1 files changed, 128 insertions, 0 deletions
diff --git a/src/qml/qml/qqmlpropertytopropertybinding.cpp b/src/qml/qml/qqmlpropertytopropertybinding.cpp
new file mode 100644
index 0000000000..ec77e8c97a
--- /dev/null
+++ b/src/qml/qml/qqmlpropertytopropertybinding.cpp
@@ -0,0 +1,128 @@
+// Copyright (C) 2022 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 "qqmlpropertytopropertybinding_p.h"
+#include <private/qqmlvmemetaobject_p.h>
+
+QT_BEGIN_NAMESPACE
+
+/*!
+ * \internal
+ * \class QQmlPropertyToPropertyBinding
+ *
+ * This class can be used to create a direct binding from a source property to
+ * a target property, without going through QQmlJavaScriptExpression and
+ * QV4::Function. In particular you don't need a compilation unit or byte code
+ * to set this up.
+ */
+
+QQmlPropertyToPropertyBinding::QQmlPropertyToPropertyBinding(
+        QQmlEngine *engine, QObject *sourceObject, int sourcePropertyIndex,
+        QObject *targetObject, int targetPropertyIndex)
+    : QQmlNotifierEndpoint(QQmlPropertyGuard)
+    , m_engine(engine)
+    , m_sourceObject(sourceObject)
+    , m_sourcePropertyIndex(sourcePropertyIndex)
+{
+    setTarget(targetObject, targetPropertyIndex, false, -1);
+}
+
+QQmlAbstractBinding::Kind QQmlPropertyToPropertyBinding::kind() const
+{
+    return PropertyToPropertyBinding;
+}
+
+void QQmlPropertyToPropertyBinding::setEnabled(bool e, QQmlPropertyData::WriteFlags flags)
+{
+    const bool wasEnabled = enabledFlag();
+    setEnabledFlag(e);
+    updateCanUseAccessor();
+    if (e && !wasEnabled)
+        update(flags);
+}
+
+void QQmlPropertyToPropertyBinding::captureProperty(
+        const QMetaObject *sourceMetaObject, int notifyIndex,
+        bool isSourceBindable, bool isTargetBindable)
+{
+    if (isSourceBindable) {
+        // if the property is a QPropery, and we're binding to a QProperty
+        // the automatic capturing process already takes care of everything
+        if (isTargetBindable)
+            return;
+
+        // We have already captured.
+        if (observer)
+            return;
+
+        observer = std::make_unique<Observer>(this);
+        QUntypedBindable bindable;
+        void *argv[] = { &bindable };
+        sourceMetaObject->metacall(
+                    m_sourceObject, QMetaObject::BindableProperty, m_sourcePropertyIndex, argv);
+        bindable.observe(observer.get());
+        return;
+    }
+
+    // We cannot capture non-bindable properties without signals
+    if (notifyIndex == -1)
+        return;
+
+    if (isConnected(m_sourceObject, notifyIndex))
+        cancelNotify();
+    else
+        connect(m_sourceObject, notifyIndex, m_engine, true);
+}
+
+void QQmlPropertyToPropertyBinding::update(QQmlPropertyData::WriteFlags flags)
+{
+    if (!enabledFlag())
+        return;
+
+    // Check that the target has not been deleted
+    QObject *target = targetObject();
+    if (QQmlData::wasDeleted(target))
+        return;
+
+    const QQmlPropertyData *d = nullptr;
+    QQmlPropertyData vtd;
+    getPropertyData(&d, &vtd);
+    Q_ASSERT(d);
+
+    // Check for a binding update loop
+    if (Q_UNLIKELY(updatingFlag())) {
+        QQmlAbstractBinding::printBindingLoopError(
+                    QQmlPropertyPrivate::restore(target, *d, &vtd, nullptr));
+        return;
+    }
+
+    setUpdatingFlag(true);
+
+    if (canUseAccessor())
+        flags.setFlag(QQmlPropertyData::BypassInterceptor);
+
+    const QMetaObject *sourceMetaObject = m_sourceObject->metaObject();
+    const QMetaProperty property = sourceMetaObject->property(m_sourcePropertyIndex);
+    if (!property.isConstant()) {
+        captureProperty(sourceMetaObject, QMetaObjectPrivate::signalIndex(property.notifySignal()),
+                        property.isBindable(), !vtd.isValid() && d->isBindable());
+    }
+
+    QQmlPropertyPrivate::writeValueProperty(
+            target, *d, vtd, property.read(m_sourceObject), {}, flags);
+
+    setUpdatingFlag(false);
+}
+
+void QQmlPropertyGuard_callback(QQmlNotifierEndpoint *e, void **)
+{
+    static_cast<QQmlPropertyToPropertyBinding *>(e)->update();
+}
+
+void QQmlPropertyToPropertyBinding::Observer::trigger(
+        QPropertyObserver *observer, QUntypedPropertyData *)
+{
+    static_cast<Observer *>(observer)->binding->update();
+}
+
+QT_END_NAMESPACE