= Handling an internal Qt MIME type =

On the `#pyqt` channel on Freenode, `reenen` asked if it was possible to handle the internal MIME type Qt uses for drag and drop between item views.

See [[PyQt/Handling Qt's internal item MIME type|Handling Qt's internal item MIME type]] for the details.

{{{
#!python
import sys
from PyQt4.QtCore import QDataStream, Qt, QVariant
from PyQt4.QtGui import *

class TreeModel(QStandardItemModel):

    def __init__(self, parent = None):
    
        QStandardItemModel.__init__(self, parent)
    
    def dropMimeData(self, data, action, row, column, parent):
    
        if data.hasFormat('application/x-qabstractitemmodeldatalist'):
            bytearray = data.data('application/x-qabstractitemmodeldatalist')
            data_items = self.decode_data(bytearray)
            
            # Decode the data, assuming that we get 6 32-bit integers to
            # start with, then a count byte followed by a string.
            text = data_items[Qt.DisplayRole].toString()
            for row in range(self.rowCount()):
                name = self.item(row, 0).text()
                if name == text:
                    number_item = self.item(row, 1)
                    number = int(number_item.text())
                    number_item.setText(str(number + 1))
                    break
            else:
                name_item = QStandardItem(text)
                number_item = QStandardItem("1")
                self.appendRow([name_item, number_item])
            
            return True
        else:
            return QStandardItemModel.dropMimeData(self, data, action, row, column, parent)
    
    def decode_data(self, bytearray):
    
        data = {}
        
        ds = QDataStream(bytearray)
        while not ds.atEnd():
        
            row = ds.readInt32()
            column = ds.readInt32()
            
            map_items = ds.readInt32()
            for i in range(map_items):
            
                key = ds.readInt32()
                
                value = QVariant()
                ds >> value
                data[Qt.ItemDataRole(key)] = value
        
        return data

app = QApplication(sys.argv)

window = QWidget()

listModel = QStringListModel(["John", "Jane", "Frank", "Henry"])
listView = QListView()
listView.setModel(listModel)
listView.setDragEnabled(True)

treeModel = TreeModel()
treeView = QTreeView()
treeView.setHeaderHidden(True)
treeView.setRootIsDecorated(False)
treeView.setAcceptDrops(True)
treeView.setModel(treeModel)

layout = QHBoxLayout(window)
layout.addWidget(listView)
layout.addWidget(treeView)

window.show()
sys.exit(app.exec_())
}}}