Advanced Settings for Focus, Drive Modes, and Bracket Modes

Introduction

The advanced settings class, CCamera::CCameraAdvancedSettings , provides access to common camera hardware settings related to image acquisition for still images and video.

Focus mode

The high level steps to set the Camera focus mode are shown here:

• Get the information about the supported focus modes on the camera using the CCamera::CCameraAdvancedSettings::SupportedFocusModes() const method.

• Set a specific focus mode on the camera using the CCamera::CCameraAdvancedSettings::SetFocusMode(TFocusMode aFocusMode) method.

• Get the current focus mode on the camera using the CCamera::CCameraAdvancedSettings::FocusMode() method.

  The enumerated type CCamera::CCameraAdvancedSettings::TFocusMode defines four supported focus modes:

  Enum Value	Description
  EFocusModeUnknown	Focus mode is unknown
  EStabilizationComplexityLow	Focus mode is automatic
  EStabilizationComplexityMedium	Focus is fixed
  EStabilizationComplexityHigh	Focus is manually set

The following example shows how to change the focus mode:

       
        
       
       // Assigns the focus mode to be set    
    CCamera::CCameraAdvancedSettings::TFocusMode focusMode = CCamera::CCameraAdvancedSettings::EFocusModeFixed;
    
    // Gets the supported modes
    TInt suppFocusModes = settings->SupportedFocusModes();// Checks if the focus mode is supported before setting it
    if (focusMode & suppFocusModes)
        {
           // Sets the focus mode if it is supported
        settings->SetFocusMode(focusMode);
        }
      

Focus range

Get the supported focus range using the enumerated type CCamera::CCameraAdvancedSettings:TFocusRange . This defines eight supported focus ranges:

The following example shows how to change the focus range:

       
        
       
       // Assigns the focus range to EFocusRangeHyperfocal and checks if it is supported
    CCamera::CCameraAdvancedSettings::TFocusRange focusRange = CCamera::CCameraAdvancedSettings::EFocusRangeHyperfocal;
        
    // Gets the supported ranges            
    TInt suppRanges = settings->SupportedFocusRanges();
    
    // Checks if the focus range is supported before setting it.
    if (focusRange & suppRanges) 
        {
        // Sets the focus range if it is supported
        settings->SetFocusRange(focusRange);
        }
      

The result of SetFocusRange is notified to the client asynchronously through MCameraObserver2::HandleEvent() and with UID KUidECamEventCameraSettingFocusRange2 .

Autofocus

Autofocus support for camera applications is controlled through the CCameraAdvancedSettings class.

Pressing the camera shutter key on the device halfway down generates additional key events. The key events can be used to activate autofocus if the camera hardware supports the functionality. Shutter release (image capture) can be triggered by pressing the key all the way down. The key presses generate separate key events. To capture other than autofocus key events from the shutter key, you need the SwEvent capability .

The settings you can use in your application depend on the camera hardware on the device. The Camera API allows you to query almost all features of the device camera. For example, to get a list of supported advanced settings, use the CCameraAdvancedSettings::GetSupportedSettingsL(RArray<TUid>& aSettings) const method.

Get the supported autofocus types using the enumerated type CCamera::CCameraAdvancedSettings:TAutoFocusType . This defines three supported focus types:

The following example shows how to change the autofocus type:

       
        
       
       CCamera::CCameraAdvancedSettings::TAutoFocusType focusType = CCamera::CCameraAdvancedSettings::EAutoFocusTypeOff;
    
    // Gets the supported focus types
    TInt suppFocusTypes = settings->SupportedAutoFocusTypes();
    
    // Checks if the focus type is supported before setting it.
    if (focusType & suppFocusTypes)
        {
        // Sets the focus type if it is supported
        settings->SetAutoFocusType(focusType);
        }
      

The result of CCamera::CCameraAdvancedSettings::SetAutoFocusType(TAutoFocusType aAutoFocusType) is notified to the client asynchronously through MCameraObserver2::HandleEvent() and with uid KUidECamEventCameraSettingAutoFocusType2 .

For more information on how to easily use the device camera with zoom and autofocus, see S60 Platform: Camera Example . The Camera Wrapper provides a unified interface for various Symbian camera APIs. The example application supports the use of both the keypad and touch UI. The application can be self-signed, but it also provides an option to use the dedicated camera key (Symbian signing required).

Drive modes

Get the supported drive modes for the camera using the enumerated type CCamera::CCameraAdvancedSettings:TDriveMode that determines how and in what succession images are captured. This defines eight supported drive modes for the camera with the following Enum Values:

The following example shows how to change the drive mode:

       
        
       
       CCamera::CCameraAdvancedSettings::TDriveMode driveMode = CCamera::CCameraAdvancedSettings::EDriveModeSingleShot;
    
    // Gets the supported drive modes
    TInt suppDriveModes = settings->SupportedDriveModes();
    
    // Checks if the drive mode is supported before setting it.
    if (driveMode & suppDriveModes) 
        {
        // Sets the drive mode
        settings->(driveMode);
        }
      

The result of CCamera::CCameraAdvancedSettings::SetDriveMode(TDriveMode aDriveMode) is notified to the client asynchronously through MCameraObserver2::HandleEvent() and with uid KUidECamEventCameraSettingDriveMode .

Bracket modes

Bracket mode is a type of drive mode, which is called using CCamera::CCameraAdvancedSettings::EDriveModeBracket .

Bracket mode involves the camera taking a sequence of pictures, while automatically varying a camera setting, such as exposure, over a range of values. The enumerated type CCamera::CCameraAdvancedSettings:TBracketMode defines three supported bracket modes for the camera. The setting that is varied is called the bracket parameter, and is represented by the CCamera::CCameraAdvancedSettings:TBracketParameter enumeration, while the scale of the change to the setting to make for each new picture is called the bracket step, and is represented by the CCamera::CCameraAdvancedSettings:TBracketStep enumeration. The possible bracket modes are:

The following example shows how to change the bracket mode:

       
        
       
       CCamera::CCameraAdvancedSettings::TBracketMode bracketMode = CCamera::CCameraAdvancedSettings::EBracketMode3Image;
    
    // Gets the supported bracket modes
    TInt suppBracketModes = settings->SupportedBracketModes();
    
    // Checks if the bracket mode is supported before setting it.
    if (bracketMode & suppBracketModes) 
        {
        settings->SetBracketMode(bracketMode);    
        }
      

Zoom Mode

The high level steps to perform various operations in zoom mode are listed below:

• Get the continuous zoom types supported by the camera using CCamera::CCameraAdvancedSettings::GetSupportedContinuousZoomTypeL(TUint& aSupportedContinuousZoomType) const method.

• Start continuous zoom using CCamera::CCameraAdvancedSettings::StartContinuousZoomL(CCamera::CCameraAdvancedSettings::TContinuousZoomParameters aContinuousZoomParameters)() method with specified continuous zoom type and the zoom direction.

• Notify the client about the extent of continuous zoom achieved using event KUidECamEvent2CameraSettingContinuousZoomPercentageCompletion . When continuous zoom reached its limit, notify the client using event KUidECamEventCameraSettingContinuousZoomReachedLimit .

• Stop continuous zoom using CCamera::CCameraAdvancedSettings::StopContinuousZoom() method.

Extending Pixel Aspect Ratio

You can use the pixel aspect ratio to provide settings for PAL, NTSC and NTSC4:3. For this, you need to extend the enumeration of enum CCamera::CCameraAdvancedSettings:TPixelAspectRatio as follows:

Use CCamera::CCameraAdvancedSettings::PixelAspectRatio() method to get the current pixel aspect ratio.

Use CCamera::CCameraAdvancedSettings::SetPixelAspectRatio(TPixelAspectRatio aPixelAspectRatio) method to set the pixel aspect ratio. Notify MCameraObserver2 clients with KUidECamEventPixelAspectRatio event.

Miscellaneous

This section details the miscellaneous APIs used in CCameraAdvancedSettings class.

• ISO rates : ISO indicates the sensitivity of the image sensor and is also a parameter that influences the exposure.

  • Get the set of camera supported ISO rates using the CCamera::CCameraAdvancedSettings::GetSupportedIsoRatesL(RArray<TInt>& aSupportedIsoRates) const method. The enum value CCamera::CCameraAdvancedSettings:TISORateType specifies the ISO type supported by the camera.

  • When camera device does not reveal the ISO supported rates, it has to be assumed that camera will work only on the permanently set value. If this value is not known, returns empty array and corresponding getter or setters for this feature should not be used in such a case.

  • Set the type of ISO rate and the exposure parameter or specific value using the CCamera::CCameraAdvancedSettings::SetISORateL(TISORateType aISORateType, TInt aParam) method.

  • Get the type of ISO rate, exposure parameter and the value set using the CCamera::CCameraAdvancedSettings::GetISORateL(TISORateType& aISORateType, TInt& aParam, TInt& aISORate) const method.

  • Get current ISO rate using CCamera::CCameraAdvancedSettings::IsoRate() const .

• Get current aperture value using CCamera::CCameraAdvancedSettings::Aperture() const . For example, the function returns 280 for the actual aperture of F2.8. If the value returned is negative, indicates the error case (system wide error code) and positive represents the current aperture value.

• Get the current shutter speed in microseconds using CCamera::CCameraAdvancedSettings::ShutterSpeed() const . If the value returned is negative, indicates the error case (system wide error code) and positive represents the current shutter speed.

• Get all supported metering modes on this camera using CCamera::CCameraAdvancedSettings::SupportedMeteringModes() const .

• Get all supported drive modes as bitfields of TDriveMode type using CCamera::CCameraAdvancedSettings::SupportedDriveModes() const .

• Get the currently set flash mode using CCamera::CCameraAdvancedSettings::FlashMode() .

See also

Overview for the advanced settings of Camera

The Advanced Camera Settings tutorials.

The S60 Platform: Camera Example .