Qt 4.8: QWSServer Class Reference

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# QWSServer Class Reference

The QWSServer class encapsulates a server process in Qt for Embedded Linux. More...

     #include <QWSServer>

Inherits: QObject.

- List of all members, including inherited members
- Obsolete members
- Qt 3 support members

## Public Types

class | KeyboardFilter
enum | IMMouse { MousePress, MouseRelease, MouseMove, MouseOutside }
enum | WindowEvent { Create, Destroy, Hide, Show, ..., Name }

## Public Functions

const QBrush & | backgroundBrush () const
const QList<QWSWindow *> & | clientWindows ()
void | closeKeyboard ()
void | closeMouse ()
void | enablePainting ( bool enable )
void | openKeyboard ()
void | openMouse ()
void | refresh ()
void | refresh ( QRegion & region )
void | resumeMouse ()
void | sendIMEvent ( const QInputMethodEvent * event )
void | sendIMQuery ( int property )
void | suspendMouse ()
QWSWindow * | windowAt ( const QPoint & position )

- 29 public functions inherited from QObject

## Signals

void | markedText ( const QString & selection )
void | newChannel ( const QString & channel )
void | removedChannel ( const QString & channel )
void | windowEvent ( QWSWindow * window, QWSServer::WindowEvent eventType )

- 1 signal inherited from QObject

## Static Public Members

void | addKeyboardFilter ( KeyboardFilter * filter )
QWSServer * | instance ()
bool | isCursorVisible ()
QWSKeyboardHandler * | keyboardHandler ()
QWSMouseHandler * | mouseHandler ()
const QList<QWSMouseHandler *> & | mouseHandlers ()
void | processKeyEvent ( int unicode, int keycode, Qt::KeyboardModifiers modifiers, bool isPress, bool autoRepeat )
void | removeKeyboardFilter ()
void | screenSaverActivate ( bool activate )
bool | screenSaverActive ()
void | sendKeyEvent ( int unicode, int keycode, Qt::KeyboardModifiers modifiers, bool isPress, bool autoRepeat )
void | setBackground ( const QBrush & brush )
void | setCurrentInputMethod ( QWSInputMethod * method )
void | setCursorVisible ( bool visible )
void | setDefaultKeyboard ( const char * keyboardDriver )
void | setDefaultMouse ( const char * mouseDriver )
void | setKeyboardHandler ( QWSKeyboardHandler * driver )
void | setMaxWindowRect ( const QRect & rectangle )
void | setMouseHandler ( QWSMouseHandler * driver )
void | setScreenSaver ( QWSScreenSaver * screenSaver )
void | setScreenSaverBlockLevel ( int eventBlockLevel )
void | setScreenSaverInterval ( int milliseconds )
void | setScreenSaverIntervals ( int * intervals )

- 7 static public members inherited from QObject

### Additional Inherited Members

- 1 property inherited from QObject
- 1 public slot inherited from QObject
- 8 protected functions inherited from QObject

## Detailed Description

The QWSServer class encapsulates a server process in Qt for Embedded Linux.

When you run a Qt for Embedded Linux application, it either runs as a server or connects to an existing server. The server and client processes have different responsibilities: The client process performs all application specific operations. The server process is responsible for managing the clients as well as taking care of the pointer handling, character input, and screen output. In addition, the server provides functionality to handle input methods.

In Qt for Embedded Linux, all system generated events are passed to the server application which then propagates the event to the appropriate client. See the Qt for Embedded Linux Architecture documentation for details.

Note that this class is instantiated by QApplication for Qt for Embedded Linux server processes; you should never construct this class yourself. Use the instance() function to retrieve a pointer to the server object.

Note that the static functions of the QWSServer class can only be used in the server process.

### Client Administration

As applications add and remove windows, the server process maintains information about each window. In Qt for Embedded Linux, top-level windows are encapsulated as QWSWindow objects. Each window can tell which client that owns it through its QWSWindow::client() function. Use the clientWindows() function to retrieve a list of the current top-level windows. Given a particular position on the display, the window containing it can be retrieved using the windowAt() function.

QWSServer also provides the windowEvent() signal which is emitted whenever something happens to a top level window; the WindowEvent enum describes the various types of events that the signal recognizes. In addition, the server class provides the markedText() signal which is emitted whenever some text has been selected in any of the windows, passing the selection as parameter.

The QCopChannel class and the QCOP communication protocol enable transfer of messages between clients. QWSServer provides the newChannel() and removedChannel() signals that is emitted whenever a new QCopChannel object is created or destroyed, respectively.

See also: QWSWindow, QWSClient and QCopChannel.

### Mouse Handling

The mouse driver (represented by an instance of the QWSMouseHandler class) is loaded by the server application when it starts running, using Qt's plugin system. A mouse driver receives mouse events from the device and encapsulates each event with an instance of the QWSEvent class which it then passes to the server.

The openMouse() function opens the mouse devices specified by the QWS_MOUSE_PROTO environment variable, and the setMouseHandler() functions sets the primary mouse driver. Alternatively, the static setDefaultMouse() function provides means of specifying the mouse driver to use if the QWS_MOUSE_PROTO variable is not defined (note that the default is otherwise platform dependent). The primary mouse driver can be retrieved using the static mouseHandler() function. Use the closeMouse() function to delete the mouse drivers.

In addition, the QWSServer class can control the flow of mouse input using the suspendMouse() and resumeMouse() functions.

See also: QWSMouseHandler and Qt for Embedded Linux Pointer Handling.

### Keyboard Handling

The keyboard driver (represented by an instance of the QWSKeyboardHandler class) is loaded by the server application when it starts running, using Qt's plugin system. A keyboard driver receives keyboard events from the device and encapsulates each event with an instance of the QWSEvent class which it then passes to the server.

The openKeyboard() function opens the keyboard devices specified by the QWS_KEYBOARD environment variable, and the setKeyboardHandler() functions sets the primary keyboard driver. Alternatively, the static setDefaultKeyboard() function provides means of specifying the keyboard driver to use if the QWS_KEYBOARD variable is not defined (note again that the default is otherwise platform dependent). The primary keyboard driver can be retrieved using the static keyboardHandler() function. Use the closeKeyboard() function to delete the keyboard drivers.

In addition, the QWSServer class can handle key events from both physical and virtual keyboards using the processKeyEvent() and sendKeyEvent() functions, respectively. Use the addKeyboardFilter() function to filter the key events from physical keyboard drivers, the most recently added filter can be removed and deleted using the removeKeyboardFilter() function.

See also: QWSKeyboardHandler and Qt for Embedded Linux Character Input.

### Display Handling

When a screen update is required, the server runs through all the top-level windows that intersect with the region that is about to be updated, and ensures that the associated clients have updated their memory buffer. Then the server uses the screen driver (represented by an instance of the QScreen class) to copy the content of the memory to the screen.

In addition, the QWSServer class provides some means of managing the screen output: Use the refresh() function to refresh the entire display, or alternatively a specified region of it. The enablePainting() function can be used to disable (and enable) painting onto the screen. QWSServer also provide the setMaxWindowRect() function restricting the area of the screen which Qt for Embedded Linux applications will consider to be the maximum area to use for windows. To set the brush used as the background in the absence of obscuring windows, QWSServer provides the static setBackground() function. The corresponding backgroundBrush() function returns the currently set brush.

QWSServer also controls the screen saver: Use the setScreenSaver() to install a custom screen saver derived from the QWSScreenSaver class. Once installed, the screensaver can be activated using the screenSaverActivate() function, and the screenSaverActive() function returns its current status. Use the setScreenSaverInterval() function to specify the timeout interval. Qt for Embedded Linux also supports multilevel screen saving, use the setScreenSaverIntervals() function to specify the various levels and their timeout intervals.

Finally, the QWSServer class controls the cursor's appearance, i.e., use the setCursorVisible() function to hide or show the cursor, and the isCursorVisible() function to determine whether the cursor is visible on the display or not.

See also: QScreen and Qt for Embedded Linux Display Management.

### Input Method Handling

Whenever the server receives an event, it queries its stack of top-level windows to find the window containing the event's position (each window can identify the client application that created it). Then the server forwards the event to the appropriate client. If an input method is installed, it is used as a filter between the server and the client application.

Derive from the QWSInputMethod class to create custom input methods, and use the server's setCurrentInputMethod() function to install it. Use the sendIMEvent() and sendIMQuery() functions to send input method events and queries.

QWSServer provides the IMMouse enum describing the various mouse events recognized by the QWSInputMethod::mouseHandler() function. The latter function allows subclasses of QWSInputMethod to handle mouse events within the preedit text.

See also QWSInputMethod.

## Member Type Documentation

### enum QWSServer::IMMouse

This enum describes the various types of mouse events recognized by the QWSInputMethod::mouseHandler() function.

Constant | Value | Description
--- | --- | ---
`QWSServer::MousePress` | `0` | An event generated by pressing a mouse button.
`QWSServer::MouseRelease` | `1` | An event generated by relasing a mouse button.
`QWSServer::MouseMove` | `2` | An event generated by moving the mouse cursor.
`QWSServer::MouseOutside` | `3` | This value is only reserved, i.e., it is not used in current implementations.

See also QWSInputMethod and setCurrentInputMethod().

### enum QWSServer::WindowEvent

This enum specifies the various events that can occur in a top-level window.

Constant | Value | Description
--- | --- | ---
`QWSServer::Create` | `0x0001` | A new window has been created (by the QWidget constructor).
`QWSServer::Destroy` | `0x0002` | The window has been closed and deleted (by the QWidget destructor).
`QWSServer::Hide` | `0x0004` | The window has been hidden using the QWidget::hide() function.
`QWSServer::Show` | `0x0008` | The window has been shown using the QWidget::show() function or similar.
`QWSServer::Raise` | `0x0010` | The window has been raised to the top of the desktop.
`QWSServer::Lower` | `0x0020` | The window has been lowered.
`QWSServer::Geometry` | `0x0040` | The window has changed size or position.
`QWSServer::Active` | `0x0080` | The window has become the active window (i.e., it has keyboard focus).
`QWSServer::Name` | `0x0100` | The window has been named.

See also windowEvent().

## Member Function Documentation

### void QWSServer::addKeyboardFilter ( KeyboardFilter * filter )`[static]`

Activates the given keyboard filter all key events generated by physical keyboard drivers (i.e., events sent using the processKeyEvent() function).

Note that the filter is not invoked for keys generated by virtual keyboard drivers (i.e., events sent using the sendKeyEvent() function).

Note that this function can only be used in the server process.

See also removeKeyboardFilter().

### const QBrush & QWSServer::backgroundBrush () const

Returns the brush used as background in the absence of obscuring windows.

See also setBackground().

### const QList<QWSWindow *> & QWSServer::clientWindows ()

Returns the list of current top-level windows.

Note that the collection of top-level windows changes as applications add and remove widgets so it should not be stored for future use. The windows are sorted in stacking order from top-most to bottom-most.

Use the QWSWindow::client() function to retrieve the client application that owns a given window.

See also windowAt() and instance().

### void QWSServer::closeKeyboard ()

Closes all the keyboard devices (specified by the QWS_KEYBOARD environment variable) by deleting the associated keyboard drivers.

See also openKeyboard() and keyboardHandler().

### void QWSServer::closeMouse ()

Closes all pointer devices (specified by the QWS_MOUSE_PROTO environment variable) by deleting the associated mouse drivers.

See also openMouse() and mouseHandler().

### void QWSServer::enablePainting ( bool enable )

Enables painting onto the screen if enable is true; otherwise painting is disabled.

See also Qt for Embedded Linux Architecture.

### QWSServer * QWSServer::instance ()`[static]`

Returns a pointer to the server instance.

Note that the pointer will be 0 if the application is not the server, i.e., if the QApplication::type() function doesn't return QApplication::GuiServer.

This function was introduced in Qt 4.2.

See also clientWindows() and windowAt().

### bool QWSServer::isCursorVisible ()`[static]`

Returns true if the cursor is visible; otherwise returns false.

Note that this function can only be used in the server process.

See also setCursorVisible().

### QWSKeyboardHandler * QWSServer::keyboardHandler ()`[static]`

Returns the primary keyboard driver.

Note that this function can only be used in the server process.

See also setKeyboardHandler(), openKeyboard(), and closeKeyboard().

### void QWSServer::markedText ( const QString & selection )`[signal]`

This signal is emitted whenever some text is selected in any of the running applications, passing the selected text in the selection parameter.

See also windowEvent().

### QWSMouseHandler * QWSServer::mouseHandler ()`[static]`

Returns the primary mouse driver.

Note that this function can only be used in the server process.

See also setMouseHandler(), openMouse(), and closeMouse().

### const QList<QWSMouseHandler *> & QWSServer::mouseHandlers ()`[static]`

Returns list of all mouse handlers

Note that this function can only be used in the server process.

This function was introduced in Qt 4.5.

See also mouseHandler(), setMouseHandler(), openMouse(), and closeMouse().

### void QWSServer::newChannel ( const QString & channel )`[signal]`

This signal is emitted whenever a new QCopChannel object is created, passing the channel's name in the channel parameter.

See also removedChannel().

### void QWSServer::openKeyboard ()

Opens the keyboard devices specified by the QWS_KEYBOARD environment variable.

See also closeKeyboard() and keyboardHandler().

### void QWSServer::openMouse ()

Opens the mouse devices specified by the QWS_MOUSE_PROTO environment variable. Be advised that closeMouse() is called first to delete all the existing mouse handlers. This behaviour could be the cause of problems if you were not expecting it.

See also closeMouse() and mouseHandler().

### void QWSServer::processKeyEvent ( int unicode, int keycode, Qt::KeyboardModifiers modifiers, bool isPress, bool autoRepeat )`[static]`

Processes the given key event. The key is identified by its unicode value and the given keycode, modifiers, isPress and autoRepeat parameters.

The keycode parameter is the Qt keycode value as defined by the Qt::Key enum. The modifiers is an OR combination of Qt::KeyboardModifier values, indicating whether Shift/Alt/Ctrl keys are pressed. The isPress parameter is true if the event is a key press event and autoRepeat is true if the event is caused by an auto-repeat mechanism and not an actual key press.

This function is typically called internally by keyboard drivers. Note that this function can only be used in the server process.

See also sendKeyEvent() and Qt for Embedded Linux Character Input.

### void QWSServer::refresh ()

Refreshes the display by making the screen driver update the entire display.

See also QScreen::exposeRegion().

### void QWSServer::refresh ( QRegion & region )

This is an overloaded function.

Refreshes the given region of the display.

### void QWSServer::removeKeyboardFilter ()`[static]`

Removes and deletes the most recently added filter.

Note that the programmer is responsible for removing each added keyboard filter.

Note that this function can only be used in the server process.

See also addKeyboardFilter().

### void QWSServer::removedChannel ( const QString & channel )`[signal]`

This signal is emitted immediately after the given the QCopChannel object specified by channel, is destroyed.

Note that a channel is not destroyed until all its listeners have been unregistered.

See also newChannel().

### void QWSServer::resumeMouse ()

Resumes pointer handling by reactivating all the mouse drivers registered by the QWS_MOUSE_PROTO environment variable.

See also suspendMouse() and QWSMouseHandler::resume().

### void QWSServer::screenSaverActivate ( bool activate )`[static]`

Activates the screen saver if activate is true; otherwise it is deactivated.

Note that this function can only be used in the server process.

See also screenSaverActive() and setScreenSaver().

### bool QWSServer::screenSaverActive ()`[static]`

Returns true if the screen saver is active; otherwise returns false.

Note that this function can only be used in the server process.

See also screenSaverActivate().

### void QWSServer::sendIMEvent ( const QInputMethodEvent * event )

Sends the given input method event.

The `QInputMethodEvent` class is derived from QWSEvent, i.e., it is a QWSEvent object of the QWSEvent::IMEvent type.

If there is a window actively composing the preedit string, the event is sent to that window. Otherwise, the event is sent to the window currently in focus.

See also sendIMQuery() and QWSInputMethod::sendEvent().

### void QWSServer::sendIMQuery ( int property )

Sends an input method query for the given property.

To receive responses to input method queries, the virtual QWSInputMethod::queryResponse() function must be reimplemented in a QWSInputMethod subclass that is activated using the setCurrentInputMethod() function.

See also sendIMEvent() and setCurrentInputMethod().

### void QWSServer::sendKeyEvent ( int unicode, int keycode, Qt::KeyboardModifiers modifiers, bool isPress, bool autoRepeat )`[static]`

Sends the given key event. The key is identified by its unicode value and the given keycode, modifiers, isPress and autoRepeat parameters.

Use this function to send key events generated by "virtual keyboards" (note that the processKeyEvent() function is impelemented using this function).

The keycode parameter is the Qt keycode value as defined by the Qt::Key enum. The modifiers is an OR combination of Qt::KeyboardModifier values, indicating whether Shift/Alt/Ctrl keys are pressed. The isPress parameter is true if the event is a key press event and autoRepeat is true if the event is caused by an auto-repeat mechanism and not an actual key press.

Note that this function can only be used in the server process.

See also processKeyEvent() and Qt for Embedded Linux Character Input.

### void QWSServer::setBackground ( const QBrush & brush )`[static]`

Sets the brush used as background in the absence of obscuring windows, to be the given brush.

Note that this function can only be used in the server process.

See also backgroundBrush().

### void QWSServer::setCurrentInputMethod ( QWSInputMethod * method )`[static]`

Sets the current input method to be the given method.

Note that this function can only be used in the server process.

See also sendIMQuery() and sendIMEvent().

### void QWSServer::setCursorVisible ( bool visible )`[static]`

Shows the cursor if visible is true: otherwise the cursor is hidden.

Note that this function can only be used in the server process.

See also isCursorVisible().

### void QWSServer::setDefaultKeyboard ( const char * keyboardDriver )`[static]`

Sets the keyboard driver that will be used if the QWS_KEYBOARD environment variable is not defined, to be the given keyboardDriver.

Note that the default is platform-dependent. This function can only be used in the server process.

See also setKeyboardHandler() and Qt for Embedded Linux Character Input.

### void QWSServer::setDefaultMouse ( const char * mouseDriver )`[static]`

Sets the mouse driver that will be used if the QWS_MOUSE_PROTO environment variable is not defined, to be the given mouseDriver.

Note that the default is platform-dependent. This function can only be used in the server process.

See also setMouseHandler() and Qt for Embedded Linux Pointer Handling.

### void QWSServer::setKeyboardHandler ( QWSKeyboardHandler * driver )`[static]`

Sets the primary keyboard driver to be the given driver.

Qt for Embedded Linux provides several ready-made keyboard drivers, and custom drivers are typically added using Qt's plugin mechanism. See the Qt for Embedded Linux Character Input documentation for details.

Note that this function can only be used in the server process.

See also keyboardHandler() and setDefaultKeyboard().

### void QWSServer::setMaxWindowRect ( const QRect & rectangle )`[static]`

Sets the maximum area of the screen that Qt for Embedded Linux applications can use, to be the given rectangle.

Note that this function can only be used in the server process.

See also QWidget::showMaximized().

### void QWSServer::setMouseHandler ( QWSMouseHandler * driver )`[static]`

Sets the primary mouse driver to be the given driver.

Qt for Embedded Linux provides several ready-made mouse drivers, and custom drivers are typically added using Qt's plugin mechanism. See the Qt for Embedded Linux Pointer Handling documentation for details.

Note that this function can only be used in the server process.

See also mouseHandler() and setDefaultMouse().

### void QWSServer::setScreenSaver ( QWSScreenSaver * screenSaver )`[static]`

Installs the given screenSaver, deleting the current screen saver.

Note that this function can only be used in the server process.

See also screenSaverActivate(), setScreenSaverInterval(), setScreenSaverIntervals(), and setScreenSaverBlockLevel().

### void QWSServer::setScreenSaverBlockLevel ( int eventBlockLevel )`[static]`

Block the key or mouse event that wakes the system from level eventBlockLevel or higher. To completely disable event blocking (the default behavior), set eventBlockLevel to -1.

The algorithm blocks the "down", "up" as well as any "repeat" events for the same key but will not block other key events after the initial "down" event. For mouse events, the algorithm blocks all mouse events until an event with no buttons pressed is received.

There are 2 keys that are never blocked, Qt::Key_F34 (POWER) and Qt::Key_F35 (LIGHT).

Example usage:

     bool MyScreenSaver::save( int level )
     {
         switch ( level ) {
             case 0:
                 if ( dim_enabled ) {
                     // dim the screen
                 }
                 return true;
             case 1:
                 if ( screenoff_enabled ) {
                     // turn off the screen
                 }
                 return true;
             case 2:
                 if ( suspend_enabled ) {
                     // suspend
                 }
                 return true;
             default:
                 return false;
         }
     }

     ...

     int timings[4];
     timings[0] = 5000;  // dim after 5 seconds
     timings[1] = 10000; // light off after 15 seconds
     timings[2] = 45000; // suspend after 60 seconds
     timings[3] = 0;
     QWSServer::setScreenSaverIntervals( timings );

     // ignore the key/mouse event that turns on the screen
     int blocklevel = 1;
     if ( !screenoff_enabled ) {
         // screenoff is disabled, ignore the key/mouse event that wakes from suspend
         blocklevel = 2;
         if ( !suspend_enabled ) {
             // suspend is disabled, never ignore events
             blocklevel = -1;
         }
     }
     QWSServer::setScreenSaverBlockLevel( blocklevel );

Note that this function can only be used in the server process.

See also setScreenSaverIntervals() and setScreenSaverInterval().

### void QWSServer::setScreenSaverInterval ( int milliseconds )`[static]`

Sets the timeout interval for the screensaver to the specified milliseconds. To turn off the screensaver, set the timout interval to 0.

Note that this function can only be used in the server process.

See also setScreenSaverIntervals() and setScreenSaverBlockLevel().

### void QWSServer::setScreenSaverIntervals ( int * intervals )`[static]`

Specifies the time intervals (in milliseconds) between the different levels of screen responsiveness.

Qt for Embedded Linux supports multilevel screen saving, i.e., it is possible to specify several different levels of screen responsiveness by implementing the QWSScreenSaver::save() function. For example, you can choose to first turn off the light before you fully activate the screensaver. See the QWSScreenSaver documentation for details.

Note that an interval of 0 milliseconds will turn off the screensaver, and that the intervals array must be 0-terminated. This function can only be used in the server process.

See also setScreenSaverInterval() and setScreenSaverBlockLevel().

### void QWSServer::suspendMouse ()

Suspends pointer handling by deactivating all the mouse drivers registered by the QWS_MOUSE_PROTO environment variable.

See also resumeMouse() and QWSMouseHandler::suspend().

### QWSWindow * QWSServer::windowAt ( const QPoint & position )

Returns the window containing the given position.

Note that if there is no window under the specified point this function returns 0.

See also clientWindows() and instance().

### void QWSServer::windowEvent ( QWSWindow * window, QWSServer::WindowEvent eventType )`[signal]`

This signal is emitted whenever something happens to a top-level window (e.g., it's created or destroyed), passing a pointer to the window and the event's type in the window and eventType parameters, respectively.

See also markedText().