我想在 a 中显示一个有限自动机QGraphicsView
。子类化 QGraphicsItem
我有一个表示状态的类:Node
它保存指向Link
指定状态之间移动的实例的指针。每个链接还保存其起点和终点(指向Node
实例的指针)。
我希望我的代码通过移动其中一个状态来更新(重绘)链接。我无法找到一种方法来调用paint()
或以某种方式强制更新链接。
节点实现:
Node::Node( QGraphicsItem * parent) :
QGraphicsObject(parent)
{
setFlag(ItemIsMovable);
setFlag(ItemSendsGeometryChanges);
setCacheMode(DeviceCoordinateCache);
setZValue(-1);
}
void Node::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
QPen pen(Qt::black);
if(option->state & QStyle::State_Selected)
{
pen.setStyle(Qt::DotLine);
pen.setWidth(2);
}
painter->setPen(pen);
painter->drawEllipse(-m_size.width()/2,-m_size.height()/2,m_size.width(),m_size.height());
painter->drawText(boundingRect(),Qt::AlignCenter,m_label);
}
QRectF Node::boundingRect() const
{
return QRectF(topLeft(),m_size);
}
//...
void Node::addLink(Link* newLink)
{
links.append(newLink);
}
// protected members
QVariant Node::itemChange(GraphicsItemChange change, const QVariant &value)
{
switch (change)
{
case ItemPositionHasChanged:
foreach (Link *link, links)
{
link->update(); // This has no effect
}
break;
default:
break;
};
return QGraphicsItem::itemChange(change, value);
}
链接实现:
Link::Link(QGraphicsItem *parent) :
QGraphicsObject(parent)
{
setFlag(ItemIsMovable);
setFlag(ItemSendsGeometryChanges);
setCacheMode(DeviceCoordinateCache);
setZValue(-1);
}
Link::Link(Node *From, Node *To, QGraphicsItem *parent ):
QGraphicsObject(parent),
from(From),
to(To)
{
setFlag(ItemIsMovable);
setFlag(ItemSendsGeometryChanges);
setCacheMode(DeviceCoordinateCache);
setZValue(-1);
}
void Link::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
m_painter = painter;
QPen pen(Qt::black);
if(option->state & QStyle::State_Selected)
{
pen.setStyle(Qt::DotLine);
pen.setWidth(2);
}
painter->setPen(pen);
painter->drawLine(from->pos(),to->pos());
}
QRectF Link::boundingRect() const
{
return QRectF(from->pos(),to->pos());
}