Instead of smooth: true doing this may achieve the same result with less memory usage:

sourceSize.width: parent.width
sourceSize.height: parent.height

In D22451#495272, @ngraham wrote:

Instead of smooth: true doing this may achieve the same result with less memory usage:

sourceSize.width: parent.width
sourceSize.height: parent.height

I tried it but got black screen...

QImageItem {
    anchors.fill: parent
    image: engine.data[provider]["Image"]
    fillMode: wallpaper.configuration.FillMode
    // Render image smoothly
    sourceSize.width: parent.width
    sourceSize.height: parent.height
}

Ah right, that's a property of Image, not QImageItem.

https://doc.qt.io/qt-5/qml-qtquick-image.html#sourceSize-prop

Can you use Image instead?

In D22451#495279, @ngraham wrote:

Ah right, that's a property of Image, not QImageItem.

https://doc.qt.io/qt-5/qml-qtquick-image.html#sourceSize-prop

Can you use Image instead?

I got a blocker: engine.data[provider]["Image"] is QImage not string. So I cannot assign it as source of Image. I don't know if it is possible.