Dragging/Moving a QPushButton in PyQt

Question

I am really struggling to figure out a way to do this. Say I implement a button very simply in a widget window: ``` self.button = QPushButton("Drag Me", self) ``` I can move its initialization point around the parent widget's area using `self.button.move(x,y)`, and I can get mouse events from `mousePressEvent(self, e)` via `e.x()` and `e.y()`, so that the button moves to wherever I click, but I just cannot seem to put all this together into a drag and drop framework. Clarification: After reading on the 'true' meaning of Drag/Drop, that's not what I need. I just want to be able to move a widget around with my mouse, much similar to the way you move magnets on a fridge.

Accepted Answer

Here is an example of a moveable button that still supports the normal click signal properly:

```
from PyQt4 import QtCore, QtGui

class DragButton(QtGui.QPushButton):

def mousePressEvent(self, event):
        self.__mousePressPos = None
        self.__mouseMovePos = None
        if event.button() == QtCore.Qt.LeftButton:
            self.__mousePressPos = event.globalPos()
            self.__mouseMovePos = event.globalPos()

super(DragButton, self).mousePressEvent(event)

def mouseMoveEvent(self, event):
        if event.buttons() == QtCore.Qt.LeftButton:
            # adjust offset from clicked point to origin of widget
            currPos = self.mapToGlobal(self.pos())
            globalPos = event.globalPos()
            diff = globalPos - self.__mouseMovePos
            newPos = self.mapFromGlobal(currPos + diff)
            self.move(newPos)

self.__mouseMovePos = globalPos

super(DragButton, self).mouseMoveEvent(event)

def mouseReleaseEvent(self, event):
        if self.__mousePressPos is not None:
            moved = event.globalPos() - self.__mousePressPos 
            if moved.manhattanLength() > 3:
                event.ignore()
                return

super(DragButton, self).mouseReleaseEvent(event)

def clicked():
    print "click as normal!"

if __name__ == "__main__":
    app = QtGui.QApplication([])
    w = QtGui.QWidget()
    w.resize(800,600)

button = DragButton("Drag", w)
    button.clicked.connect(clicked)

w.show()
    app.exec_()
```

In the `mousePressEvent` I record both the initial start position, and a position that will get updated throughout the drag.

In the `mouseMoveEvent`, I get the proper offset of the widget from where it was clicked to where the actual origin is, so that the move is accurate.

In the `mouseReleaseEvent`, I check to see if the overall move was greater than at least a tiny amount. If it was, then it was a drag and we ignore the normal event to not produce a "clicked" signal. Otherwise, we allow the normal event handler to produce the click.

Dragging/Moving a QPushButton in PyQt

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