How do you define shape for pie slice and animate?

deleted385

I've a subclass of QGraphicsItem, Slice:

#define whats16 16
Slice::Slice(float start, float sweep, QColor color)
    : m_start(start), m_sweep(sweep), m_color(color){
    setAcceptHoverEvents(true);
}
QRectF Slice::boundingRect() const { return QRectF(0,0,200,200); }
void Slice::paint(QPainter *painter, const QStyleOptionGraphicsItem*, QWidget*){
    painter->setRenderHint(QPainter::Antialiasing);
    painter->setPen(Qt::white);
    painter->setBrush(m_color);
    painter->drawPie(boundingRect(), whats16*m_start, whats16*m_sweep);
}
void Slice::hoverEnterEvent(QGraphicsSceneHoverEvent*){
    dx = 10 * cos(whats16*m_start + whats16*m_sweep / 2);
    dy = 10 * sin(whats16*m_start + whats16*m_sweep / 2);
    moveBy(-dx, dy);
}
void Slice::hoverLeaveEvent(QGraphicsSceneHoverEvent*){
    dx = 10 * cos(whats16*m_start + whats16*m_sweep / 2);
    dy = 10 * sin(whats16*m_start + whats16*m_sweep / 2);
    moveBy(dx, -dy);
}

and in PieView I add slice:

PieView::PieView(QWidget *parent) : QGraphicsView(parent){
    auto scene = new QGraphicsScene(this);
    scene->setBackgroundBrush(Qt::black);
    setScene(scene);
    QRandomGenerator rand;
    for (int i = 0; i < 360; i+=45) {
        auto color = QColor::fromRgb(rand.global()->bounded(0,255), rand.global()->bounded(0,255), rand.global()->bounded(0,255));
        auto slice = new Slice(i, 45, color);
        scene->addItem(slice);
    }
}

and this PieView is the only child of Window:

Window::Window(QWidget *parent) : QWidget(parent){
    auto pie = new PieView(this);
    auto lay = new QVBoxLayout(this);
    lay->setContentsMargins(0,0,0,0);
    lay->addWidget(pie);
    setLayout(lay);
}

all boundingRect of those slices, probably, overlaps so only one slice gets those hoverEvents:

how to return the exact shape of those slices instead of boundingRect ? One more thing, I want to animate its color and position on hover enter and leave like this:

found an example in QGraphicsItemAnimation doc but couldn't fathom! How to do that?

deleted385

With these in slice:

#define whats16 16
Slice::Slice(float start, float sweep, QColor color)
    : m_start(start), m_sweep(sweep), m_color(color){
    m_rect = QRectF(0,0,200,200);
    m_path = QPainterPath(QPointF(m_rect.width() / 2, m_rect.height() / 2));
    m_path.arcTo(m_rect, m_start, m_sweep);
    m_path.closeSubpath();
    dx = 10 * cos(m_start + m_sweep / 2);
    dy = 10 * sin(m_start + m_sweep / 2);
    setAcceptHoverEvents(true);
}
QRectF Slice::boundingRect() const { return m_rect; }
QPainterPath Slice::shape() const { return m_path;}
void Slice::hoverEnterEvent(QGraphicsSceneHoverEvent*){ moveBy(dx, dy); }
void Slice::hoverLeaveEvent(QGraphicsSceneHoverEvent*){ moveBy(-dx, -dy); }
void Slice::paint(QPainter *painter, const QStyleOptionGraphicsItem*, QWidget*){
    painter->setRenderHint(QPainter::Antialiasing);
    painter->setPen(Qt::white);
    painter->setBrush(m_color);
    painter->drawPie(boundingRect(), whats16 * m_start, whats16 * m_sweep);
}

hit test is ok BUT moveBy doesn't work as expected:

deleted385

Drawing direction and radian were the problem. With these:

#define whats16 16
Slice::Slice(float start, float sweep, QColor color, QGraphicsItem* parent)
    : QGraphicsItem(parent), m_start(start), m_sweep(sweep), m_color(color){
    m_realColor = color;
    m_rect = QRectF(0,0,200,200);
    m_path = QPainterPath(QPointF(m_rect.width() / 2, m_rect.height() / 2));
    m_path.arcTo(m_rect, -m_start, -m_sweep);
    m_path.closeSubpath();
    dx = 10 * cos((m_start + m_sweep / 2) * M_PI / 180);
    dy = 10 * sin((m_start + m_sweep / 2) * M_PI / 180);
    setAcceptHoverEvents(true);
}
QRectF Slice::boundingRect() const { return m_rect; }
QPainterPath Slice::shape() const { return m_path;}
void Slice::hoverEnterEvent(QGraphicsSceneHoverEvent*){
    m_color = Qt::gray;
    moveBy(dx, dy);
}
void Slice::hoverLeaveEvent(QGraphicsSceneHoverEvent*){
    m_color = m_realColor;
    moveBy(-dx, -dy);
}
void Slice::paint(QPainter *painter, const QStyleOptionGraphicsItem*, QWidget*){
    painter->setRenderHint(QPainter::Antialiasing);
    painter->setPen(Qt::white);
    painter->setBrush(m_color);
    painter->drawPie(m_rect, whats16 * -m_start, whats16 * -m_sweep);
}

Now, slice moves perfectly:

BUT the whole pie moves for a while (5 times as I start hovering over different slices). Why does it move?