python3+PyQt5 重新实现自定义数据拖放处理

本文分成两部分，第一部分通过python3+PyQt5实现自定义数据的拖放操作。第二部分则对第一部分的程序进行修改，增加拖放操作时，菜单提示是否移动或拷贝，还有可以通过ctrl键盘来设置移动过程中拷贝源而非会将源删除。
自定义数据MIME数据类型QMimeData，MIME是一种用于处理具有多个组成部分的自定义数据的标准化格式。MIME数据由一个数据类型和一个子类型构成–例如，text/plain，text/html，image/png，要处理自定义MIME数据，就必须要选用一种自定义数据类型和一种子类型，然后将数据封装到QMimeData对象中。本例子中，我们创建端为application/x-icon-and-text类型的新MIME数据。
注：
dragEnterEvent这是一个拖拽事件的函数，我们把文件拖拽进程序界面打开，之前必须setAcceptDrops(true)了以后拖拽，但是只设置acceptDrops还不够，还需要在dragEnterEvent事件中对拖入的对象进行筛选，判断mimeData的类型是否是你能处理的，如果是，则调用event.acceptProposedAction()放行。拖放结束后会产生dropEvent事件，在那里进行最后的放置操作。总之这是拖拽事件函数的一个筛选事件并放置的函数。

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第一部分：

#!/usr/bin/env python3import osimport sysfrom PyQt5.QtCore import (QByteArray, QDataStream, QIODevice, QMimeData,        QPoint, QSize, Qt)from PyQt5.QtWidgets import (QApplication, QDialog,QGridLayout,                             QLineEdit, QListWidget,QListWidgetItem, QWidget)from PyQt5.QtGui import QIcon,QColor,QPainter,QFontMetricsF,QDragclass DropLineEdit(QLineEdit):    def __init__(self, parent=None):        super(DropLineEdit, self).__init__(parent)        self.setAcceptDrops(True)    def dragEnterEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            event.accept()        else:            event.ignore()    def dragMoveEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            event.setDropAction(Qt.CopyAction)            event.accept()        else:            event.ignore()    def dropEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            data = event.mimeData().data("application/x-icon-and-text")            stream = QDataStream(data, QIODevice.ReadOnly)            text = ""            #stream >> text            text=stream.readQString()            self.setText(text)            event.setDropAction(Qt.CopyAction)            event.accept()        else:            event.ignore()class DnDListWidget(QListWidget):    def __init__(self, parent=None):        super(DnDListWidget, self).__init__(parent)        self.setAcceptDrops(True)        self.setDragEnabled(True)    def dragEnterEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            event.accept()        else:            event.ignore()    def dragMoveEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            event.setDropAction(Qt.MoveAction)            event.accept()        else:            event.ignore()    def dropEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            data = event.mimeData().data("application/x-icon-and-text")            stream = QDataStream(data, QIODevice.ReadOnly)            text = ""            icon = QIcon()            #stream >> text >> icon            text=stream.readQString()            stream >> icon            item = QListWidgetItem(text, self)            item.setIcon(icon)            event.setDropAction(Qt.MoveAction)            event.accept()        else:            event.ignore()    def startDrag(self, dropActions):        item = self.currentItem()        icon = item.icon()        data = QByteArray()        stream = QDataStream(data, QIODevice.WriteOnly)        #stream << item.text() << icon        stream.writeQString(item.text())        stream << icon        mimeData = QMimeData()        mimeData.setData("application/x-icon-and-text", data)        drag = QDrag(self)        drag.setMimeData(mimeData)        pixmap = icon.pixmap(24, 24)        drag.setHotSpot(QPoint(12, 12))        drag.setPixmap(pixmap)        if drag.exec(Qt.MoveAction) == Qt.MoveAction:            self.takeItem(self.row(item))class DnDWidget(QWidget):    def __init__(self, text, icon=QIcon(), parent=None):        super(DnDWidget, self).__init__(parent)        self.setAcceptDrops(True)        self.text = text        self.icon = icon    def minimumSizeHint(self):        fm = QFontMetricsF(self.font())        if self.icon.isNull():            return QSize(fm.width(self.text), fm.height() * 1.5)        return QSize(34 + fm.width(self.text), max(34, fm.height() * 1.5))    def paintEvent(self, event):        height = QFontMetricsF(self.font()).height()        painter = QPainter(self)        painter.setRenderHint(QPainter.Antialiasing)        painter.setRenderHint(QPainter.TextAntialiasing)        painter.fillRect(self.rect(), QColor(Qt.yellow).lighter())        if self.icon.isNull():            painter.drawText(10, height, self.text)        else:            pixmap = self.icon.pixmap(24, 24)            painter.drawPixmap(0, 5, pixmap)            painter.drawText(34, height,                             self.text + " (Drag to or from me!)")    def dragEnterEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            event.accept()        else:            event.ignore()    def dragMoveEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            event.setDropAction(Qt.CopyAction)            event.accept()        else:            event.ignore()    def dropEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            data = event.mimeData().data("application/x-icon-and-text")            stream = QDataStream(data, QIODevice.ReadOnly)            self.text = ""            self.icon = QIcon()            #stream >> self.text >> self.icon            self.text=stream.readQString()            stream>>self.icon            event.setDropAction(Qt.CopyAction)            event.accept()            self.updateGeometry()            self.update()        else:            event.ignore()    def mouseMoveEvent(self, event):        self.startDrag()        QWidget.mouseMoveEvent(self, event)    def startDrag(self):        icon = self.icon        if icon.isNull():            return        data = QByteArray()        stream = QDataStream(data, QIODevice.WriteOnly)        #stream << self.text << icon        stream.writeQString(self.text)        stream<<icon        mimeData = QMimeData()        mimeData.setData("application/x-icon-and-text", data)        drag = QDrag(self)        drag.setMimeData(mimeData)        pixmap = icon.pixmap(24, 24)        drag.setHotSpot(QPoint(12, 12))        drag.setPixmap(pixmap)        drag.exec(Qt.CopyAction)class Form(QDialog):    def __init__(self, parent=None):        super(Form, self).__init__(parent)        dndListWidget = DnDListWidget()        path = os.path.dirname(__file__)        for image in sorted(os.listdir(os.path.join(path, "images"))):            if image.endswith(".png"):                item = QListWidgetItem(image.split(".")[0].capitalize())                item.setIcon(QIcon(os.path.join(path,                                   "images/{0}".format(image))))                dndListWidget.addItem(item)        dndIconListWidget = DnDListWidget()        dndIconListWidget.setViewMode(QListWidget.IconMode)        dndWidget = DnDWidget("Drag to me!")        dropLineEdit = DropLineEdit()        layout = QGridLayout()        layout.addWidget(dndListWidget, 0, 0)        layout.addWidget(dndIconListWidget, 0, 1)        layout.addWidget(dndWidget, 1, 0)        layout.addWidget(dropLineEdit, 1, 1)        self.setLayout(layout)        self.setWindowTitle("Custom Drag and Drop")if __name__ == "__main__":    app = QApplication(sys.argv)    form = Form()    form.show()    app.exec_()

运行结果：

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第二部分：

#!/usr/bin/env python3import osimport sysfrom PyQt5.QtCore import (QByteArray, QDataStream, QIODevice, QMimeData,        QPoint, QSize, Qt)from PyQt5.QtWidgets import (QApplication, QDialog,QGridLayout,                             QLineEdit, QListWidget,QListWidgetItem, QWidget,QMenu)from PyQt5.QtGui import QIcon,QColor,QPainter,QFontMetricsF,QDrag,QCursorclass DropLineEdit(QLineEdit):    def __init__(self, parent=None):        super(DropLineEdit, self).__init__(parent)        self.setAcceptDrops(True)    def dragEnterEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            event.accept()        else:            event.ignore()    def dragMoveEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            event.setDropAction(Qt.CopyAction)            event.accept()        else:            event.ignore()    def dropEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            data = event.mimeData().data("application/x-icon-and-text")            stream = QDataStream(data, QIODevice.ReadOnly)            text = ""            text=stream.readQString()            self.setText(text)            event.setDropAction(Qt.CopyAction)            event.accept()        else:            event.ignore()class DnDMenuListWidget(QListWidget):    def __init__(self, parent=None):        super(DnDMenuListWidget, self).__init__(parent)        self.setAcceptDrops(True)        self.setDragEnabled(True)        self.dropAction = Qt.CopyAction    def dragEnterEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            event.accept()        else:            event.ignore()    def dragMoveEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            event.setDropAction(Qt.MoveAction)            event.accept()        else:            event.ignore()    def dropEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            data = event.mimeData().data("application/x-icon-and-text")            stream = QDataStream(data, QIODevice.ReadOnly)            text = ""            icon = QIcon()            text=stream.readQString()            stream>>icon            menu = QMenu(self)            menu.addAction("&Copy", self.setCopyAction)            menu.addAction("&Move", self.setMoveAction)            if menu.exec_(QCursor.pos()):                item = QListWidgetItem(text, self)                item.setIcon(icon)                event.setDropAction(self.dropAction)                event.accept()                return            else:                event.setDropAction(Qt.IgnoreAction)        event.ignore()    def setCopyAction(self):        self.dropAction = Qt.CopyAction    def setMoveAction(self):        self.dropAction = Qt.MoveAction    def startDrag(self, dropActions):        item = self.currentItem()        icon = item.icon()        data = QByteArray()        stream = QDataStream(data, QIODevice.WriteOnly)        stream.writeQString(item.text())        stream<<icon        mimeData = QMimeData()        mimeData.setData("application/x-icon-and-text", data)        drag = QDrag(self)        drag.setMimeData(mimeData)        pixmap = icon.pixmap(24, 24)        drag.setHotSpot(QPoint(12, 12))        drag.setPixmap(pixmap)        if (drag.exec(Qt.MoveAction|Qt.CopyAction) == Qt.MoveAction):            self.takeItem(self.row(item))class DnDCtrlListWidget(QListWidget):    def __init__(self, parent=None):        super(DnDCtrlListWidget, self).__init__(parent)        self.setAcceptDrops(True)        self.setDragEnabled(True)    def dragEnterEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            event.accept()        else:            event.ignore()    def dragMoveEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            action = Qt.MoveAction            if event.keyboardModifiers() & Qt.ControlModifier:                action = Qt.CopyAction            event.setDropAction(action)            event.accept()        else:            event.ignore()    def dropEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            data = event.mimeData().data("application/x-icon-and-text")            stream = QDataStream(data, QIODevice.ReadOnly)            text = ""            icon = QIcon()            text=stream.readQString()            stream>>icon            item = QListWidgetItem(text, self)            item.setIcon(icon)            action = Qt.MoveAction            if event.keyboardModifiers() & Qt.ControlModifier:                action = Qt.CopyAction            event.setDropAction(action)            event.accept()        else:            event.ignore()    def startDrag(self, dropActions):        item = self.currentItem()        icon = item.icon()        data = QByteArray()        stream = QDataStream(data, QIODevice.WriteOnly)        stream.writeQString(item.text())        stream<<icon        mimeData = QMimeData()        mimeData.setData("application/x-icon-and-text", data)        drag = QDrag(self)        drag.setMimeData(mimeData)        pixmap = icon.pixmap(24, 24)        drag.setHotSpot(QPoint(12, 12))        drag.setPixmap(pixmap)        if (drag.exec(Qt.MoveAction|Qt.CopyAction) == Qt.MoveAction):            self.takeItem(self.row(item))class DnDWidget(QWidget):    def __init__(self, text, icon=QIcon(), parent=None):        super(DnDWidget, self).__init__(parent)        self.setAcceptDrops(True)        self.text = text        self.icon = icon    def minimumSizeHint(self):        fm = QFontMetricsF(self.font())        if self.icon.isNull():            return QSize(fm.width(self.text), fm.height() * 1.5)        return QSize(34 + fm.width(self.text), max(34, fm.height() * 1.5))    def paintEvent(self, event):        height = QFontMetricsF(self.font()).height()        painter = QPainter(self)        painter.setRenderHint(QPainter.Antialiasing)        painter.setRenderHint(QPainter.TextAntialiasing)        painter.fillRect(self.rect(), QColor(Qt.yellow).lighter())        if self.icon.isNull():            painter.drawText(10, height, self.text)        else:            pixmap = self.icon.pixmap(24, 24)            painter.drawPixmap(0, 5, pixmap)            painter.drawText(34, height,                             self.text + " (Drag to or from me!)")    def dragEnterEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            event.accept()        else:            event.ignore()    def dragMoveEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            event.setDropAction(Qt.CopyAction)            event.accept()        else:            event.ignore()    def dropEvent(self, event):        if event.mimeData().hasFormat("application/x-icon-and-text"):            data = event.mimeData().data("application/x-icon-and-text")            stream = QDataStream(data, QIODevice.ReadOnly)            self.text = ""            self.icon = QIcon()            self.text=stream.readQString()            stream>>self.icon            event.setDropAction(Qt.CopyAction)            event.accept()            self.updateGeometry()            self.update()        else:            event.ignore()    def mouseMoveEvent(self, event):        self.startDrag()        QWidget.mouseMoveEvent(self, event)    def startDrag(self):        icon = self.icon        if icon.isNull():            return        data = QByteArray()        stream = QDataStream(data, QIODevice.WriteOnly)        stream.writeQString(self.text)        stream<<icon        mimeData = QMimeData()        mimeData.setData("application/x-icon-and-text", data)        drag = QDrag(self)        drag.setMimeData(mimeData)        pixmap = icon.pixmap(24, 24)        drag.setHotSpot(QPoint(12, 12))        drag.setPixmap(pixmap)        drag.exec(Qt.CopyAction)class Form(QDialog):    def __init__(self, parent=None):        super(Form, self).__init__(parent)        dndListWidget = DnDMenuListWidget()        path = os.path.dirname(__file__)        for image in sorted(os.listdir(os.path.join(path, "images"))):            if image.endswith(".png"):                item = QListWidgetItem(image.split(".")[0].capitalize())                item.setIcon(QIcon(os.path.join(path,                                   "images/{0}".format(image))))                dndListWidget.addItem(item)        dndIconListWidget = DnDCtrlListWidget()        dndIconListWidget.setViewMode(QListWidget.IconMode)        dndWidget = DnDWidget("Drag to me!")        dropLineEdit = DropLineEdit()        layout = QGridLayout()        layout.addWidget(dndListWidget, 0, 0)        layout.addWidget(dndIconListWidget, 0, 1)        layout.addWidget(dndWidget, 1, 0)        layout.addWidget(dropLineEdit, 1, 1)        self.setLayout(layout)        self.setWindowTitle("Custom Drag and Drop")if __name__ == "__main__":    app = QApplication(sys.argv)    form = Form()    form.show()    app.exec_()

运行结果：