qt multiple keys in keypressevent()

Question

I'm trying to create a game on Qt where the player can go diagonally. So when I press W and D, the player can go to the upper right hand corner. However, when I press W first, then D, then release D, the player does not go in the W direction. In fact, the holding of the W key isn't even being signaled to call the keypressevent() function. However, when I press W, then D, and then release W, the character goes in the D direction.

Here are my codes:

void my_qscroll::keyPressEvent(QKeyEvent *event)
{
    switch ( event->key() )
    {
    case Qt::Key_W:
        key[0] = 1;
        break;
    case Qt::Key_A:
        key[1] = 1;
        break;
    case Qt::Key_S:
        key[2] = 1;
        break;
    case Qt::Key_D:
        key[3] = 1;
        break;
    }

    for(int i = 0; i != 4 ; i++)
    {
        if(key[i] == 1)
        {
            this->B = i;
            emit Move();
        }
    }
}

void my_qscroll::keyReleaseEvent(QKeyEvent *event)
{
    switch ( event->key() )
    {
    case Qt::Key_W:
        key[0] = 0;
        qDebug() << "released W";
        break;
    case Qt::Key_A:
        key[1] = 0;
        qDebug() << "released A";
        break;
    case Qt::Key_S:
        key[2] = 0;
        qDebug() << "released S";
        break;
    case Qt::Key_D:
        key[3] = 0;
        qDebug() << "released D";
        break;
    }
}

I'm not sure how to proceed through this problem. Any ideas or links to help me would be great. Thank you in advance.

So after I asked the question, my friend sent me this link: http://www.qtforum.org/article/28368/solved-keyboard-input-for-diagonal-movement-of-game-character.html?s=387f8ec7cde86b902f20c19537f323ce1befc0aa it addressed and fixed my problem perfectly. — Jordan Huang, May 04 '14 at 00:15

score 1 · Accepted Answer · answered May 04 '14 at 05:19

You would need something like this:

void my_qscroll::keyPressEvent(QKeyEvent *event)
{
    switch ( event->key() )
    {
    case Qt::Key_W:
        key[0] = 1;
        break;
    case Qt::Key_A:
        key[1] = 1;
        break;
    case Qt::Key_S:
        key[2] = 1;
        break;
    case Qt::Key_D:
        key[3] = 1;
        break;
    }

    for(int i = 0; i != 4 ; i++)
    {
        if(key[i] == 1)
        {
            this->B = i;
            emit Move();
        }
    }
}

void my_qscroll::keyReleaseEvent(QKeyEvent *event)
{
    switch ( event->isAutoRepeat() )
    {
    case Qt::Key_W:
        key[0] = 0;
        qDebug() << "released W";
        break;
    case Qt::Key_A:
        key[1] = 0;
        qDebug() << "released A";
        break;
    case Qt::Key_S:
        key[2] = 0;
        qDebug() << "released S";
        break;
    case Qt::Key_D:
        key[3] = 0;
        qDebug() << "released D";
        break;
    }
}

void my_qscroll::movePlayer() {
  if (key[1] && key[0]) {
      left -= 2;
      top -= 2;
  } else if (key[3] && key[0]) {
      left += 2;
      top -= 2;
  } else if (key[2] && key[1]) {
      left -= 2;
      top += 2;
  } else if (key[2] && key[3]) {
      left += 2;
      top += 2;
  } else if (key[3]) {
      left += 2;
  } else if (key[1]) {
      left -= 2;
  } else if (key[2]) {
      top += 2;
  } else if (key[0]) {
      top -= 2;
  }
}

void myCanvas::updateEnv() {
    emit Move();
    repaint();
}

qt multiple keys in keypressevent()

1 Answers1