pgworksheet_1.9/pgw/Undo.py

   1 # -*- coding: latin-1; -*-
   2 #
   3 # PgWorksheet - PostgreSQL Front End
   4 # http://pgworksheet.projects.postgresql.org/
   5 #
   6 # Copyright © 2004-2008 Henri Michelon & CML http://www.e-cml.org/
   7 #
   8 # This program is free software; you can redistribute it and/or
   9 # modify it under the terms of the GNU General Public License
  10 # as published by the Free Software Foundation; either version 2
  11 # of the License, or (at your option) any later version.
  12 #
  13 # This program is distributed in the hope that it will be useful,
  14 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 # GNU General Public License for more details (read LICENSE.txt).
  17 #
  18 # You should have received a copy of the GNU General Public License
  19 # along with this program; if not, write to the Free Software
  20 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  21 #
  22 # $Id: Undo.py,v 1.4 2008/03/12 20:26:23 hmichelon Exp $
  23 #
  24
  25 # maxium size of the undo stack
  26 UNDO_MAX = 1000
  27
  28
  29 class UndoAction:
  30   """A user action : insert or delete"""
  31
  32   def __init__(self, buffer, type, start, end, value):
  33     self.buffer = buffer
  34     self.type = type
  35     self.start = start
  36     self.end = end
  37     self.value = value
  38
  39
  40 class Undo:
  41   """Records user actions and apply or revert them"""
  42
  43   def __init__(self):
  44     self.undo_stack = []
  45     self.redo_stack = []
  46     # locking is used to avoid recording
  47     # our own undo/redo actions
  48     self.lock = False
  49
  50
  51   def reset(self):
  52     """empty the stacks to restart the undo action"""
  53     self.undo_stack = []
  54     self.redo_stack = []
  55
  56
  57   def text_inserted(self, buffer, iter, text, length):
  58     """Called by Gtk when text is inserted in a buffer"""
  59     if (not self.lock):
  60       if (len(self.undo_stack) >= UNDO_MAX):
  61         self.undo_stack.pop(0)
  62       self.undo_stack.append(UndoAction(buffer, "insert",
  63                                 iter.get_offset(), iter.get_offset() + length,
  64                                 text))
  65
  66
  67   def text_deleted(self, buffer, start, end):
  68     """Called by Gtk when text is deleted from a buffer"""
  69     if (not self.lock):
  70       if (len(self.undo_stack) >= UNDO_MAX):
  71         self.undo_stack.pop(0)
  72       self.undo_stack.append(UndoAction(buffer, "delete",
  73                                 start.get_offset(), end.get_offset(),
  74                                 buffer.get_text(start, end)))
  75
  76
  77   def undo(self):
  78     """Revert the last action"""
  79     if (len(self.undo_stack) == 0):
  80       return
  81     self.lock = True
  82     action = self.undo_stack.pop()
  83     if (action.type == "insert"):
  84       action.buffer.delete(action.buffer.get_iter_at_offset(action.start),
  85                            action.buffer.get_iter_at_offset(action.end))
  86     elif (action.type == "delete"):
  87       action.buffer.insert(action.buffer.get_iter_at_offset(action.start),
  88                            action.value)
  89     self.redo_stack.append(action)
  90     self.lock = False
  91
  92
  93   def redo(self):
  94     """Apply the last reverted action"""
  95     if (len(self.redo_stack) == 0):
  96       return
  97     self.lock = True
  98     action = self.redo_stack.pop()
  99     if (action.type == "insert"):
 100       action.buffer.insert(action.buffer.get_iter_at_offset(action.start),
 101                            action.value)
 102     elif (action.type == "delete"):
 103       action.buffer.delete(action.buffer.get_iter_at_offset(action.start),
 104                            action.buffer.get_iter_at_offset(action.end))
 105     self.undo_stack.append(action)
 106     self.lock = False