[SOLVED] How to create QML Image Element from a QImage Object (C++)?
How can I convert a QImage into a QML Element? I can’t use the Image QML Element because the source property requires an URL and I only have the actual QImage in memory.
The only way I could come up with so far is to extend the QDeclarativeItem and render the image. It is far from ideal because then I can’t make use of the capabilities of the QML Image element.
Thanks,
Felipe
5 replies
Hi,
You can use QDeclarativeImageProvider [doc.qt.nokia.com] to load a QImage into an Image element.
Regards,
Michael
Yes, it’s less than ideal. Originally we allowed setting a QPixmap directly on the Image element, but there were memory management issues with that approach. QDeclarativeImageProvider was the solution we came up with to those issues for 4.7 — it may be that a better solution is possible in future releases.
Please let us know if you have any suggestions.
Michael,
Unfortunately I don’t know the details about how Qt manage memory so can’t even guess the best way to implement but I can think of two user case scenarios:
1. When you have a “legacy” model with images, you would want to initialize the Image Element with the QImage doing something hopefully as simple as this:
- Image {
- sourceX: modelData.decorationRole;
- }
2. On a little more sophisticated user case you could have a c++ class like:
set the context property:
- ui->view->rootContext()->setContextProperty("myA", new A());
and then you could bind the QImage on QML:
- Image {
- sourceWithBinding: myA.image;
- }
so the QML Image element could be notified of changes on the property (for example as result of the C++ app generating a new graph as result of the user input)
It’s maybe too late but I wrote an article about this and it can maybe help someone.
http://www.fdelgado.fr/QtQuick/2011/08/30/72/ [fdelgado.fr]
It’s in french but easily too translate with tools, and the code can be usefull.
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