Controls from scratch

qtprogrammer123

Hi,
Is making control from scratch - making all from rectangles etc. have any sense, its rally work faster in big apps?

sierdzio

@qtprogrammer123 said in Controls from scratch:

Hi,
Is making control from scratch - making all from rectangles etc. have any sense, its rally work faster in big apps?

Each Item or Rectangle you add constructs a new QObject and adds objects to drawing queue for the scene graph - so making custom components in this way is not "really faster" - it makes your app slower.

Often, on desktops, it does not matter much, but on mobile and embedded platforms it can make a big difference.

The Quick Controls 2 are built in a different way - they are subclasses of QQuickItem and do their painting directly in C++ using OpenGL (or, nowadays, using RHI) - that's why they have such good performance when compared to Controls 1.

qtprogrammer123

Ok thx, just in case i give example.

import QtQuick 2.0

Item {
    id: control

    property string text:    ''
    property bool   checked: false

    property real padding: 0.1

    width: 30 + text.paintedWidth;  height: 30

    opacity: enabled  &&  !mouseArea.pressed ? 1: 0.3

    Rectangle {
        id: rectangle

        height: control.height * (1 - 2 * padding);  width: height
        x: padding * control.height
        anchors.verticalCenter: parent.verticalCenter
        border.width: 2
        border.color: mouseArea.pressed ? "gray" : "darkgray"
        radius: 0.2 * height
        color: checked ? (mouseArea.isEntred ? "#63d7ff" : "#4fc1e9") : (mouseArea.isEntred ? "#e1e6ef" : "#ccd1d9")

        Text {
            color: "white"
            visible: checked
            anchors.centerIn: parent
            text: '\u2713'

            font.pixelSize: parent.height - parent.border.width
        }
    }

    Text {
        id: text

        text: control.text
        anchors {left: rectangle.right;  verticalCenter: rectangle.verticalCenter;  margins: padding * control.height}
        font.pixelSize: 0.5 * control.height
    }

    MouseArea {
        id: mouseArea

        property bool isEntred: false

        hoverEnabled: true
        anchors.fill: parent

        onClicked: checked = !checked
        onEntered: isEntred = true
        onExited: isEntred = false
    }
}

This will be slower at desktop app? Even i dont see it

sierdzio

Slower than what?

qtprogrammer123

Than custom checkbox but made at qucik2 CheckBox base

CheckBox{

   indicator...

  currentItem...

}

sierdzio

I don't know. To notice any performance difference I guess you'd have to spawn 50 of them and test on some slow device. I guess custom-styled Controls 2 are going to be faster due to some optimizations they can do to drawing, but I don't really know this for sure.

To me it's more of a question of what do you prefer to use as a programmer, what will be easier to write and maintain.