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131 lines
4.5 KiB
C
131 lines
4.5 KiB
C
/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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*
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* The contents of this file are subject to the Netscape Public
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* License Version 1.1 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.mozilla.org/NPL/
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*
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* Software distributed under the License is distributed on an "AS
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* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
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* implied. See the License for the specific language governing
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* rights and limitations under the License.
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*
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* The Original Code is mozilla.org code.
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*
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* The Initial Developer of the Original Code is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998 Netscape Communications Corporation. All
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* Rights Reserved.
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*
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* Contributor(s):
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*/
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/*
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undo.h --- creating and maintaining an undo list.
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Created: Terry Weissman <terry@netscape.com>, 9-Sept-95.
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*/
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#ifndef _UNDO_H_
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#define _UNDO_H_
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typedef struct UndoState UndoState;
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XP_BEGIN_PROTOS
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/* Create a new undo state. (Returns NULL if no memory available). State will
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be saved to execute up to "maxdepth" undos in a row.*/
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extern UndoState* UNDO_Create(int maxdepth);
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/* Throw away the undo state. */
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extern void UNDO_Destroy(UndoState* state);
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/* Throw away all the queued events in the undo state. If we are in the middle
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of a batch (there are outstanding calls to UNDO_StartBatch()), then future
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events in the batch are also thrown away. */
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extern void UNDO_DiscardAll(UndoState* state);
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/* Mark the beginning of a bunch of actions that should be undone as one user
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action. Should always be matched by a later call to UNDO_EndBatch().
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These calls can nest. They fail only if running out of memory, in which
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case they will call UNDO_DiscardAll(). */
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/* Note you can use the tag arguments to associate a batch of events with
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some user defined tag e.g., a name or object identifying the batch of events */
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extern int UNDO_StartBatch(UndoState* state);
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extern int UNDO_EndBatch(UndoState* state, void (*freetag)(void*), void* tag);
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/* Returns TRUE if undoing will do something (i.e., the menu item for "Undo"
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should be selectable). */
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extern XP_Bool UNDO_CanUndo(UndoState* state);
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/* Returns TRUE if redoing will do something (i.e., the menu item for "Redo"
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should be selectable). */
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extern XP_Bool UNDO_CanRedo(UndoState* state);
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/* Actually do an undo. Should only be called if UNDO_CanUndo returned TRUE.
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May not be called if there are any pending calls to UNDO_StartBatch. */
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extern int UNDO_DoUndo(UndoState* state);
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/* Actually do an redo. Should only be called if UNDO_CanRedo returned TRUE.
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May not be called if there are any pending calls to UNDO_StartBatch. */
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extern int UNDO_DoRedo(UndoState* state);
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/* Log an event. The "undoit" function is to be called with the closure to
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undo an event that just happened. It returns a success code; if negative,
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the code will be propagated up to the call to UNDO_DoUndo and UNDO_DoRedo,
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and UNDO_DiscardAll will be called. Note that the undoit function almost
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always ends up calling UNDO_LogEvent again, to log the function to undo thie
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undoing of this action. If you get my drift.
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The "freeit" function is called when the undo library decides it will never
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ever call undoit function. It is called with the closure to free storage
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used by the closure.
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If this fails (we ran out of memory), then it will return a negative failure
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code, and call UNDO_DiscardAll() and the freeit func. */
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/* Note you can use the tag arguments to associate the event with
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some user defined tag e.g., a name or object identifying the event. */
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#ifdef XP_OS2
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typedef int (*PNSLUFN)(void *);
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typedef void (*PNSLFFN)(void *);
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extern int UNDO_LogEvent(UndoState* state, PNSLUFN undoit,
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PNSLFFN freeit, void* closure,
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PNSLFFN freetag, void* tag);
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#else
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extern int UNDO_LogEvent(UndoState* state, int (*undoit)(void*),
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void (*freeit)(void*), void* closure,
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void (*freetag)(void*), void* tag);
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#endif
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/* Retrieve the undo/redo tag from the top of the corresponding stack. The
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tag is the "thing" YOU assigned during either an UNDO_EndBatch() or
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UNDO_LogEvent call. You most likely use the tag to identify the event[s]
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that can be undone/redone.
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e.g., Label the Edit|Undo menu item with, say, Edit|Undo Delete. */
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extern void *UNDO_PeekUndoTag(UndoState* state);
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extern void *UNDO_PeekRedoTag(UndoState* state);
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XP_END_PROTOS
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#endif /* !_UNDO_H_ */
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