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The QSettings class provides persistent platform-independent application settings. Más...
#include <qsettings.h>
The QSettings class provides persistent platform-independent application settings.
On Unix systems, QSettings uses text files to store settings. On Windows systems, QSettings uses the system registry. On Mac OS X, QSettings uses the Carbon preferences API.
Each setting comprises an identifying key and the data associated with the key. A key is a unicode string which consists of two or more subkeys. A subkey is a slash, '/', followed by one or more unicode characters (excluding slashes, newlines, carriage returns and equals, '=', signs). The associated data, called the entry or value, may be a boolean, an integer, a double, a string or a list of strings. Entry strings may contain any unicode characters.
If you want to save and restore the entire desktop's settings, i.e. which applications are running, use QSettings to save the settings for each individual application and QSessionManager to save the desktop's session.
Example settings:
/MyCompany/MyApplication/background color /MyCompany/MyApplication/foreground color /MyCompany/MyApplication/geometry/x /MyCompany/MyApplication/geometry/y /MyCompany/MyApplication/geometry/width /MyCompany/MyApplication/geometry/height /MyCompany/MyApplication/recent files/1 /MyCompany/MyApplication/recent files/2 /MyCompany/MyApplication/recent files/3
Each line above is a complete key, made up of subkeys.
A typical usage pattern for reading settings at application startup:
QSettings settings; settings.setPath( "MyCompany.com", "MyApplication" ); QString bgColor = settings.readEntry( "/colors/background", "white" ); int width = settings.readNumEntry( "/geometry/width", 640 ); // ...
A typical usage pattern for saving settings at application exit or 'save preferences':
QSettings settings; settings.setPath( "MyCompany.com", "MyApplication" ); settings.writeEntry( "/colors/background", bgColor ); settings.writeEntry( "/geometry/width", width ); // ...
A key prefix can be prepended to all keys using beginGroup(). The application of the prefix is stopped using endGroup(). For example:
QSettings settings; settings.beginGroup( "/MainWindow" ); settings.beginGroup( "/Geometry" ); int x = settings.readEntry( "/x" ); // ... settings.endGroup(); settings.beginGroup( "/Toolbars" ); // ... settings.endGroup(); settings.endGroup();
You can get a list of entry-holding keys by calling entryList(), and a list of key-holding keys using subkeyList().
QStringList keys = settings.entryList( "/MyApplication" ); // keys contains 'background color' and 'foreground color'. QStringList keys = settings.entryList( "/MyApplication/recent files" ); // keys contains '1', '2' and '3'. QStringList subkeys = settings.subkeyList( "/MyApplication" ); // subkeys contains 'geometry' and 'recent files' QStringList subkeys = settings.subkeyList( "/MyApplication/recent files" ); // subkeys is empty.
Since settings for Windows are stored in the registry there are some size limitations as follows: A subkey may not exceed 255 characters. An entry's value may not exceed 16,300 characters. All the values of a key (for example, all the 'recent files' subkeys values), may not exceed 65,535 characters.
These limitations are not enforced on Unix or Mac OS X.
enum QSettings::Format |
enum QSettings::Format |
enum QSettings::Scope |
enum QSettings::Scope |
Global Save settings as global as possible User Save settings in user space
enum QSettings::System |
Mac Macintosh execution environments Unix Mac OS X, Unix, Linux and Unix-like execution environments Windows Windows execution environments
enum QSettings::System |
QSettings::QSettings | ( | ) |
Creates a settings object.
Be aware that you must call setPath() or insertSearchPath() before you can use the QSettings object.
QSettings::QSettings | ( | Format | format | ) |
Creates a settings object. If format is 'Ini' the settings will be stored in a text file, using the Unix strategy (see above). If format is 'Native', the settings will be stored in a platform specific way (ie. the Windows registry).
Be aware that you must call setPath() or insertSearchPath() before you can use the QSettings object.
QSettings::~QSettings | ( | ) |
Destroys the settings object. All modifications made to the settings will automatically be saved.
QSettings::QSettings | ( | ) |
QSettings::QSettings | ( | Format | format | ) |
QSettings::~QSettings | ( | ) |
void QSettings::beginGroup | ( | const QString & | group | ) |
Appends group to the current key prefix.
QSettings settings; settings.beginGroup( "/MainWindow" ); // read values settings.endGroup();
void QSettings::beginGroup | ( | const QString & | group | ) |
void QSettings::endGroup | ( | ) |
Undo previous calls to beginGroup(). Note that a single beginGroup("a/b/c") is undone by a single call to endGroup().
QSettings settings; settings.beginGroup( "/MainWindow/Geometry" ); // read values settings.endGroup();
void QSettings::endGroup | ( | ) |
QStringList QSettings::entryList | ( | const QString & | ) | const |
QStringList QSettings::entryList | ( | const QString & | key | ) | const |
Returns a list of the keys which contain entries under key. Does not return any keys that contain subkeys.
Example settings:
/MyCompany/MyApplication/background color /MyCompany/MyApplication/foreground color /MyCompany/MyApplication/geometry/x /MyCompany/MyApplication/geometry/y /MyCompany/MyApplication/geometry/width /MyCompany/MyApplication/geometry/height
QStringList keys = settings.entryList( "/MyCompany/MyApplication" );
In the above example, keys
will contain 'background color' and 'foreground color'. It will not contain 'geometry' because this key contains subkeys not entries.
To access the geometry values, you could either use subkeyList() to read the keys then read each entry, or simply read each entry directly by specifying its full key, e.g. "/MyCompany/MyApplication/geometry/y".
QString QSettings::group | ( | ) | const |
Returns the current key prefix, or a null string if there is no key prefix set.
QString QSettings::group | ( | ) | const |
Inserts path into the settings search path. The semantics of path depends on the system s. It is usually easier and better to use setPath() instead of this function.
When s is Windows and the execution environment is not Windows the function does nothing. Similarly when s is Unix and the execution environment is not Unix the function does nothing.
When s is Windows, and the execution environment is Windows, the search path list will be used as the first subfolder of the "Software" folder in the registry.
When reading settings the folders are searched forwards from the first folder (listed below) to the last, returning the first settings found, and ignoring any folders for which the user doesn't have read permission. 1 HKEY_CURRENT_USER/Software/MyCompany/MyApplication HKEY_LOCAL_MACHINE/Software/MyCompany/MyApplication HKEY_CURRENT_USER/Software/MyApplication HKEY_LOCAL_MACHINE/Software/MyApplication
QSettings settings; settings.insertSearchPath( QSettings::Windows, "/MyCompany" ); settings.writeEntry( "/MyApplication/Tip of the day", TRUE );
The code above will write the subkey "Tip of the day" into the first of the registry folders listed below that is found and for which the user has write permission. 1 HKEY_LOCAL_MACHINE/Software/MyCompany/MyApplication HKEY_CURRENT_USER/Software/MyCompany/MyApplication HKEY_LOCAL_MACHINE/Software/MyApplication HKEY_CURRENT_USER/Software/MyApplication If a setting is found in the HKEY_CURRENT_USER space, this setting is overwritten independently of write permissions in the HKEY_LOCAL_MACHINE space.
When s is Unix, and the execution environment is Unix, the search path list will be used when trying to determine a suitable filename for reading and writing settings files. By default, there are two entries in the search path:
1 SYSCONF
- where SYSCONF
is a directory specified when configuring Qt; by default it is INSTALL/etc/settings. $HOME/
.qt/ - where $HOME
is the user's home directory.
All insertions into the search path will go before $HOME/.qt/. For example:
QSettings settings; settings.insertSearchPath( QSettings::Unix, "/opt/MyCompany/share/etc" ); settings.insertSearchPath( QSettings::Unix, "/opt/MyCompany/share/MyApplication/etc" ); // ...
Will result in a search path of: 1 SYSCONF /opt/MyCompany/share/etc /opt/MyCompany/share/MyApplication/etc $HOME/.qt When reading settings the files are searched in the order shown above, with later settings overriding earlier settings. Files for which the user doesn't have read permission are ignored. When saving settings QSettings works in the order shown above, writing to the first settings file for which the user has write permission.
Note that paths in the file system are not created by this function, so they must already exist to be useful.
Settings under Unix are stored in files whose names are based on the first subkey of the key (not including the search path). The algorithm for creating names is essentially: lowercase the first subkey, replace spaces with underscores and add 'rc', e.g. /MyCompany/MyApplication/background color
will be stored in myapplicationrc
(assuming that /MyCompany
is part of the search path).
bool QSettings::readBoolEntry | ( | const QString & | key, |
bool | def = FALSE , |
||
bool * | ok = 0 |
||
) | const [inline] |
Reads the entry specified by key, and returns a bool, or the default value, def, if the entry couldn't be read. If ok is non-null, *ok is set to TRUE if the key was read, FALSE otherwise.
bool QSettings::readBoolEntry | ( | const QString & | key, |
bool | def = FALSE , |
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bool * | ok = 0 |
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) | const [inline] |
double QSettings::readDoubleEntry | ( | const QString & | key, |
double | def = 0 , |
||
bool * | ok = 0 |
||
) | const [inline] |
Reads the entry specified by key, and returns a double, or the default value, def, if the entry couldn't be read. If ok is non-null, *ok is set to TRUE if the key was read, FALSE otherwise.
double QSettings::readDoubleEntry | ( | const QString & | key, |
double | def = 0 , |
||
bool * | ok = 0 |
||
) | const [inline] |
QString QSettings::readEntry | ( | const QString & | key, |
const QString & | def = QString::null , |
||
bool * | ok = 0 |
||
) | const [inline] |
Reads the entry specified by key, and returns a QString, or the default value, def, if the entry couldn't be read. If ok is non-null, *ok is set to TRUE if the key was read, FALSE otherwise.
QString QSettings::readEntry | ( | const QString & | , |
const QString & | def = QString::null , |
||
bool * | = 0 |
||
) |
QString QSettings::readEntry | ( | const QString & | key, |
const QString & | def = QString::null , |
||
bool * | ok = 0 |
||
) | const [inline] |
QString QSettings::readEntry | ( | const QString & | key, |
const QString & | def = QString::null , |
||
bool * | ok = 0 |
||
) |
QStringList QSettings::readListEntry | ( | const QString & | key, |
const QChar & | separator, | ||
bool * | ok = 0 |
||
) | const [inline] |
Esta es una función miembro sobrecargada que se suministra por conveniencia. Difiere de la anterior función solamente en los argumentos que acepta.
Reads the entry specified by key as a string. The separator is used to create a QStringList by calling QStringList::split(separator, entry). If ok is not 0: *ok is set to TRUE if the key was read, otherwise *ok is set to FALSE.
Note that if you want to iterate over the list, you should iterate over a copy, e.g.
QStringList list = mySettings.readListEntry( "size", " " ); QStringList::Iterator it = list.begin(); while( it != list.end() ) { myProcessing( *it ); ++it; }
QStringList QSettings::readListEntry | ( | const QString & | key, |
bool * | ok = 0 |
||
) |
QStringList QSettings::readListEntry | ( | const QString & | key, |
bool * | ok = 0 |
||
) | const [inline] |
Reads the entry specified by key as a string. If ok is not 0, *ok is set to TRUE if the key was read, otherwise *ok is set to FALSE.
Note that if you want to iterate over the list, you should iterate over a copy, e.g.
QStringList list = mySettings.readListEntry( "recentfiles" ); QStringList::Iterator it = list.begin(); while( it != list.end() ) { myProcessing( *it ); ++it; }
QStringList QSettings::readListEntry | ( | const QString & | , |
bool * | = 0 |
||
) |
QStringList QSettings::readListEntry | ( | const QString & | , |
const QChar & | sep, | ||
bool * | = 0 |
||
) |
QStringList QSettings::readListEntry | ( | const QString & | key, |
const QChar & | sep, | ||
bool * | ok = 0 |
||
) |
QStringList QSettings::readListEntry | ( | const QString & | key, |
bool * | ok = 0 |
||
) | const [inline] |
QStringList QSettings::readListEntry | ( | const QString & | key, |
const QChar & | sep, | ||
bool * | ok = 0 |
||
) | const [inline] |
Reads the entry specified by key, and returns an integer, or the default value, def, if the entry couldn't be read. If ok is non-null, *ok is set to TRUE if the key was read, FALSE otherwise.
Removes the entry specified by key.
Returns true if the entry was successfully removed; otherwise returns false. Note that removing the last entry in any given folder, will also remove the folder.
Removes all occurrences of path (using exact matching) from the settings search path for system s. Note that the default search paths cannot be removed.
void QSettings::resetGroup | ( | ) |
Set the current key prefix to the empty string.
void QSettings::resetGroup | ( | ) |
Insert platform-dependent paths from platform-independent information.
The domain should be an Internet domain name controlled by the producer of the software, eg. Trolltech products use "trolltech.com".
The product should be the official name of the product.
The scope should be QSettings::User for user-specific settings, or QSettings::Global for system-wide settings (generally these will be read-only to many users).
Not all information is relevant on all systems.
QStringList QSettings::subkeyList | ( | const QString & | ) | const |
QStringList QSettings::subkeyList | ( | const QString & | key | ) | const |
Returns a list of the keys which contain subkeys under key. Does not return any keys that contain entries.
Example settings:
/MyCompany/MyApplication/background color /MyCompany/MyApplication/foreground color /MyCompany/MyApplication/geometry/x /MyCompany/MyApplication/geometry/y /MyCompany/MyApplication/geometry/width /MyCompany/MyApplication/geometry/height /MyCompany/MyApplication/recent files/1 /MyCompany/MyApplication/recent files/2 /MyCompany/MyApplication/recent files/3
QStringList keys = settings.subkeyList( "/MyCompany/MyApplication" );
In the above example, keys
will contain 'geometry' and 'recent files'. It will not contain 'background color' or 'foreground color' because those keys contain entries not subkeys. To get a list of keys that contain entries rather than subkeys use entryList() instead.
subkeyList("/MyCompany")
/MyCompany/MyApplication/background color
bool QSettings::sync | ( | ) |
bool QSettings::sync | ( | ) |
bool QSettings::writeEntry | ( | const QString & | key, |
const QStringList & | value | ||
) |
Esta es una función miembro sobrecargada que se suministra por conveniencia. Difiere de la anterior función solamente en los argumentos que acepta. Writes the string list entry value into key key. The key is created if it doesn't exist. Any previous value is overwritten by value.
If an error occurs the settings are left unchanged and FALSE is returned; otherwise returns TRUE.
Esta es una función miembro sobrecargada que se suministra por conveniencia. Difiere de la anterior función solamente en los argumentos que acepta. Writes the integer entry value into key key. The key is created if it doesn't exist. Any previous value is overwritten by value.
If an error occurs the settings are left unchanged and FALSE is returned; otherwise TRUE is returned.
Esta es una función miembro sobrecargada que se suministra por conveniencia. Difiere de la anterior función solamente en los argumentos que acepta. Writes the string entry value into key key. The key is created if it doesn't exist. Any previous value is overwritten by value. If value is an empty string or a null string the key's value will be an empty string.
If an error occurs the settings are left unchanged and FALSE is returned; otherwise TRUE is returned.
bool QSettings::writeEntry | ( | const QString & | key, |
const QStringList & | value, | ||
const QChar & | separator | ||
) |
Esta es una función miembro sobrecargada que se suministra por conveniencia. Difiere de la anterior función solamente en los argumentos que acepta.
Writes the string list entry value into key key. The key is created if it doesn't exist. Any previous value is overwritten by value. The list is stored as a sequence of strings separated by separator (using QStringList::join()), so none of the strings in the list should contain the separator. If the list is empty or null the key's value will be an empty string.
If an error occurs the settings are left unchanged and FALSE is returned; otherwise returns TRUE.
bool QSettings::writeEntry | ( | const QString & | , |
const QStringList & | , | ||
const QChar & | sep | ||
) |
bool QSettings::writeEntry | ( | const QString & | , |
const QStringList & | |||
) |
Writes the boolean entry value into key key. The key is created if it doesn't exist. Any previous value is overwritten by value.
If an error occurs the settings are left unchanged and FALSE is returned; otherwise TRUE is returned.
Esta es una función miembro sobrecargada que se suministra por conveniencia. Difiere de la anterior función solamente en los argumentos que acepta. Writes the double entry value into key key. The key is created if it doesn't exist. Any previous value is overwritten by value.
If an error occurs the settings are left unchanged and FALSE is returned; otherwise TRUE is returned.
QApplication [friend] |