How to load a widget from a ui file saved in resource?

Daniella

I have a .ui file saved in the .qrc named treeview.ui, into this .ui i have a QTreeView that have been promoted on Qt Designer, to a subclass called TreeView.

I'm reading this file in a loop and in each iteration copying this TreeView to a QStackedWidget, the widget is being added to the container correctly, however, I'm getting this message in the console:

"QFormBuilder was unable to create a custom widget of the class 'TreeView'; defaulting to base class 'QTreeView'."

What i'm missing?

#include "treeview.h" // The file that contains the subclass promoted on Qt Designer

QUiLoader loader;
QFile file(":/ui/treeview.ui");
//file.open(QIODevice::ReadOnly);

for (i = map.begin(); i != map.end(); ++i)
{
    // ...
    file.open(QIODevice::ReadOnly);
    QWidget *form = loader.load(&file);
    file.close();

    qDebug() << form;
    if (!form) {
        qDebug() << "Error loading UI file:" << loader.errorString();
    }
    ui->treeViewContainer->addWidget(form);
}

Also, do i really need to open the file and call loader.load(&file) in each iteration of the loop to be able to make a new 'copy' of the widget in the treeViewContainer?

mpergand

@Daniella said in How to load a widget from a ui file saved in resource?:

defaulting to base class 'QTreeView'."

Be sure to specify the full path of the header file in Promote To dialog.

do i really need to open the file and call loader.load(&file) in each iteration

calling seek(0) or reset() should be enough.

Daniella

@mpergand said in How to load a widget from a ui file saved in resource?:

@Daniella said in How to load a widget from a ui file saved in resource?:

defaulting to base class 'QTreeView'."

Be sure to specify the full path of the header file in Promote To dialog.

I have tried adding the full path to the treeview.h in the qt designer promote dialog, but i still getting this message.

Roberrt

@Daniella I have found a similar post: https://forum.qt.io/topic/68045/can-t-load-custom-widget-using-quiloader/10

"What available widgets do you get, is your class present in that list?"
When i call qDebug() << loader.availableWidgets(); my subclassed TreeView* is not on the list.

I saw that the guy solved her problem by sub classing Ui loader and override the createWidget as kshegunov suggested.

@kshegunov do you mind telling how should be the subclassed Ui loader?

mpergand

@Daniella said in How to load a widget from a ui file saved in resource?:

I have tried adding the full path to the treeview.h

Do you use any namespace ?

To be honest, I don't get the goal to have a ui file as a resource ...

Daniella

@Roberrt Thank you for the link, i got it working by subclassing UiLoader

#pragma once
#include "stdafx.h"
#include "pushbutton.h"
#include "treeview.h"

class UiLoader : public QUiLoader
{
public:
    UiLoader(QObject *parent = nullptr) : QUiLoader(parent) {}

    QWidget *createWidget(const QString &className, QWidget *parent = nullptr, const QString &name = QString()) override
    {
        //qDebug() << "className: " << className;
        if (className == "PushButton")
            return new PushButton(parent);
        else if (className == "TreeView")
            return new TreeView(parent);
        else
            return QUiLoader::createWidget(className, parent, name);
    }
};

I also have no experience with this topic (uiloader etc), I wonder if the loader subclass is correctly.

@mpergand no, i'm not using namespace.

kshegunov

@mpergand said in How to load a widget from a ui file saved in resource?:

To be honest, I don't get the goal to have a ui file as a resource ...

There are niche uses where you want the UI to be built at runtime (connecting signals/slots at runtime etc.) instead of compiling it in via the code generated by uic. That way you can change the UI without actually rebuilding the application/library, but it is rare.