simple tree widget transparent dragging by customizing mouseMoveEvent

simple tree widget transparent dragging.py

#!/usr/bin/env python2
import os
import sys
import re

from PyQt4 import QtGui, QtCore
from PyQt4.QtCore import Qt, QString


class MyTreeWidget(QtGui.QTreeWidget):

    def mouseMoveEvent(self, e):
        listsQModelIndex = self.selectedIndexes()
        if listsQModelIndex:
            dataQMimeData = self.model().mimeData(listsQModelIndex)

            index = self.indexFromItem(self.currentItem(), 0)
            row = index.row()

            drag_rect = self.visualItemRect(self.itemFromIndex(index))

            header_height = self.header().sizeHint().height()

            row_height = self.rowHeight(index)
            # screenshot_y = row * row_height +  header_height +2

            screenshot_y = drag_rect.y() + row_height

            pixmap = QtGui.QPixmap.grabWidget(self, 0, screenshot_y, -1, row_height)

            painter = QtGui.QPainter(pixmap)
            painter.setCompositionMode(painter.CompositionMode_DestinationIn)
            painter.fillRect(pixmap.rect(), QtGui.QColor(0, 0, 0, 127))
            painter.end()

            # make a QDrag
            drag = QtGui.QDrag(self)
            # put our MimeData
            drag.setMimeData(dataQMimeData)
            # set its Pixmap
            drag.setPixmap(pixmap)
            # shift the Pixmap so that it coincides with the cursor position
            # drag.setHotSpot(e.pos())

            drag.setHotSpot(QtCore.QPoint(e.pos().x(), e.pos().y() - screenshot_y + row_height))

            # start the drag operation
            # exec_ will return the accepted action from dropEvent
            drag.exec_()


class TheUI(QtGui.QDialog):

    def __init__(self, args=None, parent=None):
        super(TheUI, self).__init__(parent)
        self.layout1 = QtGui.QVBoxLayout(self)
        treeWidget = MyTreeWidget()

        # treeWidget.setSelectionMode( QtGui.QAbstractItemView.ExtendedSelection )

        button1 = QtGui.QPushButton('Add')
        button2 = QtGui.QPushButton('Add Child')

        self.layout1.addWidget(treeWidget)

        self.layout2 = QtGui.QHBoxLayout()
        self.layout2.addWidget(button1)
        self.layout2.addWidget(button2)

        self.layout1.addLayout(self.layout2)

        treeWidget.setHeaderHidden(True)

        self.treeWidget = treeWidget
        self.button1 = button1
        self.button2 = button2
        self.button1.clicked.connect(lambda *x: self.addCmd())
        self.button2.clicked.connect(lambda *x: self.addChildCmd())

        HEADERS = ("script", "chunksize", "mem")
        self.treeWidget.setHeaderLabels(HEADERS)
        self.treeWidget.setColumnCount(len(HEADERS))

        self.treeWidget.setColumnWidth(0, 160)
        self.treeWidget.header().show()

        self.treeWidget.setDragDropMode(QtGui.QAbstractItemView.InternalMove)

        self.resize(500, 500)
        for i in xrange(6):
            item = self.addCmd(i)
            if i in (3, 4):
                self.addChildCmd()
                if i == 4:
                    self.addCmd('%s-2' % i, parent=item)

        self.treeWidget.expandAll()
        self.setStyleSheet("QTreeWidget::item{ height: 30px;  }")

    def addChildCmd(self):
        parent = self.treeWidget.currentItem()
        self.addCmd(parent=parent)
        self.treeWidget.setCurrentItem(parent)

    def addCmd(self, i=None, parent=None):
        'add a level to tree widget'

        root = self.treeWidget.invisibleRootItem()
        if not parent:
            parent = root

        if i is None:
            if parent == root:
                i = self.treeWidget.topLevelItemCount()
            else:
                i = str(parent.text(0))[7:]
                i = '%s-%s' % (i, parent.childCount() + 1)

        item = QtGui.QTreeWidgetItem(parent, ['script %s' % i, '1', '150'])

        self.treeWidget.setCurrentItem(item)
        self.treeWidget.expandAll()
        return item

if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    gui = TheUI()
    gui.show()
    app.exec_()