C++/Qt/QGraphicsItem
Interact with QGraphicsItem
<source lang="cpp">
Foundations of Qt Development\Chapter07\graphicsview\interaction\handleitem.cpp /*
* Copyright (c) 2006-2007, Johan Thelin * * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * Neither the name of APress nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */
- include "handleitem.h"
- include <QPainter>
- include <QPointF>
HandleItem::HandleItem( QGraphicsItem *item, QGraphicsScene *scene, QColor color, HandleItem::HandleRole role, QList<HandleItem*> handles ) : QGraphicsItem( 0, scene ) {
m_role = role; m_color = color; m_item = item; m_handles = handles; m_pressed = false; setZValue( 100 ); setFlag( ItemIsMovable );
} void HandleItem::paint( QPainter *paint, const QStyleOptionGraphicsItem *option, QWidget *widget ) {
paint->setPen( m_color ); paint->setBrush( m_color ); QRectF rect = boundingRect(); QVector<QPointF> points; switch( m_role ) { case CenterHandle: paint->drawEllipse( rect ); break; case RightHandle: points << rect.center()+QPointF(3,0) << rect.center()+QPointF(-3,-5) << rect.center()+QPointF(-3,5); paint->drawConvexPolygon( QPolygonF(points) ); break; case TopHandle: points << rect.center()+QPointF(0,-3) << rect.center()+QPointF(-5,3) << rect.center()+QPointF(5,3); paint->drawConvexPolygon( QPolygonF(points) ); break; }
} QRectF HandleItem::boundingRect() const {
QPointF point = m_item->boundingRect().center(); switch( m_role ) { case CenterHandle: return QRectF( point-QPointF(5, 5), QSize( 10, 10 ) ); case RightHandle: point.setX( m_item->boundingRect().right() ); return QRectF( point-QPointF(3, 5), QSize( 6, 10 ) ); case TopHandle: point.setY( m_item->boundingRect().top() ); return QRectF( point-QPointF(5, 3), QSize( 10, 6 ) ); } return QRectF();
} QVariant HandleItem::itemChange( GraphicsItemChange change, const QVariant &data ) {
if( change == ItemPositionChange && m_pressed ) { QPointF movement = data.toPoint() - pos(); QPointF center = m_item->boundingRect().center(); switch( m_role ) { case CenterHandle: m_item->moveBy( movement.x(), movement.y() ); foreach( HandleItem *handle, m_handles ) handle->translate( movement.x(), movement.y() ); break; case RightHandle: if( 2*movement.x() + m_item->sceneBoundingRect().width() <= 5 ) return QGraphicsItem::itemChange( change, pos() ); movement.setY( 0 ); m_item->translate( center.x(), center.y() ); m_item->scale( 1.0+2.0*movement.x()/(m_item->sceneBoundingRect().width()), 1 ); m_item->translate( -center.x(), -center.y() ); break; case TopHandle: if( -2*movement.y() + m_item->sceneBoundingRect().height() <= 5 ) return QGraphicsItem::itemChange( change, pos() ); movement.setX( 0 ); m_item->translate( center.x(), center.y() ); m_item->scale( 1, 1.0-2.0*movement.y()/(m_item->sceneBoundingRect().height()) ); m_item->translate( -center.x(), -center.y() ); break; } return QGraphicsItem::itemChange( change, pos()+movement ); } return QGraphicsItem::itemChange( change, data );
} void HandleItem::mousePressEvent( QGraphicsSceneMouseEvent *event ) {
m_pressed = true; QGraphicsItem::mousePressEvent( event );
} void HandleItem::mouseReleaseEvent( QGraphicsSceneMouseEvent *event ) {
m_pressed = false; QGraphicsItem::mouseReleaseEvent( event );
}
Foundations of Qt Development\Chapter07\graphicsview\interaction\handleitem.h /*
* Copyright (c) 2006-2007, Johan Thelin * * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * Neither the name of APress nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */
- ifndef HANDLEITEM_H
- define HANDLEITEM_H
- include <QGraphicsItem>
class HandleItem; class HandleItem : public QGraphicsItem { public:
enum HandleRole { CenterHandle, RightHandle, TopHandle }; HandleItem( QGraphicsItem *item, QGraphicsScene *scene, QColor color, HandleRole role = CenterHandle, QList<HandleItem*> handles = QList<HandleItem*>() ); void paint( QPainter *paint, const QStyleOptionGraphicsItem *option, QWidget *widget ); QRectF boundingRect() const;
protected:
void mousePressEvent( QGraphicsSceneMouseEvent *event ); void mouseReleaseEvent( QGraphicsSceneMouseEvent *event ); QVariant itemChange( GraphicsItemChange change, const QVariant &data );
private:
QGraphicsItem *m_item; HandleRole m_role; QColor m_color; QList<HandleItem*> m_handles; bool m_pressed;
};
- endif // HANDLEITEM_H
Foundations of Qt Development\Chapter07\graphicsview\interaction\main.cpp /*
* Copyright (c) 2006-2007, Johan Thelin * * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * Neither the name of APress nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */
- include <QApplication>
- include <QGraphicsScene>
- include <QGraphicsView>
- include <QGraphicsRectItem>
- include <QGraphicsEllipseItem>
- include "handleitem.h"
int main( int argc, char **argv ) {
QApplication app( argc, argv ); QGraphicsScene scene( 0, 0, 200, 200 ); QGraphicsRectItem *rectItem = new QGraphicsRectItem( QRect( 10, 10, 50, 100 ), 0, &scene ); QGraphicsEllipseItem *elItem = new QGraphicsEllipseItem( QRect( 80, 40, 100, 80 ), 0, &scene ); HandleItem *trh = new HandleItem( rectItem, &scene, Qt::red, HandleItem::TopHandle ); HandleItem *rrh = new HandleItem( rectItem, &scene, Qt::red, HandleItem::RightHandle ); HandleItem *crh = new HandleItem( rectItem, &scene, Qt::red, HandleItem::CenterHandle, QList<HandleItem*>() << trh << rrh ); HandleItem *teh = new HandleItem( elItem, &scene, Qt::green, HandleItem::TopHandle ); HandleItem *reh = new HandleItem( elItem, &scene, Qt::green, HandleItem::RightHandle ); HandleItem *ceh = new HandleItem( elItem, &scene, Qt::green, HandleItem::CenterHandle, QList<HandleItem*>() << teh << reh ); QGraphicsView view; view.setScene( &scene ); view.show(); int res = app.exec(); delete crh; delete trh; delete rrh; delete ceh; delete teh; delete reh; return res;
}
</source>
Translate and scale QGraphicsItem
<source lang="cpp">
Foundations of Qt Development\Chapter07\graphicsview\transformations\main.cpp /*
* Copyright (c) 2006-2007, Johan Thelin * * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * Neither the name of APress nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */
- include <QApplication>
- include <QGraphicsScene>
- include <QGraphicsView>
- include <QGraphicsRectItem>
QGraphicsItem *createItem( int x, QGraphicsScene *scene ) {
QGraphicsRectItem *rectItem = new QGraphicsRectItem( QRect( x+40, 40, 120, 120 ), 0, scene ); rectItem->setPen( QPen(Qt::black) ); rectItem->setBrush( Qt::gray ); QGraphicsRectItem *innerRectItem = new QGraphicsRectItem( QRect( x+50, 50, 45, 100 ), rectItem, scene ); innerRectItem->setPen( QPen(Qt::black) ); innerRectItem->setBrush( Qt::white ); QGraphicsEllipseItem *ellipseItem = new QGraphicsEllipseItem( QRect( x+105, 50, 45, 100 ), rectItem, scene ); ellipseItem->setPen( QPen(Qt::black) ); ellipseItem->setBrush( Qt::white ); return rectItem;
} int main( int argc, char **argv ) {
QApplication app( argc, argv ); QGraphicsScene scene( QRect( 0, 00, 1000, 200 ) ); QGraphicsItem *item1 = createItem( 0, &scene ); QGraphicsItem *item2 = createItem( 200, &scene ); item2->translate( 300, 100 ); item2->rotate( 30 ); item2->translate( -300, -100 ); QGraphicsItem *item3 = createItem( 400, &scene ); item3->translate( 500, 100 ); item3->scale( 0.5, 0.7 ); item3->translate( -500, -100 ); QGraphicsItem *item4 = createItem( 600, &scene ); item4->translate( 700, 100 ); item4->shear( 0.1, 0.3 ); item4->translate( -700, -100 ); QGraphicsItem *item5 = createItem( 800, &scene ); item5->translate( 900, 100 ); item5->scale( 0.5, 0.7 ); item5->rotate( 30 ); item5->shear( 0.1, 0.3 ); item5->translate( -900, -100 ); QGraphicsView view; view.setScene( &scene ); view.show(); return app.exec();
}
</source>