[wxPython] Sample code using drag & Drop with a tree

[Raul Cota]

Hi,
Anyone has a piece of sample code using drag and drop with a wxTreeCtrl?

I thought it was pretty sraight forward, following analogous code for
images, but I can't get it to work.
I'm having troubles using wxDragTreeItem

Thanks a lot,

Raul Cota

[Robin Dunn]

> Anyone has a piece of sample code using drag and drop with a wxTreeCtrl?
>
> I thought it was pretty sraight forward, following analogous code for
> images, but I can't get it to work.
> I'm having troubles using wxDragTreeItem

I havn't tried it yet, but there is some sample C++ code in
wxWindows/samples/treectrl that does it. Here's the relevant parts:

EVT_TREE_BEGIN_DRAG(TreeTest_Ctrl, MyTreeCtrl::OnBeginDrag)
EVT_TREE_BEGIN_RDRAG(TreeTest_Ctrl, MyTreeCtrl::OnBeginRDrag)

void MyTreeCtrl::OnBeginDrag(wxTreeEvent& event)
{
// need to explicitly allow drag
if ( event.GetItem() != GetRootItem() )
{
m_draggedItem = event.GetItem();

wxLogMessage("OnBeginDrag: started dragging %s",
GetItemText(m_draggedItem).c_str());

event.Allow();
}
else
{
wxLogMessage("OnBeginDrag: this item can't be dragged.");
}
}

void MyTreeCtrl::OnEndDrag(wxTreeEvent& event)
{
wxTreeItemId itemSrc = m_draggedItem,
itemDst = event.GetItem();
m_draggedItem = (wxTreeItemId)0l;

// where to copy the item?
if ( itemDst.IsOk() && !ItemHasChildren(itemDst) )
{
// copy to the parent then
itemDst = GetParent(itemDst);
}

if ( !itemDst.IsOk() )
{
wxLogMessage("OnEndDrag: can't drop here.");

return;
}

wxString text = GetItemText(itemSrc);
wxLogMessage("OnEndDrag: '%s' copied to '%s'.",
text.c_str(), GetItemText(itemDst).c_str());

// just do append here - we could also insert it just before/after the
item
// on which it was dropped, but this requires slightly more work... we
also
// completely ignore the client data and icon of the old item but could
// copy them as well.
//
// Finally, we only copy one item here but we might copy the entire tree
if
// we were dragging a folder.
int image = wxGetApp().ShowImages() ? TreeCtrlIcon_File : -1;
AppendItem(itemDst, text, image);
}

[Niki Spahiev]

Hello Raul,

Tuesday, June 19, 2001, 11:15:34 PM, you wrote:

RC> Hi,
RC> Anyone has a piece of sample code using drag and drop with a wxTreeCtrl?

RC> I thought it was pretty sraight forward, following analogous code for
RC> images, but I can't get it to work.
RC> I'm having troubles using wxDragTreeItem

RC> Thanks a lot,

RC> Raul Cota

Look at XMLtreeview in demo. Ignore XML stuff and rest is what you
want.

--
regards,
Niki Spahiev

[Rene Freund]

hi,
i test your sample, because i use a
treectrl by myself, and now
wanna do the same thing like you.
Lucky, that you send this example.
i just started coding.

But what i have noticed is, when you
dragging an item on himself the item
it will be deleted. Should that be normal?

i hope i can use some parts of your code.

bye, reen

----
Rene Freund nur ein toter bug ist ein guter bug
re...@meder.de

[DirkK]

# Drag and Drop contributed by Sam Anderson, reposted by Dirk Krause

import string

from wxPython.wx import *
from xml.parsers import expat

try:
    wxEVT_COMMAND_TREE_END_DRAG
except NameError:
    # These got left out of 2.2.5, add them manually...
    wxEVT_COMMAND_TREE_END_DRAG = 10617
    def EVT_TREE_END_DRAG(win, id, func):
        win.Connect(id, -1, wxEVT_COMMAND_TREE_END_DRAG, func)

__title__ = 'wxTreeCtrl DragNDrop Test'

# dummy xml file
xml='''<?xml version="1.0" encoding="UTF-8"?>
<Test title="Channels">
 <Channels title="Favourites">
  <Channel type="channel" title="Slashdot" uri="http://slashdot.org"/>
 </Channels>
 <Channels title="News">
  <Channel title="CNN" uri="http://cnn.com"/>
  <Channel title="BBC" uri="http://bbc.co.uk"/>
  <Channel title="The Economist" uri="http://economist.com"/>
  <Channel title="MSNB" uri="http://msnbc.com"/>
 </Channels>
 <Channels title="Sports">
  <Channel type="channel" title="ESPN" uri="http://espn.com"/>
 </Channels>
 <Trash title="Trash"/>
</Test>'''

class TestApp(wxApp):

    def OnInit(self):

        # create navigation frame
        frame = NavFrame(NULL, -1, __title__)
        tree = frame.tree

        # expand a few nodes
        # NOTE: I know this is pathetic but I couldn't figure out how
        # to walk through and expand all nodes
        root = tree.nodeStack[0]
        child, cookie = tree.GetFirstChild(root, 0)
        nchild, cookie = tree.GetFirstChild(child, 0)
        tree.Expand(root)
        tree.Expand(child)
        tree.Expand(nchild)

        # display navigation frame
        frame.Show(true)
        self.SetTopWindow(frame)
        return true

class NavFrame(wxFrame):

    def __init__(self, parent, ID, title):
        wxFrame.__init__(self, parent, ID, title,
           wxDefaultPosition,
           wxSize(270,500))

        # give the tree a unique id
        tID = NewId()

        # call the tree
        self.tree = XMLTree(self, tID, wxDefaultPosition, wxSize(270,490),
             wxTR_HAS_BUTTONS)# | wxTR_EDIT_LABELS)

        # Trees need an image list to do DnD...
        self.tree.SetImageList(self.MakeImageList())

        # Load XML into tree
        self.tree.LoadXML()

        #-------------Drag-N-Drop Event Handlers
        EVT_TREE_BEGIN_DRAG(self.tree, tID, self.OnBeginDrag)
        EVT_TREE_END_DRAG(self.tree, tID, self.OnEndDrag)

        # other events
        EVT_CLOSE(self, self.OnCloseWindow)

    def OnBeginDrag(self, event):
        item = event.GetItem()
        if item != self.tree.GetRootItem():
            self.draggingItem = item
            event.Allow()

    def OnEndDrag(self, evt):
        itemSrc = self.draggingItem
        itemDst = evt.GetItem()
        self.draggingItem = None

        if not itemDst.IsOk():
            print "Can't drag to here..."
            return

        text = self.tree.GetItemText(itemSrc)
        self.tree.AppendItem(itemDst, text)
        self.tree.Delete(itemSrc)

    def OnCloseWindow(self, event):
        self.Destroy()

    def MakeImageList(self):
        il = wxImageList(16, 16)
        bmp = wxBitmap("icon1.bmp", wxBITMAP_TYPE_BMP)
        il.Add(bmp)
        self.il = il
        return il

class XMLTree(wxTreeCtrl):

    def __init__(self, parent, id, pos, size, style):
        wxTreeCtrl.__init__(self, parent, id, pos, size, style)

        # create nodeStack and add root node
        self.nodeStack = [self.AddRoot("My InfoSpace")]

    def StartElement(self, name, attrs ):
        name = name.encode()

        id = self.AppendItem(self.nodeStack[-1], name)

        # for each element map xml attributes to an associated dictionary
        self.SetPyData(id, attrs)

        # set title of tree node based on element title attribute
        if attrs.has_key('title'):
            title = attrs['title']
            self.SetItemText(id, str(title))

        # add element to tree
        self.nodeStack.append(id)

    def EndElement(self,  name ):
        self.nodeStack = self.nodeStack[:-1]

    def CharacterData(self, data ):
        if string.strip(data):
            data = data.encode()
            self.AppendItem(self.nodeStack[-1], data)

    def LoadXML(self):
        Parser = expat.ParserCreate()

        Parser.StartElementHandler = self.StartElement
        Parser.EndElementHandler = self.EndElement
        Parser.CharacterDataHandler = self.CharacterData

        ParserStatus = Parser.Parse(xml, 1)

if __name__ == '__main__':
    app = TestApp(0)
    app.MainLoop()

Dirk Krause

[Raul Cota]

Beautiful!!!!

I didn't know that I must set an image list (wxImageList) to do Drag and
Drop (even though in my case I pass it with no bitmaps)

I just uncommented out A LOT of code
Thanks a lot