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  1. #1
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    Default Extract QImage from QQuickItem

    Hi,

    I would like to process an image loaded into a Flickable QML element in C++ land but I am failing to obtain the original image. So far I'm only seem able to obtain an image of the QQuickWindow
    and would liek to know if there is a way to obtain the whole loaded image.

    I am calling a Q_INVOKABLE method of a C++ object as follows:


    Qt Code:
    1. Flickable {
    2. id: content
    3. clip: false
    4. anchors.fill: parent
    5. boundsBehavior: Flickable.StopAtBounds
    6.  
    7. Loader {
    8. id: contentLoader
    9. anchors.centerIn: parent
    10. }
    11.  
    12. MouseArea {
    13. anchors.fill: parent
    14. onClicked: {
    15. console.log("[veo] onClicked - capture triggered")
    16. cplusplusobject.process(contentLoader.item) <----------------- call to C++
    17. }
    18. }
    To copy to clipboard, switch view to plain text mode 


    In C++ I have:

    Qt Code:
    1. void
    2. Cplusplusobject::process(const QVariant &v)
    3. {
    4. qDebug() << "[veo]" << __FUNCTION__;
    5. QQuickItem *item = qobject_cast<QQuickItem *>( v.value<QObject*>() );
    6. qDebug() << "Item dimensions:" << item->width() << item->height();
    7.  
    8. item->dumpObjectInfo();
    9.  
    10. QQuickWindow *window = item->window();
    11. QImage image = window->grabWindow();
    12. ...
    To copy to clipboard, switch view to plain text mode 

    The printed item dimensions do correspond to the original image but I fail to see how to turn the QQuickItem into a QImage.

    Any suggestions please?

  2. #2
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    Default Re: Extract QImage from QQuickItem

    Up
    I'm also interested by an answer.

    I would like to store an child QML item to an image.
    Currently, I use the grabWindow() method. It works, but this isn't what I want. This stores the whole window.

    I saw this method, which looks right:
    http://stackoverflow.com/questions/1...ving-qml-image
    But QtDeclarativeItem is obsolete, and QQuickItem hasn't got a Paint() method.
    I tried to use the QQuickPaintedItem class, which has got a paint() method, but it is virtual. I don't know how to use it in my case (I'm a newbie).

  3. #3
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    Default Re: Extract QImage from QQuickItem

    I am also interested in that. Does anyone get it?

  4. #4
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    Default Re: Extract QImage from QQuickItem

    In Qt Quick items are OpenGL primitives. If you want to get them as images, you have to force the item to be rendered on a texture, e.g. using ShaderEffectSource and then use QQuickItem API to identify the texture so that you can download it from the atlas. That is not something straightforward though.
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

    Please ask Qt related questions on the forum and not using private messages or visitor messages.


  5. #5
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    Default Re: Extract QImage from QQuickItem

    If the item is fully visible, you could grab a screenshot of the window (QWindow::grabWindow()) and the copy the area of the item into the target image.

    Cheers,
    _

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