Get the position of a QWidget that is inside a QGraphicsItem - qt

Question

I have a QWidget with a QPushButton, at the same time, this QWidget is embedded into a QGraphicsItem, which is inside a QGraphicsScene.
I need to draw a line between two of those QGraphicsItems pointing to the QPushButton. For that, I need to get the position of the QPushButton. It looks like this:
I tried getting the position of the QPushButton inside the constructor of the QGraphicsItem, but it returns 0,0. I guess this is the position of the button inside the QWidget. I guess what I need is a way to get the position on the screen.
Minimal Example: Simplified as much as possible.
QWidget:
NodeFrame::NodeFrame()
{
setFixedSize(200,80);
setStyleSheet("QFrame { background-color: #2e4076; }");
// Creates and add a QPushButton to the frame.
// I need the position of this button on the QGraohicsScene
auto button = new QPushButton("B");
button->setFixedSize(40,20);
auto layout = new QHBoxLayout();
layout->addWidget(button);
setLayout(layout);
}
QGraphicsItem:
class Node : public QGraphicsItem
{
public:
Node();
QRectF boundingRect() const override;
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override;
};
Node::Node()
{
setFlag(ItemIsMovable);
// Create a GraphicsProxyWidget to insert the nodeFrame into the scene
auto proxyWidget = new QGraphicsProxyWidget(this);
auto frame = new NodeFrame();
proxyWidget->setWidget(frame);
// Center the widget(frame) at the center of the QGraphicsItem
proxyWidget->setPos(boundingRect().center() - proxyWidget->boundingRect().center());
}
QRectF Node::boundingRect() const
{
return QRectF(-10, -10, 280, 150);
}
void Node::paint(QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget)
{
QPainterPath path;
path.addRoundedRect(boundingRect(), 10, 10);
painter->drawPath(path);
}
Main:
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
// Create scene and view
auto scene = new QGraphicsScene();
auto view = new QGraphicsView(scene);
view->setMinimumSize(800, 800);
// Create the QGraphicsItem and add it to the scene
auto item = new Node();
scene->addItem(item);
item->setPos(-50, -50);
// Show the the view
view->show();
return app.exec();
}

Answer 1

In nodeframe.cpp I add one function getButtonRect() :
#ifndef NODEFRAME_H
#define NODEFRAME_H
#include <QWidget>
#include <QPushButton>
#include <QRect>
class NodeFrame: public QWidget
{
public:
NodeFrame();
QRect getButtonRect();
private:
QPushButton *button;
QHBoxLayout *layout;
};
#endif // NODEFRAME_H
nodeframe.cpp
#include "nodeframe.h"
NodeFrame::NodeFrame()
{
setFixedSize(200, 80);
setStyleSheet("QFrame { background-color: #2e4076; }");
// Creates and add a QPushButton to the frame.
// I need the position of this button on the QGraohicsScene
button = new QPushButton("B");
button->setFixedSize(40, 20);
layout = new QHBoxLayout();
layout->addWidget(button);
setLayout(layout);
}
QRect NodeFrame::getButtonRect()
{
return layout->itemAt(0)->geometry();
}
and in Node pass this function to main.cpp because QGraphicsView is there:
node.cpp:
#include "node.h"
#include <QGraphicsProxyWidget>
#include <QPainter>
Node::Node()
{
setFlag(ItemIsMovable);
// Create a GraphicsProxyWidget to insert the nodeFrame into the scene
auto proxyWidget = new QGraphicsProxyWidget(this);
frame = new NodeFrame();
proxyWidget->setWidget(frame);
// Center the widget(frame) at the center of the QGraphicsItem
proxyWidget->setPos(boundingRect().center() - proxyWidget->boundingRect().center());
}
QRectF Node::boundingRect() const
{
return QRectF(-10, -10, 280, 150);
}
void Node::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
QPainterPath path;
path.addRoundedRect(boundingRect(), 10, 10);
painter->drawPath(path);
}
QRect Node::getButtonRect()
{
return frame->getButtonRect();
}
main.cpp
#include "node.h"
#include <QApplication>
#include <QGraphicsScene>
#include <QGraphicsView>
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
// Create scene and view
auto scene = new QGraphicsScene();
auto view = new QGraphicsView(scene);
view->setMinimumSize(800, 800);
// Create the QGraphicsItem and add it to the scene
auto item = new Node();
scene->addItem(item);
item->setPos(0, 0);
// qDebug() << "RECT bottomLeft= " << view->mapToScene(item->getButtonRect().bottomLeft());
// qDebug() << "RECT bottomRight= " << view->mapToScene(item->getButtonRect().bottomRight());
// qDebug() << "RECT topLeft= " << view->mapToScene(item->getButtonRect().topLeft());
// qDebug() << "RECT topRight= " << view->mapToScene(item->getButtonRect().topRight());
auto btnRect = item->getButtonRect();
auto ellipse = new QGraphicsEllipseItem(QRect(view->mapToGlobal(btnRect.center()).x(), view->mapToGlobal(btnRect.center()).y(), 40, 40));
qDebug() << "Center" << view->mapToGlobal(btnRect.center());
scene->addItem(ellipse);
// Show the the view
view->show();
return app.exec();
}