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>

2 files changed, 48 insertions, 0 deletions

diff --git a/src/qml/qml/qqmlcontext.cpp b/src/qml/qml/qqmlcontext.cpp
index a32ed6e998..9d2e37a2ab 100644
--- a/src/qml/qml/qqmlcontext.cpp
+++ b/src/qml/qml/qqmlcontext.cpp
@@ -330,6 +330,49 @@ void QQmlContext::setContextProperty(const QString &name, QObject *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.
  */
diff --git a/src/qml/qml/qqmlcontext.h b/src/qml/qml/qqmlcontext.h
index b2b95b7573..506ae216b2 100644
--- a/src/qml/qml/qqmlcontext.h
+++ b/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;