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Revision as of 05:38, 14 June 2012 by hamishwillee (Talk | contribs)

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Archived:Utilising media keys in Symbian C++

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Archived.pngArchived: This article is archived because it is not considered relevant for third-party developers creating commercial solutions today. If you think this article is still relevant, let us know by adding the template {{ReviewForRemovalFromArchive|user=~~~~|write your reason here}}.

Article Metadata
Tested with
Devices(s): All (S60)
Compatibility
Platform(s): S60 3rd Edition
S60 3rd Edition, FP1
S60 3rd Edition, FP2
S60 3rd Edition (initial release)
Article
Keywords: CRemConInterfaceSelector, CRemConCoreApiTarget, MRemConCoreApiTargetObserver
Created: User:Technical writer 2 (October 5, 2006, updated December 5, 2008)
Last edited: hamishwillee (14 Jun 2012)

Description

Key presses of media keys cannot be detected in the same way as other key events. Media keys, such as Play/Pause, Stop, Volume Up/Down, Rewind, and Forward keys featured on some S60 3rd Edition devices do not generate normal key events that could be handled within the application framework, for example, in HandleKeyEventL() or OfferKeyEventL().

Solution

Events from media keys can be handled with the Remote Control API. Below is a code snippet that demonstrates this.

Remote Control API requires ReadUserData capability.

 #include <remconcoreapitargetobserver.h>    // link against RemConCoreApi.lib
#include <remconcoreapitarget.h> // and
#include <remconinterfaceselector.h> // RemConInterfaceBase.lib
 
class CMediaKeysTestUi : public CAknAppUi,
public MRemConCoreApiTargetObserver
{
...
// From MRemConCoreApiTargetObserver
 
void MrccatoCommand(TRemConCoreApiOperationId aOperationId,
TRemConCoreApiButtonAction aButtonAct);
// following functions from MRemConCoreApiTargetObserver are not needed
// in this case -> use empty implementations for these:
// MrccatoPlay
// MrccatoTuneFunction
// MrccatoSelectDiskFunction
// MrccatoSelectAvInputFunction
// MrccatoSelectAudioInputFunction
private:
CRemConInterfaceSelector* iInterfaceSelector;
CRemConCoreApiTarget* iCoreTarget;
};
 
void CMediaKeysTestUi::ConstructL()
{
...
iInterfaceSelector = CRemConInterfaceSelector::NewL();
iCoreTarget = CRemConCoreApiTarget::NewL(*iInterfaceSelector, *this);
iInterfaceSelector->OpenTargetL();
}
 
// ----------------------------------------------------------------------------
// MrccatoCommand()
// Receives events (press/click/release) from the following buttons:
// ’Play/Pause’, ’Volume Up’, ’Volume Down’, ’Stop’, ’Rewind’, ’Forward’
// ----------------------------------------------------------------------------
void CMediaKeysTestUi::MrccatoCommand(TRemConCoreApiOperationId aOperationId,
TRemConCoreApiButtonAction aButtonAct)
{
TRequestStatus status;
switch( aOperationId )
{
case ERemConCoreApiPausePlayFunction:
{
switch (aButtonAct)
{
case ERemConCoreApiButtonPress:
// Play/Pause button pressed
break;
case ERemConCoreApiButtonRelease:
// Play/Pause button released
break;
case ERemConCoreApiButtonClick:
// Play/Pause button clicked
break;
default:
// Play/Pause unknown action
break;
}
//Send the response back to Remcon server
iCoreTarget->PausePlayFunctionResponse(status, KErrNone);
User::WaitForRequest(status);
break;
}
 
case ERemConCoreApiStop:
{
switch (aButtonAct)
{
// see above (case ERemConCoreApiPausePlayFunction)
// for possible actions
}
iCoreTarget->StopResponse(status, KErrNone);
User::WaitForRequest(status);
break;
}
case ERemConCoreApiRewind:
{
switch (aButtonAct)
{
// see above for possible actions
}
iCoreTarget->RewindResponse(status, KErrNone);
User::WaitForRequest(status);
break;
}
case ERemConCoreApiForward:
{
switch (aButtonAct)
{
// see above for possible actions
}
iCoreTarget->ForwardResponse(status, KErrNone);
User::WaitForRequest(status);
break;
}
case ERemConCoreApiVolumeUp:
{
switch (aButtonAct)
{
// see above for possible actions
}
iCoreTarget->VolumeUpResponse(status, KErrNone);
User::WaitForRequest(status);
break;
}
case ERemConCoreApiVolumeDown:
{
switch (aButtonAct)
{
// see above for possible actions
}
iCoreTarget->VolumeDownResponse(status, KErrNone);
User::WaitForRequest(status);
break;
}
case ERemConCoreApiFastForward:
{
switch (aButtonAct)
{
// see above for possible actions
}
iCoreTarget->FastForwardResponse(status, KErrNone);
User::WaitForRequest(status);
break;
}
case ERemConCoreApiBackward:
{
switch (aButtonAct)
{
// see above for possible actions
}
iCoreTarget->BackwardResponse(status, KErrNone);
User::WaitForRequest(status);
break;
}
default:
break;
}
}

Notes:

On most devices only volume keys can be used in 3rd party applications using this API.

Volume keys on accessories (for example, Nokia headsets) use different event types compared to keys on the device. Clients should handle ERemConCoreApiButtonClick, ERemConCoreApiButtonPress, and ERemConCoreApiButtonRelease events.

When pressed and held, media keys do not automatically repeat the commands. If repeat functionality is required, it has to be implemented with (CPeriodic) timers.

This page was last modified on 14 June 2012, at 05:38.
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