[Qt-interest] Howto make QGraphicsTextItem draggable?

[John Posner]

Wilhelm wrote:
> Hi,
>
> I want to make a QGraphicsTextItem drag and droppable AND still moveable 
> like the normal behaviour if I set QGraphicsItem::ItemIsMovable (see 
> below). Additionally I want to have the original text drawn while the 
> drag is active, so I tried to set the drag pixmap. But if I try to use a 
> painter to draw the item onto a pixmap, the application crashes with a 
> segfault (if you uncomment the commented codelines below).
> What am I doing wrong here?
>   

I can't comment on what your code does wrong, but here is some PyQt4 
code (Python) that has a dragged text item leave behind an italicized 
"ghost" of itself. The ghost disappears when you drop the text item.

#-------------------------
from PyQt4.QtCore import *
from PyQt4.QtGui import *

TEXT = "hello world"

class GhostText(QGraphicsTextItem):
    def __init__(self, txt):
        super(GhostText, self).__init__(txt)
        self.setDefaultTextColor(Qt.red)
        self.setFlags(QGraphicsItem.ItemIsMovable)
        self.ghost = None
       
    def mousePressEvent(self, evt):
        """create ghost text item at current position"""
        self.ghost = QGraphicsTextItem()
        self.ghost.setHtml("<i>%s</i>" % TEXT)
        scene.addItem(self.ghost)
        self.ghost.moveBy(self.x(), self.y())
        super(GhostText, self).mousePressEvent(evt)

    def mouseReleaseEvent(self, evt):
        """remove ghost text item"""
        scene.removeItem(self.ghost)
        self.ghost.deleteLater()
        super(GhostText, self).mouseReleaseEvent(evt)

# main program
app = QApplication([])
win = QMainWindow()
win.resize(500+25, 300+25)

# create a view, scene, and text item
view = QGraphicsView()
win.setCentralWidget(view)
scene = QGraphicsScene()
view.setScene(scene)
view.setSceneRect(0, 0, 500, 300)
scene.addItem(GhostText(TEXT))

# go
win.show()
app.exec_()
#-------------------------


HTH,
John