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= How to use Maemo 5 specific APIs from Qt application =

== Accelometer ==

=== Introduction ===

This section explains how to use the [[Accelerometers | accelerometer]] D-Bus interface in a Maemo 5 Qt application.

The following code examples are used in this section:
* [https://garage.maemo.org/svn/maemoexamples/trunk/qt-maemo-gravity-example/ qt-maemo-gravity-example]

=== D-Bus interface ===

It is up to each application how to organize interactions with the [http://maemo.org/api_refs/5.0/beta/mce-dev/ MCE] orientation interface. In [[Documentation/Maemo 5 Developer Guide/Porting Software/Porting Existing GTK+ Application to Maemo 5#Portrait Mode | some cases]] catching orientation signal can be enough, but if, e.g., more frequent updates are needed, you might want to use method calls, as demonstrated in our example.
We've moved D-Bus related functionality and orientation based calculations to a separate library that implements `DeviceOrientationNotifier' class. 
Our notifier asks MCE about orientation parameters with a certain period, 
 void DeviceOrientationNotifier::timerEvent(QTimerEvent *)
 {
   QDBusMessage msg = QDBusMessage::createMethodCall(MCE_SERVICE, MCE_REQUEST_PATH, MCE_REQUEST_IF, MCE_DEVICE_ORIENTATION_GET);
   bool sent = QDBusConnection::systemBus().callWithCallback(msg, this, SLOT(mceOrientationSlot(QString, QString, QString, int, int, int)));
 }
processes answers in `mceOrientationSlot', and emits data needed by the application with the following signal.
 void deviceOrientation(qreal pitch, qreal roll);

=== Example application ===

We've modified [http://qt.nokia.com/doc/4.5/graphicsview-collidingmice.html one of Qt4 Examples] in order to show how device orientation can be used.
In our case pitch and roll are scene's characteristics, so we've implemented a `SceneTuner', whose slot can be connected to an appropriate signal in order to setup these scene properties.
 DeviceOrientationNotifier notifier(100);
 SceneTuner tuner(&scene, TimerInterval);
 QObject::connect(&notifier, SIGNAL(deviceOrientation(qreal, qreal)), &tuner, SLOT(setProps(qreal, qreal)));
Based on that each mouse can take into account the gravity effect, see `Mouse::advance' for details.

== Using Zoom In and Zoom Out keys ==

This section uses the same qt-maemo-gravity-example to explain how to use Zoom In and Out keys in a Qt application. They are used to set the application window to fullscreen and normal modes like in the GTK+ example [[Documentation/Maemo 5 Developer Guide/Porting Software/Porting Existing GTK+ Application to Maemo 5|Maemo Sliders]].

First, the keys are released from maemo-status-volume by using <code>XChangeProperty()</code>.

hardkeyhandler.cpp:
 void HardkeyHandler::grabIncreaseDecreaseKeys(QWidget* window, bool grab)
 {
     // Tell maemo-status-volume to grab/ungrab increase/decrease keys
     unsigned long val = (grab==true)?1:0;
     Atom atom;
     atom = XInternAtom( QX11Info::display(), "_HILDON_ZOOM_KEY_ATOM", 0);
     XChangeProperty (QX11Info::display(),
                      window->winId(),
                      atom,
                      XA_INTEGER,
                      32,
                      PropModeReplace,
                      (unsigned char *) &val,
                      1);
 }

Next, a handler for keypresses is created. 73 and 74 are the keycodes for F7/F8 in the SDK and Zoom In/Out buttons in the device. Handler functions emit corresponding signals when called.

hardkeyhandler.cpp
 bool HardkeyHandler::processX11Event(XEvent* event)
 {
     if ( event->type == KeyPress )
     {
         if (event->xkey.keycode == 73 || event->xkey.keycode == QKeySequence::ZoomOut)
         {
             emit decreaseKeyPressed();
             return true;
         } 
         else if (event->xkey.keycode == 74  || event->xkey.keycode ==  QKeySequence::ZoomIn)
         {
             emit increaseKeyPressed();
             return true;
         }
     }
 
     return false;
 }

Signals need slots, of course. They are located to myapplication.h and myapplication.cpp files. Here changing to fullscreen and back are done by <code>showFullScreen()</code> and <code>showNormal()</code>.

myapplication.cpp
 void MyApplication::increaseKeyPressed()
 {
     qDebug("MyApplication::increaseKeyPressed");
     view.showFullScreen();
 
 }
 
 void MyApplication::decreaseKeyPressed()
 {
     qDebug("MyApplication::decreaseKeyPressed");
     view.showNormal();
 }

The new signals are connected to corresponding slots in <code>main()</code>.

main.cpp
 QObject::connect(app.keyHandler(), SIGNAL(decreaseKeyPressed()), &app, SLOT(decreaseKeyPressed()));
 QObject::connect(app.keyHandler(), SIGNAL(increaseKeyPressed()), &app, SLOT(increaseKeyPressed()));

Finally, gtk-x11 library and the new source and header files (hardkeyhandler.* and myapplication.*) are added to the Qt project file:

collidingmice-gravity.pro:
 LIBS += -ldevornot-qt-maemo -L/usr/local/lib -lgtk-x11-2.0
 
 HEADERS += \
     mouse.h \
     hardkeyhandler.h \
     myapplication.h \
     scenetuner.h
 SOURCES += \
     main.cpp \
     hardkeyhandler.cpp \
     myapplication.cpp \
     mouse.cpp

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Editing Documentation/Maemo 5 Developer Guide/Development Environment/Maemo Programming Environments/Using Maemo 5 specific APIs in Qt application

@@ Line 5: / Line 5: @@
 === Introduction ===
-This section explains how to use the [[N900 accelerometer|accelerometer]] D-Bus interface in a Maemo 5 Qt application.
+This section explains how to use the [[Accelerometers | accelerometer]] D-Bus interface in a Maemo 5 Qt application.
 The following code examples are used in this section:
-* [https://vcs.maemo.org/svn/maemoexamples/tags/maemo_5.0/qt-maemo-gravity-example/ qt-maemo-gravity-example]
+* [https://garage.maemo.org/svn/maemoexamples/trunk/qt-maemo-gravity-example/ qt-maemo-gravity-example]
 === D-Bus interface ===
-It is up to each application how to organize interactions with the [http://maemo.org/api_refs/5.0/beta/mce-dev/ MCE] orientation interface. In [[Documentation/Maemo 5 Developer Guide/Porting Software/Porting Existing GTK+ Application to Maemo 5#Portrait Mode|some cases]] catching orientation signal can be enough, but if more frequent updates are needed, for example, you might want to use method calls, as demonstrated in our example.
+It is up to each application how to organize interactions with the [http://maemo.org/api_refs/5.0/beta/mce-dev/ MCE] orientation interface. In [[Documentation/Maemo 5 Developer Guide/Porting Software/Porting Existing GTK+ Application to Maemo 5#Portrait Mode | some cases]] catching orientation signal can be enough, but if, e.g., more frequent updates are needed, you might want to use method calls, as demonstrated in our example.
-We've moved D-Bus related functionality and orientation based calculations to a separate library that implements <code>DeviceOrientationNotifier</code> class.
+We've moved D-Bus related functionality and orientation based calculations to a separate library that implements `DeviceOrientationNotifier' class.
 Our notifier asks MCE about orientation parameters with a certain period,
-<source lang="cpp-qt">
+ void DeviceOrientationNotifier::timerEvent(QTimerEvent *)
-void DeviceOrientationNotifier::timerEvent(QTimerEvent *)
+ {
-{
+   QDBusMessage msg = QDBusMessage::createMethodCall(MCE_SERVICE, MCE_REQUEST_PATH, MCE_REQUEST_IF, MCE_DEVICE_ORIENTATION_GET);
-  QDBusMessage msg = QDBusMessage::createMethodCall(MCE_SERVICE, MCE_REQUEST_PATH, MCE_REQUEST_IF, MCE_DEVICE_ORIENTATION_GET);
+   bool sent = QDBusConnection::systemBus().callWithCallback(msg, this, SLOT(mceOrientationSlot(QString, QString, QString, int, int, int)));
-  bool sent = QDBusConnection::systemBus().callWithCallback(msg, this, SLOT(mceOrientationSlot(QString, QString, QString, int, int, int)));
+ }
-}
+processes answers in `mceOrientationSlot', and emits data needed by the application with the following signal.
-</source>
+ void deviceOrientation(qreal pitch, qreal roll);
-processes answers in `mceOrientationSlot', and emits data needed by the application with the following signal:
-<source lang="cpp-qt">
-void deviceOrientation(qreal pitch, qreal roll);
-</source>
 === Example application ===
@@ Line 31: / Line 27: @@
 We've modified [http://qt.nokia.com/doc/4.5/graphicsview-collidingmice.html one of Qt4 Examples] in order to show how device orientation can be used.
 In our case pitch and roll are scene's characteristics, so we've implemented a `SceneTuner', whose slot can be connected to an appropriate signal in order to setup these scene properties.
-<source lang="cpp-qt">
+ DeviceOrientationNotifier notifier(100);
-DeviceOrientationNotifier notifier(100);
+ SceneTuner tuner(&scene, TimerInterval);
-SceneTuner tuner(&scene, TimerInterval);
+ QObject::connect(&notifier, SIGNAL(deviceOrientation(qreal, qreal)), &tuner, SLOT(setProps(qreal, qreal)));
-QObject::connect(&notifier, SIGNAL(deviceOrientation(qreal, qreal)), &tuner, SLOT(setProps(qreal, qreal)));
-</source>
 Based on that each mouse can take into account the gravity effect, see `Mouse::advance' for details.
@@ Line 45: / Line 39: @@
 hardkeyhandler.cpp:
-<source lang="cpp-qt">
+ void HardkeyHandler::grabIncreaseDecreaseKeys(QWidget* window, bool grab)
-void HardkeyHandler::grabIncreaseDecreaseKeys(QWidget* window, bool grab)
+ {
-{
+     // Tell maemo-status-volume to grab/ungrab increase/decrease keys
-    // Tell maemo-status-volume to grab/ungrab increase/decrease keys
+     unsigned long val = (grab==true)?1:0;
-    unsigned long val = (grab==true)?1:0;
+     Atom atom;
-    Atom atom;
+     atom = XInternAtom( QX11Info::display(), "_HILDON_ZOOM_KEY_ATOM", 0);
-    atom = XInternAtom( QX11Info::display(), "_HILDON_ZOOM_KEY_ATOM", 0);
+     XChangeProperty (QX11Info::display(),
-    XChangeProperty (QX11Info::display(),
+                      window->winId(),
-                     window->winId(),
+                      atom,
-                     atom,
+                      XA_INTEGER,
-                     XA_INTEGER,
+,
-,
+                      PropModeReplace,
-                     PropModeReplace,
+                      (unsigned char *) &val,
-                     (unsigned char *) &val,
+);
-);
+ }
-}
-</source>
 Next, a handler for keypresses is created. 73 and 74 are the keycodes for F7/F8 in the SDK and Zoom In/Out buttons in the device. Handler functions emit corresponding signals when called.
-hardkeyhandler.cpp:
+hardkeyhandler.cpp
-<source lang="cpp-qt">
+ bool HardkeyHandler::processX11Event(XEvent* event)
-bool HardkeyHandler::processX11Event(XEvent* event)
+ {
-{
+     if ( event->type == KeyPress )
-    if ( event->type == KeyPress )
+     {
-    {
+         if (event->xkey.keycode == 73 || event->xkey.keycode == QKeySequence::ZoomOut)
-        if (event->xkey.keycode == 73 || event->xkey.keycode == QKeySequence::ZoomOut)
+         {
-        {
+             emit decreaseKeyPressed();
-            emit decreaseKeyPressed();
+             return true;
-            return true;
+         }
-        }
+         else if (event->xkey.keycode == 74  || event->xkey.keycode ==  QKeySequence::ZoomIn)
-        else if (event->xkey.keycode == 74  || event->xkey.keycode ==  QKeySequence::ZoomIn)
+         {
-        {
+             emit increaseKeyPressed();
-            emit increaseKeyPressed();
+             return true;
-            return true;
+         }
-        }
+     }
-    }
+     return false;
+ }
-    return false;
-}
-</source>
-Signals need slots, of course. They are located in <code>myapplication.h</code> and <code>myapplication.cpp</code> files. Here changing to fullscreen and back are done by <code>showFullScreen()</code> and <code>showNormal()</code>.
+Signals need slots, of course. They are located to myapplication.h and myapplication.cpp files. Here changing to fullscreen and back are done by <code>showFullScreen()</code> and <code>showNormal()</code>.
-myapplication.cpp:
+myapplication.cpp
-<source lang="cpp-qt">
+ void MyApplication::increaseKeyPressed()
-void MyApplication::increaseKeyPressed()
+ {
-{
+     qDebug("MyApplication::increaseKeyPressed");
-    qDebug("MyApplication::increaseKeyPressed");
+     view.showFullScreen();
-    view.showFullScreen();
+ }
+ void MyApplication::decreaseKeyPressed()
+ {
+     qDebug("MyApplication::decreaseKeyPressed");
+     view.showNormal();
+ }
-}
-void MyApplication::decreaseKeyPressed()
-{
-    qDebug("MyApplication::decreaseKeyPressed");
-    view.showNormal();
-}
-</source>
 The new signals are connected to corresponding slots in <code>main()</code>.
-main.cpp:
+main.cpp
-<source lang="cpp-qt">
+ QObject::connect(app.keyHandler(), SIGNAL(decreaseKeyPressed()), &app, SLOT(decreaseKeyPressed()));
-QObject::connect(app.keyHandler(), SIGNAL(decreaseKeyPressed()), &app, SLOT(decreaseKeyPressed()));
+ QObject::connect(app.keyHandler(), SIGNAL(increaseKeyPressed()), &app, SLOT(increaseKeyPressed()));
-QObject::connect(app.keyHandler(), SIGNAL(increaseKeyPressed()), &app, SLOT(increaseKeyPressed()));
-</source>
-Finally, <code>gtk-x11</code> library and the new source and header files (hardkeyhandler.* and myapplication.*) are added to the Qt project file:
+Finally, gtk-x11 library and the new source and header files (hardkeyhandler.* and myapplication.*) are added to the Qt project file:
 collidingmice-gravity.pro:
-<pre>
+ LIBS += -ldevornot-qt-maemo -L/usr/local/lib -lgtk-x11-2.0
-LIBS += -ldevornot-qt-maemo -L/usr/local/lib -lgtk-x11-2.0
+ HEADERS += \
-HEADERS += \
+     mouse.h \
-    mouse.h \
+     hardkeyhandler.h \
-    hardkeyhandler.h \
+     myapplication.h \
-    myapplication.h \
+     scenetuner.h
-    scenetuner.h
+ SOURCES += \
-SOURCES += \
+     main.cpp \
-    main.cpp \
+     hardkeyhandler.cpp \
-    hardkeyhandler.cpp \
+     myapplication.cpp \
-    myapplication.cpp \
+     mouse.cpp
-    mouse.cpp
-</pre>
-[[Category:Development]]
-[[Category:Documentation]]
-[[Category:Fremantle]]