QML Image source is not updated while mouse is pressed

Question

I have ImageButton.qml which should change image when user holds the button.

import QtQuick 2.0

Image {
    id: svg

    property string idleImage
    property string hoverImage

    signal clicked

    state: "idle"

    source: state === "idle" ? idleImage : hoverImage

    onSourceChanged: {
        console.log("source = " + source)
    }

    MouseArea {
        id: mouseArea
        anchors.fill: parent
        acceptedButtons: Qt.LeftButton

        onPressedChanged: {
            svg.state = pressed ? "hover" : "idle"
        }

        onClicked: svg.clicked()
    }
}

But the image is not changed immediately. It's changed only when I hold the button for several seconds. When I press and release mouse button immediately I never see the hover image. onSourceChanged is executed immediately and outputs to console the right image source. This strange bug happens only when I use QQuickWidget. When I don't use widgets, but qml only everything works as expected.

Answer 1

I found the issue. I am using QOpenGLWidget in the MainWindow. And I called update method in paintGL.

void Workspace::paintGL() {
    QOpenGLWidget::paintGL();
    workspaceDrawer.draw();
    update();
}

I replaced update call with a timer, running every 1000 / 60 milliseconds. And the issue was gone. It's strange that it was reproduced only when a mouse button was pressed, otherwise everything was updated correctly.