@SGaist I have tried many things so there are a few comments
Here the minimal code below:
main.cpp:
#include "QApplication"
#include "graphicsitemgroup.h"
#include "qgraphicslinearlayout.h"
#include "qgraphicsscene.h"
#include "qgraphicsview.h"
#include "graphicswidget.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
auto widget = new QGraphicsWidget(nullptr, Qt::Window);
auto item_0 = new GraphicsItemGroup(widget);
auto item_1 = new GraphicsItemGroup(widget);
auto linearLayout = new QGraphicsLinearLayout();
linearLayout->addItem(item_0);
linearLayout->addItem(item_1);
widget->setLayout(linearLayout);
QGraphicsScene scene;
scene.addItem(widget);
QGraphicsView view(&scene);
view.setResizeAnchor(QGraphicsView::AnchorViewCenter);
view.setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
view.setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
view.show();
return app.exec();
}
graphicsitemgroup.h:
#ifndef GRAPHICSITEMGROUP_H
#define GRAPHICSITEMGROUP_H
#include "qgraphicslayoutitem.h"
#include "QGraphicsItemGroup"
#include "qsize.h"
class GraphicsItem;
/**
* @brief Placeholder for graphics items
*/
class GraphicsItemGroup : public QGraphicsLayoutItem, public QGraphicsItemGroup
{
public:
GraphicsItemGroup(QGraphicsItem* parent = nullptr);
virtual ~GraphicsItemGroup();
void setGeometry(const QRectF& geometry) override;
QSizeF sizeHint(Qt::SizeHint which, const QSizeF& constraint = QSizeF()) const override;
// QRectF boundingRect() const override;
void paint(QPainter *painter, const QStyleOptionGraphicsItem* option,
QWidget* widget) override;
private:
QSizeF m_size;
GraphicsItem* m_item;
};
#endif // GRAPHICSITEMGROUP_H
graphicsitemgroup.cpp:
#include "graphicsitemgroup.h"
#include "graphicsitem.h"
#include "qpainter.h"
#include "qdebug.h"
GraphicsItemGroup::GraphicsItemGroup(QGraphicsItem* parent)
: QGraphicsItemGroup(parent)
, m_size(QSize(100, 100))
, m_item(new GraphicsItem(QSizeF(50, 50)))
{
addToGroup(m_item);
setGraphicsItem(this);
}
GraphicsItemGroup::~GraphicsItemGroup() = default;
void GraphicsItemGroup::setGeometry(const QRectF& geometry)
{
prepareGeometryChange();
QGraphicsLayoutItem::setGeometry(geometry);
setPos(geometry.topLeft());
qDebug() << __PRETTY_FUNCTION__;
}
QSizeF GraphicsItemGroup::sizeHint(Qt::SizeHint which, const QSizeF& constraint) const
{
switch (which)
{
case Qt::MinimumSize:
case Qt::PreferredSize:
return m_size;
case Qt::MaximumSize:
default:
break;
}
return constraint;
}
//QRectF GraphicsItemGroup::boundingRect() const
//{
// return QRectF(QPointF(0, 0), geometry().size());
//}
void GraphicsItemGroup::paint(QPainter* painter, const QStyleOptionGraphicsItem* option,
QWidget* widget)
{
painter->drawRect(QRectF(QPointF(0, 0), geometry().size()));
}
graphicsitem.h:
#ifndef GRAPHICSITEM_H
#define GRAPHICSITEM_H
#include "qgraphicslayoutitem.h"
#include "qgraphicsitem.h"
#include "qsize.h"
class QRectF;
class QPainter;
class QStyleOptionGraphicsItem;
class GraphicsItem : /*public QGraphicsLayoutItem,*/ public QGraphicsItem
{
public:
GraphicsItem(QSizeF size, QGraphicsItem* parent = nullptr);
virtual ~GraphicsItem();
// void setGeometry(const QRectF& geometry) override;
// QSizeF sizeHint(Qt::SizeHint which, const QSizeF& constraint = QSizeF()) const override;
QRectF boundingRect() const override;
void paint(QPainter *painter, const QStyleOptionGraphicsItem* option,
QWidget* widget) override;
private:
QSizeF m_size;
};
#endif
graphicsitem.cpp:
#include "graphicsitem.h"
#include "qpainter.h"
#include "qrect.h"
#include "qdebug.h"
GraphicsItem::GraphicsItem(QSizeF size, QGraphicsItem* parent)
: QGraphicsItem(parent)
, m_size(size)
{
// setGraphicsItem(this);
}
GraphicsItem::~GraphicsItem() = default;
//void GraphicsItem::setGeometry(const QRectF& geometry)
//{
// prepareGeometryChange();
// QGraphicsLayoutItem::setGeometry(geometry);
// setPos(geometry.topLeft());
//
// qDebug() << __PRETTY_FUNCTION__;
//}
//
//QSizeF GraphicsItem::sizeHint(Qt::SizeHint which, const QSizeF& constraint) const
//{
// switch (which)
// {
// case Qt::MinimumSize:
// case Qt::PreferredSize:
// return m_size;
// case Qt::MaximumSize:
// default:
// break;
// }
//
// return constraint;
//}
QRectF GraphicsItem::boundingRect() const
{
return QRectF(QPointF(20, 20), m_size);
}
void GraphicsItem::paint(QPainter *painter, const QStyleOptionGraphicsItem* option, QWidget* widget)
{
painter->drawRect(boundingRect());
}
CMakeLists.txt:
cmake_minimum_required(VERSION 3.0)
project(GraphicsLayoutExample)
find_package(Qt5
COMPONENTS
Core REQUIRED
Widgets REQUIRED
Gui REQUIRED
)
add_executable(${CMAKE_PROJECT_NAME}
main.cpp
graphicsitemgroup.cpp
graphicsitem.cpp
)
target_include_directories(${CMAKE_PROJECT_NAME} PUBLIC .)
target_link_libraries(${CMAKE_PROJECT_NAME} PRIVATE Qt5::Widgets Qt5::Core Qt5::Gui)
I would like to have the graphics item (here a little rectangle) to be resized depending on the a graphics item group (the latter paints another rectangle just to have a visual on what is going on). In the future, I have planned to put two graphics items (one over the other) in the group. Thanks for your help.
