QML / QWidget & Window icons

[J.Hilk]

Hi everyone,

I'm looking for the QML equivalent of QWidget::SetWindowIcon and I seem unable to find it in the docu:

Theres the title property but, one for the icon seems to be missing.

I can set an Icon by calling
QApplication::setWindowIcon(); inside the main.cpp
but, thats global and can't be changed, once exec() is called.

My last Idea(untested so far) would be, to move from QQmlApplicationEngine to a QQuickView, because that one has a setIcon function, but I would rather not go the way over QWidgets.

[J.Hilk]

Thanks @SGaist and @GrecKo for your input on this issue.

I ended up following the tip I found in the mailing list conversation SGaist posted.

A QML Window is a QQuickWindow which is a subclass of QWindow, so the method you would want to call is QWindow::setIcon(QIcon &). Maybe you can create a subclass of QQuickWindow in C++ ...

this is also basicaly what GrecKo suggested, I think.

The fix was surprisingly easy, and I'm surpised that this hasn't been added to the official release yet, the Mailinglist conversation was on Jan 29, 2013 !

the Custom QQuickWindow

#ifndef QUICKWINDOW_H
#define QUICKWINDOW_H

#include <QQuickWindow>
#include <QIcon>

class QuickWindow : public QQuickWindow
{
    Q_OBJECT

    Q_PROPERTY(QString windowIcon READ windowIcon WRITE setWindowIcon NOTIFY windowIconChanged)
public:
    explicit QuickWindow(QQuickWindow *parent = nullptr) : QQuickWindow(parent)  {}

    const inline QString &windowIcon(){return str;}
    inline void setWindowIcon(const QString &str){
         if(str != m_str){
             m_str = str;
             setIcon(QIcon(m_str));
             emit windowIconChanged();
         }
   }

signals:
    void windowIconChanged();

private:
    QString m_str;

};

#endif // QUICKWINDOW_H

main.cpp

#include "quickwindow.h"

int main(int argc, char *argv[]){
   ....
   qmlRegisterType<QuickWindow>("QuickWindow",1,0, "QuickWindow");
    
   QQmlApplicationEngine engine;
   engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
   ....
}

main.qml

import QuickWindow 1.0

QuickWindow{
    ....
    title: qsTr("MyApp")
    windowIcon: ":/Path/to/image.png"
    ....
}

and done.

Thanks for the help guys.

[SGaist]

Hi,

This interest mailing list thread might be of use.

It looks like the Window type is missing some APIs.

[GrecKo]

What I would do:

Create an attached type for the window with an icon property, effectively calling QWindow::setIcon.
Usage would be like this:

ApplicationWindow {
    // ...
    WindowHelper.icon: "qrc:/windowIconFile" 
  // ...
}

reference: http://doc.qt.io/qt-5/qtqml-cppintegration-definetypes.html#providing-attached-properties

[J.Hilk]

Thanks @SGaist and @GrecKo for your input on this issue.

I ended up following the tip I found in the mailing list conversation SGaist posted.

A QML Window is a QQuickWindow which is a subclass of QWindow, so the method you would want to call is QWindow::setIcon(QIcon &). Maybe you can create a subclass of QQuickWindow in C++ ...

this is also basicaly what GrecKo suggested, I think.

The fix was surprisingly easy, and I'm surpised that this hasn't been added to the official release yet, the Mailinglist conversation was on Jan 29, 2013 !

the Custom QQuickWindow

#ifndef QUICKWINDOW_H
#define QUICKWINDOW_H

#include <QQuickWindow>
#include <QIcon>

class QuickWindow : public QQuickWindow
{
    Q_OBJECT

    Q_PROPERTY(QString windowIcon READ windowIcon WRITE setWindowIcon NOTIFY windowIconChanged)
public:
    explicit QuickWindow(QQuickWindow *parent = nullptr) : QQuickWindow(parent)  {}

    const inline QString &windowIcon(){return str;}
    inline void setWindowIcon(const QString &str){
         if(str != m_str){
             m_str = str;
             setIcon(QIcon(m_str));
             emit windowIconChanged();
         }
   }

signals:
    void windowIconChanged();

private:
    QString m_str;

};

#endif // QUICKWINDOW_H

main.cpp

#include "quickwindow.h"

int main(int argc, char *argv[]){
   ....
   qmlRegisterType<QuickWindow>("QuickWindow",1,0, "QuickWindow");
    
   QQmlApplicationEngine engine;
   engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
   ....
}

main.qml

import QuickWindow 1.0

QuickWindow{
    ....
    title: qsTr("MyApp")
    windowIcon: ":/Path/to/image.png"
    ....
}

and done.

Thanks for the help guys.

[nightshift]

@J.Hilk said in QML / QWidget & Window icons:

const inline QString &windowIcon(){return str;}

Hi J.Hilk,

I just wonder that your solution work..
I got a "str was not declared in this scope for

const inline QString &windowIcon(){return str;}

May you can give your code a try with the recend Qt-Version and QtCreator 4.9.0?

Kind regards,

J-I W.

Here for reference my system environment:

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Qt Creator 4.9.0
Based on Qt 5.12.2 (GCC 5.3.1 20160406 (Red Hat 5.3.1-6), 64 bit)
From revision 7885bc899f
Built on Apr 12 2019 00:20:28

{noformat}

[J.Hilk]

hi @nightshift and welcome
that must have been a copy and past error on my side, as windowIcon() should return the member variable m_str
can't believe, I missed that x)

[GrecKo]

This must be a typo. return m_str will work.

Note that by using QQuickWindow as a base class, you will lose some of the functionnality of QML Window, and even more of ApplicationWindow.

That's why I suggested using an attached object so that it could attach to any arbitrary window without having to subclass one.

[nightshift]

@J.Hilk thanks you for the quick answer. :)
It's just the simple things which break the biggest inventions.
@GrecKo:
Thanks for the Note, if I'am a pure Newbie and currently stumbling around Qt and C++, I don't think it will make a big issue for me, losing some funcionality. :D

Have all a nice day!

[JoeCFD]

Today I came cross the same issue as well. Is it a better solution without QuickWindow?
After main.qml is loaded:

    auto root_window = qobject_cast< QQuickWindow * >( m_qmlAppEngine->rootObjects()[ 0 ] );
    if ( nullptr != root_window ) {
        root_window->setIcon( QIcon( "***" ) );
    }

this works for me.

[pourjour]

@GrecKo for more information about what @GrecKo mentioned refer to this example:

https://doc.qt.io/qt-6/qtqml-referenceexamples-extended-example.html