Qt5.5 image resizing jitter and not smooth - qt

Question

i'm learning Qt5. I start with a really simple QtQuick QML app with just one image filling the background. It works, but when i resize the window (Windows 8.1 64 bit), the resize is not smooth. There is substantial jitter and sometimes significant lag. It should be using OGL for this right?
Here's my code:
import QtQuick 2.5
import QtQuick.Controls 1.4
import QtQuick.Dialogs 1.2
ApplicationWindow {
visible: true
width: 640
height: 480
title: qsTr("Hello World")
menuBar: MenuBar {
Menu {
title: qsTr("File")
MenuItem {
text: qsTr("&Open")
onTriggered: console.log("Open action triggered");
}
MenuItem {
text: qsTr("Exit")
onTriggered: Qt.quit();
}
}
}
MainForm {
anchors.fill: parent
}
}
and
import QtQuick 2.5
import QtQuick.Controls 1.4
import QtQuick.Layouts 1.2
Item {
visible: true
width: 640
height: 480
Image {
id: image1
sourceSize.height: 687
sourceSize.width: 1280
smooth: false
anchors.fill: parent
source: "images/showcase1280.jpg"
}
}
suggetions appreciated.

Answer 1

It is not smooth.
The image has a property named smooth the aim of which is to hold:
[...] whether the image is smoothly filtered when scaled or transformed.
Another interesting property is mimap, for which the documentation says that:
This property holds whether the image uses mipmap filtering when scaled or transformed.
Mipmap filtering gives better visual quality when scaling down compared to smooth, but it may come at a performance cost (both when initializing the image and during rendering).
Note that in your code you set:
smooth: false
Maybe you are doing it wrong if you want smooth changes, try setting the above mentioned properties to true.

Answer 2

I`m not pretend by solve your task. But i think you can use animation, as a variant:
import QtQuick 2.4
import QtQuick.Controls 1.3
import QtQuick.Layouts 1.1
Item {
Image {
anchors.centerIn: parent
width: parent.width
height: parent.height
sourceSize.height: 1000
sourceSize.width: 2000
source: "https://upload.wikimedia.org/wikipedia/ru/archive/8/88/20090512220306!Qt_logostrap_CMYK.png"
smooth: false
fillMode: Image.Stretch
asynchronous: true
Behavior on width {
animation: whAnimation
}
Behavior on height {
animation: whAnimation
}
NumberAnimation {
id: whAnimation
duration: 150
}
}
}