没有子类化的 PyQt Drop 事件？

Question

这个 python pyqt 代码按我的意图工作。 但是，我不喜欢将 QLineEdit 子类化，这样我就可以检测到文件拖放到我的 QLineEdit 字段上。我喜欢更优雅、更简单的“连接”技术（新型信号/插槽处理），我用它来检测编辑字段的文本更改。

我的问题：是否有一个信号/插槽连接解决方​​案来处理编辑字段上的滴，而不必继承 QLineEdit？

另外，我必须在子类中实现这两种方法很烦人... dragEnterEvent 和 dropEvent 才能使 drop 工作！

import sys
from PyQt4 import QtGui, QtCore

class dropedit(QtGui.QLineEdit):   # subclass 
    def __init__(self, parent=None):
        super(dropedit, self).__init__(parent)
        self.setDragEnabled(True)
        self.setAcceptDrops(True)

    def dragEnterEvent(self, event):
        print "dragEnterEvent:"

        if event.mimeData().hasUrls():
            event.accept()   # must accept the dragEnterEvent or else the dropEvent can't occur !!!
        else:
            event.ignore()

    def dropEvent(self, event):

        if event.mimeData().hasUrls():   # if file or link is dropped

            urlcount = len(event.mimeData().urls())  # count number of drops

            url = event.mimeData().urls()[0]   # get first url

            self.setText(url.toString())   # assign first url to editline

            #event.accept()  # doesnt appear to be needed

class testDialog(QtGui.QDialog):
    def __init__(self, parent=None):
        super(testDialog, self).__init__(parent)


        form = QtGui.QFormLayout()
        form.setHorizontalSpacing(0)

        myedit = dropedit()
        form.addWidget(myedit)

        self.setLayout(form)
        self.setGeometry(300, 300, 400, 0)
        self.setWindowTitle('drop test')

        myedit.textChanged.connect(self.editchange)   # new style signal slot connections

    @QtCore.pyqtSlot(str)   # int represent the column value
    def editchange(self,data):
        print "editchange:", data

if __name__ == "__main__":

    app = QtGui.QApplication([])
    dl = testDialog()
    dl.exec_()
    sys.exit(app.closeAllWindows())

Answer 1

无需子类化：您可以使用事件过滤器：

import sys
from PyQt4 import QtGui, QtCore

class testDialog(QtGui.QDialog):
    def __init__(self, parent=None):
        super(testDialog, self).__init__(parent)

        form = QtGui.QFormLayout()
        form.setHorizontalSpacing(0)

        self.myedit = QtGui.QLineEdit()
        self.myedit.setDragEnabled(True)
        self.myedit.setAcceptDrops(True)
        self.myedit.installEventFilter(self)

        form.addWidget(self.myedit)

        self.setLayout(form)
        self.setGeometry(300, 300, 400, 0)
        self.setWindowTitle('drop test')

        self.myedit.textChanged.connect(self.editchange)   # new style signal slot connections

    @QtCore.pyqtSlot(str)   # int represent the column value
    def editchange(self,data):
        print "editchange:", data.toLatin1()

    def eventFilter(self, object, event):
        if (object is self.myedit):
            if (event.type() == QtCore.QEvent.DragEnter):
                if event.mimeData().hasUrls():
                    event.accept()   # must accept the dragEnterEvent or else the dropEvent can't occur !!!
                    print "accept"
                else:
                    event.ignore()
                    print "ignore"
            if (event.type() == QtCore.QEvent.Drop):
                if event.mimeData().hasUrls():   # if file or link is dropped
                    urlcount = len(event.mimeData().urls())  # count number of drops
                    url = event.mimeData().urls()[0]   # get first url
                    object.setText(url.toString())   # assign first url to editline
                    #event.accept()  # doesnt appear to be needed
            return False # lets the event continue to the edit
        return False

if __name__ == "__main__":

    app = QtGui.QApplication([])
    dl = testDialog()
    dl.exec_()
    sys.exit(app.closeAllWindows())

Answer 2

我今天遇到了同样的问题，并且能够以不同的（也许不那么正统）的方式解决它。 因此，还可以将 dropEvent 函数从树重新映射到另一个名称，无论是在实例内部还是到拥有该实例的类，并为 dropEvent 分配一个新的自定义函数。这个新函数可以调用或不调用原来的函数，这取决于您是要保留一些功能，还是只重写所有内容。 这是一个sn-p：

import sys
from PyQt5.QtWidgets import QTreeView
from PyQt5.QtGui import QDropEvent

class Demo: 

    def __init__(self):
        self.tree = QTreeView()
        self.tree.setDragEnabled(True)
        self.tree.setAcceptDrops(True)
        self.tree.original_dropEvent = self.dataView.dropEvent
        self.tree.dropEvent = self._dataview_dropevent

    def _tree_dropevent(self, event: QDropEvent):
        # do stuff ...
        self.tree.original_dropEvent(event)
        # maybe more stuff ..

.