Graphical effect Glow increases startup time

markugra

Hi there,

I am working on a Qml application that contains many text fields that are supposed to show sensor values. In order to highlight the numbers in case the user clicks on them I implemented a "text glow" using the Glow effect of the QGraphicalEffects module. However, I noticed now that this causes a significant increase (+3 seconds) in the application's startup time and I was wondering why (the visibility property of the effect is set to false by default i.e. on startup) and if there is a way to improve it?

Thanks in advance for any input!

ODБOï

hi @markugra ;
Could you please show your code ?

markugra

Thanks for your response. Below you find the code of the component (i.e. a separate qml file) that I am using to display the numbers. This is used all over the place in my application (I cannot provide all code but I hope this is sufficient).

import QtQuick 2.0
import QtGraphicalEffects 1.0
import "."

Item{
    id: root
    property real number: 0.0
    property string prefix:""
    property string suffix:""
    property int precision: 2
    property alias font: numberText.font
    property alias color: numberText.color
    property alias horizontalAlignment: numberText.horizontalAlignment
    property bool glowOn: false
    implicitHeight: numberText.implicitHeight
    implicitWidth: numberText.implicitWidth

    Text{
        id: numberText
        anchors.fill: parent
        text: root.prefix + Number(root.number).toLocaleString(Qt.locale(),"f",root.precision) + root.suffix
    }
    Glow {
        id: textGlow
        anchors.fill: numberText
        radius: 8
        samples: 1 + radius * 2
        color: numberText.color 
        spread :0.2
        source: numberText
        visible: root.glowOn
        transparentBorder: true 
        fast: true 
        antialiasing: true
    }
}

ODБOï

Im not sure but maybe try enabled:visible

You may be interested
http://doc.qt.io/qt-5/qquickitem.html
http://doc.qt.io/qt-5/qtquick-performance.html

markugra

@LeLev: Thanks for your answer. Unfortunately, setting enabled to false does not have an effect on the startup time either.

What I did do now is to create an additional separate Component that contains both the Text and Glow. Using a Loader, that Component is then loaded only when the glowOn property is set to true otherwise my file above just contains the Text component. It's not that elegant since I have to replace the Text with the same Text (+Glow), but it does the trick.