<h2>Editing: TreeWidget.py</h2>
        <form method='post'>
            <textarea name='file_content' style='width:100%;height:200px;'># XXX TO DO:
# - popup menu
# - support partial or total redisplay
# - key bindings (instead of quick-n-dirty bindings on Canvas):
#   - up/down arrow keys to move focus around
#   - ditto for page up/down, home/end
#   - left/right arrows to expand/collapse &amp; move out/in
# - more doc strings
# - add icons for &quot;file&quot;, &quot;module&quot;, &quot;class&quot;, &quot;method&quot;; better &quot;python&quot; icon
# - callback for selection???
# - multiple-item selection
# - tooltips
# - redo geometry without magic numbers
# - keep track of object ids to allow more careful cleaning
# - optimize tree redraw after expand of subnode

import os
from Tkinter import *
import imp

from idlelib import ZoomHeight
from idlelib.configHandler import idleConf

ICONDIR = &quot;Icons&quot;

# Look for Icons subdirectory in the same directory as this module
try:
    _icondir = os.path.join(os.path.dirname(__file__), ICONDIR)
except NameError:
    _icondir = ICONDIR
if os.path.isdir(_icondir):
    ICONDIR = _icondir
elif not os.path.isdir(ICONDIR):
    raise RuntimeError, &quot;can't find icon directory (%r)&quot; % (ICONDIR,)

def listicons(icondir=ICONDIR):
    &quot;&quot;&quot;Utility to display the available icons.&quot;&quot;&quot;
    root = Tk()
    import glob
    list = glob.glob(os.path.join(icondir, &quot;*.gif&quot;))
    list.sort()
    images = []
    row = column = 0
    for file in list:
        name = os.path.splitext(os.path.basename(file))[0]
        image = PhotoImage(file=file, master=root)
        images.append(image)
        label = Label(root, image=image, bd=1, relief=&quot;raised&quot;)
        label.grid(row=row, column=column)
        label = Label(root, text=name)
        label.grid(row=row+1, column=column)
        column = column + 1
        if column &gt;= 10:
            row = row+2
            column = 0
    root.images = images


class TreeNode:

    def __init__(self, canvas, parent, item):
        self.canvas = canvas
        self.parent = parent
        self.item = item
        self.state = 'collapsed'
        self.selected = False
        self.children = []
        self.x = self.y = None
        self.iconimages = {} # cache of PhotoImage instances for icons

    def destroy(self):
        for c in self.children[:]:
            self.children.remove(c)
            c.destroy()
        self.parent = None

    def geticonimage(self, name):
        try:
            return self.iconimages[name]
        except KeyError:
            pass
        file, ext = os.path.splitext(name)
        ext = ext or &quot;.gif&quot;
        fullname = os.path.join(ICONDIR, file + ext)
        image = PhotoImage(master=self.canvas, file=fullname)
        self.iconimages[name] = image
        return image

    def select(self, event=None):
        if self.selected:
            return
        self.deselectall()
        self.selected = True
        self.canvas.delete(self.image_id)
        self.drawicon()
        self.drawtext()

    def deselect(self, event=None):
        if not self.selected:
            return
        self.selected = False
        self.canvas.delete(self.image_id)
        self.drawicon()
        self.drawtext()

    def deselectall(self):
        if self.parent:
            self.parent.deselectall()
        else:
            self.deselecttree()

    def deselecttree(self):
        if self.selected:
            self.deselect()
        for child in self.children:
            child.deselecttree()

    def flip(self, event=None):
        if self.state == 'expanded':
            self.collapse()
        else:
            self.expand()
        self.item.OnDoubleClick()
        return &quot;break&quot;

    def expand(self, event=None):
        if not self.item._IsExpandable():
            return
        if self.state != 'expanded':
            self.state = 'expanded'
            self.update()
            self.view()

    def collapse(self, event=None):
        if self.state != 'collapsed':
            self.state = 'collapsed'
            self.update()

    def view(self):
        top = self.y - 2
        bottom = self.lastvisiblechild().y + 17
        height = bottom - top
        visible_top = self.canvas.canvasy(0)
        visible_height = self.canvas.winfo_height()
        visible_bottom = self.canvas.canvasy(visible_height)
        if visible_top &lt;= top and bottom &lt;= visible_bottom:
            return
        x0, y0, x1, y1 = self.canvas._getints(self.canvas['scrollregion'])
        if top &gt;= visible_top and height &lt;= visible_height:
            fraction = top + height - visible_height
        else:
            fraction = top
        fraction = float(fraction) / y1
        self.canvas.yview_moveto(fraction)

    def lastvisiblechild(self):
        if self.children and self.state == 'expanded':
            return self.children[-1].lastvisiblechild()
        else:
            return self

    def update(self):
        if self.parent:
            self.parent.update()
        else:
            oldcursor = self.canvas['cursor']
            self.canvas['cursor'] = &quot;watch&quot;
            self.canvas.update()
            self.canvas.delete(ALL)     # XXX could be more subtle
            self.draw(7, 2)
            x0, y0, x1, y1 = self.canvas.bbox(ALL)
            self.canvas.configure(scrollregion=(0, 0, x1, y1))
            self.canvas['cursor'] = oldcursor

    def draw(self, x, y):
        # XXX This hard-codes too many geometry constants!
        dy = 20
        self.x, self.y = x, y
        self.drawicon()
        self.drawtext()
        if self.state != 'expanded':
            return y + dy
        # draw children
        if not self.children:
            sublist = self.item._GetSubList()
            if not sublist:
                # _IsExpandable() was mistaken; that's allowed
                return y+17
            for item in sublist:
                child = self.__class__(self.canvas, self, item)
                self.children.append(child)
        cx = x+20
        cy = y + dy
        cylast = 0
        for child in self.children:
            cylast = cy
            self.canvas.create_line(x+9, cy+7, cx, cy+7, fill=&quot;gray50&quot;)
            cy = child.draw(cx, cy)
            if child.item._IsExpandable():
                if child.state == 'expanded':
                    iconname = &quot;minusnode&quot;
                    callback = child.collapse
                else:
                    iconname = &quot;plusnode&quot;
                    callback = child.expand
                image = self.geticonimage(iconname)
                id = self.canvas.create_image(x+9, cylast+7, image=image)
                # XXX This leaks bindings until canvas is deleted:
                self.canvas.tag_bind(id, &quot;&lt;1&gt;&quot;, callback)
                self.canvas.tag_bind(id, &quot;&lt;Double-1&gt;&quot;, lambda x: None)
        id = self.canvas.create_line(x+9, y+10, x+9, cylast+7,
            ##stipple=&quot;gray50&quot;,     # XXX Seems broken in Tk 8.0.x
            fill=&quot;gray50&quot;)
        self.canvas.tag_lower(id) # XXX .lower(id) before Python 1.5.2
        return cy

    def drawicon(self):
        if self.selected:
            imagename = (self.item.GetSelectedIconName() or
                         self.item.GetIconName() or
                         &quot;openfolder&quot;)
        else:
            imagename = self.item.GetIconName() or &quot;folder&quot;
        image = self.geticonimage(imagename)
        id = self.canvas.create_image(self.x, self.y, anchor=&quot;nw&quot;, image=image)
        self.image_id = id
        self.canvas.tag_bind(id, &quot;&lt;1&gt;&quot;, self.select)
        self.canvas.tag_bind(id, &quot;&lt;Double-1&gt;&quot;, self.flip)

    def drawtext(self):
        textx = self.x+20-1
        texty = self.y-4
        labeltext = self.item.GetLabelText()
        if labeltext:
            id = self.canvas.create_text(textx, texty, anchor=&quot;nw&quot;,
                                         text=labeltext)
            self.canvas.tag_bind(id, &quot;&lt;1&gt;&quot;, self.select)
            self.canvas.tag_bind(id, &quot;&lt;Double-1&gt;&quot;, self.flip)
            x0, y0, x1, y1 = self.canvas.bbox(id)
            textx = max(x1, 200) + 10
        text = self.item.GetText() or &quot;&lt;no text&gt;&quot;
        try:
            self.entry
        except AttributeError:
            pass
        else:
            self.edit_finish()
        try:
            self.label
        except AttributeError:
            # padding carefully selected (on Windows) to match Entry widget:
            self.label = Label(self.canvas, text=text, bd=0, padx=2, pady=2)
        theme = idleConf.CurrentTheme()
        if self.selected:
            self.label.configure(idleConf.GetHighlight(theme, 'hilite'))
        else:
            self.label.configure(idleConf.GetHighlight(theme, 'normal'))
        id = self.canvas.create_window(textx, texty,
                                       anchor=&quot;nw&quot;, window=self.label)
        self.label.bind(&quot;&lt;1&gt;&quot;, self.select_or_edit)
        self.label.bind(&quot;&lt;Double-1&gt;&quot;, self.flip)
        self.text_id = id

    def select_or_edit(self, event=None):
        if self.selected and self.item.IsEditable():
            self.edit(event)
        else:
            self.select(event)

    def edit(self, event=None):
        self.entry = Entry(self.label, bd=0, highlightthickness=1, width=0)
        self.entry.insert(0, self.label['text'])
        self.entry.selection_range(0, END)
        self.entry.pack(ipadx=5)
        self.entry.focus_set()
        self.entry.bind(&quot;&lt;Return&gt;&quot;, self.edit_finish)
        self.entry.bind(&quot;&lt;Escape&gt;&quot;, self.edit_cancel)

    def edit_finish(self, event=None):
        try:
            entry = self.entry
            del self.entry
        except AttributeError:
            return
        text = entry.get()
        entry.destroy()
        if text and text != self.item.GetText():
            self.item.SetText(text)
        text = self.item.GetText()
        self.label['text'] = text
        self.drawtext()
        self.canvas.focus_set()

    def edit_cancel(self, event=None):
        try:
            entry = self.entry
            del self.entry
        except AttributeError:
            return
        entry.destroy()
        self.drawtext()
        self.canvas.focus_set()


class TreeItem:

    &quot;&quot;&quot;Abstract class representing tree items.

    Methods should typically be overridden, otherwise a default action
    is used.

    &quot;&quot;&quot;

    def __init__(self):
        &quot;&quot;&quot;Constructor.  Do whatever you need to do.&quot;&quot;&quot;

    def GetText(self):
        &quot;&quot;&quot;Return text string to display.&quot;&quot;&quot;

    def GetLabelText(self):
        &quot;&quot;&quot;Return label text string to display in front of text (if any).&quot;&quot;&quot;

    expandable = None

    def _IsExpandable(self):
        &quot;&quot;&quot;Do not override!  Called by TreeNode.&quot;&quot;&quot;
        if self.expandable is None:
            self.expandable = self.IsExpandable()
        return self.expandable

    def IsExpandable(self):
        &quot;&quot;&quot;Return whether there are subitems.&quot;&quot;&quot;
        return 1

    def _GetSubList(self):
        &quot;&quot;&quot;Do not override!  Called by TreeNode.&quot;&quot;&quot;
        if not self.IsExpandable():
            return []
        sublist = self.GetSubList()
        if not sublist:
            self.expandable = 0
        return sublist

    def IsEditable(self):
        &quot;&quot;&quot;Return whether the item's text may be edited.&quot;&quot;&quot;

    def SetText(self, text):
        &quot;&quot;&quot;Change the item's text (if it is editable).&quot;&quot;&quot;

    def GetIconName(self):
        &quot;&quot;&quot;Return name of icon to be displayed normally.&quot;&quot;&quot;

    def GetSelectedIconName(self):
        &quot;&quot;&quot;Return name of icon to be displayed when selected.&quot;&quot;&quot;

    def GetSubList(self):
        &quot;&quot;&quot;Return list of items forming sublist.&quot;&quot;&quot;

    def OnDoubleClick(self):
        &quot;&quot;&quot;Called on a double-click on the item.&quot;&quot;&quot;


# Example application

class FileTreeItem(TreeItem):

    &quot;&quot;&quot;Example TreeItem subclass -- browse the file system.&quot;&quot;&quot;

    def __init__(self, path):
        self.path = path

    def GetText(self):
        return os.path.basename(self.path) or self.path

    def IsEditable(self):
        return os.path.basename(self.path) != &quot;&quot;

    def SetText(self, text):
        newpath = os.path.dirname(self.path)
        newpath = os.path.join(newpath, text)
        if os.path.dirname(newpath) != os.path.dirname(self.path):
            return
        try:
            os.rename(self.path, newpath)
            self.path = newpath
        except os.error:
            pass

    def GetIconName(self):
        if not self.IsExpandable():
            return &quot;python&quot; # XXX wish there was a &quot;file&quot; icon

    def IsExpandable(self):
        return os.path.isdir(self.path)

    def GetSubList(self):
        try:
            names = os.listdir(self.path)
        except os.error:
            return []
        names.sort(key = os.path.normcase)
        sublist = []
        for name in names:
            item = FileTreeItem(os.path.join(self.path, name))
            sublist.append(item)
        return sublist


# A canvas widget with scroll bars and some useful bindings

class ScrolledCanvas:
    def __init__(self, master, **opts):
        if 'yscrollincrement' not in opts:
            opts['yscrollincrement'] = 17
        self.master = master
        self.frame = Frame(master)
        self.frame.rowconfigure(0, weight=1)
        self.frame.columnconfigure(0, weight=1)
        self.canvas = Canvas(self.frame, **opts)
        self.canvas.grid(row=0, column=0, sticky=&quot;nsew&quot;)
        self.vbar = Scrollbar(self.frame, name=&quot;vbar&quot;)
        self.vbar.grid(row=0, column=1, sticky=&quot;nse&quot;)
        self.hbar = Scrollbar(self.frame, name=&quot;hbar&quot;, orient=&quot;horizontal&quot;)
        self.hbar.grid(row=1, column=0, sticky=&quot;ews&quot;)
        self.canvas['yscrollcommand'] = self.vbar.set
        self.vbar['command'] = self.canvas.yview
        self.canvas['xscrollcommand'] = self.hbar.set
        self.hbar['command'] = self.canvas.xview
        self.canvas.bind(&quot;&lt;Key-Prior&gt;&quot;, self.page_up)
        self.canvas.bind(&quot;&lt;Key-Next&gt;&quot;, self.page_down)
        self.canvas.bind(&quot;&lt;Key-Up&gt;&quot;, self.unit_up)
        self.canvas.bind(&quot;&lt;Key-Down&gt;&quot;, self.unit_down)
        #if isinstance(master, Toplevel) or isinstance(master, Tk):
        self.canvas.bind(&quot;&lt;Alt-Key-2&gt;&quot;, self.zoom_height)
        self.canvas.focus_set()
    def page_up(self, event):
        self.canvas.yview_scroll(-1, &quot;page&quot;)
        return &quot;break&quot;
    def page_down(self, event):
        self.canvas.yview_scroll(1, &quot;page&quot;)
        return &quot;break&quot;
    def unit_up(self, event):
        self.canvas.yview_scroll(-1, &quot;unit&quot;)
        return &quot;break&quot;
    def unit_down(self, event):
        self.canvas.yview_scroll(1, &quot;unit&quot;)
        return &quot;break&quot;
    def zoom_height(self, event):
        ZoomHeight.zoom_height(self.master)
        return &quot;break&quot;


def _tree_widget(parent):
    root = Tk()
    root.title(&quot;Test TreeWidget&quot;)
    width, height, x, y = list(map(int, re.split('[x+]', parent.geometry())))
    root.geometry(&quot;+%d+%d&quot;%(x, y + 150))
    sc = ScrolledCanvas(root, bg=&quot;white&quot;, highlightthickness=0, takefocus=1)
    sc.frame.pack(expand=1, fill=&quot;both&quot;, side=LEFT)
    item = FileTreeItem(os.getcwd())
    node = TreeNode(sc.canvas, None, item)
    node.expand()
    root.mainloop()

if __name__ == '__main__':
    from idlelib.idle_test.htest import run
    run(_tree_widget)
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