cinelerra/undostack.C

   1 #include "undostack.h"
   2 #include "undostackitem.h"
   3
   4
   5 UndoStack::UndoStack() : List<UndoStackItem>()
   6 {
   7         current = 0;
   8 }
   9
  10 UndoStack::~UndoStack()
  11 {
  12 }
  13
  14 void UndoStack::push(UndoStackItem *item)
  15 {
  16 // current is only 0 if before first undo
  17         if(current)
  18                 current = insert_after(current, item);
  19         else
  20                 current = insert_before(first, item);
  21
  22 // delete future undos if necessary
  23         if(current && current->next)
  24         {
  25                 while(current->next) remove(last);
  26         }
  27 }
  28
  29 int UndoStack::pull()
  30 {
  31         if(current) current = PREVIOUS;
  32 }
  33
  34 UndoStackItem* UndoStack::pull_next()
  35 {
  36 // use first entry if none
  37         if(!current) current = first;
  38         else
  39 // use next entry if there is a next entry
  40         if(current->next)
  41                 current = NEXT;
  42 // don't change current if there is no next entry
  43         else
  44                 return 0;
  45
  46         return current;
  47 }
  48
  49 // enforces that the undo stack does not exceed a size of UNDOMEMORY
  50 // except that it always has at least UNDOMINLEVELS entries
  51 void UndoStack::prune()
  52 {
  53         int size = 0;
  54         int levels = 0;
  55
  56         UndoStackItem* i = last;
  57         while (i != 0 && (levels < UNDOMINLEVELS || size <= UNDOMEMORY))
  58         {
  59                 size += i->get_size();
  60                 ++levels;
  61                 i = i->previous;
  62         }
  63
  64         if (i != 0)
  65         {
  66 // truncate everything before and including i
  67                 while (first != i)
  68                         remove(first);
  69                 remove(first);
  70         }
  71 }