[Solved]Edit qml property from c++

ealione

I have a qml file that contains a number of properties (it displays a rectangle, and the properties are its dimensions).

Is it possible for me to be able to alter those properties, lets say the 'width' property, from c++ and have that change reflected on my qml rectangle.

? Offline

Yes.

@
object->setProperty("width", 500);
@

For more information see "Interacting with QML Objects from C++":http://doc.qt.io/qt-5/qtqml-cppintegration-interactqmlfromcpp.html .

p3c0

Hi,

To add to Wieland's answer, if the Item whose property you need to change from C++ is not root Item, you may need to find that particular Item using findChild and passing it the Item's objectName.

ealione

My qml file looks like this

@import QtQuick 2.3

import MyCustoms 1.0

Rectangle {

property int    x Val               : 20
property int    yVal                : 3
property int    radiusVal        : 10

id: content
color: "red"
antialiasing: true
anchors.fill: parent; anchors.margins: 10; radius: radiusVal
Rectangle { // smaller rectangle with another colour }
}@

and I instantiate it from c++ like this

@view = new QQuickView();

view->setSource(QUrl("qrc:/qmlRect.qml"));
view->setResizeMode(QQuickView::SizeRootObjectToView);
view->show();@

The first thing I tried was in some function have this

@view->setProperty("radiusVal", 40);@

and call it at some point.

No change whatsoever can be observed on my rectangle though.

EDIT

Even if I try

@QObject *rootObject = view->rootObject();
rootObject->setProperty("radiusVal",30);@

won't have any effect.

p3c0

@
view->setProperty("radiusVal", 40)
@

would update QQuickView's property and not Rectangle's.
The other approach should work. Could be some other problem.

ealione

It is indeed working, I had another mistake on my source files they prevented the change.

Rolias

I published my third course on Qt this month. The final course is on " Integrating Qt Quick with C++ ":http://bit.ly/qtquickcpp. Watching it might save you some time, your question is covered directly in the course. Pluralsight is a subscription site but they have a free ten-day trial (limited to 4 hours) and I also have some VIP passes left. The VIP pass is good for a week but includes the ability to watch unlimited hours during the week, download the course materials, and watch offline (offline content will expire with the pass). If you want a pass, just send me an email through this forum.

ealione

Hi Rolias, I will check that out. I don't believe i will need the VIP pass if as you say I can watch 4 hours for free.

Rolias

Of course I hope you'll want to watch more than just one course! Also if you watch with a VIP pass the time you spend watching counts for my course, with the 10 day trial I get no credit.

ealione

Didn't know that. Well since I plan to watch them anyway I might as well do it with a pass. If you still have any left please do email me.