@HappyVisualizer

Since your view is in a layout... have you tried to set the layout margin to 0?

I solved my problem via event filter of scene.

ui->graphicsView->scene()->installEventFilter(this); bool MainWindow::eventFilter(QObject* obj, QEvent* event){ if(event->type() == QEvent::GraphicsSceneMousePress){ if(ui->addServerBtn->isChecked()){ QGraphicsSceneMouseEvent* mouseSceneEvent; mouseSceneEvent = static_cast<QGraphicsSceneMouseEvent *>(event); Server *serv = new Server(mouseSceneEvent->scenePos().toPoint()); scene->addItem((QGraphicsPixmapItem*)serv); } } return false; }

For any1 wondering, its more or less >
item->setPos(mNodeViewPtr->mapToScene(mNodeViewPtr->mapFromGlobal(QCursor::pos())));
you can most likely do mNodeViewPtr->viewport()->mapFromGlobal() for more precision I think but I didn't test it.

@sticky-thermos said in Receive Drag/Drop events for items in QGraphicsScene:

void ChessBoard::mouseMoveEvent(QMouseEvent *event) {
std::cout << FUNCTION << std::endl;
QGraphicsView::mousePressEvent(event);
QDrag *drag = new QDrag(this);
QMimeData *mime = new QMimeData; // this is necessary even if nothing is set in the mime data
drag->setMimeData(mime);
drag->exec();
}

Looks good, but I would add a check to differenciate whether your mouseButton is down. Otherwise you are creating a lot of drags from just moving your mouse around on your chessBoard.

Also, you are passing the ChessBoard::mouseMoveEvent(QMouseEvent *event) to QGraphicsView::mousePressEvent(event).
QGraphicsView::mouseMoveEvent would be more fitting :)

Thanks for the reply @SGaist . This helps

@Chris-Kawa Noted thank you. Now it compiles without errors. I think I need to read a bit about newer c++...

@TenG
Be aware that not all of Qt modules are supported in WASM. Before anything, check the list at https://doc.qt.io/qt-5/wasm.html#supported-qt-modules against what is in your app. For example, it doesn't do databases, you can't access the local file system, and so on. Also I noticed this time that it requires a Qt static build, but maybe you have to have that for iOS anyway, I don't know.

If it works for you it's a really simple solution compared to rewriting anything. Just check out the gotchas.

I guess I provided inadequate subtext for that example. It's documentation in a project I work on, explaining that qObject.signal.connect(lambda: anotherQObject.function(arg)) is unsafe in PyQt if anotherQObject might be destroyed before qObject. The same would happen in C++ with QObject::connect(qObject, &MyClass::signal, [&]() { anotherQObject->function(arg); });

In C++, one possible solution is to use QObject::Connect(sender, signal, context object, functor). To the best of my knowledge In PyQt5, and I suspect in PySide2/Qt for Python, there is no equivalent. You can write one by taking the connection object returned by object.signal.connect() and using it in a slot connected to anotherQObject.destroyed.

@Asperamanca said in Future of QGraphicsView and QGraphicsScene:

@jeremy_k said in Future of QGraphicsView and QGraphicsScene:

@Asperamanca I think my point was missed. There's no need to choose Quick|Graphics View|Widgets for the entire application. Use each where they make sense and use the underlying Qt core functionality to communicate.

Yes, I missed your point. But maybe you missed mine: There is currently no better technology (in Qt) for some use cases than GraphicsView. Of course I can mix and match, depending on what I need.

No, I didn't.
We're in agreement there. It's easy to look at the graphics silos and forget that they can cooperate.

@newToQt26
Hi
Good to hear. :)

If the user can add or delete layers, it's pretty important you make sure
curScene/curView always points to something valid as else you get a nasty crash.

I currently don't know but since the behaviour is different, I would fill a bug. If it's intended, the documentation should reflect that.

@amansahil
Check after setting the position if polygon->scenePos() - clickPoint == (0, 0). If it is, there's a problem with the event->scenePos(), and if not, there's a problem with how the polygon position is being set.

The right conversion would be

polygon->setPos( clickPoint - polygonParent->scenePos() )

mapFromScene() is better than mapToScene() since you have the coordinates in the scene frame and you want them in local coordinates. But it still isn't quite right! You specify position in the local parent coordinates, not the local item frame. So that approach to use is

polygon->setPos( polygonParent->mapFromScene(clickPoint) )

@galou_breizh
I think point_size is too small and the ellipse generated is "pixelated" because of that.

This gives a nice circle filled with blue

# -*- coding: utf-8 -*- """Show an incomprehension in setScale for QGraphicsItemGroup.""" from PySide2 import QtCore from PySide2 import QtGui from PySide2 import QtWidgets point_size = 10.0 # In real-world units. # Get entrypoint through which we control underlying Qt framework app = QtWidgets.QApplication([]) scene = QtWidgets.QGraphicsScene() group = QtWidgets.QGraphicsItemGroup() scale = 50.0 # 1 real-world units = 500 px. !! Has no apparent effect. pen = QtGui.QPen(QtCore.Qt.red) brush = QtGui.QBrush(QtCore.Qt.blue) x = 1.0 # Real-world units. y = 2.0 # Real-world units. top_left = (x - point_size / 2.0, y - point_size / 2.0) ellipse = QtWidgets.QGraphicsEllipseItem( QtCore.QRectF(*top_left, point_size, point_size)) ellipse.setPen(pen) ellipse.setBrush(brush) ellipse.setScale(scale) group.addToGroup(ellipse) # group.setScale(scale) scene.addItem(group) view = QtWidgets.QGraphicsView(scene) view.show() # Start Qt/PySide2 application. If we don't show any windows, the # app would just loop at this point without the means to exit app.exec_()

@galou_breizh I answered in the other post. But it's not a good way to duplicate post for the same issue. Please try to avoid it in the future, thanks