QKeyEvent Class Reference

Detailed Description

Key events occur when a key is pressed or released when a widget has keyboard input focus.

A key event contains a special accept flag that indicates whether the receiver wants the key event. You should call QKeyEvent::ignore() if the key press or release event is not handled by your widget. A key event is propagated up the parent widget chain until a widget accepts it with QKeyEvent::accept() or an event filter consumes it. Key events for multi media keys are ignored by default. You should call QKeyEvent::accept() if your widget handles those events.

The QWidget::setEnable() function can be used to enable or disable mouse and keyboard events for a widget.

The event handlers QWidget::keyPressEvent() and QWidget::keyReleaseEvent() receive key events.

See also QFocusEvent, QWidget::grabKeyboard(), and Event Classes.

Member Function Documentation

QKeyEvent::QKeyEvent ( Type type, int key, int ascii, int state, const QString & text = QString::null, bool autorep = FALSE, ushort count = 1 )

Constructs a key event object.

The type parameter must be QEvent::KeyPress or QEvent::KeyRelease. If key is 0 the event is not a result of a known key (e.g. it may be the result of a compose sequence or keyboard macro). ascii is the ASCII code of the key that was pressed or released. state holds the keyboard modifiers. text is the Unicode text that the key generated. If autorep is TRUE, isAutoRepeat() will be TRUE. count is the number of single keys.

The accept flag is set to TRUE.

void QKeyEvent::accept ()

Sets the accept flag of the key event object.

Setting the accept parameter indicates that the receiver of the event wants the key event. Unwanted key events are sent to the parent widget.

The accept flag is set by default.

See also ignore().

int QKeyEvent::ascii () const

Returns the ASCII code of the key that was pressed or released. We recommend using text() instead.

See also text().

Example: picture/picture.cpp.

int QKeyEvent::count () const

Returns the number of single keys for this event. If text() is not empty, this is simply the length of the string.

See also QWidget::setKeyCompression().

void QKeyEvent::ignore ()

Clears the accept flag parameter of the key event object.

Clearing the accept parameter indicates that the event receiver does not want the key event. Unwanted key events are sent to the parent widget.

The accept flag is set by default.

See also accept().

bool QKeyEvent::isAccepted () const

Returns TRUE if the receiver of the event wants to keep the key; otherwise returns FALSE

bool QKeyEvent::isAutoRepeat () const

Returns TRUE if this event comes from an auto-repeating key and FALSE if it comes from an initial key press.

Note that if the event is a multiple-key compressed event that is partly due to auto-repeat, this function could return either TRUE or FALSE indeterminately.

int QKeyEvent::key () const

Returns the code of the key that was pressed or released.

See Qt::Key for the list of keyboard codes. These codes are independent of the underlying window system.

A value of either 0 or Key_unknown means that the event is not the result of a known key (e.g. it may be the result of a compose sequence or a keyboard macro, or due to key event compression).

See also QWidget::setKeyCompression().

Example: fileiconview/qfileiconview.cpp.

ButtonState QKeyEvent::state () const

Returns the keyboard modifier flags that existed immediately before the event occurred.

The returned value is ShiftButton, ControlButton, AltButton and MetaButton OR'ed together.

See also stateAfter().

Example: fileiconview/qfileiconview.cpp.

ButtonState QKeyEvent::stateAfter () const

Returns the keyboard modifier flags that existed immediately after the event occurred.

Warning: This function cannot be trusted.

See also state().

QString QKeyEvent::text () const

Returns the Unicode text that this key generated. The text returned migth be text().isNull == TRUE, which is the case when pressing or releasing modifying keys as Shift, Control, Alt and Meta. In these cases key() will contain a valid value.

See also QWidget::setKeyCompression().

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