如何隱藏自定義QGraphicsItem中的場景中的子項目，當我調整自定義項目的大小

Question

我有一個自定義QGraphicsItem其中我創建了一些項目。當我調整父母QGraphicsItem的大小時，我想要隱藏不在父項目內的其餘子項目部分。

#include "mysquare.h" 
#include "mysvgitem.h" 
#include <QTranslator> 

MySquare::MySquare() 
     :QGraphicsItem() 
{ 
    myItemRect = QRectF(0, 0, 150, 70); // Default value 
    setFlag(ItemIsMovable); 
    setFlag(QGraphicsItem::ItemIsSelectable); 
    setMyPolygon();//member function 
    setFlag(ItemSendsScenePositionChanges, true); 
    posXY = new QString(QString::number(this->x()) + ", " + 
      QString::number(this->y())); 
    itemXY = new QGraphicsTextItem(this); 
    itemXY->setPlainText((*posXY)); 
    itemXY->setTextInteractionFlags(Qt::TextEditorInteraction); 
    itemXY->setZValue(2000); 
    //text->setHtml("<heloooooooooo>"); 
    itemXY->setPos(this->x(), this->y()); 
    this->setCacheMode(QGraphicsItem::DeviceCoordinateCache); 
    this->setPos(100, 100); 
} 


QRectF MySquare::boundingRect() const 
{ 
    return myItemRect; 
} 


void MySquare::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) 
{ 
    Q_UNUSED(widget); 
    Q_UNUSED(option); 
    QRectF rect = boundingRect(); 
    QBrush brush(Qt::green); 
    QPainterPath path; 
    path.addRoundedRect(rect.translated(0.3, 0.3), 5.0, 5.0); 
    QFont font; 
    //font.setFamily("Armenian (phonetic)"); 
    font.setPointSize(20); 
    //QString mystr = "Partners and\nCustomers"; 
    //path.addText(QPointF(40, 30), font, tr("Partners \nand Customers")); 
    painter->fillPath(path, Qt::white); 
    painter->setPen(Qt::blue); 
    //painter->drawText(QRect(105, 55, 115, 35), Qt::AlignLeft, mystr); 
    painter->drawText(MyTextRect, Qt::AlignLeft, MyText); 
    QPen pen(Qt::black, 1); 
    painter->setPen(pen); 
    //painter->setBrush(brush); 

    painter->setRenderHint(QPainter::Antialiasing); // This is for rectangle alignment 
    painter->drawPath(path); 
} 


void MySquare::mousePressEvent(QGraphicsSceneMouseEvent *event) 
{ 
    //Pressed = true; 
    //update(); 
    QString *xy = new QString(QString::number(event->pos().x()) + ", " + 
           QString::number(event->pos().y())); 
    itemXY->setPlainText((*xy)); 
    QPointF p = event->pos(); 
    QRectF r = sceneBoundingRect(); // Relative to scene 
    QPointF tl = mapFromScene(r.topLeft()); 
    QPointF br = mapFromScene(r.bottomRight()); 
    if (p.x() <= tl.x() + 10) 
    { 
     resize_direction_ = rd_left; 
     itemXY->setPlainText("rd_left"); 
    } 
    else if (p.x() >= br.x() - 10) 
    { 
     resize_direction_ = rd_right; 
    } 
    else if (p.y() <= tl.y() + 10) 
    { 
     resize_direction_ = rd_top; 
    } 
    else if (p.y() >= br.y()-10) 
    { 
     resize_direction_ = rd_bottom; 
     qDebug() << "rd_right" ; 
    } 
    else 
    { 
     resize_direction_ = rd_none; 
    } 
    //this->setCursor(Qt::SizeAllCursor); 

    QGraphicsItem::mousePressEvent(event); 
} 


void MySquare::mouseMoveEvent(QGraphicsSceneMouseEvent *event) 
{ 
    //was_moved_ = true; 
    if (isSelected()) 
    { 
     // Resize border to mouse position 
     QPointF p = event->pos(); 
     QPointF pp = mapToItem(this, p); 
     //QRectF r = rect(); 
     QRectF r = boundingRect(); 

     switch (resize_direction_) 
     { 
      case rd_left: 
       r.setLeft(pp.x() + 10); 
       prepareGeometryChange(); 
       myItemRect = r ; 
       break; 

      case rd_top: 
       r.setTop(pp.y()); 
       prepareGeometryChange(); 
       myItemRect = r ; 
       break; 

      case rd_right: 
       r.setRight(pp.x()); 
       prepareGeometryChange(); 
       myItemRect = r ; 
       break; 

      case rd_bottom: 
       r.setBottom(pp.y()); 
       prepareGeometryChange(); 
       myItemRect = r ; 
       break; 

      default: 
       QGraphicsItem::mouseMoveEvent(event); 
       qDebug() << " default moving "; 
       this->setCursor(Qt::ArrowCursor); 
       break; 
     } 
     return; // 
    } 
    QGraphicsItem::mouseMoveEvent(event); 
} 

void MySquare::mouseReleaseEvent(QGraphicsSceneMouseEvent *event) 
{ 
    //Pressed = false; 
    //update(); 
    //emit click(); 
    qDebug() << sceneBoundingRect(); 
    QTimer::singleShot(500, this, SIGNAL(click())); 
    QGraphicsItem::mouseReleaseEvent(event); 
} 

QVariant MySquare::itemChange(GraphicsItemChange change, const QVariant &value) 
{ 
    if (change == QGraphicsItem::ItemPositionChange && scene()) { 
     foreach (Arrow *arrow, arrows) { 
      arrow->updatePosition(); 
     } 
     *posXY = QString::number(this->x()) + ", " + 
           QString::number(this->y()); 
     //itemXY->setPlainText((*posXY)); 

    } 
    if (change == QGraphicsItem::ItemOpacityChange) { 
     foreach (Arrow *arrow, arrows) { 
      arrow->setOpacity(this->opacity()); 
     } 
    } 
    return QGraphicsItem::itemChange(change, value); 
} 

void MySquare::addArrow(Arrow *arrow) 
{ 
    arrows.append(arrow); 
} 

QPointF MySquare::returnCenter() 
{ 
    QRectF rect = boundingRect(); 
    qreal width = rect.width(); 
    qreal height = rect.height(); 
    QPointF p = QPointF(width/2 + rect.x(), rect.y() + height/2); 
    //return p; // Changed for test 
    return this->pos() + p; // Changed for test 
} 


void MySquare::setMyPolygon() 
{ 
    QRectF rec = boundingRect(); 
    QPolygonF poly ; 
    //QPointF p = rec.topLeft(); 
    poly << rec.topLeft() + this->pos() << rec.topRight() + this->pos() 
     << rec.bottomRight() + this->pos() << rec.bottomLeft() + this->pos() 
     << rec.topLeft() + this->pos(); 
    myPolygon = poly; 
} 


void MySquare::setItemSize(qreal width, qreal height) 
{ 
    myItemRect.setWidth(width); 
    myItemRect.setHeight(height); 
    update(); 
} 


void MySquare::setSize(QSize size) 
{ 
    prepareGeometryChange(); 
    myItemRect.setWidth(size.width()); 
    myItemRect.setHeight(size.height()); 
} 


QSize MySquare::size() 
{ 
    return QSize(myItemRect.width(), myItemRect.height()); 
} 


void MySquare::setImage(const QString& str) 
{ 
    QImage image(QCoreApplication::applicationDirPath() + "/" + str); 

    QImage img = image; 
    QGraphicsItem *item = new QGraphicsPixmapItem(\ 
        QPixmap::fromImage(img)); 

    //item->setSize(size); 
    //svg->setMaximumCacheSize(QSize(350, 350)); 
    Q_ASSERT(!item.isNull()); 
    item->setParentItem(this); 
} 

void MySquare::setImage(const QString& str, const QSize size) 
{ 
    QImage image(QCoreApplication::applicationDirPath() + "/" + str); 

    QImage img = image.scaled(size); 
    /* QGraphicsPixmapItem* item = new QGraphicsPixmapItem(\ 
        QPixmap::fromImage(image)); */ 
    QGraphicsItem *item = new QGraphicsPixmapItem(\ 
        QPixmap::fromImage(img)); 

    //item->setSize(size); 
    //svg->setMaximumCacheSize(QSize(350, 350)); 
    Q_ASSERT(!item.isNull()); 
    item->setPos(21, 11); 
    item->setParentItem(this); 
} 


void MySquare::setImage(const QString& str, QRectF rec) 
{ 
    QImage image(QCoreApplication::applicationDirPath() + "/" + str); 

    QImage img = image.scaled(QSize(rec.width(), rec.height())); 
    /* QGraphicsPixmapItem* item = new QGraphicsPixmapItem(\ 
        QPixmap::fromImage(image)); */ 
    QGraphicsItem *item = new QGraphicsPixmapItem(\ 
        QPixmap::fromImage(img)); 
    Q_ASSERT(!item.isNull()); 
    //item->setSize(QSize(rec.width(), rec.height())); 
    item->setParentItem(this); 
    item->setPos(rec.x(), rec.y()); 
} 


void MySquare::setSvgImage(const QString& str) 
{ 
    QGraphicsItem *m_svgItem = new QGraphicsSvgItem(\ 
     QCoreApplication::applicationDirPath() + "/" + str); 
    Q_ASSERT(!m_svgItem.isNull()); 
    m_svgItem->setPos(5, 5); 
    m_svgItem->setParentItem(this); 
} 


void MySquare::setSvgImage(const QString& str, QSizeF size) 
{ 
    /* QGraphicsSvgItem *svg = new QGraphicsSvgItem(\ 
      QCoreApplication::applicationDirPath() + "/" + str); */ 
    MySvgItem *svg = new MySvgItem(\ 
      QCoreApplication::applicationDirPath() + "/" + str); 
    svg->setSize(size); 
    //svg->setMaximumCacheSize(QSize(350, 350)); 
    Q_ASSERT(!svg.isNull()); 
    QGraphicsItem *m_svgItem = svg; 
    //m_svgItem->setPos(5, 5); 
    m_svgItem->setParentItem(this); 
    m_svgItem->setZValue(-1000); 
} 


void MySquare::setSvgImage(const QString& str, QRectF rec) 
{ 
    MySvgItem *svg = new MySvgItem(\ 
      QCoreApplication::applicationDirPath() + "/" + str); 
    Q_ASSERT(!svg.isNull()); 
    svg->setSize(QSize(rec.width(), rec.height())); 
    QGraphicsItem *m_svgItem = svg; 
    m_svgItem->setParentItem(this); 
    m_svgItem->setPos(rec.x(), rec.y()); 
    m_svgItem->setZValue(-1000); 
} 


void MySquare::setText(const QString& str, QRectF rec) 
{ 
    QGraphicsTextItem *text = new QGraphicsTextItem(this); 
    //text->setTextInteractionFlags(Qt::TextEditorInteraction); 
    text->setHtml(str); 
    text->setPos(rec.x(), rec.y()); 
} 


MySquare::~MySquare() 
{ 
    for (int i=0; i< arrows.count(); i++) 
    { 
     if (arrows.at(i) == NULL){ 
      delete arrows.at(i); 
     } 
    } 
} 

Answer 1

剛剛添加setFlag（QGraphicsItem :: ItemClipsChildrenToShape，true）;