/****************************************************************************
**
** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtGui module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QtCore/qdebug.h>
#include "qundostack.h"
#include "qundogroup.h"
#include "qundostack_p.h"
#ifndef QT_NO_UNDOCOMMAND
QT_BEGIN_NAMESPACE
/*!
\class QUndoCommand
\brief The QUndoCommand class is the base class of all commands stored on a QUndoStack.
\since 4.2
For an overview of Qt's Undo Framework, see the
\l{Overview of Qt's Undo Framework}{overview document}.
A QUndoCommand represents a single editing action on a document; for example,
inserting or deleting a block of text in a text editor. QUndoCommand can apply
a change to the document with redo() and undo the change with undo(). The
implementations for these functions must be provided in a derived class.
\snippet doc/src/snippets/code/src_gui_util_qundostack.cpp 0
A QUndoCommand has an associated text(). This is a short string
describing what the command does. It is used to update the text
properties of the stack's undo and redo actions; see
QUndoStack::createUndoAction() and QUndoStack::createRedoAction().
QUndoCommand objects are owned by the stack they were pushed on.
QUndoStack deletes a command if it has been undone and a new command is pushed. For example:
\snippet doc/src/snippets/code/src_gui_util_qundostack.cpp 1
In effect, when a command is pushed, it becomes the top-most command
on the stack.
To support command compression, QUndoCommand has an id() and the virtual function
mergeWith(). These functions are used by QUndoStack::push().
To support command macros, a QUndoCommand object can have any number of child
commands. Undoing or redoing the parent command will cause the child
commands to be undone or redone. A command can be assigned
to a parent explicitly in the constructor. In this case, the command
will be owned by the parent.
The parent in this case is usually an empty command, in that it doesn't
provide its own implementation of undo() and redo(). Instead, it uses
the base implementations of these functions, which simply call undo() or
redo() on all its children. The parent should, however, have a meaningful
text().
\snippet doc/src/snippets/code/src_gui_util_qundostack.cpp 2
Another way to create macros is to use the convenience functions
QUndoStack::beginMacro() and QUndoStack::endMacro().
\sa QUndoStack
*/
/*!
Constructs a QUndoCommand object with the given \a parent and \a text.
If \a parent is not 0, this command is appended to parent's child list.
The parent command then owns this command and will delete it in its
destructor.
\sa ~QUndoCommand()
*/
QUndoCommand::QUndoCommand(const QString &text, QUndoCommand *parent)
{
d = new QUndoCommandPrivate;
if (parent != 0)
parent->d->child_list.append(this);
d->text = text;
}
/*!
Constructs a QUndoCommand object with parent \a parent.
If \a parent is not 0, this command is appended to parent's child list.
The parent command then owns this command and will delete it in its
destructor.
\sa ~QUndoCommand()
*/
QUndoCommand::QUndoCommand(QUndoCommand *parent)
{
d = new QUndoCommandPrivate;
if (parent != 0)
parent->d->child_list.append(this);
}
/*!
Destroys the QUndoCommand object and all child commands.
\sa QUndoCommand()
*/
QUndoCommand::~QUndoCommand()
{
qDeleteAll(d->child_list);
delete d;
}
/*!
Returns the ID of this command.
A command ID is used in command compression. It must be an integer unique to
this command's class, or -1 if the command doesn't support compression.
If the command supports compression this function must be overridden in the
derived class to return the correct ID. The base implementation returns -1.
QUndoStack::push() will only try to merge two commands if they have the
same ID, and the ID is not -1.
\sa mergeWith(), QUndoStack::push()
*/
int QUndoCommand::id() const
{
return -1;
}
/*!
Attempts to merge this command with \a command. Returns true on
success; otherwise returns false.
If this function returns true, calling this command's redo() must have the same
effect as redoing both this command and \a command.
Similarly, calling this command's undo() must have the same effect as undoing
\a command and this command.
QUndoStack will only try to merge two commands if they have the same id, and
the id is not -1.
The default implementation returns false.
\snippet doc/src/snippets/code/src_gui_util_qundostack.cpp 3
\sa id() QUndoStack::push()
*/
bool QUndoCommand::mergeWith(const QUndoCommand *command)
{
Q_UNUSED(command);
return false;
}
/*!
Applies a change to the document. This function must be implemented in
the derived class. Calling QUndoStack::push(),
QUndoStack::undo() or QUndoStack::redo() from this function leads to
undefined beahavior.
The default implementation calls redo() on all child commands.
\sa undo()
*/
void QUndoCommand::redo()
{
for (int i = 0; i < d->child_list.size(); ++i)
d->child_list.at(i)->redo();
}
/*!
Reverts a change to the document. After undo() is called, the state of
the document should be the same as before redo() was called. This function must
be implemented in the derived class. Calling QUndoStack::push(),
QUndoStack::undo() or QUndoStack::redo() from this function leads to
undefined beahavior.
The default implementation calls undo() on all child commands in reverse order.
\sa redo()
*/
void QUndoCommand::undo()
{
for (int i = d->child_list.size() - 1; i >= 0; --i)
d->child_list.at(i)->undo();
}
/*!
Returns a short text string describing what this command does; for example,
"insert text".
The text is used when the text properties of the stack's undo and redo
actions are updated.
\sa setText(), QUndoStack::createUndoAction(), QUndoStack::createRedoAction()
*/
QString QUndoCommand::text() const
{
return d->text;
}
/*!
Sets the command's text to be the \a text specified.
The specified text should be a short user-readable string describing what this
command does.
\sa text() QUndoStack::createUndoAction() QUndoStack::createRedoAction()
*/
void QUndoCommand::setText(const QString &text)
{
d->text = text;
}
/*!
\since 4.4
Returns the number of child commands in this command.
\sa child()
*/
int QUndoCommand::childCount() const
{
return d->child_list.count();
}
/*!
\since 4.4
Returns the child command at \a index.
\sa childCount(), QUndoStack::command()
*/
const QUndoCommand *QUndoCommand::child(int index) const
{
if (index < 0 || index >= d->child_list.count())
return 0;
return d->child_list.at(index);
}
#endif // QT_NO_UNDOCOMMAND
#ifndef QT_NO_UNDOSTACK
/*!
\class QUndoStack
\brief The QUndoStack class is a stack of QUndoCommand objects.
\since 4.2
For an overview of Qt's Undo Framework, see the
\l{Overview of Qt's Undo Framework}{overview document}.
An undo stack maintains a stack of commands that have been applied to a
document.
New commands are pushed on the stack using push(). Commands can be
undone and redone using undo() and redo(), or by triggering the
actions returned by createUndoAction() and createRedoAction().
QUndoStack keeps track of the \a current command. This is the command
which will be executed by the next call to redo(). The index of this
command is returned by index(). The state of the edited object can be
rolled forward or back using setIndex(). If the top-most command on the
stack has already been redone, index() is equal to count().
QUndoStack provides support for undo and redo actions, command
compression, command macros, and supports the concept of a
\e{clean state}.
\section1 Undo and Redo Actions
QUndoStack provides convenient undo and redo QAction objects, which
can be inserted into a menu or a toolbar. When commands are undone or
redone, QUndoStack updates the text properties of these actions
to reflect what change they will trigger. The actions are also disabled
when no command is available for undo or redo. These actions
are returned by QUndoStack::createUndoAction() and QUndoStack::createRedoAction().
\section1 Command Compression and Macros
Command compression is useful when several commands can be compressed
into a single command that can be undone and redone in a single operation.
For example, when a user types a character in a text editor, a new command
is created. This command inserts the character into the document at the
cursor position. However, it is more convenient for the user to be able
to undo or redo typing of whole words, sentences, or paragraphs.
Command compression allows these single-character commands to be merged
into a single command which inserts or deletes sections of text.
For more information, see QUndoCommand::mergeWith() and push().
A command macro is a sequence of commands, all of which are undone and
redone in one go. Command macros are created by giving a command a list
of child commands.
Undoing or redoing the parent command will cause the child commands to
be undone or redone. Command macros may be created explicitly
by specifying a parent in the QUndoCommand constructor, or by using the
convenience functions beginMacro() and endMacro().
Although command compression and macros appear to have the same effect to the
user, they often have different uses in an application. Commands that
perform small changes to a document may be usefully compressed if there is
no need to individually record them, and if only larger changes are relevant
to the user.
However, for commands that need to be recorded individually, or those that
cannot be compressed, it is useful to use macros to provide a more convenient
user experience while maintaining a record of each command.
\section1 Clean State
QUndoStack supports the concept of a clean state. When the
document is saved to disk, the stack can be marked as clean using
setClean(). Whenever the stack returns to this state through undoing and
redoing commands, it emits the signal cleanChanged(). This signal
is also emitted when the stack leaves the clean state. This signal is
usually used to enable and disable the save actions in the application,
and to update the document's title to reflect that it contains unsaved
changes.
\sa QUndoCommand, QUndoView
*/
#ifndef QT_NO_ACTION
QUndoAction::QUndoAction(const QString &prefix, QObject *parent)
: QAction(parent)
{
m_prefix = prefix;
}
void QUndoAction::setPrefixedText(const QString &text)
{
QString s = m_prefix;
if (!m_prefix.isEmpty() && !text.isEmpty())
s.append(QLatin1Char(' '));
s.append(text);
setText(s);
}
#endif // QT_NO_ACTION
/*! \internal
Sets the current index to \a idx, emitting appropriate signals. If \a clean is true,
makes \a idx the clean index as well.
*/
void QUndoStackPrivate::setIndex(int idx, bool clean)
{
Q_Q(QUndoStack);
bool was_clean = index == clean_index;
if (idx != index) {
index = idx;
emit q->indexChanged(index);
emit q->canUndoChanged(q->canUndo());
emit q->undoTextChanged(q->undoText());
emit q->canRedoChanged(q->canRedo());
emit q->redoTextChanged(q->redoText());
}
if (clean)
clean_index = index;
bool is_clean = index == clean_index;
if (is_clean != was_clean)
emit q->cleanChanged(is_clean);
}
/*! \internal
If the number of commands on the stack exceedes the undo limit, deletes commands from
the bottom of the stack.
Returns true if commands were deleted.
*/
bool QUndoStackPrivate::checkUndoLimit()
{
if (undo_limit <= 0 || !macro_stack.isEmpty() || undo_limit >= command_list.count())
return false;
int del_count = command_list.count() - undo_limit;
for (int i = 0; i < del_count; ++i)
delete command_list.takeFirst();
index -= del_count;
if (clean_index != -1) {
if (clean_index < del_count)
clean_index = -1; // we've deleted the clean command
else
clean_index -= del_count;
}
return true;
}
/*!
Constructs an empty undo stack with the parent \a parent. The
stack will initally be in the clean state. If \a parent is a
QUndoGroup object, the stack is automatically added to the group.
\sa push()
*/
QUndoStack::QUndoStack(QObject *parent)
: QObject(*(new QUndoStackPrivate), parent)
{
#ifndef QT_NO_UNDOGROUP
if (QUndoGroup *group = qobject_cast<QUndoGroup*>(parent))
group->addStack(this);
#endif
}
/*!
Destroys the undo stack, deleting any commands that are on it. If the
stack is in a QUndoGroup, the stack is automatically removed from the group.
\sa QUndoStack()
*/
QUndoStack::~QUndoStack()
{
#ifndef QT_NO_UNDOGROUP
Q_D(QUndoStack);
if (d->group != 0)
d->group->removeStack(this);
#endif
clear();
}
/*!
Clears the command stack by deleting all commands on it, and returns the stack
to the clean state.
Commands are not undone or redone; the state of the edited object remains
unchanged.
This function is usually used when the contents of the document are
abandoned.
\sa QUndoStack()
*/
void QUndoStack::clear()
{
Q_D(QUndoStack);
if (d->command_list.isEmpty())
return;
bool was_clean = isClean();
d->macro_stack.clear();
qDeleteAll(d->command_list);
d->command_list.clear();
d->index = 0;
d->clean_index = 0;
emit indexChanged(0);
emit canUndoChanged(false);
emit undoTextChanged(QString());
emit canRedoChanged(false);
emit redoTextChanged(QString());
if (!was_clean)
emit cleanChanged(true);
}
/*!
Pushes \a cmd on the stack or merges it with the most recently executed command.
In either case, executes \a cmd by calling its redo() function.
If \a cmd's id is not -1, and if the id is the same as that of the
most recently executed command, QUndoStack will attempt to merge the two
commands by calling QUndoCommand::mergeWith() on the most recently executed
command. If QUndoCommand::mergeWith() returns true, \a cmd is deleted.
In all other cases \a cmd is simply pushed on the stack.
If commands were undone before \a cmd was pushed, the current command and
all commands above it are deleted. Hence \a cmd always ends up being the
top-most on the stack.
Once a command is pushed, the stack takes ownership of it. There
are no getters to return the command, since modifying it after it has
been executed will almost always lead to corruption of the document's
state.
\sa QUndoCommand::id() QUndoCommand::mergeWith()
*/
void QUndoStack::push(QUndoCommand *cmd)
{
Q_D(QUndoStack);
cmd->redo();
bool macro = !d->macro_stack.isEmpty();
QUndoCommand *cur = 0;
if (macro) {
QUndoCommand *macro_cmd = d->macro_stack.last();
if (!macro_cmd->d->child_list.isEmpty())
cur = macro_cmd->d->child_list.last();
} else {
if (d->index > 0)
cur = d->command_list.at(d->index - 1);
while (d->index < d->command_list.size())
delete d->command_list.takeLast();
if (d->clean_index > d->index)
d->clean_index = -1; // we've deleted the clean state
}
bool try_merge = cur != 0
&& cur->id() != -1
&& cur->id() == cmd->id()
&& (macro || d->index != d->clean_index);
if (try_merge && cur->mergeWith(cmd)) {
delete cmd;
if (!macro) {
emit indexChanged(d->index);
emit canUndoChanged(canUndo());
emit undoTextChanged(undoText());
emit canRedoChanged(canRedo());
emit redoTextChanged(redoText());
}
} else {
if (macro) {
d->macro_stack.last()->d->child_list.append(cmd);
} else {
d->command_list.append(cmd);
d->checkUndoLimit();
d->setIndex(d->index + 1, false);
}
}
}
/*!
Marks the stack as clean and emits cleanChanged() if the stack was
not already clean.
Whenever the stack returns to this state through the use of undo/redo
commands, it emits the signal cleanChanged(). This signal is also
emitted when the stack leaves the clean state.
\sa isClean(), cleanIndex()
*/
void QUndoStack::setClean()
{
Q_D(QUndoStack);
if (!d->macro_stack.isEmpty()) {
qWarning("QUndoStack::setClean(): cannot set clean in the middle of a macro");
return;
}
d->setIndex(d->index, true);
}
/*!
If the stack is in the clean state, returns true; otherwise returns false.
\sa setClean() cleanIndex()
*/
bool QUndoStack::isClean() const
{
Q_D(const QUndoStack);
if (!d->macro_stack.isEmpty())
return false;
return d->clean_index == d->index;
}
/*!
Returns the clean index. This is the index at which setClean() was called.
A stack may not have a clean index. This happens if a document is saved,
some commands are undone, then a new command is pushed. Since
push() deletes all the undone commands before pushing the new command, the stack
can't return to the clean state again. In this case, this function returns -1.
\sa isClean() setClean()
*/
int QUndoStack::cleanIndex() const
{
Q_D(const QUndoStack);
return d->clean_index;
}
/*!
Undoes the command below the current command by calling QUndoCommand::undo().
Decrements the current command index.
If the stack is empty, or if the bottom command on the stack has already been
undone, this function does nothing.
\sa redo() index()
*/
void QUndoStack::undo()
{
Q_D(QUndoStack);
if (d->index == 0)
return;
if (!d->macro_stack.isEmpty()) {
qWarning("QUndoStack::undo(): cannot undo in the middle of a macro");
return;
}
int idx = d->index - 1;
d->command_list.at(idx)->undo();
d->setIndex(idx, false);
}
/*!
Redoes the current command by calling QUndoCommand::redo(). Increments the current
command index.
If the stack is empty, or if the top command on the stack has already been
redone, this function does nothing.
\sa undo() index()
*/
void QUndoStack::redo()
{
Q_D(QUndoStack);
if (d->index == d->command_list.size())
return;
if (!d->macro_stack.isEmpty()) {
qWarning("QUndoStack::redo(): cannot redo in the middle of a macro");
return;
}
d->command_list.at(d->index)->redo();
d->setIndex(d->index + 1, false);
}
/*!
Returns the number of commands on the stack. Macro commands are counted as
one command.
\sa index() setIndex() command()
*/
int QUndoStack::count() const
{
Q_D(const QUndoStack);
return d->command_list.size();
}
/*!
Returns the index of the current command. This is the command that will be
executed on the next call to redo(). It is not always the top-most command
on the stack, since a number of commands may have been undone.
\sa undo() redo() count()
*/
int QUndoStack::index() const
{
Q_D(const QUndoStack);
return d->index;
}
/*!
Repeatedly calls undo() or redo() until the current command index reaches
\a idx. This function can be used to roll the state of the document forwards
of backwards. indexChanged() is emitted only once.
\sa index() count() undo() redo()
*/
void QUndoStack::setIndex(int idx)
{
Q_D(QUndoStack);
if (!d->macro_stack.isEmpty()) {
qWarning("QUndoStack::setIndex(): cannot set index in the middle of a macro");
return;
}
if (idx < 0)
idx = 0;
else if (idx > d->command_list.size())
idx = d->command_list.size();
int i = d->index;
while (i < idx)
d->command_list.at(i++)->redo();
while (i > idx)
d->command_list.at(--i)->undo();
d->setIndex(idx, false);
}
/*!
Returns true if there is a command available for undo; otherwise returns false.
This function returns false if the stack is empty, or if the bottom command
on the stack has already been undone.
Synonymous with index() == 0.
\sa index() canRedo()
*/
bool QUndoStack::canUndo() const
{
Q_D(const QUndoStack);
if (!d->macro_stack.isEmpty())
return false;
return d->index > 0;
}
/*!
Returns true if there is a command available for redo; otherwise returns false.
This function returns false if the stack is empty or if the top command
on the stack has already been redone.
Synonymous with index() == count().
\sa index() canUndo()
*/
bool QUndoStack::canRedo() const
{
Q_D(const QUndoStack);
if (!d->macro_stack.isEmpty())
return false;
return d->index < d->command_list.size();
}
/*!
Returns the text of the command which will be undone in the next call to undo().
\sa QUndoCommand::text() redoText()
*/
QString QUndoStack::undoText() const
{
Q_D(const QUndoStack);
if (!d->macro_stack.isEmpty())
return QString();
if (d->index > 0)
return d->command_list.at(d->index - 1)->text();
return QString();
}
/*!
Returns the text of the command which will be redone in the next call to redo().
\sa QUndoCommand::text() undoText()
*/
QString QUndoStack::redoText() const
{
Q_D(const QUndoStack);
if (!d->macro_stack.isEmpty())
return QString();
if (d->index < d->command_list.size())
return d->command_list.at(d->index)->text();
return QString();
}
#ifndef QT_NO_ACTION
/*!
Creates an undo QAction object with the given \a parent.
Triggering this action will cause a call to undo(). The text of this action
is the text of the command which will be undone in the next call to undo(),
prefixed by the specified \a prefix. If there is no command available for undo,
this action will be disabled.
If \a prefix is empty, the default prefix "Undo" is used.
\sa createRedoAction(), canUndo(), QUndoCommand::text()
*/
QAction *QUndoStack::createUndoAction(QObject *parent, const QString &prefix) const
{
QString pref = prefix.isEmpty() ? tr("Undo") : prefix;
QUndoAction *result = new QUndoAction(pref, parent);
result->setEnabled(canUndo());
result->setPrefixedText(undoText());
connect(this, SIGNAL(canUndoChanged(bool)),
result, SLOT(setEnabled(bool)));
connect(this, SIGNAL(undoTextChanged(QString)),
result, SLOT(setPrefixedText(QString)));
connect(result, SIGNAL(triggered()), this, SLOT(undo()));
return result;
}
/*!
Creates an redo QAction object with the given \a parent.
Triggering this action will cause a call to redo(). The text of this action
is the text of the command which will be redone in the next call to redo(),
prefixed by the specified \a prefix. If there is no command available for redo,
this action will be disabled.
If \a prefix is empty, the default prefix "Redo" is used.
\sa createUndoAction(), canRedo(), QUndoCommand::text()
*/
QAction *QUndoStack::createRedoAction(QObject *parent, const QString &prefix) const
{
QString pref = prefix.isEmpty() ? tr("Redo") : prefix;
QUndoAction *result = new QUndoAction(pref, parent);
result->setEnabled(canRedo());
result->setPrefixedText(redoText());
connect(this, SIGNAL(canRedoChanged(bool)),
result, SLOT(setEnabled(bool)));
connect(this, SIGNAL(redoTextChanged(QString)),
result, SLOT(setPrefixedText(QString)));
connect(result, SIGNAL(triggered()), this, SLOT(redo()));
return result;
}
#endif // QT_NO_ACTION
/*!
Begins composition of a macro command with the given \a text description.
An empty command described by the specified \a text is pushed on the stack.
Any subsequent commands pushed on the stack will be appended to the empty
command's children until endMacro() is called.
Calls to beginMacro() and endMacro() may be nested, but every call to
beginMacro() must have a matching call to endMacro().
While a macro is composed, the stack is disabled. This means that:
\list
\i indexChanged() and cleanChanged() are not emitted,
\i canUndo() and canRedo() return false,
\i calling undo() or redo() has no effect,
\i the undo/redo actions are disabled.
\endlist
The stack becomes enabled and appropriate signals are emitted when endMacro()
is called for the outermost macro.
\snippet doc/src/snippets/code/src_gui_util_qundostack.cpp 4
This code is equivalent to:
\snippet doc/src/snippets/code/src_gui_util_qundostack.cpp 5
\sa endMacro()
*/
void QUndoStack::beginMacro(const QString &text)
{
Q_D(QUndoStack);
QUndoCommand *cmd = new QUndoCommand();
cmd->setText(text);
if (d->macro_stack.isEmpty()) {
while (d->index < d->command_list.size())
delete d->command_list.takeLast();
if (d->clean_index > d->index)
d->clean_index = -1; // we've deleted the clean state
d->command_list.append(cmd);
} else {
d->macro_stack.last()->d->child_list.append(cmd);
}
d->macro_stack.append(cmd);
if (d->macro_stack.count() == 1) {
emit canUndoChanged(false);
emit undoTextChanged(QString());
emit canRedoChanged(false);
emit redoTextChanged(QString());
}
}
/*!
Ends composition of a macro command.
If this is the outermost macro in a set nested macros, this function emits
indexChanged() once for the entire macro command.
\sa beginMacro()
*/
void QUndoStack::endMacro()
{
Q_D(QUndoStack);
if (d->macro_stack.isEmpty()) {
qWarning("QUndoStack::endMacro(): no matching beginMacro()");
return;
}
d->macro_stack.removeLast();
if (d->macro_stack.isEmpty()) {
d->checkUndoLimit();
d->setIndex(d->index + 1, false);
}
}
/*!
\since 4.4
Returns a const pointer to the command at \a index.
This function returns a const pointer, because modifying a command,
once it has been pushed onto the stack and executed, almost always
causes corruption of the state of the document, if the command is
later undone or redone.
\sa QUndoCommand::child()
*/
const QUndoCommand *QUndoStack::command(int index) const
{
Q_D(const QUndoStack);
if (index < 0 || index >= d->command_list.count())
return 0;
return d->command_list.at(index);
}
/*!
Returns the text of the command at index \a idx.
\sa beginMacro()
*/
QString QUndoStack::text(int idx) const
{
Q_D(const QUndoStack);
if (idx < 0 || idx >= d->command_list.size())
return QString();
return d->command_list.at(idx)->text();
}
/*!
\property QUndoStack::undoLimit
\brief the maximum number of commands on this stack.
\since 4.3
When the number of commands on a stack exceedes the stack's undoLimit, commands are
deleted from the bottom of the stack. Macro commands (commands with child commands)
are treated as one command. The default value is 0, which means that there is no
limit.
This property may only be set when the undo stack is empty, since setting it on a
non-empty stack might delete the command at the current index. Calling setUndoLimit()
on a non-empty stack prints a warning and does nothing.
*/
void QUndoStack::setUndoLimit(int limit)
{
Q_D(QUndoStack);
if (!d->command_list.isEmpty()) {
qWarning("QUndoStack::setUndoLimit(): an undo limit can only be set when the stack is empty");
return;
}
if (limit == d->undo_limit)
return;
d->undo_limit = limit;
d->checkUndoLimit();
}
int QUndoStack::undoLimit() const
{
Q_D(const QUndoStack);
return d->undo_limit;
}
/*!
\property QUndoStack::active
\brief the active status of this stack.
An application often has multiple undo stacks, one for each opened document. The active
stack is the one associated with the currently active document. If the stack belongs
to a QUndoGroup, calls to QUndoGroup::undo() or QUndoGroup::redo() will be forwarded
to this stack when it is active. If the QUndoGroup is watched by a QUndoView, the view
will display the contents of this stack when it is active. If the stack does not belong to
a QUndoGroup, making it active has no effect.
It is the programmer's responsibility to specify which stack is active by
calling setActive(), usually when the associated document window receives focus.
\sa QUndoGroup
*/
void QUndoStack::setActive(bool active)
{
#ifdef QT_NO_UNDOGROUP
Q_UNUSED(active);
#else
Q_D(QUndoStack);
if (d->group != 0) {
if (active)
d->group->setActiveStack(this);
else if (d->group->activeStack() == this)
d->group->setActiveStack(0);
}
#endif
}
bool QUndoStack::isActive() const
{
#ifdef QT_NO_UNDOGROUP
return true;
#else
Q_D(const QUndoStack);
return d->group == 0 || d->group->activeStack() == this;
#endif
}
/*!
\fn void QUndoStack::indexChanged(int idx)
This signal is emitted whenever a command modifies the state of the document.
This happens when a command is undone or redone. When a macro
command is undone or redone, or setIndex() is called, this signal
is emitted only once.
\a idx specifies the index of the current command, ie. the command which will be
executed on the next call to redo().
\sa index() setIndex()
*/
/*!
\fn void QUndoStack::cleanChanged(bool clean)
This signal is emitted whenever the stack enters or leaves the clean state.
If \a clean is true, the stack is in a clean state; otherwise this signal
indicates that it has left the clean state.
\sa isClean() setClean()
*/
/*!
\fn void QUndoStack::undoTextChanged(const QString &undoText)
This signal is emitted whenever the value of undoText() changes. It is
used to update the text property of the undo action returned by createUndoAction().
\a undoText specifies the new text.
*/
/*!
\fn void QUndoStack::canUndoChanged(bool canUndo)
This signal is emitted whenever the value of canUndo() changes. It is
used to enable or disable the undo action returned by createUndoAction().
\a canUndo specifies the new value.
*/
/*!
\fn void QUndoStack::redoTextChanged(const QString &redoText)
This signal is emitted whenever the value of redoText() changes. It is
used to update the text property of the redo action returned by createRedoAction().
\a redoText specifies the new text.
*/
/*!
\fn void QUndoStack::canRedoChanged(bool canRedo)
This signal is emitted whenever the value of canRedo() changes. It is
used to enable or disable the redo action returned by createRedoAction().
\a canRedo specifies the new value.
*/
QT_END_NAMESPACE
#endif // QT_NO_UNDOSTACK