How to put QscrollArea into gridlayout?

[nanor]

Hi everyone
I wrote a simple program where the dialog window opens in maximized mode and there are some labels and buttons set to this window. I set a gridlayout to my window and added the labels and buttons to the layout , and my code worked fine. When I try to use scrollarea instead of the pink label(which is in row=1 and column=1), I don't get the same result that I got from putting the pink label in (row=1 and column=1).
I know that when labels or buttons are supposed to be in a scrollarea, I must declare a widget and setwidget to the scrollarea, then declare a layout and setlayout to the widget. But for this case(where the scrollarea itself must be in a layout) I don't know what to do.
I would appreciate if someone could help me
Thanks

Here is the code:

    this->setWindowState(this->windowState() ^ Qt::WindowMaximized);
    this->setWindowFlags(windowFlags() | Qt::WindowMinimizeButtonHint | 
    Qt::WindowMaximizeButtonHint);

    int widthW = this->frameGeometry().width();
    int heightW = this->frameGeometry().height();


    red_label = new QLabel(this);
    red_label->showFullScreen();
    red_label->setAlignment(Qt::AlignVCenter | Qt::AlignHCenter);
    red_label->setLayoutDirection(Qt::RightToLeft);
    red_label->setObjectName("forlumha_Name");
    red_label->setStyleSheet(
    "QLabel#forlumha_Name {"
        "background-color:red;"
                "}"
                );

    pink_label = new QLabel(this);
    pink_label ->showFullScreen();
    pink_label ->setAlignment(Qt::AlignVCenter | Qt::AlignHCenter);
    pink_label ->setLayoutDirection(Qt::RightToLeft);
    pink_label ->setObjectName("forlumha_Name");
    pink_label ->setStyleSheet(
    "QLabel#forlumha_Name {"
        "background-color:pink;"
                "}"
                );



    yellow_label = new QLabel(this);
    yellow_label->showFullScreen();
    yellow_label->setAlignment(Qt::AlignVCenter | Qt::AlignHCenter);
    yellow_label->setLayoutDirection(Qt::RightToLeft);
    yellow_label->setObjectName("forlumha_Name");
    yellow_label->setStyleSheet(
    "QLabel#forlumha_Name {"
        "background-color:yellow;"
                "}"
                );



    button_one = new QPushButton(this);
    button_one->setFixedSize(50,50);
    button_two = new QPushButton(this);
    button_two->setFixedSize(50,50);
    button_three = new QPushButton(this);
    button_three->setFixedSize(50,50);



    //..........set layouts......//

    QGridLayout *layout = new QGridLayout();
    this->setLayout( layout );
    layout->addWidget(red_label,0,0,15,1);
    layout->addWidget(yellow_label,0,1,1,1);
    layout->addWidget(pink_label,1,1,14,1);

    layout->addWidget(button_one,6,2,1,1);
    layout->addWidget(button_two,7,2,1,1);
    layout->addWidget(button_three,8,2,1,1);

The output :

When I comment the pink_label parts and declare a scrollArea and put it in row=1 and column=1,the output is :

[SGaist]

Hi,

Which version of Qt are you using ?
On which OS ?

Can you provide a full minimal buildable example to ensure we can test in the same conditions as you ?

By the way, you did not show how you setup the version with the QScrollArea.

[Psnarf]

I would let Designer do much of the work. From Qt Creator, create a dialog project with a Form class so all the glue is already built in, setting up the UI class, the Dialog widget and all. Open designer.ui in Creator's built-in designer, drag/drop a ScrollArea onto your Dialog widget, add a GridLayout, place your buttons and labels, change the label palettes to your colors and all. You wouldn't need to write a line of code. Can't show you an example designer class, since, like SGaist said, you left out much of the details.

[nanor]

@SGaist Hi. I am using Qt creator 4.3.1. , Based on Qt 5.9.0(MSC 2015,32bit). OS: windows 10, 64bit.
the complete code :
dialog.h:

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>
#include <QLabel>
#include <QPushButton>
#include <QScrollArea>


namespace Ui {
class Dialog;
}

class Dialog : public QDialog
{
    Q_OBJECT

public:
    explicit Dialog(QWidget *parent = 0);
    ~Dialog();
    QLabel *red_label;
    QLabel *pink_label;
    QLabel *yellow_label;
    QScrollArea *scrollArea;
    QPushButton *button_one;
    QPushButton * button_two;
    QPushButton * button_three;


private:
    Ui::Dialog *ui;
};
    #endif // DIALOG_H

dialog.cpp:

#include "dialog.h"
#include "ui_dialog.h"
#include <QLabel>
#include <QGridLayout>
#include <QWidget>

Dialog::Dialog(QWidget *parent) :
   QDialog(parent),
   ui(new Ui::Dialog)
{
   ui->setupUi(this);

   this->setWindowState(this->windowState() ^ Qt::WindowMaximized);
   this->setWindowFlags(windowFlags() | Qt::WindowMinimizeButtonHint | Qt::WindowMaximizeButtonHint);



   red_label = new QLabel(this);
   red_label->showFullScreen();
   red_label->setAlignment(Qt::AlignVCenter | Qt::AlignHCenter);
   red_label->setLayoutDirection(Qt::RightToLeft);
   red_label->setObjectName("forlumha_Name");
   red_label->setStyleSheet(
   "QLabel#forlumha_Name {"
       "background-color:red;"
               "}"
               );

  /* pink_label = new QLabel(this);
   pink_label ->showFullScreen();
   pink_label ->setAlignment(Qt::AlignVCenter | Qt::AlignHCenter);
   pink_label ->setLayoutDirection(Qt::RightToLeft);
   pink_label ->setObjectName("forlumha_Name");
   pink_label ->setStyleSheet(
   "QLabel#forlumha_Name {"
       "background-color:pink;"
               "}"
               );*/



   yellow_label = new QLabel(this);
   yellow_label->showFullScreen();
   yellow_label->setAlignment(Qt::AlignVCenter | Qt::AlignHCenter);
   yellow_label->setLayoutDirection(Qt::RightToLeft);
   yellow_label->setObjectName("forlumha_Name");
   yellow_label->setStyleSheet(
   "QLabel#forlumha_Name {"
       "background-color:yellow;"
               "}"
               );



   button_one = new QPushButton(this);
   button_one->setFixedSize(50,50);
   button_two = new QPushButton(this);
   button_two->setFixedSize(50,50);
   button_three = new QPushButton(this);
   button_three->setFixedSize(50,50);

   //.......adding scrollarea........//
   scrollArea = new QScrollArea(this);


   //..........set layouts......//

   QGridLayout *layout = new QGridLayout();
   this->setLayout( layout );
   layout->addWidget(red_label,0,0,15,1);
   layout->addWidget(yellow_label,0,1,1,1);
   //layout->addWidget(pink_label,1,1,14,1);
   layout->addWidget(scrollArea,1,1,14,1);


   layout->addWidget(button_one,6,2,1,1);
   layout->addWidget(button_two,7,2,1,1);
   layout->addWidget(button_three,8,2,1,1);




}

Dialog::~Dialog()
{
   delete ui;
}

pro file:

#-------------------------------------------------
#
# Project created by QtCreator 2020-11-25T19:05:12
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = maximized2
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0


SOURCES += \
        main.cpp \
        dialog.cpp

HEADERS += \
        dialog.h

FORMS += \
        dialog.ui

CONFIG += mobility
MOBILITY = 

main.cpp:

#include "dialog.h"
#include <QApplication>

int main(int argc, char *argv[])
{
   QApplication a(argc, argv);
   Dialog w;
   w.show();

   return a.exec();
}

[nanor]

@Psnarf Hi. I posted the complete code. Actually I am supposed to use this code in another project, where I have to write it without using designer.

[Psnarf]

First, you need to upgrade Qt and Creator, if you can. Using zero instead of nullptr may be considered bad form. I know Creator v4.13.3 no longer uses an integer for a pointer.

Dialog(QWidget *parent = nullptr);

"the scrollarea itself must be in a layout"
Did you read https://doc.qt.io/qt-5/layout.html?

[nanor]

@Psnarf Yes I read the documentation. I set width to the red label:

red_label->setFixedWidth(500);

and the code worked fine.
I don't know why in the case of using labels(red and pink labels in the code) I don't need set width to the red label, but when I replace scrollarea with the pink label, the red label collapses, so I have to set width to the red label.