setAutoFillBackgroundRole not working

ofmrew

I check the autoFillBackground box and
ui->canvas->setAutoFillBackground(QPalette::Base);

but I do not get the canvas filled with white.
Canvas is a new class and in Designer I added a widget, promoted it to MyCanvas and added the line above to MainWindow. I have done this more times than I can remember, but this is the first time it has failed. Can some one suggest how I can find out why this fail?

JonB

@ofmrew
QWidget::setAutoFillBackground(bool enabled) has always taken a bool, not QPalette::Base.

ofmrew

@JonB I am referring to creating the UI in Designer, I have never created a ui programmatically; However, I looks like I must.

ofmrew

@ofmrew All of the examples I have seen start with QWidget and not QMainWindow; however, I need the features that QMainWindows provides. Can you point me to and example of a UI based on QMainWindows?

mrjj

@ofmrew

Hi
Its also a property so you should be able to set in designer.
alt text

ofmrew

@mrjj I stated in the first line that that was done.

mrjj

@ofmrew
Ah The question is how to set the color for the
setAutoFillBackground(bool) then ?

You can change its palette or use a stylesheet.
(you can change palette in the designer)

ofmrew

Update. I created a new UI using the same steps as before and I works fine! Sometimes Designer drives me crazy, especially when layouts are involved. However, for now, problem solved. Thanks for your input. However, I would still like that reference to programmatically creating a UI with QMainWindow.

JonB

@ofmrew
A QMainWindow is a QWidget, so anything & everything you can do with the latter you can do too with the former. For QMainWindow concepts and code start at https://doc.qt.io/qt-6/qmainwindow.html#details.

mrjj

@ofmrew
Ok super.

You mean a QMainWindow based one from code ?

#include <QApplication>
#include <QMainWindow>
#include <QMenuBar>
#include <QStatusBar>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QMainWindow MainWindow;
    MainWindow.setObjectName(QString::fromUtf8("MainWindow"));
    MainWindow.resize(800, 600);
 // mainwin has a special area called centralwidget where you put stuff
    QWidget *centralwidget = new QWidget(&MainWindow);
    MainWindow.setCentralWidget(centralwidget);
// and a menu bar
    QMenuBar *menubar = new QMenuBar(&MainWindow);
    MainWindow.setMenuBar(menubar);
// and a status bar
    QStatusBar *statusbar = new QStatusBar(&MainWindow);
    MainWindow.setStatusBar(statusbar);
    MainWindow.show();
    return a.exec();
}

ofmrew

@JonB I had that, I was looking for more. So, I will post what I find out.

ofmrew

@mrjj Thanks. I will use that code as a starting point and post my results.

ofmrew

@mrjj I am using your code in QtCreator Widget Application, not Console Application because when I tried that the includes could not be found. I have searched the documentation and I have this :

        QWidget *centralwidget = new QWidget(&MainWindow);
        MainWindow.setCentralWidget(centralwidget);
        QVBoxLayout * centraLWidgetLayout = new QVBoxLayout(centralwidget);
        QHBoxLayout * buttonLayout = new QHBoxLayout();
        QWidget * mainWindow = new QWidget(centralwidget);
        QPushButton * button1 = new QPushButton("Button 1");
        QPushButton * button2 = new QPushButton("Button 2");
        buttonLayout->addWidget(button1);
        buttonLayout->addWidget(button2);

I know that there must be a layout associated with the central widget but how do I get centraLWidgetLayout associated with the central widget and I assume that buttonLayout must be associated with some widget, but what is that widget? I can add my buttons to the buttonLayout and I what that layout and MyCanvas widget In the centraLWidgetLayout.

This why I was looking for an example that starts with QMainWindow and not QWidget. The documentation says what happens, but not how to get what you want to happen. Help.

ofmrew

I finally got it:

#include "mainwindow.h"
#include <QMainWindow>
#include <QMenuBar>
#include <QStatusBar>
#include <QHBoxLayout>
#include <QVBoxLayout>
#include <QWidget>
#include <QPushButton>
#include "mycanvas.h"
#include <QApplication>

int main(int argc, char *argv[])
{

    QApplication a(argc, argv);
    QMainWindow MainWindow;
        MainWindow.setObjectName(QString::fromUtf8("MainWindow"));
        MainWindow.resize(800, 600);
     // mainwin has a special area called centralwidget where you put stuff
        QWidget *centralwidget = new QWidget(&MainWindow);
        MainWindow.setCentralWidget(centralwidget);
        QVBoxLayout * centraLWidgetLayout = new QVBoxLayout(centralwidget);
        MyCanvas * canvas = new MyCanvas(centralwidget);
        canvas->setAutoFillBackground(true);
        canvas->setBackgroundRole(QPalette::Base);
        QHBoxLayout * buttonLayout = new QHBoxLayout();
        QPushButton * button1 = new QPushButton("Button 1");
        QPushButton * button2 = new QPushButton("Button 2");
        buttonLayout->addWidget(button1);
        buttonLayout->addWidget(button2);
        centraLWidgetLayout->addWidget(canvas);
        centraLWidgetLayout->addLayout(buttonLayout);
    // and a menu bar
        QMenuBar *menubar = new QMenuBar(&MainWindow);
        MainWindow.setMenuBar(menubar);
    // and a status bar
        QStatusBar *statusbar = new QStatusBar(&MainWindow);
        MainWindow.setStatusBar(statusbar);
    MainWindow.show();
    return a.exec();
}

Thanks mrjj.
I need to add horizontal spacers.
Easier than I thought it would be.

Now I need to find out why the .h and .ccp file were not found when I tried console mode.

ofmrew

The following is a updated version. The last version did not do anything so I add signals and slots so it would be useful.

#include "mainwindow.h"
#include <QMainWindow>
#include <QMenuBar>
#include <QStatusBar>
#include <QHBoxLayout>
#include <QVBoxLayout>
#include <QWidget>
#include <QPushButton>
#include "mycanvas.h"
#include <QDebug>
#include <QApplication>

int main(int argc, char *argv[])
{

    QApplication a(argc, argv);

    QMainWindow MainWindow;
    MainWindow.setObjectName(QString::fromUtf8("MainWindow"));
    MainWindow.setWindowTitle("My Try");
    MainWindow.resize(800, 600);
    QWidget *centralwidget = new QWidget(&MainWindow);
    MainWindow.setCentralWidget(centralwidget);
    QVBoxLayout * centraLWidgetLayout = new QVBoxLayout(centralwidget);
    MyCanvas * canvas = new MyCanvas(centralwidget);
    canvas->setAutoFillBackground(true);
    canvas->setBackgroundRole(QPalette::Base);
    QHBoxLayout * buttonLayout = new QHBoxLayout();
    QPushButton * button1 = new QPushButton("Button 1");
    QPushButton * button2 = new QPushButton("Button 2");
    buttonLayout->addWidget(button1);
    buttonLayout->addWidget(button2);
    buttonLayout->insertSpacing(1,30);
    centraLWidgetLayout->addWidget(canvas);
    centraLWidgetLayout->addLayout(buttonLayout);
    // and a menu bar
        QMenuBar *menubar = new QMenuBar(&MainWindow);
        MainWindow.setMenuBar(menubar);
    // and a status bar
        QStatusBar *statusbar = new QStatusBar(&MainWindow);
        MainWindow.setStatusBar(statusbar);
    MainWindow.connect(button1, &QPushButton::clicked,[statusbar](){statusbar->showMessage("clicked 1");});
    MainWindow.show();
    return a.exec();
}

However, after adding the spacer to separate the two buttons and looking at the work still to be done, really makes me appreciate Designer, even with all it quirks. Hope this might help someone else.