PyQt5组件间拖放时DropEvent未触发问题求助

我之前遇到过完全一样的情况，你的问题根源很明确：虽然给MyQDialog设置了setAcceptDrops(True)，但没有实现dragEnterEvent和dragMoveEvent。当鼠标拖拽到组件之间的空白区域（属于MyQDialog范围但没被MyFrame覆盖）时，默认的事件处理会拒绝这些拖拽事件，导致松开鼠标时系统认为这个区域不接受放置，自然不会触发dropEvent。

简单修复方案 #

只需要给MyQDialog补上dragEnterEvent和dragMoveEvent的实现，让整个窗口的所有区域都认可拖拽操作就行。另外还有个小优化点可以顺手调整，下面是完整的修改后代码：

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'DS_Test.ui'
#
# Created by: PyQt5 UI code generator 5.15.7
#
# WARNING: Any manual changes made to this file will be lost when pyuic5 is
# run again.  Do not edit this file unless you know what you are doing.


from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtGui import QDragEnterEvent, QDropEvent


class MyButton(QtWidgets.QPushButton):
    def mouseMoveEvent(self, event):
        btn_img = self.grab()
        painter = QtGui.QPainter(btn_img)
        painter.setCompositionMode(painter.CompositionMode_DestinationIn)
        painter.fillRect(btn_img.rect(), QtGui.QColor(0, 0, 0, 150))
        painter.end()

        data = QtCore.QMimeData()
        drag = QtGui.QDrag(self)
        drag.setMimeData(data)
        drag.setPixmap(btn_img)

        drag.setHotSpot(event.pos())
        self._pos = event.pos()

        # 执行拖拽，这里不需要调用super，默认的mouseMoveEvent不处理拖拽逻辑
        drag.exec_(QtCore.Qt.CopyAction)


class MyFrame(QtWidgets.QFrame):
    def __init__(self, parent):
        super().__init__(parent)
        self.setAcceptDrops(True)
        
    def dragEnterEvent(self, e: QDragEnterEvent):
        e.accept()

    def dragMoveEvent(self, e):
        e.accept()

    def dropEvent(self, e: QDropEvent):
        self.parent().dropEvent(e)


class MyQDialog(QtWidgets.QDialog):
    def __init__(self):
        super().__init__()
        self.setAcceptDrops(True)

    def dragEnterEvent(self, e: QDragEnterEvent):
        # 接受所有进入窗口的拖拽事件
        e.accept()

    def dragMoveEvent(self, e):
        # 允许拖拽在窗口内任意区域移动
        e.accept()

    def dropEvent(self, e: QDropEvent):
        print("dropEvent - is done")
        # 这里可以添加向服务器发送消息的逻辑
        e.accept()

class Ui_Dialog(object):
    def setupUi(self, Dialog):
        Dialog.setObjectName("Dialog")
        Dialog.resize(1051, 800)
        self.verticalLayout = QtWidgets.QVBoxLayout(Dialog)
        self.verticalLayout.setObjectName("verticalLayout")
        self.horizontalFrame = MyFrame(Dialog)
        self.horizontalFrame.setStyleSheet("background-color: qlineargradient(spread:pad, x1:0, y1:0, x2:1, y2:0, stop:0 rgba(255, 0, 0, 211), stop:0.166 rgba(255, 255, 0, 211), stop:0.333 rgba(0, 255, 0, 211), stop:0.5 rgba(0, 255, 255, 211), stop:0.666 rgba(0, 0, 255, 211), stop:0.833 rgba(255, 0, 255, 211), stop:1 rgba(255, 0, 0, 211));")
        self.horizontalFrame.setObjectName("horizontalFrame")
        self.horizontalLayout_6 = QtWidgets.QHBoxLayout(self.horizontalFrame)
        self.horizontalLayout_6.setObjectName("horizontalLayout_6")
        self.pushButton_3 = MyButton(self.horizontalFrame)
        self.pushButton_3.setObjectName("pushButton_3")
        self.horizontalLayout_6.addWidget(self.pushButton_3)
        self.pushButton_2 = MyButton(self.horizontalFrame)
        self.pushButton_2.setObjectName("pushButton_2")
        self.horizontalLayout_6.addWidget(self.pushButton_2)
        self.pushButton = MyButton(self.horizontalFrame)
        self.pushButton.setObjectName("pushButton")
        self.horizontalLayout_6.addWidget(self.pushButton)
        self.verticalLayout.addWidget(self.horizontalFrame)
        self.horizontalFrame_2 = MyFrame(Dialog)
        self.horizontalFrame_2.setStyleSheet("background-color: qlineargradient(spread:pad, x1:0, y1:0, x2:1, y2:0, stop:0 rgba(9, 41, 4, 255), stop:0.085 rgba(2, 79, 0, 255), stop:0.19 rgba(50, 147, 22, 255), stop:0.275 rgba(236, 191, 49, 255), stop:0.39 rgba(243, 61, 34, 255), stop:0.555 rgba(135, 81, 60, 255), stop:0.667 rgba(121, 75, 255, 255), stop:0.825 rgba(164, 255, 244, 255), stop:0.885 rgba(104, 222, 71, 255), stop:1 rgba(93, 128, 0, 255));")
        self.horizontalFrame_2.setObjectName("horizontalFrame_2")
        self.horizontalLayout_7 = QtWidgets.QHBoxLayout(self.horizontalFrame_2)
        self.horizontalLayout_7.setObjectName("horizontalLayout_7")
        self.verticalLayout.addWidget(self.horizontalFrame_2)
        self.horizontalFrame_3 = MyFrame(Dialog)
        self.horizontalFrame_3.setStyleSheet("background-color: qlineargradient(spread:pad, x1:0, y1:1, x2:0, y2:0, stop:0 rgba(0, 0, 0, 255), stop:0.05 rgba(14, 8, 73, 255), stop:0.36 rgba(28, 17, 145, 255), stop:0.6 rgba(126, 14, 81, 255), stop:0.75 rgba(234, 11, 11, 255), stop:0.79 rgba(244, 70, 5, 255), stop:0.86 rgba(255, 136, 0, 255), stop:0.935 rgba(239, 236, 55, 255));")
        self.horizontalFrame_3.setObjectName("horizontalFrame_3")
        self.horizontalLayout_8 = QtWidgets.QHBoxLayout(self.horizontalFrame_3)
        self.horizontalLayout_8.setObjectName("horizontalLayout_8")
        self.verticalLayout.addWidget(self.horizontalFrame_3)

        self.retranslateUi(Dialog)
        QtCore.QMetaObject.connectSlotsByName(Dialog)

    def retranslateUi(self, Dialog):
        _translate = QtCore.QCoreApplication.translate
        Dialog.setWindowTitle(_translate("Dialog", "Dialog"))
        self.pushButton_3.setText(_translate("Dialog", "PushButton"))
        self.pushButton_2.setText(_translate("Dialog", "PushButton"))
        self.pushButton.setText(_translate("Dialog", "PushButton"))


if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    Dialog = MyQDialog()
    ui = Ui_Dialog()
    ui.setupUi(Dialog)
    Dialog.show()
    sys.exit(app.exec_())

修改细节说明 #

1. 给MyQDialog添加事件处理：新增了dragEnterEvent和dragMoveEvent，在这两个方法里调用e.accept()，相当于告诉系统“这个区域可以接受拖拽”，这样不管鼠标在窗口内哪个位置松开，都会触发dropEvent。
2. 移除MyButton中的super调用：drag.exec_()是阻塞执行的，拖拽完成后才会继续往下走，而默认的mouseMoveEvent对拖拽逻辑没有帮助，所以去掉这个调用避免不必要的事件处理。

这样修改后，你就可以放心地在dropEvent里添加向服务器发送消息的代码了，每次拖拽结束都会触发这个方法~

内容的提问来源于stack exchange，提问作者Игорь Платонов