Camera Key Event Disposal in Qt on Symbian

On Symbian the camera hardware key launches the native camera app. This article explains how to dispose of the camera key event so that the key can be used to take pictures using your own Qt app.

Note: This is an entry in the PureView Imaging Competition 2012Q2

Article Metadata

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Compatibility

Platform(s): Qt 4.6 and later

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Article

Keywords: Camera

Created: r60600 (08 May 2012)

Last edited: hamishwillee (11 Oct 2012)

Introduction

Mobile users often use the camera key when they capture image or video. So the developers must add key event disposal in their Qt application.

After Qt 4.7,there are 2 enumerations in the qnamespace.h: Qt::Key_Camera and Qt::Key_CameraFocus

The usual camera key event disposal way is

void Camera::keyPressEvent(QKeyEvent * event)
{
    if (event->isAutoRepeat())
        return;
 
    switch (event->key()) {
    #if QT_VERSION >= 0x040700
        case Qt::Key_CameraFocus:
 
             //focus operation
 
             event->accept();
             break;
        case Qt::Key_Camera:
 
             //capture operation
 
             event->accept();
             break;
    #endif
    default:
        QMainWindow::keyPressEvent(event);
    }
}
 
void Camera::keyReleaseEvent(QKeyEvent * event)
{
    if (event->isAutoRepeat())
        return;
 
    switch (event->key()) {
    #if QT_VERSION >= 0x040700
        case Qt::Key_CameraFocus:
 
             //Un-focus operation
 
             break;
#endif
    default:
        QMainWindow::keyReleaseEvent(event);
    }
}

Last, application had better add a listener to dispose Symbian camera key event for Symbian device like this:

#include "camerakeyevent_symbian.h"
 
...
#if defined (Q_OS_SYMBIAN)
 
   QApplication::setGraphicsSystem("raster");
 
   QApplication app(argc, argv);    // lock orientation before constructing camera
 
   CAknAppUi* appUi = dynamic_cast<CAknAppUi*>(CEikonEnv::Static()->AppUi());
 
   if(appUi){QT_TRAP_THROWING(appUi ->SetOrientationL(CAknAppUi::EAppUiOrientationLandscape));}
  ...
 
   new QSymbianCameraKeyListener(&camera);
 
#endif