keyPressEvent

privatepepper

Hello,

Could someone tell me why my keyPressEvent doesn't work when I use arrow keys?
When I use Qt::Key_W/S/D/A everything works fine. I also tried to use Key_Up/Down..., this way also didn't work

void MainWindow::keyPressEvent(QKeyEvent *event)
{
    switch (event->key()) {
        case Qt::UpArrow:
        if (current_square_y != 0 && is_legal_move(current_square_y, current_square_x, current_square_y -1, current_square_x)){

            current_square_y--;

            background_color_squares[current_square_y][current_square_x]->setBrush(start_and_path_background_color);
            background_color_squares[previous_square_cord.first][previous_square_cord.second]->setBrush(maze_background_color);
            previous_square_cord = {current_square_y, current_square_x};

            square_moved++;

        }break;
        case Qt::DownArrow:
        if (current_square_y != maze_height - 1 && is_legal_move(current_square_y, current_square_x, current_square_y + 1, current_square_x)){

            current_square_y++;

            background_color_squares[current_square_y][current_square_x]->setBrush(start_and_path_background_color);
            background_color_squares[previous_square_cord.first][previous_square_cord.second]->setBrush(maze_background_color);
            previous_square_cord = {current_square_y, current_square_x};

            square_moved++;

        }break;
        case Qt::RightArrow:
        if (current_square_x != maze_width - 1 && is_legal_move(current_square_y, current_square_x, current_square_y, current_square_x + 1)){

            current_square_x++;

            background_color_squares[current_square_y][current_square_x]->setBrush(start_and_path_background_color);
            background_color_squares[previous_square_cord.first][previous_square_cord.second]->setBrush(maze_background_color);
            previous_square_cord = {current_square_y, current_square_x};

            square_moved++;

        }break;

        case Qt::Key_Left:
        if (current_square_x != 0 && is_legal_move(current_square_y, current_square_x, current_square_y, current_square_x - 1)){

            current_square_x--;

            background_color_squares[current_square_y][current_square_x]->setBrush(start_and_path_background_color);
            background_color_squares[previous_square_cord.first][previous_square_cord.second]->setBrush(maze_background_color);
            previous_square_cord = {current_square_y, current_square_x};

            square_moved++;
        }break;
    }
    if (won_game()){
        QMessageBox::about(this, "t", "You won!!!");
        on_pushButton_3_clicked();
    }
}

Bonnie

Qt::UpArrow/Qt::DownArrow/Qt::RightArrow are not Keys.
I think it should be Key_Up/Down, but you said you already tried that.

Step 1: Print log in the keyPressEvent no matter what key it is.
Then try to press up/down to see is there any log from keyPressEvent.
If there is, then it is simple, you can print the key value in the log.

Step 2: If there is no log, then maybe the up/down events are handled by other widgets.
If the MainWindow is the only widget that need to response to key events, you could use

void QWidget::grabKeyboard()

to make sure all key events go through it.

privatepepper

How can I print to log to check which key is pressed? I know that I can use qDebug to print to console, but how to print a key which is pressed?

privatepepper

oh I figured out how to print to log to check which key is pressed:D
But it didn't work:/, only with normal keys.

if (event->key () == Qt::Key_Up){
        qDebug() << "working";
    }

privatepepper

Okay, so I figured out how to make it to work, I changed my widget focus to StrongFocus, but
I don't understand why this "setFocusPolicy" makes to work my Key_Up/Down/Left/Right, maybe someone could explain it?

this->setFocusPolicy(Qt::StrongFocus);

KH-219Design

@privatepepper In this code that you shared:

this->setFocusPolicy(Qt::StrongFocus);

What is the type of "this"? You mentioned it was a widget. Is it a QWidget? If so, then this should be the relevant doc:

https://doc.qt.io/qt-5/qwidget.html#focusPolicy-prop

That doc mentions that the default is Qt::NoFocus, and that "You must enable keyboard focus for a widget if it processes keyboard events."

Does that help?

I ran into similar confusion, but in QML. I just reread my notes about QML focusPolicy, but the QML related issues seem unlreated to yours. I was hoping maybe some of my "struggle" could translate back to the non-QML world. But I guess you solved your problem anyway, so congrats!

privatepepper

@KH-219Design

Thanks for the reply :) , but "this" is QMainWindow, oh and good luck with your problem:)

KH-219Design

@privatepepper ah. Well based on the doc for QMainWindow:

// QMainWindow Class

// The QMainWindow class provides a main application window. More...

// Header:	#include <QMainWindow>

// Inherits:	QWidget

Via inheritance, it still "is a" QWidget. So I still think the relevant doc to explain your outcome is:

https://doc.qt.io/qt-5/qwidget.html#focusPolicy-prop

privatepepper

@KH-219Design

Oh:D, thanks for the reply again:), I am such a newbie