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//! [0]
class SimpleItem : public QGraphicsItem
{
public:
QRectF boundingRect() const
{
qreal penWidth = 1;
return QRectF(-10 - penWidth / 2, -10 - penWidth / 2,
20 + penWidth, 20 + penWidth);
}
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
QWidget *widget)
{
painter->drawRoundedRect(-10, -10, 20, 20, 5, 5);
}
};
//! [0]
//! [1]
class CustomItem : public QGraphicsItem
{
...
enum { Type = UserType + 1 };
int type() const
{
// Enable the use of qgraphicsitem_cast with this item.
return Type;
}
...
};
//! [1]
//! [2]
item->setCursor(Qt::IBeamCursor);
//! [2]
//! [3]
item->setCursor(Qt::IBeamCursor);
//! [3]
//! [4]
QGraphicsRectItem rect;
rect.setPos(100, 100);
rect.sceneTransform().map(QPointF(0, 0));
// returns QPointF(100, 100);
rect.sceneTransform().inverted().map(QPointF(100, 100));
// returns QPointF(0, 0);
//! [4]
//! [5]
QGraphicsRectItem rect;
rect.setPos(100, 100);
rect.deviceTransform(view->viewportTransform()).map(QPointF(0, 0));
// returns the item's (0, 0) point in view's viewport coordinates
rect.deviceTransform(view->viewportTransform()).inverted().map(QPointF(100, 100));
// returns view's viewport's (100, 100) coordinate in item coordinates
//! [5]
//! [6]
// Rotate an item 45 degrees around (0, 0).
item->rotate(45);
// Rotate an item 45 degrees around (x, y).
item->setTransform(QTransform().translate(x, y).rotate(45).translate(-x, -y));
//! [6]
//! [7]
// Scale an item by 3x2 from its origin
item->scale(3, 2);
// Scale an item by 3x2 from (x, y)
item->setTransform(QTransform().translate(x, y).scale(3, 2).translate(-x, -y));
//! [7]
//! [8]
QRectF CircleItem::boundingRect() const
{
qreal penWidth = 1;
return QRectF(-radius - penWidth / 2, -radius - penWidth / 2,
diameter + penWidth, diameter + penWidth);
}
//! [8]
//! [9]
QPainterPath RoundItem::shape() const
{
QPainterPath path;
path.addEllipse(boundingRect());
return path;
}
//! [9]
//! [10]
void RoundRectItem::paint(QPainter *painter,
const QStyleOptionGraphicsItem *option,
QWidget *widget)
{
painter->drawRoundedRect(-10, -10, 20, 20, 5, 5);
}
//! [10]
//! [11]
static const int ObjectName = 0;
QGraphicsItem *item = scene.itemAt(100, 50);
if (item->data(ObjectName).toString().isEmpty()) {
if (qgraphicsitem_cast<ButtonItem *>(item))
item->setData(ObjectName, "Button");
}
//! [11]
//! [12]
QGraphicsScene scene;
QGraphicsEllipseItem *ellipse = scene.addEllipse(QRectF(-10, -10, 20, 20));
QGraphicsLineItem *line = scene.addLine(QLineF(-10, -10, 20, 20));
line->installSceneEventFilter(ellipse);
// line's events are filtered by ellipse's sceneEventFilter() function.
ellipse->installSceneEventFilter(line);
// ellipse's events are filtered by line's sceneEventFilter() function.
//! [12]
//! [13]
void CustomItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
{
QMenu menu;
QAction *removeAction = menu.addAction("Remove");
QAction *markAction = menu.addAction("Mark");
QAction *selectedAction = menu.exec(event->screenPos());
// ...
}
//! [13]
//! [14]
CustomItem::CustomItem()
{
setAcceptDrops(true);
...
}
void CustomItem::dragEnterEvent(QGraphicsSceneDragDropEvent *event)
{
event->setAccepted(event->mimeData()->hasFormat("text/plain"));
}
//! [14]
//! [15]
QVariant Component::itemChange(GraphicsItemChange change, const QVariant &value)
{
if (change == ItemPositionChange && scene()) {
// value is the new position.
QPointF newPos = value.toPointF();
QRectF rect = scene()->sceneRect();
if (!rect.contains(newPos)) {
// Keep the item inside the scene rect.
newPos.setX(qMin(rect.right(), qMax(newPos.x(), rect.left())));
newPos.setY(qMin(rect.bottom(), qMax(newPos.y(), rect.top())));
return newPos;
}
}
return QGraphicsItem::itemChange(change, value);
}
//! [15]
//! [16]
void CircleItem::setRadius(qreal newRadius)
{
if (radius != newRadius) {
prepareGeometryChange();
radius = newRadius;
}
}
//! [16]
//! [17]
// Group all selected items together
QGraphicsItemGroup *group = scene->createItemGroup(scene->selecteditems());
// Destroy the group, and delete the group item
scene->destroyItemGroup(group);
//! [17]
//! [QGraphicsItem type]
class CustomItem : public QGraphicsItem
{
...
enum { Type = UserType + 1 };
int type() const
{
// Enable the use of qgraphicsitem_cast with this item.
return Type;
}
...
};
//! [QGraphicsItem type]
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