PyQt5 Drag and drop a button wid

drag and drop a button widget.

代码：

# coding='utf-8'

from PyQt5.QtWidgets import QApplication, QWidget,\
    QPushButton
from PyQt5.QtGui import QDrag
from PyQt5.QtCore import Qt, QMimeData
import sys


class Button(QPushButton):
    def __init__(self, title, parent):
        super().__init__(title, parent)

    # This the place where the drag and drop operation begins.
    def mouseMoveEvent(self, e) -> None:
        # The MouseButtons class is a\
        #   set of flags whose values are\
        #   the members of the MouseButton\
        #   enum. Instances of the class\
        #   support the standard Python int methods.

        # Here we decide that we can perform\
        #   drag and drop only with a right mouse\
        #   button. The left mouse button is\
        #   reserved for clicking on the button.
        # 注意这里必须要用按键的枚举值:buttons,不能用button,\
        #  可能是因为右键按下的操作是一个持久拖拉的过程,\
        #  而不是像点击那样一下子就能完成,所以要用枚举值\
        #  (这些枚举值按键里面有右键就行)
        if e.buttons() != Qt.RightButton:
            return
        # The QMimeData class provides a container\
        #   for data that records information about\
        #   its MIME type.
        mime_data = QMimeData()
        # QDrag对象的实例化支持MIME-based的拖拉操作使得数据转换
        drag = QDrag(self)
        drag.setMimeData(mime_data)
        drag.setHotSpot(e.pos() - self.rect().topLeft())
        # 从这个exec_方法开始拖或者拉的操作
        dropAction = drag.exec_(Qt.MoveAction)

    def mousePressEvent(self, e) -> None:
        # Notice that we call mousePressEvent()\
        #   method on the parent as well. Otherwise,\
        #   we would not see the button being pushed.
        # 就是说我们重写了别人父类的方法,但是还想用别人父类的方法,\
        #   就必须要手动调用父类这个方法
        super().mousePressEvent(e)
        # 如果是左键的按下
        if e.button() == Qt.LeftButton:
            print('press')


class Gui(QWidget):
    def __init__(self):
        super(Gui, self).__init__()
        self.start()

    def start(self):
        # 使得主窗体能够被拖/拉后放置在主窗体的某个地方
        self.setAcceptDrops(True)

        self.button = Button('按钮', self)
        self.button.move(100, 65)

        self.setGeometry(300, 300, 280, 150)
        self.setWindowTitle('点击按钮或者移动它')
        self.show()

    # 当抓取操作开始,鼠标点击了但是还没放开
    def dragEnterEvent(self, e) -> None:
        # 无论主窗体上拖动的东西是何种类型,都能接受-->下一步的放下,
        #     如果不接受(e.ignore)的话,拖动后是不能松手放下去的
        e.accept()

    # 紧按着的鼠标放开了(拖拉到了某个位置)
    def dropEvent(self, e) -> None:
        # 我们这个 程序不是开始拖拽后控件就一直跟着鼠标,\
        #       只是松手后控件move过去.
        # 立刻获得当前(拖动后)的位置
        position = e.pos()
        # 把按钮移动到拖动后的位置
        self.button.move(position)
        # 使得drop 操作的类型具体化(具体化成move action)
        e.setDropAction(Qt.MoveAction)
        # 也是使得主窗体每个地方都能放下拖拉后的控件,\
        #     感觉这个无论是ignore还是accept都没有太大的影响
        e.ignore()


app = QApplication(sys.argv)
gui = Gui()
sys.exit(app.exec_())

运行结果：左键点击: image.png
右键拖拉： image.png