ListView: text disappears when scrolling (delegate is text over image)

alexein1983

Hi,
I have ListView with simple delegate of text over Image:
Image
{
width: 200
height: 100
source: backend.imageList[ model.id]
Row
{
width: parent.width
height: 40
spacing: 2

   Text
    {
        width: 100
        height: 40
        horizontalAlignment: Qt.AlignHCenter
        verticalAlignment: Qt.AlignVCenter
        text: model.id
    }

    Text
    {
        width: 100
        height: 40
        elide: Qt.ElideMiddle
        horizontalAlignment: Qt.AlignHCenter
        verticalAlignment: Qt.AlignVCenter
        text: "Fixed text 2"
    }

}

When i perform scrolling: the text surprisingly disappeared on some y positions.
The effect happens everytime with specific image.
Changing the Image with Rectangle fix the problem.

Platform: both Linux and Windows.

Any help would be appreciated.

vladstelmahovsky

Hi

probably you adding elements to your model not in GUI thread?

alexein1983

@vladstelmahovsky
No, the model which i use lives within main GUI thread.

? Offline

Hi,
I experienced this, too, when putting Text over a Rectangle with round corners.

alexein1983

My problem is image delegate only.

I found addiotional regularity: problematic delegates have the same picture as last top delegate hidden during scroll down within ListView.
It seems scrolling out delegate from visible area forces it's image repaint in other delegates, which are in visible area.

This repaint seems to hide the text element, declered with z-order above the image.
Reset the visible property (visible=false, visible=true) at end of each scrolling (using onMovementEneded) solves the problem.
But, i don't want to pay the repaint price of such solution as my application is running on embedded device.