Move an item in a scene Qt

Question

I try to move an item in a scene and for that, I use QKeypressEvent and moveBy that works both perfectly but I'd like to recover the "key press event", so I decided first, to use a boolean that returns true when the key is pressed and false when it's not, and then to create a new function where I call the moveBy if my boolean is true, but unfortunately is doesn't work. This is what I've done in my file.cpp

Perso::Perso()
{
        right= false;
        left= false;
        up= false;
        down= false;


        moveOnMap();
        setFlag(QGraphicsItem::ItemIsFocusable);
}

void Perso::moveOnMap(){


    if (left) {
        moveBy(-10,0);
    }

    if (right) {
        moveBy(10,0);
    }

    if (up) {
        moveBy(0, -10);

    }
    if (down) { 
        moveBy(0, +10);
    }
}



void Perso::keyPressEvent(QKeyEvent *event){

    switch(event->key()){

    case Qt::Key_Up:
        up=true;
        //moveBy(0, -10);
        break;

    case Qt::Key_Right:
        right=true;
       // moveBy(10,0);
        break;

    case Qt::Key_Left:
        left=true;
       //moveBy(-10,0);
        break;

    case Qt::Key_Down:
        down= true;
        //moveBy(0, 10);
        break;
    }

    update();
}


void Perso::keyReleaseEvent(QKeyEvent *event){

    switch(event->key()){

    case Qt::Key_Up:
        up=false;
        break;

    case Qt::Key_Right:
        right= false;
        break;

    case Qt::Key_Left:
        left= false;
        break;
    case Qt::Key_Down:
        down= false;
        break;
    }

}

Anyone can help me to understand where I am wrong?

score 2 · Accepted Answer · answered Oct 19 '14 at 17:41

I can't see here that you call your moveOnMap(); If in your original code you don't call this method that it is normal that it is not work. You call it only in constructor but you should call this method every key pressing. So try to call this method in your key events:

void Perso::keyPressEvent(QKeyEvent *event){

    switch(event->key()){

    case Qt::Key_Up:
        up=true;
        //moveBy(0, -10);
        break;

    case Qt::Key_Right:
        right=true;
       // moveBy(10,0);
        break;

    case Qt::Key_Left:
        left=true;
       //moveBy(-10,0);
        break;

    case Qt::Key_Down:
        down= true;
        //moveBy(0, 10);
        break;
    }

    moveOnMap();
    update();
}


void Perso::keyReleaseEvent(QKeyEvent *event){

    switch(event->key()){

    case Qt::Key_Up:
        up=false;
        break;

    case Qt::Key_Right:
        right= false;
        break;

    case Qt::Key_Left:
        left= false;
        break;
    case Qt::Key_Down:
        down= false;
        break;
    }
    moveOnMap();

}

@Ary Thank you for your accepting of my answer. I appreciate your comment but the best way to say "thank you" on Stack Overflow is vote up and accept as written here http://stackoverflow.com/help/someone-answers. You have enough reputation to do this, so can you please vote up my answer? It is just one click on upper triangle near answer. Thank you too. — Jablonski, Oct 20 '14 at 12:26
Sorry it was accepted but I couldn't vote up before! Done ;) — Ary, Oct 20 '14 at 14:10

Move an item in a scene Qt

1 Answers1