6.0

Increments or decrements the current undo level of the drawing.

extern "C" void WINAPI VCIncrementUndoLevel(short* iError);
extern "C" void WINAPI VCDecrementUndoLevel(short* iError);

procedure VCIncrementUndoLevel(var iError: Smallint); stdcall;
procedure VCDecrementUndoLevel(var iError: Smallint); stdcall;

Sub IncrementUndoLevel()
Sub DecrementUndoLevel()

None.

None.

0 - Success
1 - Invalid world

The undo and redo levels of an entity control how the entity behaves when using native commands such as Undo and Redo or calling API functions such as VCUndo and VCRedo. The undo and redo levels are sequential numbers which control the order in which entities are undone or redone. The current undo level of the drawing is the level which will be applied to the next undo or redo operation on the drawing. Note that entities have both an undo and redo level but the drawing has only one level, called the current undo level by convention, which then applies to both undo and redo of the entities. For example, if the current undo level of the drawing is 4, then all entities with an undo level of 4 will be undone and erased by the Undo command or the VCUndo function. Entities with an undo or redo level of 0 (zero) cannot be undone or redone, respectively. Call VCIncrementUndoLevel to increment the current undo level of the drawing by 1 (one), typically before adding new entities or deleting existing entities which you want to have their own undo and/or redo levels for the Undo and Redo commands. Call VCDecrementUndoLevel to decrement the current undo level of the drawing by 1 (one), typically when you abort your tool and want to return the current undo level of the drawing to its previous level.  See Managing Undo and Redo for further description of undo and redo.

VCSetCurrentEntityUndo, VCSetCurrentEntityRedo, VCUndo, VCRedo, VCGetCurrentUndoLevel