Solved keyPressEvent
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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 workvoid 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(); } }
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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 usevoid QWidget::grabKeyboard()
to make sure all key events go through it.
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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?
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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"; }
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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);
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@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: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!
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Thanks for the reply :) , but "this" is QMainWindow, oh and good luck with your problem:)
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@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:
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Oh:D, thanks for the reply again:), I am such a newbie