Implementations of buttons in Qt / C++ - c++

Question

Im looking to implement a sudoku gui in Qt. First things first im trying to generate a grid of QToolButtons, which when pressed will increment their value by one.
Here is my header for window.h
class Window : public QWidget
{
Q_OBJECT
public:
Window(QWidget *parent = nullptr);
private slots:
void digitClicked();
private:
Button *createButton(const QString &text, const char *member);
QString *readFileChar(const QString file_name, QString digit[] );
QGridLayout *previewLayout;
void setSudokuChar(const int digit, const char *member);
enum { NumDigitButtons = 81 };
Button *digitButtons[NumDigitButtons];
QString digit[NumDigitButtons];
protected:
void paintEvent(QPaintEvent *event) override;
void mouseReleaseEvent(QMouseEvent * event) override;
};
And the corresponding source file window.cpp
Window::Window(QWidget *parent) : QWidget(parent) //constrcutor
{
//button creation
QString* current_digit = readFileChar("/home/pi/Documents/ELEC1204/P6/sudoku.txt", digit);
for(int i = 0; i < NumDigitButtons; i++){
digitButtons[i] = createButton(*(current_digit++), SLOT(digitClicked())); //initialize sudoku
}
// set form size
QGridLayout *mainLayout = new QGridLayout;
setMaximumSize(600,600);
mainLayout->setSizeConstraint(QLayout::SetFixedSize);
setWindowTitle(tr("button game"));
// place each digit button
for(int i = 1; i < NumDigitButtons; i++){
int row = (81 - i) / 9 ; // y position for button
int col = (i - 1) % 9 ; // x position for button
mainLayout->addWidget(digitButtons[i], row, col);
}
}
void Window::digitClicked()
{
Button *clickedButton = qobject_cast<Button*>(sender()); //clicked button = object button that was pressed
int val = ++(clickedButton->text().toInt()); //incrememt digit value of the button which was pressed
setSudokuChar(val, clickedButton); //updates sudoku with new value
}
QString* Window::readFileChar(const QString file_name, QString digit[]) //reads in file to initialize buttons
{
QFile file(file_name);
int i = 0;
if(file.open(QIODevice::ReadOnly | QIODevice::Text)){
QTextStream in(&file);
while(!in.atEnd()){
digit[i] = in.read(1); //read each character into an array of QStrings
i++ ;
}
}
else{
QTextStream(stdout) << "could not open file, program terminating" << endl;
exit(1);
}
return digit;
}
Button *Window::createButton(const QString &text, const char *member)
{
Button *button = new Button(text);
connect(button, SIGNAL(clicked()), this, member);
return button;
}
void setSudokuChar(const int digit, Button* clickedButton) //takes in a digit, and assigns its value to the char that was pass
{
}
Please note that the function to update the button's value when pressed 'setSudokuChar' is yet to be implemented, but that pretty irrelevant for now.
Here is the button class header button.h, it's only a small modification of the QToolButton class to aid in resizing.
class Button : public QToolButton
{
Q_OBJECT
public:
explicit Button(const QString &text, QWidget *parent = nullptr);
QSize sizeHint() const override;
};
And finally, here is the button.cpp source file
Button::Button(const QString &text, QWidget *parent) : QToolButton(parent)
{
setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Preferred);
setText(text);
}
QSize Button::sizeHint() const
{
QSize size = QToolButton::sizeHint();
size.rheight() += 20;
size.rwidth() = qMax(size.width(), size.height());
return size;
}
Hopefully thats not too much to digest, I'm still a beginner!
**My problem is ... ** when I run the code, a window is produced but its blank, which means the compilation is fine, but the program is not working as intended. Could anyone by chance spot what is going wrong? All that i do in the main function is create a window as follows :
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
Window window;
window.show();
return app.exec();
}
Any and all help is thoroughly appreciated.