How to shrink a QMainWindow when its central widget is shrinked

[franky]

Hi all,

Please take a look at these files:

List.h:

#ifndef LIST_H
#define LIST_H
 
#include <QMainWindow>
#include "task.h"
#include <QVector>
 
class QLabel;
class QPushButton;
class QHBoxLayout;
class QVBoxLayout;
 
class List : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit List(QWidget *parent = nullptr);
    void updateStatus();
    ~List();
 
public slots:
    void addTask();
    void removeTask(Task*);
    void taskStatusChanged();
 
private:
    QVector<Task*> mTasks;
    QLabel* statusLabel;
    QPushButton* addTaskButtun;
    QHBoxLayout* hBox;
    QVBoxLayout* vBox;
};
 
#endif // LIST_H

#ifndef LIST_H
#define LIST_H

#include <QMainWindow>
#include "task.h"
#include <QVector>

class QLabel;
class QPushButton;
class QHBoxLayout;
class QVBoxLayout;

class List : public QMainWindow
{
    Q_OBJECT

public:
    explicit List(QWidget *parent = nullptr);
    void updateStatus();
    ~List();

public slots:
    void addTask();
    void removeTask(Task*);
    void taskStatusChanged();

private:
    QVector<Task*> mTasks;
    QLabel* statusLabel;
    QPushButton* addTaskButtun;
    QHBoxLayout* hBox;
    QVBoxLayout* vBox;
};

#endif // LIST_H

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List.cpp:

#include "list.h"
#include <QPushButton>
#include <QLabel>
#include <QHBoxLayout>
#include <QVBoxLayout>
#include <QString>
#include <QInputDialog>
#include <QLineEdit>
 
List::List(QWidget *parent)
    : QMainWindow(parent), mTasks()
{
    statusLabel = new QLabel(tr("Status: 0 todo / 0 done"));
    addTaskButtun = new QPushButton(tr("Add task"));
 
    hBox = new QHBoxLayout;
    hBox->addWidget(statusLabel);
    hBox->addStretch();
    hBox->addWidget(addTaskButtun);
 
    vBox = new QVBoxLayout;
    vBox->addLayout(hBox);
    vBox->addStretch();
 
    QWidget *widget = new QWidget;
    widget->setLayout(vBox);
    setCentralWidget(widget);
 
    connect(addTaskButtun, &QPushButton::clicked, this, &List::addTask);
    updateStatus();
}
 
//************************************************
 
void List::addTask() {
   bool ok;
   QString name = QInputDialog::getText(this, tr("Add Task"), tr("Task name"),
                                       QLineEdit::Normal, tr("Untitled task"), &ok);
 
   if(ok && !name.isEmpty()) {
       Task* task = new Task(name);
       connect(task, &Task::removed, this, &List::removeTask);
       connect(task, &Task::statusChanged, this, &List::taskStatusChanged);
       mTasks.append(task);
       vBox->addWidget(task);
       updateStatus();
   }
}
 
//*********************************************
 
void List::removeTask(Task* task) {
   mTasks.removeOne(task);
   vBox->removeWidget(task);
   delete task;
   updateStatus();
}
 
//**************************************
 
void List::taskStatusChanged() {
    updateStatus();
}
 
//************************************
 
void List::updateStatus() {
    int completedCount = 0;
 
    for(auto t: mTasks)
        if(t->isCompleted())
            completedCount++;
 
    int todoCount = mTasks.size() - completedCount;
    statusLabel->setText(QString("Statuse: %1 todo / %2 completed")
                                .arg(todoCount) .arg(completedCount));
}
 
//*****************************
 
List::~List()
{
    delete vBox;
}

#include "list.h"
#include <QPushButton>
#include <QLabel>
#include <QHBoxLayout>
#include <QVBoxLayout>
#include <QString>
#include <QInputDialog>
#include <QLineEdit>

List::List(QWidget *parent)
    : QMainWindow(parent), mTasks()
{
    statusLabel = new QLabel(tr("Status: 0 todo / 0 done"));
    addTaskButtun = new QPushButton(tr("Add task"));

    hBox = new QHBoxLayout;
    hBox->addWidget(statusLabel);
    hBox->addStretch();
    hBox->addWidget(addTaskButtun);

    vBox = new QVBoxLayout;
    vBox->addLayout(hBox);
    vBox->addStretch();

    QWidget *widget = new QWidget;
    widget->setLayout(vBox);
    setCentralWidget(widget);

    connect(addTaskButtun, &QPushButton::clicked, this, &List::addTask);
    updateStatus();
}

//************************************************

void List::addTask() {
   bool ok;
   QString name = QInputDialog::getText(this, tr("Add Task"), tr("Task name"),
                                       QLineEdit::Normal, tr("Untitled task"), &ok);

   if(ok && !name.isEmpty()) {
       Task* task = new Task(name);
       connect(task, &Task::removed, this, &List::removeTask);
       connect(task, &Task::statusChanged, this, &List::taskStatusChanged);
       mTasks.append(task);
       vBox->addWidget(task);
       updateStatus();
   }
}

//*********************************************

void List::removeTask(Task* task) {
   mTasks.removeOne(task);
   vBox->removeWidget(task);
   delete task;
   updateStatus();
}

//**************************************

void List::taskStatusChanged() {
    updateStatus();
}

//************************************

void List::updateStatus() {
    int completedCount = 0;

    for(auto t: mTasks)
        if(t->isCompleted())
            completedCount++;

    int todoCount = mTasks.size() - completedCount;
    statusLabel->setText(QString("Statuse: %1 todo / %2 completed")
                                .arg(todoCount) .arg(completedCount));
}

//*****************************

List::~List()
{
    delete vBox;
}

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Task.h:

#ifndef TASK_H
#define TASK_H
 
#include <QWidget>
#include <QString>
 
class QCheckBox;
class QPushButton;
class QHBoxLayout;
 
class Task : public QWidget
{
    Q_OBJECT
 
public:
    explicit Task(const QString&, QWidget* parent = nullptr);
 
    void setName(const QString&);
    QString name() const;
    bool isCompleted() const;
 
    ~Task();
 
public slots:
    void rename();
 
signals:
   void removed(Task*);
   void statusChanged(Task*);
 
private slots:
   void checked(bool);
 
private:
   QCheckBox* checkbox;
   QPushButton* editButton;
   QPushButton* removeButton;
   QHBoxLayout* hBox;
};
 
#endif // TASK_H

#ifndef TASK_H
#define TASK_H

#include <QWidget>
#include <QString>

class QCheckBox;
class QPushButton;
class QHBoxLayout;

class Task : public QWidget
{
    Q_OBJECT

public:
    explicit Task(const QString&, QWidget* parent = nullptr);

    void setName(const QString&);
    QString name() const;
    bool isCompleted() const;

    ~Task();

public slots:
    void rename();

signals:
   void removed(Task*);
   void statusChanged(Task*);

private slots:
   void checked(bool);

private:
   QCheckBox* checkbox;
   QPushButton* editButton;
   QPushButton* removeButton;
   QHBoxLayout* hBox;
};

#endif // TASK_H

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Task.cpp:

#include "task.h"
#include "list.h"
#include <QInputDialog>
#include <QWidget>
#include <QHBoxLayout>
#include <QPushButton>
#include <QCheckBox>
 
Task::Task(const QString& name, QWidget* parent) : QWidget (parent)
{
    checkbox = new QCheckBox;
    editButton = new QPushButton(tr("Edit"));
    removeButton = new QPushButton(tr("Remove"));
 
    hBox = new QHBoxLayout;
    hBox->addWidget(checkbox);
    hBox->addStretch();
    hBox->addWidget(editButton);
    hBox->addWidget(removeButton);
 
    setLayout(hBox);
 
    setName(name);
 
    connect(editButton, &QPushButton::clicked, this, &Task::rename);
    connect(removeButton, &QPushButton::clicked, [this]()->void {
        emit removed(this);
            });
    connect(checkbox, &QCheckBox::toggled, this, &Task::checked);
};
 
//*************************************
 
void Task::setName(const QString& name) {
    checkbox->setText(name);
}
 
//********************************************
 
QString Task::name() const {
    return checkbox->text();
}
 
//*****************************
 
bool Task::isCompleted() const {
    return checkbox->isChecked();
}
 
//****************************************
 
void Task::rename() {
    bool ok;
    QString value = QInputDialog::getText(this, tr("Edit task"), tr("Task name"),
                                          QLineEdit::Normal, this->name(), &ok);
    if(ok && !value.isEmpty())
        setName(value);
}
 
//************************************
 
void Task::checked(bool checked) {
    QFont font(checkbox->font());
    font.setStrikeOut(checked);
    checkbox->setFont(font);
 
    emit statusChanged(this);
}
 
//**************************************************
 
Task::~Task() {
    delete hBox;
}

#include "task.h"
#include "list.h"
#include <QInputDialog>
#include <QWidget>
#include <QHBoxLayout>
#include <QPushButton>
#include <QCheckBox>

Task::Task(const QString& name, QWidget* parent) : QWidget (parent)
{
    checkbox = new QCheckBox;
    editButton = new QPushButton(tr("Edit"));
    removeButton = new QPushButton(tr("Remove"));

    hBox = new QHBoxLayout;
    hBox->addWidget(checkbox);
    hBox->addStretch();
    hBox->addWidget(editButton);
    hBox->addWidget(removeButton);

    setLayout(hBox);

    setName(name);

    connect(editButton, &QPushButton::clicked, this, &Task::rename);
    connect(removeButton, &QPushButton::clicked, [this]()->void {
        emit removed(this);
            });
    connect(checkbox, &QCheckBox::toggled, this, &Task::checked);
};

//*************************************

void Task::setName(const QString& name) {
    checkbox->setText(name);
}

//********************************************

QString Task::name() const {
    return checkbox->text();
}

//*****************************

bool Task::isCompleted() const {
    return checkbox->isChecked();
}

//****************************************

void Task::rename() {
    bool ok;
    QString value = QInputDialog::getText(this, tr("Edit task"), tr("Task name"),
                                          QLineEdit::Normal, this->name(), &ok);
    if(ok && !value.isEmpty())
        setName(value);
}

//************************************

void Task::checked(bool checked) {
    QFont font(checkbox->font());
    font.setStrikeOut(checked);
    checkbox->setFont(font);

    emit statusChanged(this);
}

//**************************************************

Task::~Task() {
    delete hBox;
}

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When I add tasks "untitled task 1" to "untitled task 3", image number 1 below:

3.jpg

then remove "untitled task 2", the frame/window doesn't shrink and the space for that task is just vacant, image number 2. I like it to decrease and fit the remained tasks, like image number 3. When a task is added, the window increases in size, so when one is removed, it should decrease in size too.

I tested the followings one by one in void List::updateStatus() {, but none worked as expected!

What should be used instead, please?

this->sizeHint();
this->update();
this->resize(sizeHint());
this->adjustSize();

this->sizeHint();
this->update();
this->resize(sizeHint());
this->adjustSize();

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