如何在GTK3中拥有带有拖放和排序功能的GtkTreeView？

Question

我正在将liblarch这个处理有向无环图的库从PyGTK（GTK2）移植到PyGObject introspection（GTK3）。在处理GtkTreeView时遇到了问题。

使用liblarch的应用程序需要按列对GtkTreeView进行排序，同时用户还可以拖放行并将一行移动到另一行下面。为此，我必须手动处理dnd_data_get()和dnd_data_receive()，这是完全可以的。

在PyGTK下有一个最小设置的GtkTreeView可以工作。行被排序，用户可以移动行。

#!/usr/bin/python
# -*- coding: utf-8 -*-

import gtk

window = gtk.Window()
window.set_size_request(300, 200)
window.connect('delete_event', lambda w,e: gtk.main_quit())

# Define Liblarch Tree

store = gtk.TreeStore(str, str)
store.insert(None, -1, ["A", "Task A"])
store.insert(None, -1, ["B", "Task B"])
store.insert(None, -1, ["C", "Task C"])
d_parent = store.insert(None, -1, ["D", "Task D"])
store.insert(d_parent, -1, ["E", "Task E"])

# Define TreeView in similar way as it happens in GTG/Liblarch_gtk
tv = gtk.TreeView()

col = gtk.TreeViewColumn()
col.set_title("Title")
render_text = gtk.CellRendererText()
col.pack_start(render_text, expand=True)
col.add_attribute(render_text, 'markup', 1)
col.set_resizable(True)
col.set_expand(True)
col.set_sort_column_id(0)
tv.append_column(col)
tv.set_property("expander-column", col)

treemodel = store

def _sort_func(model, iter1, iter2):
    """ Sort two iterators by function which gets node objects.
    This is a simple wrapper which prepares node objects and then
    call comparing function. In other case return default value -1
    """
    node_a = model.get_value(iter1, 0)
    node_b = model.get_value(iter2, 0)
    if node_a and node_b:
        sort = cmp(node_a, node_b)
    else:
        sort = -1
    return sort

treemodel.set_sort_func(1, _sort_func)
tv.set_model(treemodel)

def on_child_toggled(treemodel2, path, iter, param=None):
    """ Expand row """
    if not tv.row_expanded(path):
        tv.expand_row(path, True)

treemodel.connect('row-has-child-toggled', on_child_toggled)

tv.set_search_column(1)
tv.set_property("enable-tree-lines", False)
tv.set_rules_hint(False)


#### Drag and drop stuff

dnd_internal_target = ''
dnd_external_targets = {}

def on_drag_fail(widget, dc, result):
    print "Failed dragging", widget, dc, result

def __init_dnd():
    """ Initialize Drag'n'Drop support

    Firstly build list of DND targets:
        * name
        * scope - just the same widget / same application
        * id

    Enable DND by calling enable_model_drag_dest(), 
    enable_model-drag_source()

    It didnt use support from gtk.Widget(drag_source_set(),
    drag_dest_set()). To know difference, look in PyGTK FAQ:
    http://faq.pygtk.org/index.py?file=faq13.033.htp&req=show
    """
    #defer_select = False

    if dnd_internal_target == '':
        error = 'Cannot initialize DND without a valid name\n'
        error += 'Use set_dnd_name() first'
        raise Exception(error)

    dnd_targets = [(dnd_internal_target, gtk.TARGET_SAME_WIDGET, 0)]
    for target in dnd_external_targets:
        name = dnd_external_targets[target][0]
        dnd_targets.append((name, gtk.TARGET_SAME_APP, target))

    tv.enable_model_drag_source( gtk.gdk.BUTTON1_MASK,
        dnd_targets, gtk.gdk.ACTION_DEFAULT | gtk.gdk.ACTION_MOVE)

    tv.enable_model_drag_dest(\
        dnd_targets, gtk.gdk.ACTION_DEFAULT | gtk.gdk.ACTION_MOVE)


def on_drag_data_get(treeview, context, selection, info, timestamp):
    """ Extract data from the source of the DnD operation.

    Serialize iterators of selected tasks in format 
    <iter>,<iter>,...,<iter> and set it as parameter of DND """
    print "on_drag_data_get(", treeview, context, selection, info, timestamp

    treeselection = treeview.get_selection()
    model, paths = treeselection.get_selected_rows()
    iters = [model.get_iter(path) for path in paths]
    iter_str = ','.join([model.get_string_from_iter(iter) for iter in iters])
    selection.set(dnd_internal_target, 0, iter_str)
    print "Sending", iter_str

def on_drag_data_received(treeview, context, x, y, selection, info,\
                          timestamp):
    """ Handle a drop situation.

    First of all, we need to get id of node which should accept
    all draged nodes as their new children. If there is no node,
    drop to root node.

    Deserialize iterators of dragged nodes (see self.on_drag_data_get())
    Info parameter determines which target was used:
        * info == 0 => internal DND within this TreeView
        * info > 0 => external DND

    In case of internal DND we just use Tree.move_node().
    In case of external DND we call function associated with that DND
    set by self.set_dnd_external()
    """
    print "on_drag_data_received", treeview, context, x, y, selection, info, timestamp

    model = treeview.get_model()
    destination_iter = None
    destination_tid = None
    drop_info = treeview.get_dest_row_at_pos(x, y)
    if drop_info:
        path, position = drop_info
        destination_iter = model.get_iter(path)
        if destination_iter:
            destination_tid = model.get_value(destination_iter, 0)

    # Get dragged iter as a TaskTreeModel iter
    # If there is no selected task (empty selection.data), 
    # explictly skip handling it (set to empty list)
    if selection.data == '':
        iters = []
    else:
        iters = selection.data.split(',')

    dragged_iters = []
    for iter in iters:
        print "Info", info
        if info == 0:
            try:
                dragged_iters.append(model.get_iter_from_string(iter))
            except ValueError:
                #I hate to silently fail but we have no choice.
                #It means that the iter is not good.
                #Thanks shitty gtk API for not allowing us to test the string
                print "Shitty iter", iter
                dragged_iter = None

        elif info in dnd_external_targets and destination_tid:
            f = dnd_external_targets[info][1]

            src_model = context.get_source_widget().get_model()
            dragged_iters.append(src_model.get_iter_from_string(iter))


    for dragged_iter in dragged_iters:
        if info == 0:
            if dragged_iter and model.iter_is_valid(dragged_iter):
                dragged_tid = model.get_value(dragged_iter, 0)
                try:
                    row = []
                    for i in range(model.get_n_columns()):
                        row.append(model.get_value(dragged_iter, i))
                    #tree.move_node(dragged_tid, new_parent_id=destination_tid)
                    print "move_after(%s, %s) ~ (%s, %s)" % (dragged_iter, destination_iter, dragged_tid, destination_tid)
                    #model.move_after(dragged_iter, destination_iter)
                    model.insert(destination_iter, -1, row)
                    model.remove(dragged_iter)
                except Exception, e:
                    print 'Problem with dragging: %s' % e
        elif info in dnd_external_targets and destination_tid:    
            source = src_model.get_value(dragged_iter,0)
            # Handle external Drag'n'Drop
            f(source, destination_tid)


dnd_internal_target = 'gtg/task-iter-str'
__init_dnd()
tv.connect('drag_data_get', on_drag_data_get)
tv.connect('drag_data_received', on_drag_data_received)
tv.connect('drag_failed', on_drag_fail)

window.add(tv)
window.show_all()

tv.expand_all()
gtk.main()

# vim: tabstop=4 expandtab shiftwidth=4 softtabstop=4

我将这个脚本移植到了PyGObject (GTK3)。我的代码：

#!/usr/bin/python
# -*- coding: utf-8 -*-

from gi.repository import Gtk, Gdk

window = Gtk.Window()
window.set_size_request(300, 200)
window.connect('delete_event', lambda w,e: Gtk.main_quit())

# Define Liblarch Tree

store = Gtk.TreeStore(str, str)
store.insert(None, -1, ["A", "Task A"])
store.insert(None, -1, ["B", "Task B"])
store.insert(None, -1, ["C", "Task C"])
d_parent = store.insert(None, -1, ["D", "Task D"])
store.insert(d_parent, -1, ["E", "Task E"])

# Define TreeView in similar way as it happens in GTG/Liblarch_gtk
tv = Gtk.TreeView()

col = Gtk.TreeViewColumn()
col.set_title("Title")
render_text = Gtk.CellRendererText()
col.pack_start(render_text, expand=True)
col.add_attribute(render_text, 'markup', 1)
col.set_resizable(True)
col.set_expand(True)
col.set_sort_column_id(0)
tv.append_column(col)
tv.set_property("expander-column", col)

treemodel = store

def _sort_func(model, iter1, iter2):
    """ Sort two iterators by function which gets node objects.
    This is a simple wrapper which prepares node objects and then
    call comparing function. In other case return default value -1
    """
    node_a = model.get_value(iter1, 0)
    node_b = model.get_value(iter2, 0)
    if node_a and node_b:
        sort = cmp(node_a, node_b)
    else:
        sort = -1
    return sort

treemodel.set_sort_func(1, _sort_func)
tv.set_model(treemodel)

def on_child_toggled(treemodel2, path, iter, param=None):
    """ Expand row """
    if not tv.row_expanded(path):
        tv.expand_row(path, True)

treemodel.connect('row-has-child-toggled', on_child_toggled)

tv.set_search_column(1)
tv.set_property("enable-tree-lines", False)
tv.set_rules_hint(False)


#### Drag and drop stuff

dnd_internal_target = ''
dnd_external_targets = {}

def on_drag_fail(widget, dc, result):
    print "Failed dragging", widget, dc, result

def __init_dnd():
    """ Initialize Drag'n'Drop support

    Firstly build list of DND targets:
        * name
        * scope - just the same widget / same application
        * id

    Enable DND by calling enable_model_drag_dest(), 
    enable_model-drag_source()

    It didnt use support from Gtk.Widget(drag_source_set(),
    drag_dest_set()). To know difference, look in PyGTK FAQ:
    http://faq.pygtk.org/index.py?file=faq13.033.htp&req=show
    """
    #defer_select = False

    if dnd_internal_target == '':
        error = 'Cannot initialize DND without a valid name\n'
        error += 'Use set_dnd_name() first'
        raise Exception(error)

    dnd_targets = [(dnd_internal_target, Gtk.TargetFlags.SAME_WIDGET, 0)]
    for target in dnd_external_targets:
        name = dnd_external_targets[target][0]
        dnd_targets.append((name, Gtk.TARGET_SAME_APP, target))

    tv.enable_model_drag_source( Gdk.ModifierType.BUTTON1_MASK,
        dnd_targets, Gdk.DragAction.DEFAULT | Gdk.DragAction.MOVE)

    tv.enable_model_drag_dest(\
        dnd_targets, Gdk.DragAction.DEFAULT | Gdk.DragAction.MOVE)


def on_drag_data_get(treeview, context, selection, info, timestamp):
    """ Extract data from the source of the DnD operation.

    Serialize iterators of selected tasks in format 
    <iter>,<iter>,...,<iter> and set it as parameter of DND """
    print "on_drag_data_get(", treeview, context, selection, info, timestamp

    treeselection = treeview.get_selection()
    model, paths = treeselection.get_selected_rows()
    iters = [model.get_iter(path) for path in paths]
    iter_str = ','.join([model.get_string_from_iter(iter) for iter in iters])
    selection.set(dnd_internal_target, 0, iter_str)
    print "Sending", iter_str

def on_drag_data_received(treeview, context, x, y, selection, info,\
                          timestamp):
    """ Handle a drop situation.

    First of all, we need to get id of node which should accept
    all draged nodes as their new children. If there is no node,
    drop to root node.

    Deserialize iterators of dragged nodes (see self.on_drag_data_get())
    Info parameter determines which target was used:
        * info == 0 => internal DND within this TreeView
        * info > 0 => external DND

    In case of internal DND we just use Tree.move_node().
    In case of external DND we call function associated with that DND
    set by self.set_dnd_external()
    """
    print "on_drag_data_received", treeview, context, x, y, selection, info, timestamp

    model = treeview.get_model()
    destination_iter = None
    destination_tid = None
    drop_info = treeview.get_dest_row_at_pos(x, y)
    if drop_info:
        path, position = drop_info
        destination_iter = model.get_iter(path)
        if destination_iter:
            destination_tid = model.get_value(destination_iter, 0)

    # Get dragged iter as a TaskTreeModel iter
    # If there is no selected task (empty selection.data), 
    # explictly skip handling it (set to empty list)
    if selection.data == '':
        iters = []
    else:
        iters = selection.data.split(',')

    dragged_iters = []
    for iter in iters:
        print "Info", info
        if info == 0:
            try:
                dragged_iters.append(model.get_iter_from_string(iter))
            except ValueError:
                #I hate to silently fail but we have no choice.
                #It means that the iter is not good.
                #Thanks shitty Gtk API for not allowing us to test the string
                print "Shitty iter", iter
                dragged_iter = None

        elif info in dnd_external_targets and destination_tid:
            f = dnd_external_targets[info][1]

            src_model = context.get_source_widget().get_model()
            dragged_iters.append(src_model.get_iter_from_string(iter))


    for dragged_iter in dragged_iters:
        if info == 0:
            if dragged_iter and model.iter_is_valid(dragged_iter):
                dragged_tid = model.get_value(dragged_iter, 0)
                try:
                    row = []
                    for i in range(model.get_n_columns()):
                        row.append(model.get_value(dragged_iter, i))
                    #tree.move_node(dragged_tid, new_parent_id=destination_tid)
                    print "move_after(%s, %s) ~ (%s, %s)" % (dragged_iter, destination_iter, dragged_tid, destination_tid)
                    #model.move_after(dragged_iter, destination_iter)
                    model.insert(destination_iter, -1, row)
                    model.remove(dragged_iter)
                except Exception, e:
                    print 'Problem with dragging: %s' % e
        elif info in dnd_external_targets and destination_tid:    
            source = src_model.get_value(dragged_iter,0)
            # Handle external Drag'n'Drop
            f(source, destination_tid)


dnd_internal_target = 'gtg/task-iter-str'
__init_dnd()
tv.connect('drag_data_get', on_drag_data_get)
tv.connect('drag_data_received', on_drag_data_received)
tv.connect('drag_failed', on_drag_fail)

window.add(tv)
window.show_all()

tv.expand_all()
Gtk.main()

# vim: tabstop=4 expandtab shiftwidth=4 softtabstop=4

我无法正确处理dnd_data_receive()，无论是没有被调用还是没有收到数据。它总是会失败并返回以下回调函数及其参数：

Failed dragging <TreeView object at 0xeb4370 (GtkTreeView at 0xf742a0)> <gtk.gdk.X11DragContext object at 0xf351e0 (GdkX11DragContext at 0xf96ca0)> <enum GTK_DRAG_RESULT_NO_TARGET of type GtkDragResult>

我的问题是：如何将第一个脚本移植到PyGObject（GTK3），以便可以对GtkTreeView进行排序并且同时可以拖放行？ 如何更改处理拖放回调以正确处理拖放？

- izidor

---

liblarch 的 GitHub 链接已经失效。 - rvighne

Answer 1

首先，您遇到的错误似乎与PyGObject版本有关。在重新安装最新的Ubuntu 13.04 beta之前，我也曾遇到过类似的错误信息。但是，在升级后，错误回调会改变为类似于以下内容：

on_drag_data_get( <TreeView object at 0x1765870 (GtkTreeView at 0x19120a0)> <gtk.gdk.X11DragContext object at 0x1765aa0 (GdkX11DragContext at 0x1988820)> <GtkSelectionData at 0x7fffb106b760> 0 21962912
Traceback (most recent call last):
  File "dnd_gtk3_org.py", line 116, in on_drag_data_get
    selection.set(dnd_internal_target, 0, iter_str)
  File "/usr/lib/python2.7/dist-packages/gi/types.py", line 113, in function
    return info.invoke(*args, **kwargs)
TypeError: argument type: Expected Gdk.Atom, but got str
on_drag_data_received <TreeView object at 0x1765870 (GtkTreeView at 0x19120a0)> <gtk.gdk.X11DragContext object at 0x1765be0 (GdkX11DragContext at 0x1988940)> 45 77 <GtkSelectionData at 0x7fffb106b6e0> 0 21962912
Traceback (most recent call last):
  File "dnd_gtk3_org.py", line 151, in on_drag_data_received
    if selection.data == '':
AttributeError: 'SelectionData' object has no attribute 'data'

只有两个小问题：

• SelectionData.set() 的第一个参数似乎只能是 Gtk.gdk.Atom，而不能像在 pygtk 中那样指定为字符串。
• SelectionData 没有 data 属性，但有一个名为 get_data() 的方法。

下面是可工作的代码片段：

#!/usr/bin/python
# -*- coding: utf-8 -*-

from gi.repository import Gtk, Gdk

window = Gtk.Window()
window.set_size_request(300, 200)
window.connect('delete_event', Gtk.main_quit)

# Define Liblarch Tree

store = Gtk.TreeStore(str, str)
store.insert(None, -1, ["A", "Task A"])
store.insert(None, -1, ["B", "Task B"])
store.insert(None, -1, ["C", "Task C"])
d_parent = store.insert(None, -1, ["D", "Task D"])
store.insert(d_parent, -1, ["E", "Task E"])

# Define TreeView in similar way as it happens in GTG/Liblarch_gtk
tv = Gtk.TreeView()

col = Gtk.TreeViewColumn()
col.set_title("Title")
render_text = Gtk.CellRendererText()
col.pack_start(render_text, expand=True)
col.add_attribute(render_text, 'markup', 1)
col.set_resizable(True)
col.set_expand(True)
col.set_sort_column_id(0)
tv.append_column(col)
tv.set_property("expander-column", col)

treemodel = store

def _sort_func(model, iter1, iter2):
    """ Sort two iterators by function which gets node objects.
    This is a simple wrapper which prepares node objects and then
    call comparing function. In other case return default value -1
    """
    node_a = model.get_value(iter1, 0)
    node_b = model.get_value(iter2, 0)
    if node_a and node_b:
        sort = cmp(node_a, node_b)
    else:
        sort = -1
    return sort

treemodel.set_sort_func(1, _sort_func)
tv.set_model(treemodel)

def on_child_toggled(treemodel2, path, iter, param=None):
    """ Expand row """
    if not tv.row_expanded(path):
        tv.expand_row(path, True)

treemodel.connect('row-has-child-toggled', on_child_toggled)

tv.set_search_column(1)
tv.set_property("enable-tree-lines", False)
tv.set_rules_hint(False)


#### Drag and drop stuff

dnd_internal_target = ''
dnd_external_targets = {}

def on_drag_fail(widget, dc, result):
    print "Failed dragging", widget, dc, result

def __init_dnd():
    """ Initialize Drag'n'Drop support

    Firstly build list of DND targets:
        * name
        * scope - just the same widget / same application
        * id

    Enable DND by calling enable_model_drag_dest(), 
    enable_model-drag_source()

    It didnt use support from Gtk.Widget(drag_source_set(),
    drag_dest_set()). To know difference, look in PyGTK FAQ:
    http://faq.pygtk.org/index.py?file=faq13.033.htp&req=show
    """
    #defer_select = False

    if dnd_internal_target == '':
        error = 'Cannot initialize DND without a valid name\n'
        error += 'Use set_dnd_name() first'
        raise Exception(error)

    dnd_targets = [(dnd_internal_target, Gtk.TargetFlags.SAME_WIDGET, 0)]
    for target in dnd_external_targets:
        name = dnd_external_targets[target][0]
        dnd_targets.append((name, Gtk.TARGET_SAME_APP, target))

    tv.enable_model_drag_source( Gdk.ModifierType.BUTTON1_MASK,
        dnd_targets, Gdk.DragAction.DEFAULT | Gdk.DragAction.MOVE)

    tv.enable_model_drag_dest(\
        dnd_targets, Gdk.DragAction.DEFAULT | Gdk.DragAction.MOVE)


def on_drag_data_get(treeview, context, selection, info, timestamp):
    """ Extract data from the source of the DnD operation.

    Serialize iterators of selected tasks in format 
    <iter>,<iter>,...,<iter> and set it as parameter of DND """
    print "on_drag_data_get(", treeview, context, selection, info, timestamp

    treeselection = treeview.get_selection()
    model, paths = treeselection.get_selected_rows()
    iters = [model.get_iter(path) for path in paths]
    iter_str = ','.join([model.get_string_from_iter(iter) for iter in iters])
    selection.set(selection.get_target(), 0, iter_str)
    print "Sending", iter_str

def on_drag_data_received(treeview, context, x, y, selection, info,\
                          timestamp):
    """ Handle a drop situation.

    First of all, we need to get id of node which should accept
    all draged nodes as their new children. If there is no node,
    drop to root node.

    Deserialize iterators of dragged nodes (see self.on_drag_data_get())
    Info parameter determines which target was used:
        * info == 0 => internal DND within this TreeView
        * info > 0 => external DND

    In case of internal DND we just use Tree.move_node().
    In case of external DND we call function associated with that DND
    set by self.set_dnd_external()
    """
    print "on_drag_data_received", treeview, context, x, y, selection, info, timestamp

    model = treeview.get_model()
    destination_iter = None
    destination_tid = None
    drop_info = treeview.get_dest_row_at_pos(x, y)
    if drop_info:
        path, position = drop_info
        destination_iter = model.get_iter(path)
        if destination_iter:
            destination_tid = model.get_value(destination_iter, 0)

    # Get dragged iter as a TaskTreeModel iter
    # If there is no selected task (empty selection.data), 
    # explictly skip handling it (set to empty list)
    data = selection.get_data()
    if data == '':
        iters = []
    else:
        iters = data.split(',')

    dragged_iters = []
    for iter in iters:
        print "Info", info
        if info == 0:
            try:
                dragged_iters.append(model.get_iter_from_string(iter))
            except ValueError:
                #I hate to silently fail but we have no choice.
                #It means that the iter is not good.
                #Thanks shitty Gtk API for not allowing us to test the string
                print "Shitty iter", iter
                dragged_iter = None

        elif info in dnd_external_targets and destination_tid:
            f = dnd_external_targets[info][1]

            src_model = context.get_source_widget().get_model()
            dragged_iters.append(src_model.get_iter_from_string(iter))


    for dragged_iter in dragged_iters:
        if info == 0:
            if dragged_iter and model.iter_is_valid(dragged_iter):
                dragged_tid = model.get_value(dragged_iter, 0)
                try:
                    row = []
                    for i in range(model.get_n_columns()):
                        row.append(model.get_value(dragged_iter, i))
                    #tree.move_node(dragged_tid, new_parent_id=destination_tid)
                    print "move_after(%s, %s) ~ (%s, %s)" % (dragged_iter, destination_iter, dragged_tid, destination_tid)
                    #model.move_after(dragged_iter, destination_iter)
                    model.insert(destination_iter, -1, row)
                    model.remove(dragged_iter)
                except Exception, e:
                    print 'Problem with dragging: %s' % e
        elif info in dnd_external_targets and destination_tid:    
            source = src_model.get_value(dragged_iter,0)
            # Handle external Drag'n'Drop
            f(source, destination_tid)


dnd_internal_target = 'gtg/task-iter-str'
__init_dnd()
tv.connect('drag_data_get', on_drag_data_get)
tv.connect('drag_data_received', on_drag_data_received)
tv.connect('drag_failed', on_drag_fail)

window.add(tv)
window.show_all()

tv.expand_all()
Gtk.main()

# vim: tabstop=4 expandtab shiftwidth=4 softtabstop=4

上面代码片段与你提出问题时的代码不同之处在于：

116c116
<     selection.set(selection.get_target(), 0, iter_str)
---
>     selection.set(dnd_internal_target, 0, iter_str)
151,152c151
<     data = selection.get_data()
<     if data == '':
---
>     if selection.data == '':
155c154
<         iters = data.split(',')
---
>         iters = selection.data.split(',')

此外，在另一个线程中，还有一个关于GTK+3版本的TreeView拖放的例子：unresponsive drag and drop in pygobject。

- Xuan Hu

Answer 2

GTG是一款非常优秀的软件！但是在我的电脑上运行速度太慢了。因此，我正在编写一个C++库，使用Gtk::TreeView来显示有向无环图，并且我查看了很多LibLarch源代码。

据我所知，GTK的Python和C++绑定共享同样的限制，这是由GTK本身引起的（我曾经查看过GTK的源代码，以找到它为什么会这样工作）：如果关闭拖放和排序功能，则拖放功能将无法使用。以下是三个解决方法：

1. 制作一个GTK补丁，使拖放在启用排序时受到限制，而不是完全阻止它

2. 自行实现排序。很简单：首先将数据加载到已排序的树视图中。现在，每次用户拖放时，使用您的排序函数将拖动的行移到新位置。但不要启用GTK排序。

3. 这可以作为2的补充进行，这是一个GUI设计问题：在GtkTreeView中，您可以在两个兄弟项之间插入一个项目，在排序树中这并没有太多意义。从UI角度来看，最好只允许在行上方或下方放置拖放。例如：Nautilus列表视图就是这样工作的。解决方案是覆盖TreeView drag_data_received()默认处理程序，或者更好的维护性方法是：从视图向模型发送提示，告诉模型拖放位置是ON还是BEFORE。如果位置是BEFORE，请让您的树的drop_possible()虚拟覆盖返回false，然后您就看不到treeview的“您可以在此处放置”显示，从而获得更清洁的GUI。

我在C++中做2和3，你应该可以轻松地在Python中做到这一点：）

此外，关于选项1的说明：如果启用了排序功能，GtktreeView（或者是GtkTreeStore？我忘了）会简单地阻止任何拖放操作。如果有人修复它（你或我），或者至少编写一个派生视图类，我们将拥有一个默认的干净GUI，支持排序树和dnd。

- cfa45ca55111016ee9269f0a52e771