Qt 4.0: QKeySequence Class Reference

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# QKeySequence Class Reference
[QtGui module]

The QKeySequence class encapsulates a key sequence as used by shortcuts. More...

    #include <QKeySequence>

- List of all members, including inherited members
- Obsolete members

### Public Types

- enum SequenceMatch { NoMatch, PartialMatch, ExactMatch }

### Public Functions

- QKeySequence ()
- QKeySequence ( const QString & key )
- QKeySequence ( int k1, int k2 = 0, int k3 = 0, int k4 = 0 )
- QKeySequence ( const QKeySequence & keysequence )
- ~QKeySequence ()
- uint count () const
- bool isEmpty () const
- SequenceMatch matches ( const QKeySequence & seq ) const
- operator QString () const
- operator QVariant () const
- bool operator!= ( const QKeySequence & other ) const
- bool operator< ( const QKeySequence & other ) const
- bool operator<= ( const QKeySequence & other ) const
- QKeySequence & operator= ( const QKeySequence & other )
- bool operator== ( const QKeySequence & other ) const
- bool operator> ( const QKeySequence & other ) const
- bool operator>= ( const QKeySequence & other ) const
- int operator[] ( uint index ) const

### Static Public Members

- QKeySequence mnemonic ( const QString & text )

### Related Non-Members

- QDataStream & operator<< ( QDataStream & stream, const QKeySequence & sequence )
- QDataStream & operator>> ( QDataStream & stream, QKeySequence & sequence )

## Detailed Description

The QKeySequence class encapsulates a key sequence as used by shortcuts.

A key sequence consists of up to four keyboard codes, each optionally combined with modifiers, such as Qt::SHIFT, Qt::CTRL, Qt::ALT or Qt::META. For example, Qt::CTRL + Qt::Key_P might be a sequence used as a shortcut for printing a document. Valid codes for keys and modifiers are listed in Qt::Key and Qt::Modifier. As an alternative, use the unicode code point of the character; for example, 'A' gives the same key sequence as Qt::Key_A.

Key sequences can be constructed either from an integer key code, or from a human readable translatable string such as "Ctrl+X,Alt+Space". A key sequence can be cast to a QString to obtain a human readable translated version of the sequence. Translations are done in the "QShortcut" context.

See also QShortcut.

## Member Type Documentation

### enum QKeySequence::SequenceMatch

Constant | Value | Description
--- | --- | ---
`QKeySequence::NoMatch` | `0` | The key sequences are different; not even partially matching.
`QKeySequence::PartialMatch` | `1` | The key sequences match partially, but are not the same.
`QKeySequence::ExactMatch` | `2` | The key sequences are the same.

## Member Function Documentation

### QKeySequence::QKeySequence ()

Constructs an empty key sequence.

### QKeySequence::QKeySequence ( const QString & key )

Creates a key sequence from the key string. For example "Ctrl+O" gives CTRL+'O'. The strings "Ctrl", "Shift", "Alt" and "Meta" are recognized, as well as their translated equivalents in the "QShortcut" context (using QObject::tr()).

Up to four key codes may be entered by separating them with commas, e.g. "Alt+X,Ctrl+S,Q".

This contructor is typically used with tr(), so that shortcut keys can be replaced in translations:

        QMenu *file = new QMenu(this);
        file->addAction(tr("&Open..."), this, SLOT(open()),
                          QKeySequence(tr("Ctrl+O", "File|Open")));

Note the "File|Open" translator comment. It is by no means necessary, but it provides some context for the human translator.

### QKeySequence::QKeySequence ( int k1, int k2 = 0, int k3 = 0, int k4 = 0 )

Constructs a key sequence with up to 4 keys k1, k2, k3 and k4.

The key codes are listed in Qt::Key and can be combined with modifiers (see Qt::Modifier) such as Qt::SHIFT, Qt::CTRL, Qt::ALT, or Qt::META.

### QKeySequence::QKeySequence ( const QKeySequence & keysequence )

Copy constructor. Makes a copy of keysequence.

### QKeySequence::~QKeySequence ()

Destroys the key sequence.

### uint QKeySequence::count () const

Returns the number of keys in the key sequence. The maximum is 4.

### bool QKeySequence::isEmpty () const

Returns true if the key sequence is empty; otherwise returns false.

### SequenceMatch QKeySequence::matches ( const QKeySequence & seq ) const

Matches the sequence with seq. Returns ExactMatch if successful, PartialMatch if seq matches incompletely, and NoMatch if the sequences have nothing in common. Returns NoMatch if seq is shorter.

### QKeySequence QKeySequence::mnemonic ( const QString & text ) `[static]`

Returns the shortcut key sequence for the mnemonic in text, or an empty key sequence if no mnemonics are found.

For example, mnemonic("E&xit") returns `Qt::ALT+Qt::Key_X`, mnemonic("&Quit") returns `ALT+Key_Q`, and mnemonic("Quit") returns an empty QKeySequence.

We provide a list of common mnemonics in English. At the time of writing, Microsoft and Open Group do not appear to have issued equivalent recommendations for other languages.

### QKeySequence::operator QString () const

Creates a shortcut string for the key sequence.

For example, the value Qt::CTRL+Qt::Key_O results in "Ctrl+O". If the key sequence has multiple key codes, each is separated by commas in the string returned, such as "Alt+X, Ctrl+Y, Z". The strings, "Ctrl", "Shift", etc. are translated using QObject::tr() in the "QShortcut" scope.

If the key sequence has no keys, an empty string is returned.

On Mac OS X, the string returned resembles the sequence that is shown in the menubar.

### QKeySequence::operator QVariant () const

Returns the key sequence as a QVariant

### bool QKeySequence::operator!= ( const QKeySequence & other ) const

Returns true if this key sequence is not equal to the other key sequence; otherwise returns false.

### bool QKeySequence::operator< ( const QKeySequence & other ) const

Provides an arbitrary comparison of this key sequence and other key sequence. All that is guaranteed is that the operator returns false if both key sequences are equal and that (ks1 < ks2) == !( ks2 < ks1) if the key sequences are not equal.

This function is useful in some circumstances, for example if you want to use QKeySequence objects as keys in a QMap.

See also operator==(), operator!=(), operator>(), operator<=(), and operator>=().

### bool QKeySequence::operator<= ( const QKeySequence & other ) const

Returns true if this key sequence is smaller or equal to the other key sequence; otherwise returns false.

See also operator==(), operator!=(), operator<(), operator>(), and operator>=().

### QKeySequence & QKeySequence::operator= ( const QKeySequence & other )

Assignment operator. Assigns the other key sequence to this object.

### bool QKeySequence::operator== ( const QKeySequence & other ) const

Returns true if this key sequence is equal to the other key sequence; otherwise returns false.

### bool QKeySequence::operator> ( const QKeySequence & other ) const

Returns true if this key sequence is larger than the other key sequence; otherwise returns false.

See also operator==(), operator!=(), operator<(), operator<=(), and operator>=().

### bool QKeySequence::operator>= ( const QKeySequence & other ) const

Returns true if this key sequence is larger or equal to the other key sequence; otherwise returns false.

See also operator==(), operator!=(), operator<(), operator>(), and operator<=().

### int QKeySequence::operator[] ( uint index ) const

Returns a reference to the element at position index in the key sequence. This can only be used to read an element.

## Related Non-Members

### QDataStream & operator<< ( QDataStream & stream, const QKeySequence & sequence )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Writes the key sequence to the stream.

See also Format of the QDataStream operators.

### QDataStream & operator>> ( QDataStream & stream, QKeySequence & sequence )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Reads a key sequence from the stream into the key sequence.

See also Format of the QDataStream operators.