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POSubclassing QGraphicsLayoutItem
 

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  1. POSubclassing QGraphicsLayoutItem
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    <p>How exactly can I subclass QGraphicsLayoutItem? I write a class that subclass QGraphicsLayoutItem and reimplement sizeHint and setGeometry but when I add my custom item to linear or grid layout. It does not shown? What is missing?</p> <p>Here is my trial.</p> <pre><code>//basicitem.h #include &lt;QGraphicsWidget&gt; #include &lt;QtCore/QRectF&gt; #include &lt;QtGui/QPainter&gt; #include &lt;QtGui/QBrush&gt; #include &lt;QtGui/QPen&gt; #include &lt;QtCore/QSizeF&gt; class BasicItem : public QGraphicsWidget { public: BasicItem(qreal x1,qreal y1,qreal x2,qreal y2); ~BasicItem(); QRectF boundingRect() const; void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0); QSizeF sizeHint(Qt::SizeHint which, const QSizeF &amp;constraint = QSizeF()) const; private: qreal x1,y1,x2,y2; }; //basicitem.cpp #include "basicitem.h" #include &lt;math.h&gt; BasicItem::BasicItem(qreal x1, qreal y1, qreal x2, qreal y2) { this-&gt;x1 = x1; this-&gt;y1 = y1; this-&gt;x2 = x2; this-&gt;y2 = y2; } BasicItem::~BasicItem() { } QRectF BasicItem::boundingRect() const { return QRectF(x1,y1,abs(x2-x1),5); } void BasicItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) { Q_UNUSED(option); Q_UNUSED(widget); painter-&gt;setRenderHint(QPainter::Antialiasing); painter-&gt;setPen(QPen(QBrush(Qt::yellow),4,Qt::SolidLine,Qt::FlatCap,Qt::BevelJoin)); painter-&gt;drawLine(x1,y1,x2,y2); } QSizeF BasicItem::sizeHint(Qt::SizeHint which, const QSizeF &amp;constraint) const { Q_UNUSED(which); Q_UNUSED(constraint); return QSizeF(abs(x2-x1),5); } //compositeitem.h #include &lt;QGraphicsItemGroup&gt; #include &lt;QGraphicsLayoutItem&gt; #include &lt;QSizeF&gt; #include &lt;QList&gt; #include "basicitem.h" class CompositeItem:public QGraphicsItemGroup,public QGraphicsLayoutItem { public: CompositeItem(QList&lt;BasicItem *&gt; children); ~CompositeItem(); QSizeF sizeHint(Qt::SizeHint which, const QSizeF &amp;constraint = QSizeF()) const; void setGeometry(const QRectF &amp;rect); void updateGeometry(); }; //compositeitem.cpp #include "compositeitem.h" CompositeItem::CompositeItem(QList&lt;BasicItem *&gt; children) { BasicItem *child; foreach(child,children) { addToGroup(child); } } CompositeItem::~CompositeItem() { } QSizeF CompositeItem::sizeHint(Qt::SizeHint which, const QSizeF &amp;constraint) const { Q_UNUSED(which); Q_UNUSED(constraint); //Arbitrary values but big enough return QSizeF(300,300); } void CompositeItem::setGeometry(const QRectF &amp;rect) { Q_UNUSED(rect); QGraphicsLayoutItem::setGeometry(QRectF(0,0,300,300)); } void CompositeItem::updateGeometry() { QGraphicsLayoutItem::updateGeometry(); } //mainwindow.cpp - important parts ... QGraphicsScene *scene = new QGraphicsScene; ui-&gt;graphicsView-&gt;setScene(scene); BasicItem *basic1 = new BasicItem(10,400,110,400); BasicItem *basic2 = new BasicItem(10,400,110,500); QList&lt;BasicItem *&gt; basicItemList; basicItemList.push_back(basic1); basicItemList.push_back(basic2); CompositeItem *ci = new CompositeItem(basicItemList); QGraphicsLinearLayout *layout = new QGraphicsLinearLayout; layout-&gt;addItem(ci); QGraphicsWidget *container = new QGraphicsWidget; container-&gt;setLayout(layout); scene-&gt;addItem(container); ... </code></pre>
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    1. USonurozcelik
    1. USonurozcelik
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    1. COThe Qt documentation suggests to reimplement the updateGeometry method. If this doesn't help, can you provide us a sample of your code?
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      1. USLohrun
    2. CO@onurozcelik: It's will be better, if you post here your sample code, which doesn't work.
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      1. USmosg
    3. COHi, pardon me, but adding code in comments not a good decision, because it's not read able at all. Better to edit your first post (your first question) and add code there.
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      1. USmosg
 

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