Add setContextProperties()

Setting all properties in one batch avoids unnecessary
refreshing of expressions and is therefore a lot
faster if there are many expressions in the context.

In an example I created it takes 500ms to set 10 context properties
using setContextProperty() and it takes about 150ms to set the
context properties using setContextProperties.

Change-Id: Ic7cf03cda292b316198f37f963b61a2388a288c9
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

src/qml/qml/qqmlcontext.cpp

@@ -329,6 +329,49 @@ void QQmlContext::setContextProperty(const QString &name, QObject *value)
     setContextProperty(name, QVariant::fromValue(value));
 }
 
+/*!
+    \since 5.11
+
+    Set a batch of \a properties on this context.
+
+    Setting all properties in one batch avoids unnecessary
+    refreshing  expressions, and is therefore recommended
+    instead of calling \l setContextProperty() for each individual property.
+
+    \sa QQmlContext::setContextProperty()
+*/
+void QQmlContext::setContextProperties(const QVector<PropertyPair> &properties)
+{
+    Q_D(const QQmlContext);
+
+    QQmlContextData *data = d->data;
+
+    QQmlJavaScriptExpression *expressions = data->expressions;
+    QQmlContextData *childContexts = data->childContexts;
+
+    data->expressions = 0;
+    data->childContexts = 0;
+
+    for (auto property : properties)
+        setContextProperty(property.name, property.value);
+
+    data->expressions = expressions;
+    data->childContexts = childContexts;
+
+    data->refreshExpressions();
+}
+
+/*!
+    \since 5.11
+
+    \class QQmlContext::PropertyPair
+
+    This struct contains a property name and a property value.
+    It is used as a parameter for the \c setContextProperties function.
+
+    \sa QQQmlContext::setContextProperties()
+*/
+
 /*!
   Returns the value of the \a name property for this context
   as a QVariant.

src/qml/qml/qqmlcontext.h

@@ -42,6 +42,8 @@
 
 #include <QtCore/qurl.h>
 #include <QtCore/qobject.h>
+#include <QtCore/qlist.h>
+#include <QtCore/qpair.h>
 #include <QtQml/qjsvalue.h>
 #include <QtCore/qmetatype.h>
 #include <QtCore/qvariant.h>
@@ -62,6 +64,8 @@ class Q_QML_EXPORT QQmlContext : public QObject
     Q_DECLARE_PRIVATE(QQmlContext)
 
 public:
+    struct PropertyPair { QString name; QVariant value; };
+
     QQmlContext(QQmlEngine *parent, QObject *objParent = nullptr);
     QQmlContext(QQmlContext *parent, QObject *objParent = nullptr);
     virtual ~QQmlContext();
@@ -77,6 +81,7 @@ public:
     QVariant contextProperty(const QString &) const;
     void setContextProperty(const QString &, QObject *);
     void setContextProperty(const QString &, const QVariant &);
+    void setContextProperties(const QVector<PropertyPair> &properties);
 
     // ### Qt 6: no need for a mutable object, this should become a const QObject pointer
     QString nameForObject(QObject *) const;

tests/auto/qml/qqmlcontext/tst_qqmlcontext.cpp

@@ -47,6 +47,7 @@ private slots:
     void engineMethod();
     void parentContext();
     void setContextProperty();
+    void setContextProperties();
     void setContextObject();
     void destruction();
     void idAsContextProperty();
@@ -363,6 +364,32 @@ void tst_qqmlcontext::setContextProperty()
     }
 }
 
+void tst_qqmlcontext::setContextProperties()
+{
+    QQmlContext ctxt(&engine);
+
+    TestObject obj1;
+    obj1.setA(3345);
+    TestObject obj2;
+    obj2.setA(-19);
+
+    QVector<QQmlContext::PropertyPair> properties;
+
+    properties.append({QString("a"), QVariant(10)});
+    properties.append({QString("b"), QVariant(19)});
+    properties.append({QString("d"), QVariant::fromValue<TestObject*>(&obj2)});
+    properties.append({QString("c"), QVariant(QString("Hello World!"))});
+    properties.append({QString("e"), QVariant::fromValue<TestObject*>(&obj1)});
+
+    ctxt.setContextProperties(properties);
+
+    TEST_CONTEXT_PROPERTY(&ctxt, a, QVariant(10));
+    TEST_CONTEXT_PROPERTY(&ctxt, b, QVariant(19));
+    TEST_CONTEXT_PROPERTY(&ctxt, c, QVariant(QString("Hello World!")));
+    TEST_CONTEXT_PROPERTY(&ctxt, d.a, QVariant(-19));
+    TEST_CONTEXT_PROPERTY(&ctxt, e.a, QVariant(3345));
+}
+
 void tst_qqmlcontext::setContextObject()
 {
     QQmlContext ctxt(&engine);