.h>
+#include <QtGui/qwindow.h>
+
+QT_BEGIN_NAMESPACE
+
+Q_DECLARE_JNI_CLASS(QtView, "org/qtproject/qt/android/QtView");
+Q_DECLARE_JNI_CLASS(QtEmbeddedDelegate, "org/qtproject/qt/android/QtEmbeddedDelegate");
+
+namespace QtAndroidWindowEmbedding {
+    void createRootWindow(JNIEnv *, jclass, QtJniTypes::View rootView)
+    {
+        // QWindow should be constructed on the Qt thread rather than directly in the caller thread
+        // To avoid hitting checkReceiverThread assert in QCoreApplication::doNotify
+        QMetaObject::invokeMethod(qApp, [rootView] {
+            QWindow *parentWindow = QWindow::fromWinId(reinterpret_cast<WId>(rootView.object()));
+            rootView.callMethod<void>("createWindow", reinterpret_cast<jlong>(parentWindow));
+        });
+    }
+
+    void deleteWindow(JNIEnv *, jclass, jlong windowRef)
+    {
+        QWindow *window = reinterpret_cast<QWindow*>(windowRef);
+        window->deleteLater();
+    }
+
+    void setWindowVisible(JNIEnv *, jclass, jlong windowRef, jboolean visible)
+    {
+        QMetaObject::invokeMethod(qApp, [windowRef, visible] {
+            QWindow *window = reinterpret_cast<QWindow*>(windowRef);
+            if (visible) {
+                window->showNormal();
+                if (!window->parent()->isVisible())
+                    window->parent()->show();
+            } else {
+                window->hide();
+            }
+        });
+    }
+
+    bool registerNatives(QJniEnvironment& env) {
+        using namespace QtJniTypes;
+        bool success = env.registerNativeMethods(Traits<QtEmbeddedDelegate>::className(),
+                            {Q_JNI_NATIVE_SCOPED_METHOD(createRootWindow, QtAndroidWindowEmbedding),
+                             Q_JNI_NATIVE_SCOPED_METHOD(deleteWindow, QtAndroidWindowEmbedding)});
+
+        success &= env.registerNativeMethods(Traits<QtView>::className(),
+                            {Q_JNI_NATIVE_SCOPED_METHOD(setWindowVisible, QtAndroidWindowEmbedding)});
+        return success;
+
+    }
+}
+
+QT_END_NAMESPACE
diff --git a/src/plugins/platforms/android/androidwindowembedding.h b/src/plugins/platforms/android/androidwindowembedding.h
new file mode 100644
index 0000000000..f9d92d4afc
--- /dev/null
+++ b/src/plugins/platforms/android/androidwindowembedding.h
@@ -0,0 +1,38 @@
+// 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
+
+#ifndef QTANDROIDWINDOWEMBEDDING_H
+#define QTANDROIDWINDOWEMBEDDING_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qjnienvironment.h>
+#include <QtCore/qjnitypes.h>
+
+QT_BEGIN_NAMESPACE
+
+Q_DECLARE_JNI_CLASS(View, "android/view/View");
+
+namespace QtAndroidWindowEmbedding
+{
+    bool registerNatives(QJniEnvironment& env);
+    void createRootWindow(JNIEnv *, jclass, QtJniTypes::View rootView);
+    Q_DECLARE_JNI_NATIVE_METHOD_IN_CURRENT_SCOPE(createRootWindow)
+    void deleteWindow(JNIEnv *, jclass, jlong window);
+    Q_DECLARE_JNI_NATIVE_METHOD_IN_CURRENT_SCOPE(deleteWindow)
+    void setWindowVisible(JNIEnv *, jclass, jlong window, jboolean visible);
+    Q_DECLARE_JNI_NATIVE_METHOD_IN_CURRENT_SCOPE(setWindowVisible)
+};
+
+QT_END_NAMESPACE
+
+#endif // QTANDROIDWINDOWEMBEDDING_H