[Pyobjc-dev] NSTableView and Drag and Drop

[John S. <jo...@sk...>]

Hi PyObjC list,

I have a table view that I'd like to add drag and drop support to. I  
borrowed a lot of code from the bookmarks example and some Objective-C  
examples I've found across the net (and I used  
tableView_writeRowsWithIndexes_toPasteboard_ rather than  
tableView_writeRows_toPasteboard_ since I read writeRows is  
deprecated). I've also modified it a little since my application is  
not document-based. Ideally the user would be able to reorder items in  
the table (I don't anticipate the need for copy and paste).  I have it  
almost working--I can drag an element, but on drop, I get the  
following error:

An unexpected error has occurred
(TypeError: 'NoneType' object is not iterable)

I've implemented the three methods I believe I'm supposed to implement  
for DND table support and I've declared a pasteboard type. I don't  
know if it's because the acceptDrop or validateDrop methods aren't  
working. Ideas?

My code is below:

"""
   ApplicationDelegate.py
   Controller class for the application
"""

from Foundation import *
from AppKit import *
from PyObjCTools import NibClassBuilder
import objc
from objc import YES, NO, IBOutlet, IBAction

from ApplicationModel import *

MovedRowsType = u"MOVED_ROWS_TYPE"

class ApplicationDelegate(NSObject):
   # Outlets
   arrayController = objc.IBOutlet()
   tableView = objc.IBOutlet()

   # Class methods
   def init(self):
     self = NSObject.init(self)
     return self

   def awakeFromNib(self):
     # register for drag and drop
     self.tableView.registerForDraggedTypes_([MovedRowsType])

   def tableView_writeRowsWithIndexes_toPasteboard_(self, tv,  
rowIndexes, pboard):
     typesArray = [MovedRowsType]
     data = NSKeyedArchiver.archivedDataWithRootObject_(rowIndexes)
     pboard.declareTypes_owner_(typesArray, self)
     #pboard.setData_forType_(typesArray, self)
     NSLog("boo-yeah")
     return YES

   def tableView_validateDrop_proposedRow_proposedDropOperation_(self,  
tv, info, row, op):
     dragOp =  NSDragOperationMove
     tv.setDropRow_dropOperation_(row, NSTableViewDropAbove)
     return dragOp

   def tableView_acceptDrop_row_dropOperation_(self, tv, info, row, op):
     if row < 0:
       row = 0

     if info.draggingSource() == self.tableView:
       rows =  
info.draggingPasteboard().propertyListForType_(MovedRowsType)
       indexSet = self.indexSetFromRows_(rows)
       self.moveObjectsInArrangedObjectsFromIndexes_toIndex_(indexSet,  
row)

       rowsAbove = self.rowsAboveRow_inIndexSet_(row, indexSet)
       aRange = NSMakeRange(row - rowsAbove, indexSet.count())
       indexSet = NSIndexSet.indexSetWithIndexesInRange_(aRange)
       self.arrayController.setSelectionIndexes_(indexSet)
       return YES
     return NO

   def moveObjectsInArrangedObjectsFromIndexes_toIndex_(self,  
indexSet, insertIndex):
     objects = self.arrayController.arrangedObjects()
     index = indexSet.lastIndex()
     aboveInsertIndexCount = 0
     removeIndex = 0
     while index != NSNotFound:
       if index >= insertIndex:
         removeIndex = index + aboveInsertIndexCount
         aboveInsertIndexCount += 1
       else:
         removeIndex = index
         insertIndex -= 1
       obj = objects.objectAtIndex_(removeIndex)
        
self.arrayController.removeObjectAtArrangedObjectIndex_(removeIndex)
       self.arrayController.insertObject_atArrangedObjectIndex_(obj,  
insertIndex)
       index = indexSet.indexLessThanIndex_(index)

   def indexSetFromRows_(self, rows):
     indexSet = NSMutableIndexSet.indexSet()
     for row in rows:
       indexSet.addIndex_(row)
     return indexSet

   def rowsAboveRow_inIndexSet_(self, row, indexSet):
     currentIndex = indexSet.firstIndex()
     i = 0
     while currentIndex != NSNotFound:
       if currentIndex < row:
         i += 1
     currentIndex = indexSet.indexGreaterThanIndex_(currentIndex)
     return i