Image rename tool

imgren.py

#!/usr/bin/python
import os
from gi.repository import Gtk, GLib

class SignalHandler(object):
    selected_model = None
    def __init__(self, builder):
        self.builder = builder

    def on_quit(self, window, ev):
        Gtk.main_quit()

    def on_fname_edited(self, renderer, path, newval):
        oldname=self.selected_model[path][0]
        if oldname == newval:
            return
        copy_nr=0
        new_filename=newval
        while os.path.exists(new_filename):
            copy_nr+=1
            new_filename=newval.rsplit(".", 1)
            if len(new_filename)>1:
                new_filename="%s (%d).%s"%(new_filename[0], copy_nr, new_filename[1])
            else: new_filename="%s (%d)"%(new_filename[0], copy_nr)

        newval=new_filename

        os.rename(oldname, newval)
        self.selected_model[path][0]=newval

    def on_selected(self, treesel):
        self.selected_model, rows=treesel.get_selected_rows()
        if not len(rows): return
        fname=self.selected_model[rows[0]][0]
        image=self.builder.get_object("image")
        image.set_from_file(fname)

    def on_edit_start(self, renderer, entry, path):
        try: dot_idx=entry.get_text().rindex(".")
        except ValueError: return
        GLib.timeout_add(50, lambda: entry.select_region(0, dot_idx))


def main():
    bld=Gtk.Builder()
    bld.add_from_file(__file__[:-3]+".ui")

    bld.connect_signals(SignalHandler(bld))

    fname_store=bld.get_object("filenames")

    for fname in os.listdir("."):
        fname_store.append((fname,))

    Gtk.main()

if __name__ == '__main__':
    main()

imgren.ui

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.18.3 -->
<interface>
  <requires lib="gtk+" version="3.12"/>
  <object class="GtkListStore" id="filenames">
    <columns>
      <!-- column-name filename -->
      <column type="gchararray"/>
    </columns>
  </object>
  <object class="GtkWindow" id="window1">
    <property name="visible">True</property>
    <property name="can_focus">False</property>
    <signal name="delete-event" handler="on_quit" swapped="no"/>
    <child>
      <object class="GtkPaned" id="paned1">
        <property name="visible">True</property>
        <property name="can_focus">True</property>
        <child>
          <object class="GtkScrolledWindow" id="scrolledwindow1">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="shadow_type">in</property>
            <child>
              <object class="GtkTreeView" id="treeview1">
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="model">filenames</property>
                <child internal-child="selection">
                  <object class="GtkTreeSelection" id="treeview-selection1">
                    <signal name="changed" handler="on_selected" swapped="no"/>
                  </object>
                </child>
                <child>
                  <object class="GtkTreeViewColumn" id="treeviewcolumn1">
                    <property name="title" translatable="yes">column</property>
                    <child>
                      <object class="GtkCellRendererText" id="cellrenderertext1">
                        <property name="editable">True</property>
                        <signal name="edited" handler="on_fname_edited" swapped="no"/>
                        <signal name="editing-started" handler="on_edit_start" swapped="no"/>
                      </object>
                      <attributes>
                        <attribute name="text">0</attribute>
                      </attributes>
                    </child>
                  </object>
                </child>
              </object>
            </child>
          </object>
          <packing>
            <property name="resize">False</property>
            <property name="shrink">True</property>
          </packing>
        </child>
        <child>
          <object class="GtkScrolledWindow" id="scrolledwindow2">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="shadow_type">in</property>
            <child>
              <object class="GtkViewport" id="viewport1">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <child>
                  <object class="GtkImage" id="image">
                    <property name="visible">True</property>
                    <property name="can_focus">False</property>
                    <property name="stock">gtk-missing-image</property>
                  </object>
                </child>
              </object>
            </child>
          </object>
          <packing>
            <property name="resize">True</property>
            <property name="shrink">True</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>