Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
787 views
in Technique[技术] by (71.8m points)

python - Dragging/Moving a QPushButton in PyQt

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.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

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.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...